Ticket #44269: general-template.php

<?php
/**
 * General template tags that can go anywhere in a template.
 *
 * @package WordPress
 * @subpackage Template
 */

/**
 * Load header template.
 *
 * Includes the header template for a theme or if a name is specified then a
 * specialised header will be included.
 *
 * For the parameter, if the file is called "header-special.php" then specify
 * "special".
 *
 * @since 1.5.0
 *
 * @param string $name The name of the specialised header.
 */
function get_header( $name = null ) {
        /**
         * Fires before the header template file is loaded.
         *
         * @since 2.1.0
         * @since 2.8.0 $name parameter added.
         *
         * @param string|null $name Name of the specific header file to use. null for the default header.
         */
        do_action( 'get_header', $name );

        $templates = array();
        $name = (string) $name;
        if ( '' !== $name ) {
                $templates[] = "header-{$name}.php";
        }

        $templates[] = 'header.php';

        locate_template( $templates, true );
}

/**
 * Load footer template.
 *
 * Includes the footer template for a theme or if a name is specified then a
 * specialised footer will be included.
 *
 * For the parameter, if the file is called "footer-special.php" then specify
 * "special".
 *
 * @since 1.5.0
 *
 * @param string $name The name of the specialised footer.
 */
function get_footer( $name = null ) {
        /**
         * Fires before the footer template file is loaded.
         *
         * @since 2.1.0
         * @since 2.8.0 $name parameter added.
         *
         * @param string|null $name Name of the specific footer file to use. null for the default footer.
         */
        do_action( 'get_footer', $name );

        $templates = array();
        $name = (string) $name;
        if ( '' !== $name ) {
                $templates[] = "footer-{$name}.php";
        }

        $templates[]    = 'footer.php';

        locate_template( $templates, true );
}

/**
 * Load sidebar template.
 *
 * Includes the sidebar template for a theme or if a name is specified then a
 * specialised sidebar will be included.
 *
 * For the parameter, if the file is called "sidebar-special.php" then specify
 * "special".
 *
 * @since 1.5.0
 *
 * @param string $name The name of the specialised sidebar.
 */
function get_sidebar( $name = null ) {
        /**
         * Fires before the sidebar template file is loaded.
         *
         * @since 2.2.0
         * @since 2.8.0 $name parameter added.
         *
         * @param string|null $name Name of the specific sidebar file to use. null for the default sidebar.
         */
        do_action( 'get_sidebar', $name );

        $templates = array();
        $name = (string) $name;
        if ( '' !== $name )
                $templates[] = "sidebar-{$name}.php";

        $templates[] = 'sidebar.php';

        locate_template( $templates, true );
}

/**
 * Loads a template part into a template.
 *
 * Provides a simple mechanism for child themes to overload reusable sections of code
 * in the theme.
 *
 * Includes the named template part for a theme or if a name is specified then a
 * specialised part will be included. If the theme contains no {slug}.php file
 * then no template will be included.
 *
 * The template is included using require, not require_once, so you may include the
 * same template part multiple times.
 *
 * For the $name parameter, if the file is called "{slug}-special.php" then specify
 * "special".
 *
 * @since 3.0.0
 *
 * @param string $slug The slug name for the generic template.
 * @param string $name The name of the specialised template.
 */
function get_template_part( $slug, $name = null ) {
        /**
         * Fires before the specified template part file is loaded.
         *
         * The dynamic portion of the hook name, `$slug`, refers to the slug name
         * for the generic template part.
         *
         * @since 3.0.0
         *
         * @param string      $slug The slug name for the generic template.
         * @param string|null $name The name of the specialized template.
         */
        do_action( "get_template_part_{$slug}", $slug, $name );

        $templates = array();
        $name = (string) $name;
        if ( '' !== $name )
                $templates[] = "{$slug}-{$name}.php";

        $templates[] = "{$slug}.php";

        locate_template($templates, true, false);
}

/**
 * Display search form.
 *
 * Will first attempt to locate the searchform.php file in either the child or
 * the parent, then load it. If it doesn't exist, then the default search form
 * will be displayed. The default search form is HTML, which will be displayed.
 * There is a filter applied to the search form HTML in order to edit or replace
 * it. The filter is {@see 'get_search_form'}.
 *
 * This function is primarily used by themes which want to hardcode the search
 * form into the sidebar and also by the search widget in WordPress.
 *
 * There is also an action that is called whenever the function is run called,
 * {@see 'pre_get_search_form'}. This can be useful for outputting JavaScript that the
 * search relies on or various formatting that applies to the beginning of the
 * search. To give a few examples of what it can be used for.
 *
 * @since 2.7.0
 *
 * @param bool $echo Default to echo and not return the form.
 * @return string|void String when $echo is false.
 */
function get_search_form( $echo = true ) {
        /**
         * Fires before the search form is retrieved, at the start of get_search_form().
         *
         * @since 2.7.0 as 'get_search_form' action.
         * @since 3.6.0
         *
         * @link https://core.trac.wordpress.org/ticket/19321
         */
        do_action( 'pre_get_search_form' );

        $format = current_theme_supports( 'html5', 'search-form' ) ? 'html5' : 'xhtml';

        /**
         * Filters the HTML format of the search form.
         *
         * @since 3.6.0
         *
         * @param string $format The type of markup to use in the search form.
         *                       Accepts 'html5', 'xhtml'.
         */
        $format = apply_filters( 'search_form_format', $format );

        $search_form_template = locate_template( 'searchform.php' );
        if ( '' != $search_form_template ) {
                ob_start();
                require( $search_form_template );
                $form = ob_get_clean();
        } else {
                if ( 'html5' == $format ) {
                        $form = '<form role="search" method="get" class="search-form" action="' . esc_url( home_url( '/' ) ) . '">
                                <label>
                                        <span class="screen-reader-text">' . _x( 'Search for:', 'label' ) . '</span>
                                        <input type="search" class="search-field" placeholder="' . esc_attr_x( 'Search &hellip;', 'placeholder' ) . '" value="' . get_search_query() . '" name="s" />
                                </label>
                                <input type="submit" class="search-submit" value="'. esc_attr_x( 'Search', 'submit button' ) .'" />
                        </form>';
                } else {
                        $form = '<form role="search" method="get" id="searchform" class="searchform" action="' . esc_url( home_url( '/' ) ) . '">
                                <div>
                                        <label class="screen-reader-text" for="s">' . _x( 'Search for:', 'label' ) . '</label>
                                        <input type="text" value="' . get_search_query() . '" name="s" id="s" />
                                        <input type="submit" id="searchsubmit" value="'. esc_attr_x( 'Search', 'submit button' ) .'" />
                                </div>
                        </form>';
                }
        }

        /**
         * Filters the HTML output of the search form.
         *
         * @since 2.7.0
         *
         * @param string $form The search form HTML output.
         */
        $result = apply_filters( 'get_search_form', $form );

        if ( null === $result )
                $result = $form;

        if ( $echo )
                echo $result;
        else
                return $result;
}

/**
 * Display the Log In/Out link.
 *
 * Displays a link, which allows users to navigate to the Log In page to log in
 * or log out depending on whether they are currently logged in.
 *
 * @since 1.5.0
 *
 * @param string $redirect Optional path to redirect to on login/logout.
 * @param bool   $echo     Default to echo and not return the link.
 * @return string|void String when retrieving.
 */
function wp_loginout($redirect = '', $echo = true) {
        if ( ! is_user_logged_in() )
                $link = '<a href="' . esc_url( wp_login_url($redirect) ) . '">' . __('Log in') . '</a>';
        else
                $link = '<a href="' . esc_url( wp_logout_url($redirect) ) . '">' . __('Log out') . '</a>';

        if ( $echo ) {
                /**
                 * Filters the HTML output for the Log In/Log Out link.
                 *
                 * @since 1.5.0
                 *
                 * @param string $link The HTML link content.
                 */
                echo apply_filters( 'loginout', $link );
        } else {
                /** This filter is documented in wp-includes/general-template.php */
                return apply_filters( 'loginout', $link );
        }
}

/**
 * Retrieves the logout URL.
 *
 * Returns the URL that allows the user to log out of the site.
 *
 * @since 2.7.0
 *
 * @param string $redirect Path to redirect to on logout.
 * @return string The logout URL. Note: HTML-encoded via esc_html() in wp_nonce_url().
 */
function wp_logout_url($redirect = '') {
        $args = array( 'action' => 'logout' );
        if ( !empty($redirect) ) {
                $args['redirect_to'] = urlencode( $redirect );
        }

        $logout_url = add_query_arg($args, site_url('wp-login.php', 'login'));
        $logout_url = wp_nonce_url( $logout_url, 'log-out' );

        /**
         * Filters the logout URL.
         *
         * @since 2.8.0
         *
         * @param string $logout_url The HTML-encoded logout URL.
         * @param string $redirect   Path to redirect to on logout.
         */
        return apply_filters( 'logout_url', $logout_url, $redirect );
}

/**
 * Retrieves the login URL.
 *
 * @since 2.7.0
 *
 * @param string $redirect     Path to redirect to on log in.
 * @param bool   $force_reauth Whether to force reauthorization, even if a cookie is present.
 *                             Default false.
 * @return string The login URL. Not HTML-encoded.
 */
function wp_login_url($redirect = '', $force_reauth = false) {
        $login_url = site_url('wp-login.php', 'login');

        if ( !empty($redirect) )
                $login_url = add_query_arg('redirect_to', urlencode($redirect), $login_url);

        if ( $force_reauth )
                $login_url = add_query_arg('reauth', '1', $login_url);

        /**
         * Filters the login URL.
         *
         * @since 2.8.0
         * @since 4.2.0 The `$force_reauth` parameter was added.
         *
         * @param string $login_url    The login URL. Not HTML-encoded.
         * @param string $redirect     The path to redirect to on login, if supplied.
         * @param bool   $force_reauth Whether to force reauthorization, even if a cookie is present.
         */
        return apply_filters( 'login_url', $login_url, $redirect, $force_reauth );
}

/**
 * Returns the URL that allows the user to register on the site.
 *
 * @since 3.6.0
 *
 * @return string User registration URL.
 */
function wp_registration_url() {
        /**
         * Filters the user registration URL.
         *
         * @since 3.6.0
         *
         * @param string $register The user registration URL.
         */
        return apply_filters( 'register_url', site_url( 'wp-login.php?action=register', 'login' ) );
}

/**
 * Provides a simple login form for use anywhere within WordPress.
 *
 * The login format HTML is echoed by default. Pass a false value for `$echo` to return it instead.
 *
 * @since 3.0.0
 *
 * @param array $args {
 *     Optional. Array of options to control the form output. Default empty array.
 *
 *     @type bool   $echo           Whether to display the login form or return the form HTML code.
 *                                  Default true (echo).
 *     @type string $redirect       URL to redirect to. Must be absolute, as in "https://example.com/mypage/".
 *                                  Default is to redirect back to the request URI.
 *     @type string $form_id        ID attribute value for the form. Default 'loginform'.
 *     @type string $label_username Label for the username or email address field. Default 'Username or Email Address'.
 *     @type string $label_password Label for the password field. Default 'Password'.
 *     @type string $label_remember Label for the remember field. Default 'Remember Me'.
 *     @type string $label_log_in   Label for the submit button. Default 'Log In'.
 *     @type string $id_username    ID attribute value for the username field. Default 'user_login'.
 *     @type string $id_password    ID attribute value for the password field. Default 'user_pass'.
 *     @type string $id_remember    ID attribute value for the remember field. Default 'rememberme'.
 *     @type string $id_submit      ID attribute value for the submit button. Default 'wp-submit'.
 *     @type bool   $remember       Whether to display the "rememberme" checkbox in the form.
 *     @type string $value_username Default value for the username field. Default empty.
 *     @type bool   $value_remember Whether the "Remember Me" checkbox should be checked by default.
 *                                  Default false (unchecked).
 *
 * }
 * @return string|void String when retrieving.
 */
function wp_login_form( $args = array() ) {
        $defaults = array(
                'echo' => true,
                // Default 'redirect' value takes the user back to the request URI.
                'redirect' => ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'],
                'form_id' => 'loginform',
                'label_username' => __( 'Username or Email Address' ),
                'label_password' => __( 'Password' ),
                'label_remember' => __( 'Remember Me' ),
                'label_log_in' => __( 'Log In' ),
                'id_username' => 'user_login',
                'id_password' => 'user_pass',
                'id_remember' => 'rememberme',
                'id_submit' => 'wp-submit',
                'remember' => true,
                'value_username' => '',
                // Set 'value_remember' to true to default the "Remember me" checkbox to checked.
                'value_remember' => false,
        );

        /**
         * Filters the default login form output arguments.
         *
         * @since 3.0.0
         *
         * @see wp_login_form()
         *
         * @param array $defaults An array of default login form arguments.
         */
        $args = wp_parse_args( $args, apply_filters( 'login_form_defaults', $defaults ) );

        /**
         * Filters content to display at the top of the login form.
         *
         * The filter evaluates just following the opening form tag element.
         *
         * @since 3.0.0
         *
         * @param string $content Content to display. Default empty.
         * @param array  $args    Array of login form arguments.
         */
        $login_form_top = apply_filters( 'login_form_top', '', $args );

        /**
         * Filters content to display in the middle of the login form.
         *
         * The filter evaluates just following the location where the 'login-password'
         * field is displayed.
         *
         * @since 3.0.0
         *
         * @param string $content Content to display. Default empty.
         * @param array  $args    Array of login form arguments.
         */
        $login_form_middle = apply_filters( 'login_form_middle', '', $args );

        /**
         * Filters content to display at the bottom of the login form.
         *
         * The filter evaluates just preceding the closing form tag element.
         *
         * @since 3.0.0
         *
         * @param string $content Content to display. Default empty.
         * @param array  $args    Array of login form arguments.
         */
        $login_form_bottom = apply_filters( 'login_form_bottom', '', $args );

        $form = '
                <form name="' . $args['form_id'] . '" id="' . $args['form_id'] . '" action="' . esc_url( site_url( 'wp-login.php', 'login_post' ) ) . '" method="post">
                        ' . $login_form_top . '
                        <p class="login-username">
                                <label for="' . esc_attr( $args['id_username'] ) . '">' . esc_html( $args['label_username'] ) . '</label>
                                <input type="text" name="log" id="' . esc_attr( $args['id_username'] ) . '" class="input" value="' . esc_attr( $args['value_username'] ) . '" size="20" />
                        </p>
                        <p class="login-password">
                                <label for="' . esc_attr( $args['id_password'] ) . '">' . esc_html( $args['label_password'] ) . '</label>
                                <input type="password" name="pwd" id="' . esc_attr( $args['id_password'] ) . '" class="input" value="" size="20" />
                        </p>
                        ' . $login_form_middle . '
                        ' . ( $args['remember'] ? '<p class="login-remember"><label><input name="rememberme" type="checkbox" id="' . esc_attr( $args['id_remember'] ) . '" value="forever"' . ( $args['value_remember'] ? ' checked="checked"' : '' ) . ' /> ' . esc_html( $args['label_remember'] ) . '</label></p>' : '' ) . '
                        <p class="login-submit">
                                <input type="submit" name="wp-submit" id="' . esc_attr( $args['id_submit'] ) . '" class="button button-primary" value="' . esc_attr( $args['label_log_in'] ) . '" />
                                <input type="hidden" name="redirect_to" value="' . esc_url( $args['redirect'] ) . '" />
                        </p>
                        ' . $login_form_bottom . '
                </form>';

        if ( $args['echo'] )
                echo $form;
        else
                return $form;
}

/**
 * Returns the URL that allows the user to retrieve the lost password
 *
 * @since 2.8.0
 *
 * @param string $redirect Path to redirect to on login.
 * @return string Lost password URL.
 */
function wp_lostpassword_url( $redirect = '' ) {
        $args = array( 'action' => 'lostpassword' );
        if ( !empty($redirect) ) {
                $args['redirect_to'] = urlencode( $redirect );
        }

        $lostpassword_url = add_query_arg( $args, network_site_url('wp-login.php', 'login') );

        /**
         * Filters the Lost Password URL.
         *
         * @since 2.8.0
         *
         * @param string $lostpassword_url The lost password page URL.
         * @param string $redirect         The path to redirect to on login.
         */
        return apply_filters( 'lostpassword_url', $lostpassword_url, $redirect );
}

/**
 * Display the Registration or Admin link.
 *
 * Display a link which allows the user to navigate to the registration page if
 * not logged in and registration is enabled or to the dashboard if logged in.
 *
 * @since 1.5.0
 *
 * @param string $before Text to output before the link. Default `<li>`.
 * @param string $after  Text to output after the link. Default `</li>`.
 * @param bool   $echo   Default to echo and not return the link.
 * @return string|void String when retrieving.
 */
function wp_register( $before = '<li>', $after = '</li>', $echo = true ) {
        if ( ! is_user_logged_in() ) {
                if ( get_option('users_can_register') )
                        $link = $before . '<a href="' . esc_url( wp_registration_url() ) . '">' . __('Register') . '</a>' . $after;
                else
                        $link = '';
        } elseif ( current_user_can( 'read' ) ) {
                $link = $before . '<a href="' . admin_url() . '">' . __('Site Admin') . '</a>' . $after;
        } else {
                $link = '';
        }

        /**
         * Filters the HTML link to the Registration or Admin page.
         *
         * Users are sent to the admin page if logged-in, or the registration page
         * if enabled and logged-out.
         *
         * @since 1.5.0
         *
         * @param string $link The HTML code for the link to the Registration or Admin page.
         */
        $link = apply_filters( 'register', $link );

        if ( $echo ) {
                echo $link;
        } else {
                return $link;
        }
}

/**
 * Theme container function for the 'wp_meta' action.
 *
 * The {@see 'wp_meta'} action can have several purposes, depending on how you use it,
 * but one purpose might have been to allow for theme switching.
 *
 * @since 1.5.0
 *
 * @link https://core.trac.wordpress.org/ticket/1458 Explanation of 'wp_meta' action.
 */
function wp_meta() {
        /**
         * Fires before displaying echoed content in the sidebar.
         *
         * @since 1.5.0
         */
        do_action( 'wp_meta' );
}

/**
 * Displays information about the current site.
 *
 * @since 0.71
 *
 * @see get_bloginfo() For possible `$show` values
 *
 * @param string $show Optional. Site information to display. Default empty.
 */
function bloginfo( $show = '' ) {
        echo get_bloginfo( $show, 'display' );
}

/**
 * Retrieves information about the current site.
 *
 * Possible values for `$show` include:
 *
 * - 'name' - Site title (set in Settings > General)
 * - 'description' - Site tagline (set in Settings > General)
 * - 'wpurl' - The WordPress address (URL) (set in Settings > General)
 * - 'url' - The Site address (URL) (set in Settings > General)
 * - 'admin_email' - Admin email (set in Settings > General)
 * - 'charset' - The "Encoding for pages and feeds"  (set in Settings > Reading)
 * - 'version' - The current WordPress version
 * - 'html_type' - The content-type (default: "text/html"). Themes and plugins
 *   can override the default value using the {@see 'pre_option_html_type'} filter
 * - 'text_direction' - The text direction determined by the site's language. is_rtl()
 *   should be used instead
 * - 'language' - Language code for the current site
 * - 'stylesheet_url' - URL to the stylesheet for the active theme. An active child theme
 *   will take precedence over this value
 * - 'stylesheet_directory' - Directory path for the active theme.  An active child theme
 *   will take precedence over this value
 * - 'template_url' / 'template_directory' - URL of the active theme's directory. An active
 *   child theme will NOT take precedence over this value
 * - 'pingback_url' - The pingback XML-RPC file URL (xmlrpc.php)
 * - 'atom_url' - The Atom feed URL (/feed/atom)
 * - 'rdf_url' - The RDF/RSS 1.0 feed URL (/feed/rfd)
 * - 'rss_url' - The RSS 0.92 feed URL (/feed/rss)
 * - 'rss2_url' - The RSS 2.0 feed URL (/feed)
 * - 'comments_atom_url' - The comments Atom feed URL (/comments/feed)
 * - 'comments_rss2_url' - The comments RSS 2.0 feed URL (/comments/feed)
 *
 * Some `$show` values are deprecated and will be removed in future versions.
 * These options will trigger the _deprecated_argument() function.
 *
 * Deprecated arguments include:
 *
 * - 'siteurl' - Use 'url' instead
 * - 'home' - Use 'url' instead
 *
 * @since 0.71
 *
 * @global string $wp_version
 *
 * @param string $show   Optional. Site info to retrieve. Default empty (site name).
 * @param string $filter Optional. How to filter what is retrieved. Default 'raw'.
 * @return string Mostly string values, might be empty.
 */
function get_bloginfo( $show = '', $filter = 'raw' ) {
        switch( $show ) {
                case 'home' : // DEPRECATED
                case 'siteurl' : // DEPRECATED
                        _deprecated_argument( __FUNCTION__, '2.2.0', sprintf(
                                /* translators: 1: 'siteurl'/'home' argument, 2: bloginfo() function name, 3: 'url' argument */
                                __( 'The %1$s option is deprecated for the family of %2$s functions. Use the %3$s option instead.' ),
                                '<code>' . $show . '</code>',
                                '<code>bloginfo()</code>',
                                '<code>url</code>'
                        ) );
                case 'url' :
                        $output = home_url();
                        break;
                case 'wpurl' :
                        $output = site_url();
                        break;
                case 'description':
                        $output = get_option('blogdescription');
                        break;
                case 'rdf_url':
                        $output = get_feed_link('rdf');
                        break;
                case 'rss_url':
                        $output = get_feed_link('rss');
                        break;
                case 'rss2_url':
                        $output = get_feed_link('rss2');
                        break;
                case 'atom_url':
                        $output = get_feed_link('atom');
                        break;
                case 'comments_atom_url':
                        $output = get_feed_link('comments_atom');
                        break;
                case 'comments_rss2_url':
                        $output = get_feed_link('comments_rss2');
                        break;
                case 'pingback_url':
                        $output = site_url( 'xmlrpc.php' );
                        break;
                case 'stylesheet_url':
                        $output = get_stylesheet_uri();
                        break;
                case 'stylesheet_directory':
                        $output = get_stylesheet_directory_uri();
                        break;
                case 'template_directory':
                case 'template_url':
                        $output = get_template_directory_uri();
                        break;
                case 'admin_email':
                        $output = get_option('admin_email');
                        break;
                case 'charset':
                        $output = get_option('blog_charset');
                        if ('' == $output) $output = 'UTF-8';
                        break;
                case 'html_type' :
                        $output = get_option('html_type');
                        break;
                case 'version':
                        global $wp_version;
                        $output = $wp_version;
                        break;
                case 'language':
                        /* translators: Translate this to the correct language tag for your locale,
                         * see https://www.w3.org/International/articles/language-tags/ for reference.
                         * Do not translate into your own language.
                         */
                        $output = __( 'html_lang_attribute' );
                        if ( 'html_lang_attribute' === $output || preg_match( '/[^a-zA-Z0-9-]/', $output ) ) {
                                $output = is_admin() ? get_user_locale() : get_locale();
                                $output = str_replace( '_', '-', $output );
                        }
                        break;
                case 'text_direction':
                        _deprecated_argument( __FUNCTION__, '2.2.0', sprintf(
                                /* translators: 1: 'text_direction' argument, 2: bloginfo() function name, 3: is_rtl() function name */
                                __( 'The %1$s option is deprecated for the family of %2$s functions. Use the %3$s function instead.' ),
                                '<code>' . $show . '</code>',
                                '<code>bloginfo()</code>',
                                '<code>is_rtl()</code>'
                        ) );
                        if ( function_exists( 'is_rtl' ) ) {
                                $output = is_rtl() ? 'rtl' : 'ltr';
                        } else {
                                $output = 'ltr';
                        }
                        break;
                case 'name':
                default:
                        $output = get_option('blogname');
                        break;
        }

        $url = true;
        if (strpos($show, 'url') === false &&
                strpos($show, 'directory') === false &&
                strpos($show, 'home') === false)
                $url = false;

        if ( 'display' == $filter ) {
                if ( $url ) {
                        /**
                         * Filters the URL returned by get_bloginfo().
                         *
                         * @since 2.0.5
                         *
                         * @param mixed $output The URL returned by bloginfo().
                         * @param mixed $show   Type of information requested.
                         */
                        $output = apply_filters( 'bloginfo_url', $output, $show );
                } else {
                        /**
                         * Filters the site information returned by get_bloginfo().
                         *
                         * @since 0.71
                         *
                         * @param mixed $output The requested non-URL site information.
                         * @param mixed $show   Type of information requested.
                         */
                        $output = apply_filters( 'bloginfo', $output, $show );
                }
        }

        return $output;
}

/**
 * Returns the Site Icon URL.
 *
 * @since 4.3.0
 *
 * @param int    $size    Optional. Size of the site icon. Default 512 (pixels).
 * @param string $url     Optional. Fallback url if no site icon is found. Default empty.
 * @param int    $blog_id Optional. ID of the blog to get the site icon for. Default current blog.
 * @return string Site Icon URL.
 */
function get_site_icon_url( $size = 512, $url = '', $blog_id = 0 ) {
        $switched_blog = false;

        if ( is_multisite() && ! empty( $blog_id ) && (int) $blog_id !== get_current_blog_id() ) {
                switch_to_blog( $blog_id );
                $switched_blog = true;
        }

        $site_icon_id = get_option( 'site_icon' );

        if ( $site_icon_id ) {
                if ( $size >= 512 ) {
                        $size_data = 'full';
                } else {
                        $size_data = array( $size, $size );
                }
                $url = wp_get_attachment_image_url( $site_icon_id, $size_data );
        }

        if ( $switched_blog ) {
                restore_current_blog();
        }

        /**
         * Filters the site icon URL.
         *
         * @since 4.4.0
         *
         * @param string $url     Site icon URL.
         * @param int    $size    Size of the site icon.
         * @param int    $blog_id ID of the blog to get the site icon for.
         */
        return apply_filters( 'get_site_icon_url', $url, $size, $blog_id );
}

/**
 * Displays the Site Icon URL.
 *
 * @since 4.3.0
 *
 * @param int    $size    Optional. Size of the site icon. Default 512 (pixels).
 * @param string $url     Optional. Fallback url if no site icon is found. Default empty.
 * @param int    $blog_id Optional. ID of the blog to get the site icon for. Default current blog.
 */
function site_icon_url( $size = 512, $url = '', $blog_id = 0 ) {
        echo esc_url( get_site_icon_url( $size, $url, $blog_id ) );
}

/**
 * Whether the site has a Site Icon.
 *
 * @since 4.3.0
 *
 * @param int $blog_id Optional. ID of the blog in question. Default current blog.
 * @return bool Whether the site has a site icon or not.
 */
function has_site_icon( $blog_id = 0 ) {
        return (bool) get_site_icon_url( 512, '', $blog_id );
}

/**
 * Determines whether the site has a custom logo.
 *
 * @since 4.5.0
 *
 * @param int $blog_id Optional. ID of the blog in question. Default is the ID of the current blog.
 * @return bool Whether the site has a custom logo or not.
 */
function has_custom_logo( $blog_id = 0 ) {
        $switched_blog = false;

        if ( is_multisite() && ! empty( $blog_id ) && (int) $blog_id !== get_current_blog_id() ) {
                switch_to_blog( $blog_id );
                $switched_blog = true;
        }

        $custom_logo_id = get_theme_mod( 'custom_logo' );

        if ( $switched_blog ) {
                restore_current_blog();
        }

        return (bool) $custom_logo_id;
}

/**
 * Returns a custom logo, linked to home.
 *
 * @since 4.5.0
 *
 * @param int $blog_id Optional. ID of the blog in question. Default is the ID of the current blog.
 * @return string Custom logo markup.
 */
function get_custom_logo( $blog_id = 0 ) {
        $html = '';
        $switched_blog = false;

        if ( is_multisite() && ! empty( $blog_id ) && (int) $blog_id !== get_current_blog_id() ) {
                switch_to_blog( $blog_id );
                $switched_blog = true;
        }

        $custom_logo_id = get_theme_mod( 'custom_logo' );

        // We have a logo. Logo is go.
        if ( $custom_logo_id ) {
                $custom_logo_attr = array(
                        'class'    => 'custom-logo',
                        'itemprop' => 'logo',
                );

                /*
                 * If the logo alt attribute is empty, get the site title and explicitly
                 * pass it to the attributes used by wp_get_attachment_image().
                 */
                $image_alt = get_post_meta( $custom_logo_id, '_wp_attachment_image_alt', true );
                if ( empty( $image_alt ) ) {
                        $custom_logo_attr['alt'] = get_bloginfo( 'name', 'display' );
                }

                /*
                 * If the alt attribute is not empty, there's no need to explicitly pass
                 * it because wp_get_attachment_image() already adds the alt attribute.
                 */
                $html = sprintf( '<a href="%1$s" class="custom-logo-link" rel="home" itemprop="url">%2$s</a>',
                        esc_url( home_url( '/' ) ),
                        wp_get_attachment_image( $custom_logo_id, 'full', false, $custom_logo_attr )
                );
        }

        // If no logo is set but we're in the Customizer, leave a placeholder (needed for the live preview).
        elseif ( is_customize_preview() ) {
                $html = sprintf( '<a href="%1$s" class="custom-logo-link" style="display:none;"><img class="custom-logo"/></a>',
                        esc_url( home_url( '/' ) )
                );
        }

        if ( $switched_blog ) {
                restore_current_blog();
        }

        /**
         * Filters the custom logo output.
         *
         * @since 4.5.0
         * @since 4.6.0 Added the `$blog_id` parameter.
         *
         * @param string $html    Custom logo HTML output.
         * @param int    $blog_id ID of the blog to get the custom logo for.
         */
        return apply_filters( 'get_custom_logo', $html, $blog_id );
}

/**
 * Displays a custom logo, linked to home.
 *
 * @since 4.5.0
 *
 * @param int $blog_id Optional. ID of the blog in question. Default is the ID of the current blog.
 */
function the_custom_logo( $blog_id = 0 ) {
        echo get_custom_logo( $blog_id );
}

/**
 * Returns document title for the current page.
 *
 * @since 4.4.0
 *
 * @global int $page  Page number of a single post.
 * @global int $paged Page number of a list of posts.
 *
 * @return string Tag with the document title.
 */
function wp_get_document_title() {

        /**
         * Filters the document title before it is generated.
         *
         * Passing a non-empty value will short-circuit wp_get_document_title(),
         * returning that value instead.
         *
         * @since 4.4.0
         *
         * @param string $title The document title. Default empty string.
         */
        $title = apply_filters( 'pre_get_document_title', '' );
        if ( ! empty( $title ) ) {
                return $title;
        }

        global $page, $paged;

        $title = array(
                'title' => '',
        );

        // If it's a 404 page, use a "Page not found" title.
        if ( is_404() ) {
                $title['title'] = __( 'Page not found' );

        // If it's a search, use a dynamic search results title.
        } elseif ( is_search() ) {
                /* translators: %s: search phrase */
                $title['title'] = sprintf( __( 'Search Results for &#8220;%s&#8221;' ), get_search_query() );

        // If on the front page, use the site title.
        } elseif ( is_front_page() ) {
                $title['title'] = get_bloginfo( 'name', 'display' );

        // If on a post type archive, use the post type archive title.
        } elseif ( is_post_type_archive() ) {
                $title['title'] = post_type_archive_title( '', false );

        // If on a taxonomy archive, use the term title.
        } elseif ( is_tax() ) {
                $title['title'] = single_term_title( '', false );

        /*
         * If we're on the blog page that is not the homepage or
         * a single post of any post type, use the post title.
         */
        } elseif ( is_home() || is_singular() ) {
                $title['title'] = single_post_title( '', false );

        // If on a category or tag archive, use the term title.
        } elseif ( is_category() || is_tag() ) {
                $title['title'] = single_term_title( '', false );

        // If on an author archive, use the author's display name.
        } elseif ( is_author() && $author = get_queried_object() ) {
                $title['title'] = $author->display_name;

        // If it's a date archive, use the date as the title.
        } elseif ( is_year() ) {
                $title['title'] = get_the_date( _x( 'Y', 'yearly archives date format' ) );

        } elseif ( is_month() ) {
                $title['title'] = get_the_date( _x( 'F Y', 'monthly archives date format' ) );

        } elseif ( is_day() ) {
                $title['title'] = get_the_date();
        }

        // Add a page number if necessary.
        if ( ( $paged >= 2 || $page >= 2 ) && ! is_404() ) {
                $title['page'] = sprintf( __( 'Page %s' ), max( $paged, $page ) );
        }

        // Append the description or site title to give context.
        if ( is_front_page() ) {
                $title['tagline'] = get_bloginfo( 'description', 'display' );
        } else {
                $title['site'] = get_bloginfo( 'name', 'display' );
        }

        /**
         * Filters the separator for the document title.
         *
         * @since 4.4.0
         *
         * @param string $sep Document title separator. Default '-'.
         */
        $sep = apply_filters( 'document_title_separator', '-' );

        /**
         * Filters the parts of the document title.
         *
         * @since 4.4.0
         *
         * @param array $title {
         *     The document title parts.
         *
         *     @type string $title   Title of the viewed page.
         *     @type string $page    Optional. Page number if paginated.
         *     @type string $tagline Optional. Site description when on home page.
         *     @type string $site    Optional. Site title when not on home page.
         * }
         */
        $title = apply_filters( 'document_title_parts', $title );

        $title = implode( " $sep ", array_filter( $title ) );
        $title = wptexturize( $title );
        $title = convert_chars( $title );
        $title = esc_html( $title );
        $title = capital_P_dangit( $title );

        return $title;
}

/**
 * Displays title tag with content.
 *
 * @ignore
 * @since 4.1.0
 * @since 4.4.0 Improved title output replaced `wp_title()`.
 * @access private
 */
function _wp_render_title_tag() {
        if ( ! current_theme_supports( 'title-tag' ) ) {
                return;
        }

        echo '<title>' . wp_get_document_title() . '</title>' . "\n";
}

/**
 * Display or retrieve page title for all areas of blog.
 *
 * By default, the page title will display the separator before the page title,
 * so that the blog title will be before the page title. This is not good for
 * title display, since the blog title shows up on most tabs and not what is
 * important, which is the page that the user is looking at.
 *
 * There are also SEO benefits to having the blog title after or to the 'right'
 * of the page title. However, it is mostly common sense to have the blog title
 * to the right with most browsers supporting tabs. You can achieve this by
 * using the seplocation parameter and setting the value to 'right'. This change
 * was introduced around 2.5.0, in case backward compatibility of themes is
 * important.
 *
 * @since 1.0.0
 *
 * @global WP_Locale $wp_locale
 *
 * @param string $sep         Optional, default is '&raquo;'. How to separate the various items
 *                            within the page title.
 * @param bool   $display     Optional, default is true. Whether to display or retrieve title.
 * @param string $seplocation Optional. Direction to display title, 'right'.
 * @return string|null String on retrieve, null when displaying.
 */
function wp_title( $sep = '&raquo;', $display = true, $seplocation = '' ) {
        global $wp_locale;

        $m        = get_query_var( 'm' );
        $year     = get_query_var( 'year' );
        $monthnum = get_query_var( 'monthnum' );
        $day      = get_query_var( 'day' );
        $search   = get_query_var( 's' );
        $title    = '';

        $t_sep = '%WP_TITLE_SEP%'; // Temporary separator, for accurate flipping, if necessary

        // If there is a post
        if ( is_single() || ( is_home() && ! is_front_page() ) || ( is_page() && ! is_front_page() ) ) {
                $title = single_post_title( '', false );
        }

        // If there's a post type archive
        if ( is_post_type_archive() ) {
                $post_type = get_query_var( 'post_type' );
                if ( is_array( $post_type ) ) {
                        $post_type = reset( $post_type );
                }
                $post_type_object = get_post_type_object( $post_type );
                if ( ! $post_type_object->has_archive ) {
                        $title = post_type_archive_title( '', false );
                }
        }

        // If there's a category or tag
        if ( is_category() || is_tag() ) {
                $title = single_term_title( '', false );
        }

        // If there's a taxonomy
        if ( is_tax() ) {
                $term = get_queried_object();
                if ( $term ) {
                        $tax   = get_taxonomy( $term->taxonomy );
                        $title = single_term_title( $tax->labels->name . $t_sep, false );
                }
        }

        // If there's an author
        if ( is_author() && ! is_post_type_archive() ) {
                $author = get_queried_object();
                if ( $author ) {
                        $title = $author->display_name;
                }
        }

        // Post type archives with has_archive should override terms.
        if ( is_post_type_archive() && $post_type_object->has_archive ) {
                $title = post_type_archive_title( '', false );
        }

        // If there's a month
        if ( is_archive() && ! empty( $m ) ) {
                $my_year  = substr( $m, 0, 4 );
                $my_month = $wp_locale->get_month( substr( $m, 4, 2 ) );
                $my_day   = intval( substr( $m, 6, 2 ) );
                $title    = $my_year . ( $my_month ? $t_sep . $my_month : '' ) . ( $my_day ? $t_sep . $my_day : '' );
        }

        // If there's a year
        if ( is_archive() && ! empty( $year ) ) {
                $title = $year;
                if ( ! empty( $monthnum ) ) {
                        $title .= $t_sep . $wp_locale->get_month( $monthnum );
                }
                if ( ! empty( $day ) ) {
                        $title .= $t_sep . zeroise( $day, 2 );
                }
        }

        // If it's a search
        if ( is_search() ) {
                /* translators: 1: separator, 2: search phrase */
                $title = sprintf( __( 'Search Results %1$s %2$s' ), $t_sep, strip_tags( $search ) );
        }

        // If it's a 404 page
        if ( is_404() ) {
                $title = __( 'Page not found' );
        }

        $prefix = '';
        if ( ! empty( $title ) ) {
                $prefix = " $sep ";
        }

        /**
         * Filters the parts of the page title.
         *
         * @since 4.0.0
         *
         * @param array $title_array Parts of the page title.
         */
        $title_array = apply_filters( 'wp_title_parts', explode( $t_sep, $title ) );

        // Determines position of the separator and direction of the breadcrumb
        if ( 'right' == $seplocation ) { // sep on right, so reverse the order
                $title_array = array_reverse( $title_array );
                $title       = implode( " $sep ", $title_array ) . $prefix;
        } else {
                $title = $prefix . implode( " $sep ", $title_array );
        }

        /**
         * Filters the text of the page title.
         *
         * @since 2.0.0
         *
         * @param string $title Page title.
         * @param string $sep Title separator.
         * @param string $seplocation Location of the separator (left or right).
         */
        $title = apply_filters( 'wp_title', $title, $sep, $seplocation );

        // Send it out
        if ( $display ) {
                echo $title;
        } else {
                return $title;
        }
}

/**
 * Display or retrieve page title for post.
 *
 * This is optimized for single.php template file for displaying the post title.
 *
 * It does not support placing the separator after the title, but by leaving the
 * prefix parameter empty, you can set the title separator manually. The prefix
 * does not automatically place a space between the prefix, so if there should
 * be a space, the parameter value will need to have it at the end.
 *
 * @since 0.71
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving.
 */
function single_post_title( $prefix = '', $display = true ) {
        $_post = get_queried_object();

        if ( !isset($_post->post_title) )
                return;

        /**
         * Filters the page title for a single post.
         *
         * @since 0.71
         *
         * @param string $_post_title The single post page title.
         * @param object $_post       The current queried object as returned by get_queried_object().
         */
        $title = apply_filters( 'single_post_title', $_post->post_title, $_post );
        if ( $display )
                echo $prefix . $title;
        else
                return $prefix . $title;
}

/**
 * Display or retrieve title for a post type archive.
 *
 * This is optimized for archive.php and archive-{$post_type}.php template files
 * for displaying the title of the post type.
 *
 * @since 3.1.0
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving, null when displaying or failure.
 */
function post_type_archive_title( $prefix = '', $display = true ) {
        if ( ! is_post_type_archive() )
                return;

        $post_type = get_query_var( 'post_type' );
        if ( is_array( $post_type ) )
                $post_type = reset( $post_type );

        $post_type_obj = get_post_type_object( $post_type );

        /**
         * Filters the post type archive title.
         *
         * @since 3.1.0
         *
         * @param string $post_type_name Post type 'name' label.
         * @param string $post_type      Post type.
         */
        $title = apply_filters( 'post_type_archive_title', $post_type_obj->labels->name, $post_type );

        if ( $display )
                echo $prefix . $title;
        else
                return $prefix . $title;
}

/**
 * Display or retrieve page title for category archive.
 *
 * Useful for category template files for displaying the category page title.
 * The prefix does not automatically place a space between the prefix, so if
 * there should be a space, the parameter value will need to have it at the end.
 *
 * @since 0.71
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving.
 */
function single_cat_title( $prefix = '', $display = true ) {
        return single_term_title( $prefix, $display );
}

/**
 * Display or retrieve page title for tag post archive.
 *
 * Useful for tag template files for displaying the tag page title. The prefix
 * does not automatically place a space between the prefix, so if there should
 * be a space, the parameter value will need to have it at the end.
 *
 * @since 2.3.0
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving.
 */
function single_tag_title( $prefix = '', $display = true ) {
        return single_term_title( $prefix, $display );
}

/**
 * Display or retrieve page title for taxonomy term archive.
 *
 * Useful for taxonomy term template files for displaying the taxonomy term page title.
 * The prefix does not automatically place a space between the prefix, so if there should
 * be a space, the parameter value will need to have it at the end.
 *
 * @since 3.1.0
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving.
 */
function single_term_title( $prefix = '', $display = true ) {
        $term = get_queried_object();

        if ( !$term )
                return;

        if ( is_category() ) {
                /**
                 * Filters the category archive page title.
                 *
                 * @since 2.0.10
                 *
                 * @param string $term_name Category name for archive being displayed.
                 */
                $term_name = apply_filters( 'single_cat_title', $term->name );
        } elseif ( is_tag() ) {
                /**
                 * Filters the tag archive page title.
                 *
                 * @since 2.3.0
                 *
                 * @param string $term_name Tag name for archive being displayed.
                 */
                $term_name = apply_filters( 'single_tag_title', $term->name );
        } elseif ( is_tax() ) {
                /**
                 * Filters the custom taxonomy archive page title.
                 *
                 * @since 3.1.0
                 *
                 * @param string $term_name Term name for archive being displayed.
                 */
                $term_name = apply_filters( 'single_term_title', $term->name );
        } else {
                return;
        }

        if ( empty( $term_name ) )
                return;

        if ( $display )
                echo $prefix . $term_name;
        else
                return $prefix . $term_name;
}

/**
 * Display or retrieve page title for post archive based on date.
 *
 * Useful for when the template only needs to display the month and year,
 * if either are available. The prefix does not automatically place a space
 * between the prefix, so if there should be a space, the parameter value
 * will need to have it at the end.
 *
 * @since 0.71
 *
 * @global WP_Locale $wp_locale
 *
 * @param string $prefix  Optional. What to display before the title.
 * @param bool   $display Optional, default is true. Whether to display or retrieve title.
 * @return string|void Title when retrieving.
 */
function single_month_title($prefix = '', $display = true ) {
        global $wp_locale;

        $m = get_query_var('m');
        $year = get_query_var('year');
        $monthnum = get_query_var('monthnum');

        if ( !empty($monthnum) && !empty($year) ) {
                $my_year = $year;
                $my_month = $wp_locale->get_month($monthnum);
        } elseif ( !empty($m) ) {
                $my_year = substr($m, 0, 4);
                $my_month = $wp_locale->get_month(substr($m, 4, 2));
        }

        if ( empty($my_month) )
                return false;

        $result = $prefix . $my_month . $prefix . $my_year;

        if ( !$display )
                return $result;
        echo $result;
}

/**
 * Display the archive title based on the queried object.
 *
 * @since 4.1.0
 *
 * @see get_the_archive_title()
 *
 * @param string $before Optional. Content to prepend to the title. Default empty.
 * @param string $after  Optional. Content to append to the title. Default empty.
 */
function the_archive_title( $before = '', $after = '' ) {
        $title = get_the_archive_title();

        if ( ! empty( $title ) ) {
                echo $before . $title . $after;
        }
}

/**
 * Retrieve the archive title based on the queried object.
 *
 * @since 4.1.0
 *
 * @return string Archive title.
 */
function get_the_archive_title() {
        if ( is_category() ) {
                /* translators: Category archive title. 1: Category name */
                $title = sprintf( __( 'Category: %s' ), single_cat_title( '', false ) );
        } elseif ( is_tag() ) {
                /* translators: Tag archive title. 1: Tag name */
                $title = sprintf( __( 'Tag: %s' ), single_tag_title( '', false ) );
        } elseif ( is_author() ) {
                /* translators: Author archive title. 1: Author name */
                $title = sprintf( __( 'Author: %s' ), '<span class="vcard">' . get_the_author() . '</span>' );
        } elseif ( is_year() ) {
                /* translators: Yearly archive title. 1: Year */
                $title = sprintf( __( 'Year: %s' ), get_the_date( _x( 'Y', 'yearly archives date format' ) ) );
        } elseif ( is_month() ) {
                /* translators: Monthly archive title. 1: Month name and year */
                $title = sprintf( __( 'Month: %s' ), get_the_date( _x( 'F Y', 'monthly archives date format' ) ) );
        } elseif ( is_day() ) {
                /* translators: Daily archive title. 1: Date */
                $title = sprintf( __( 'Day: %s' ), get_the_date( _x( 'F j, Y', 'daily archives date format' ) ) );
        } elseif ( is_tax( 'post_format' ) ) {
                if ( is_tax( 'post_format', 'post-format-aside' ) ) {
                        $title = _x( 'Asides', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-gallery' ) ) {
                        $title = _x( 'Galleries', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-image' ) ) {
                        $title = _x( 'Images', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-video' ) ) {
                        $title = _x( 'Videos', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-quote' ) ) {
                        $title = _x( 'Quotes', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-link' ) ) {
                        $title = _x( 'Links', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-status' ) ) {
                        $title = _x( 'Statuses', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-audio' ) ) {
                        $title = _x( 'Audio', 'post format archive title' );
                } elseif ( is_tax( 'post_format', 'post-format-chat' ) ) {
                        $title = _x( 'Chats', 'post format archive title' );
                }
        } elseif ( is_post_type_archive() ) {
                /* translators: Post type archive title. 1: Post type name */
                $title = sprintf( __( 'Archives: %s' ), post_type_archive_title( '', false ) );
        } elseif ( is_tax() ) {
                $tax = get_taxonomy( get_queried_object()->taxonomy );
                /* translators: Taxonomy term archive title. 1: Taxonomy singular name, 2: Current taxonomy term */
                $title = sprintf( __( '%1$s: %2$s' ), $tax->labels->singular_name, single_term_title( '', false ) );
        } else {
                $title = __( 'Archives' );
        }

        /**
         * Filters the archive title.
         *
         * @since 4.1.0
         *
         * @param string $title Archive title to be displayed.
         */
        return apply_filters( 'get_the_archive_title', $title );
}

/**
 * Display category, tag, term, or author description.
 *
 * @since 4.1.0
 *
 * @see get_the_archive_description()
 *
 * @param string $before Optional. Content to prepend to the description. Default empty.
 * @param string $after  Optional. Content to append to the description. Default empty.
 */
function the_archive_description( $before = '', $after = '' ) {
        $description = get_the_archive_description();
        if ( $description ) {
                echo $before . $description . $after;
        }
}

/**
 * Retrieves the description for an author, post type, or term archive.
 *
 * @since 4.1.0
 * @since 4.7.0 Added support for author archives.
 * @since 4.9.0 Added support for post type archives.
 *
 * @see term_description()
 *
 * @return string Archive description.
 */
function get_the_archive_description() {
        if ( is_author() ) {
                $description = get_the_author_meta( 'description' );
        } elseif ( is_post_type_archive() ) {
                $description = get_the_post_type_description();
        } else {
                $description = term_description();
        }

        /**
         * Filters the archive description.
         *
         * @since 4.1.0
         *
         * @param string $description Archive description to be displayed.
         */
        return apply_filters( 'get_the_archive_description', $description );
}

/**
 * Retrieves the description for a post type archive.
 *
 * @since 4.9.0
 *
 * @return string The post type description.
 */
function get_the_post_type_description() {
        $post_type = get_query_var( 'post_type' );

        if ( is_array( $post_type ) ) {
                $post_type = reset( $post_type );
        }

        $post_type_obj = get_post_type_object( $post_type );

        // Check if a description is set.
        if ( isset( $post_type_obj->description ) ) {
                $description = $post_type_obj->description;
        } else {
                $description = '';
        }

        /**
         * Filters the description for a post type archive.
         *
         * @since 4.9.0
         *
         * @param string       $description   The post type description.
         * @param WP_Post_Type $post_type_obj The post type object.
         */
        return apply_filters( 'get_the_post_type_description', $description, $post_type_obj );
}

/**
 * Retrieve archive link content based on predefined or custom code.
 *
 * The format can be one of four styles. The 'link' for head element, 'option'
 * for use in the select element, 'html' for use in list (either ol or ul HTML
 * elements). Custom content is also supported using the before and after
 * parameters.
 *
 * The 'link' format uses the `<link>` HTML element with the **archives**
 * relationship. The before and after parameters are not used. The text
 * parameter is used to describe the link.
 *
 * The 'option' format uses the option HTML element for use in select element.
 * The value is the url parameter and the before and after parameters are used
 * between the text description.
 *
 * The 'html' format, which is the default, uses the li HTML element for use in
 * the list HTML elements. The before parameter is before the link and the after
 * parameter is after the closing link.
 *
 * The custom format uses the before parameter before the link ('a' HTML
 * element) and the after parameter after the closing link tag. If the above
 * three values for the format are not used, then custom format is assumed.
 *
 * @since 1.0.0
 *
 * @param string $url    URL to archive.
 * @param string $text   Archive text description.
 * @param string $format Optional, default is 'html'. Can be 'link', 'option', 'html', or custom.
 * @param string $before Optional. Content to prepend to the description. Default empty.
 * @param string $after  Optional. Content to append to the description. Default empty.
 * @return string HTML link content for archive.
 */
function get_archives_link($url, $text, $format = 'html', $before = '', $after = '') {
        $text = wptexturize($text);
        $url = esc_url($url);

        if ('link' == $format)
                $link_html = "\t<link rel='archives' title='" . esc_attr( $text ) . "' href='$url' />\n";
        elseif ('option' == $format)
                $link_html = "\t<option value='$url'>$before $text $after</option>\n";
        elseif ('html' == $format)
                $link_html = "\t<li>$before<a href='$url'>$text</a>$after</li>\n";
        else // custom
                $link_html = "\t$before<a href='$url'>$text</a>$after\n";

        /**
         * Filters the archive link content.
         *
         * @since 2.6.0
         * @since 4.5.0 Added the `$url`, `$text`, `$format`, `$before`, and `$after` parameters.
         *
         * @param string $link_html The archive HTML link content.
         * @param string $url       URL to archive.
         * @param string $text      Archive text description.
         * @param string $format    Link format. Can be 'link', 'option', 'html', or custom.
         * @param string $before    Content to prepend to the description.
         * @param string $after     Content to append to the description.
         */
        return apply_filters( 'get_archives_link', $link_html, $url, $text, $format, $before, $after );
}

/**
 * Display archive links based on type and format.
 *
 * @since 1.2.0
 * @since 4.4.0 $post_type arg was added.
 *
 * @see get_archives_link()
 *
 * @global wpdb      $wpdb
 * @global WP_Locale $wp_locale
 *
 * @param string|array $args {
 *     Default archive links arguments. Optional.
 *
 *     @type string     $type            Type of archive to retrieve. Accepts 'daily', 'weekly', 'monthly',
 *                                       'yearly', 'postbypost', or 'alpha'. Both 'postbypost' and 'alpha'
 *                                       display the same archive link list as well as post titles instead
 *                                       of displaying dates. The difference between the two is that 'alpha'
 *                                       will order by post title and 'postbypost' will order by post date.
 *                                       Default 'monthly'.
 *     @type string|int $limit           Number of links to limit the query to. Default empty (no limit).
 *     @type string     $format          Format each link should take using the $before and $after args.
 *                                       Accepts 'link' (`<link>` tag), 'option' (`<option>` tag), 'html'
 *                                       (`<li>` tag), or a custom format, which generates a link anchor
 *                                       with $before preceding and $after succeeding. Default 'html'.
 *     @type string     $before          Markup to prepend to the beginning of each link. Default empty.
 *     @type string     $after           Markup to append to the end of each link. Default empty.
 *     @type bool       $show_post_count Whether to display the post count alongside the link. Default false.
 *     @type bool|int   $echo            Whether to echo or return the links list. Default 1|true to echo.
 *     @type string     $order           Whether to use ascending or descending order. Accepts 'ASC', or 'DESC'.
 *                                       Default 'DESC'.
 *     @type string     $post_type       Post type. Default 'post'.
 * }
 * @return string|void String when retrieving.
 */
function wp_get_archives( $args = '' ) {
        global $wpdb, $wp_locale;

        $defaults = array(
                'type' => 'monthly', 'limit' => '',
                'format' => 'html', 'before' => '',
                'after' => '', 'show_post_count' => false,
                'echo' => 1, 'order' => 'DESC',
                'post_type' => 'post'
        );

        $r = wp_parse_args( $args, $defaults );

        $post_type_object = get_post_type_object( $r['post_type'] );
        if ( ! is_post_type_viewable( $post_type_object ) ) {
                return;
        }
        $r['post_type'] = $post_type_object->name;

        if ( '' == $r['type'] ) {
                $r['type'] = 'monthly';
        }

        if ( ! empty( $r['limit'] ) ) {
                $r['limit'] = absint( $r['limit'] );
                $r['limit'] = ' LIMIT ' . $r['limit'];
        }

        $order = strtoupper( $r['order'] );
        if ( $order !== 'ASC' ) {
                $order = 'DESC';
        }

        // this is what will separate dates on weekly archive links
        $archive_week_separator = '&#8211;';

        $sql_where = $wpdb->prepare( "WHERE post_type = %s AND post_status = 'publish'", $r['post_type'] );

        /**
         * Filters the SQL WHERE clause for retrieving archives.
         *
         * @since 2.2.0
         *
         * @param string $sql_where Portion of SQL query containing the WHERE clause.
         * @param array  $r         An array of default arguments.
         */
        $where = apply_filters( 'getarchives_where', $sql_where, $r );

        /**
         * Filters the SQL JOIN clause for retrieving archives.
         *
         * @since 2.2.0
         *
         * @param string $sql_join Portion of SQL query containing JOIN clause.
         * @param array  $r        An array of default arguments.
         */
        $join = apply_filters( 'getarchives_join', '', $r );

        $output = '';

        $last_changed = wp_cache_get_last_changed( 'posts' );

        $limit = $r['limit'];

        if ( 'monthly' == $r['type'] ) {
                $query = "SELECT YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date $order $limit";
                $key = md5( $query );
                $key = "wp_get_archives:$key:$last_changed";
                if ( ! $results = wp_cache_get( $key, 'posts' ) ) {
                        $results = $wpdb->get_results( $query );
                        wp_cache_set( $key, $results, 'posts' );
                }
                if ( $results ) {
                        $after = $r['after'];
                        foreach ( (array) $results as $result ) {
                                $url = get_month_link( $result->year, $result->month );
                                if ( 'post' !== $r['post_type'] ) {
                                        $url = add_query_arg( 'post_type', $r['post_type'], $url );
                                }
                                /* translators: 1: month name, 2: 4-digit year */
                                $text = sprintf( __( '%1$s %2$d' ), $wp_locale->get_month( $result->month ), $result->year );
                                if ( $r['show_post_count'] ) {
                                        $r['after'] = '&nbsp;(' . $result->posts . ')' . $after;
                                }
                                $output .= get_archives_link( $url, $text, $r['format'], $r['before'], $r['after'] );
                        }
                }
        } elseif ( 'yearly' == $r['type'] ) {
                $query = "SELECT YEAR(post_date) AS `year`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date) ORDER BY post_date $order $limit";
                $key = md5( $query );
                $key = "wp_get_archives:$key:$last_changed";
                if ( ! $results = wp_cache_get( $key, 'posts' ) ) {
                        $results = $wpdb->get_results( $query );
                        wp_cache_set( $key, $results, 'posts' );
                }
                if ( $results ) {
                        $after = $r['after'];
                        foreach ( (array) $results as $result) {
                                $url = get_year_link( $result->year );
                                if ( 'post' !== $r['post_type'] ) {
                                        $url = add_query_arg( 'post_type', $r['post_type'], $url );
                                }
                                $text = sprintf( '%d', $result->year );
                                if ( $r['show_post_count'] ) {
                                        $r['after'] = '&nbsp;(' . $result->posts . ')' . $after;
                                }
                                $output .= get_archives_link( $url, $text, $r['format'], $r['before'], $r['after'] );
                        }
                }
        } elseif ( 'daily' == $r['type'] ) {
                $query = "SELECT YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, DAYOFMONTH(post_date) AS `dayofmonth`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date), MONTH(post_date), DAYOFMONTH(post_date) ORDER BY post_date $order $limit";
                $key = md5( $query );
                $key = "wp_get_archives:$key:$last_changed";
                if ( ! $results = wp_cache_get( $key, 'posts' ) ) {
                        $results = $wpdb->get_results( $query );
                        wp_cache_set( $key, $results, 'posts' );
                }
                if ( $results ) {
                        $after = $r['after'];
                        foreach ( (array) $results as $result ) {
                                $url  = get_day_link( $result->year, $result->month, $result->dayofmonth );
                                if ( 'post' !== $r['post_type'] ) {
                                        $url = add_query_arg( 'post_type', $r['post_type'], $url );
                                }
                                $date = sprintf( '%1$d-%2$02d-%3$02d 00:00:00', $result->year, $result->month, $result->dayofmonth );
                                $text = mysql2date( get_option( 'date_format' ), $date );
                                if ( $r['show_post_count'] ) {
                                        $r['after'] = '&nbsp;(' . $result->posts . ')' . $after;
                                }
                                $output .= get_archives_link( $url, $text, $r['format'], $r['before'], $r['after'] );
                        }
                }
        } elseif ( 'weekly' == $r['type'] ) {
                $week = _wp_mysql_week( '`post_date`' );
                $query = "SELECT DISTINCT $week AS `week`, YEAR( `post_date` ) AS `yr`, DATE_FORMAT( `post_date`, '%Y-%m-%d' ) AS `yyyymmdd`, count( `ID` ) AS `posts` FROM `$wpdb->posts` $join $where GROUP BY $week, YEAR( `post_date` ) ORDER BY `post_date` $order $limit";
                $key = md5( $query );
                $key = "wp_get_archives:$key:$last_changed";
                if ( ! $results = wp_cache_get( $key, 'posts' ) ) {
                        $results = $wpdb->get_results( $query );
                        wp_cache_set( $key, $results, 'posts' );
                }
                $arc_w_last = '';
                if ( $results ) {
                        $after = $r['after'];
                        foreach ( (array) $results as $result ) {
                                if ( $result->week != $arc_w_last ) {
                                        $arc_year       = $result->yr;
                                        $arc_w_last     = $result->week;
                                        $arc_week       = get_weekstartend( $result->yyyymmdd, get_option( 'start_of_week' ) );
                                        $arc_week_start = date_i18n( get_option( 'date_format' ), $arc_week['start'] );
                                        $arc_week_end   = date_i18n( get_option( 'date_format' ), $arc_week['end'] );
                                        $url            = add_query_arg( array( 'm' => $arc_year, 'w' => $result->week, ), home_url( '/' ) );
                                        if ( 'post' !== $r['post_type'] ) {
                                                $url = add_query_arg( 'post_type', $r['post_type'], $url );
                                        }
                                        $text           = $arc_week_start . $archive_week_separator . $arc_week_end;
                                        if ( $r['show_post_count'] ) {
                                                $r['after'] = '&nbsp;(' . $result->posts . ')' . $after;
                                        }
                                        $output .= get_archives_link( $url, $text, $r['format'], $r['before'], $r['after'] );
                                }
                        }
                }
        } elseif ( ( 'postbypost' == $r['type'] ) || ('alpha' == $r['type'] ) ) {
                $orderby = ( 'alpha' == $r['type'] ) ? 'post_title ASC ' : 'post_date DESC, ID DESC ';
                $query = "SELECT * FROM $wpdb->posts $join $where ORDER BY $orderby $limit";
                $key = md5( $query );
                $key = "wp_get_archives:$key:$last_changed";
                if ( ! $results = wp_cache_get( $key, 'posts' ) ) {
                        $results = $wpdb->get_results( $query );
                        wp_cache_set( $key, $results, 'posts' );
                }
                if ( $results ) {
                        foreach ( (array) $results as $result ) {
                                if ( $result->post_date != '0000-00-00 00:00:00' ) {
                                        $url = get_permalink( $result );
                                        if ( $result->post_title ) {
                                                /** This filter is documented in wp-includes/post-template.php */
                                                $text = strip_tags( apply_filters( 'the_title', $result->post_title, $result->ID ) );
                                        } else {
                                                $text = $result->ID;
                                        }
                                        $output .= get_archives_link( $url, $text, $r['format'], $r['before'], $r['after'] );
                                }
                        }
                }
        }
        if ( $r['echo'] ) {
                echo $output;
        } else {
                return $output;
        }
}

/**
 * Get number of days since the start of the week.
 *
 * @since 1.5.0
 *
 * @param int $num Number of day.
 * @return float Days since the start of the week.
 */
function calendar_week_mod($num) {
        $base = 7;
        return ($num - $base*floor($num/$base));
}

/**
 * Display calendar with days that have posts as links.
 *
 * The calendar is cached, which will be retrieved, if it exists. If there are
 * no posts for the month, then it will not be displayed.
 *
 * @since 1.0.0
 *
 * @global wpdb      $wpdb
 * @global int       $m
 * @global int       $monthnum
 * @global int       $year
 * @global WP_Locale $wp_locale
 * @global array     $posts
 *
 * @param bool $initial Optional, default is true. Use initial calendar names.
 * @param bool $echo    Optional, default is true. Set to false for return.
 * @return string|void String when retrieving.
 */
function get_calendar( $initial = true, $echo = true ) {
        global $wpdb, $m, $monthnum, $year, $wp_locale, $posts;

        $key = md5( $m . $monthnum . $year );
        $cache = wp_cache_get( 'get_calendar', 'calendar' );

        if ( $cache && is_array( $cache ) && isset( $cache[ $key ] ) ) {
                /** This filter is documented in wp-includes/general-template.php */
                $output = apply_filters( 'get_calendar', $cache[ $key ] );

                if ( $echo ) {
                        echo $output;
                        return;
                }

                return $output;
        }

        if ( ! is_array( $cache ) ) {
                $cache = array();
        }

        // Quick check. If we have no posts at all, abort!
        if ( ! $posts ) {
                $gotsome = $wpdb->get_var("SELECT 1 as test FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' LIMIT 1");
                if ( ! $gotsome ) {
                        $cache[ $key ] = '';
                        wp_cache_set( 'get_calendar', $cache, 'calendar' );
                        return;
                }
        }

        if ( isset( $_GET['w'] ) ) {
                $w = (int) $_GET['w'];
        }
        // week_begins = 0 stands for Sunday
        $week_begins = (int) get_option( 'start_of_week' );
        $ts = current_time( 'timestamp' );

        // Let's figure out when we are
        if ( ! empty( $monthnum ) && ! empty( $year ) ) {
                $thismonth = zeroise( intval( $monthnum ), 2 );
                $thisyear = (int) $year;
        } elseif ( ! empty( $w ) ) {
                // We need to get the month from MySQL
                $thisyear = (int) substr( $m, 0, 4 );
                //it seems MySQL's weeks disagree with PHP's
                $d = ( ( $w - 1 ) * 7 ) + 6;
                $thismonth = $wpdb->get_var("SELECT DATE_FORMAT((DATE_ADD('{$thisyear}0101', INTERVAL $d DAY) ), '%m')");
        } elseif ( ! empty( $m ) ) {
                $thisyear = (int) substr( $m, 0, 4 );
                if ( strlen( $m ) < 6 ) {
                        $thismonth = '01';
                } else {
                        $thismonth = zeroise( (int) substr( $m, 4, 2 ), 2 );
                }
        } else {
                $thisyear = gmdate( 'Y', $ts );
                $thismonth = gmdate( 'm', $ts );
        }

        $unixmonth = mktime( 0, 0 , 0, $thismonth, 1, $thisyear );
        $last_day = date( 't', $unixmonth );

        // Get the next and previous month and year with at least one post
        $previous = $wpdb->get_row("SELECT MONTH(post_date) AS month, YEAR(post_date) AS year
                FROM $wpdb->posts
                WHERE post_date < '$thisyear-$thismonth-01'
                AND post_type = 'post' AND post_status = 'publish'
                        ORDER BY post_date DESC
                        LIMIT 1");
        $next = $wpdb->get_row("SELECT MONTH(post_date) AS month, YEAR(post_date) AS year
                FROM $wpdb->posts
                WHERE post_date > '$thisyear-$thismonth-{$last_day} 23:59:59'
                AND post_type = 'post' AND post_status = 'publish'
                        ORDER BY post_date ASC
                        LIMIT 1");

        /* translators: Calendar caption: 1: month name, 2: 4-digit year */
        $calendar_caption = _x('%1$s %2$s', 'calendar caption');
        $calendar_output = '<table id="wp-calendar">
        <caption>' . sprintf(
                $calendar_caption,
                $wp_locale->get_month( $thismonth ),
                date( 'Y', $unixmonth )
        ) . '</caption>
        <thead>
        <tr>';

        $myweek = array();

        for ( $wdcount = 0; $wdcount <= 6; $wdcount++ ) {
                $myweek[] = $wp_locale->get_weekday( ( $wdcount + $week_begins ) % 7 );
        }

        foreach ( $myweek as $wd ) {
                $day_name = $initial ? $wp_locale->get_weekday_initial( $wd ) : $wp_locale->get_weekday_abbrev( $wd );
                $wd = esc_attr( $wd );
                $calendar_output .= "\n\t\t<th scope=\"col\" title=\"$wd\">$day_name</th>";
        }

        $calendar_output .= '
        </tr>
        </thead>

        <tfoot>
        <tr>';

        if ( $previous ) {
                $calendar_output .= "\n\t\t".'<td colspan="3" id="prev"><a href="' . get_month_link( $previous->year, $previous->month ) . '">&laquo; ' .
                        $wp_locale->get_month_abbrev( $wp_locale->get_month( $previous->month ) ) .
                '</a></td>';
        } else {
                $calendar_output .= "\n\t\t".'<td colspan="3" id="prev" class="pad">&nbsp;</td>';
        }

        $calendar_output .= "\n\t\t".'<td class="pad">&nbsp;</td>';

        if ( $next ) {
                $calendar_output .= "\n\t\t".'<td colspan="3" id="next"><a href="' . get_month_link( $next->year, $next->month ) . '">' .
                        $wp_locale->get_month_abbrev( $wp_locale->get_month( $next->month ) ) .
                ' &raquo;</a></td>';
        } else {
                $calendar_output .= "\n\t\t".'<td colspan="3" id="next" class="pad">&nbsp;</td>';
        }

        $calendar_output .= '
        </tr>
        </tfoot>

        <tbody>
        <tr>';

        $daywithpost = array();

        // Get days with posts
        $dayswithposts = $wpdb->get_results("SELECT DISTINCT DAYOFMONTH(post_date)
                FROM $wpdb->posts WHERE post_date >= '{$thisyear}-{$thismonth}-01 00:00:00'
                AND post_type = 'post' AND post_status = 'publish'
                AND post_date <= '{$thisyear}-{$thismonth}-{$last_day} 23:59:59'", ARRAY_N);
        if ( $dayswithposts ) {
                foreach ( (array) $dayswithposts as $daywith ) {
                        $daywithpost[] = $daywith[0];
                }
        }

        // See how much we should pad in the beginning
        $pad = calendar_week_mod( date( 'w', $unixmonth ) - $week_begins );
        if ( 0 != $pad ) {
                $calendar_output .= "\n\t\t".'<td colspan="'. esc_attr( $pad ) .'" class="pad">&nbsp;</td>';
        }

        $newrow = false;
        $daysinmonth = (int) date( 't', $unixmonth );

        for ( $day = 1; $day <= $daysinmonth; ++$day ) {
                if ( isset($newrow) && $newrow ) {
                        $calendar_output .= "\n\t</tr>\n\t<tr>\n\t\t";
                }
                $newrow = false;

                if ( $day == gmdate( 'j', $ts ) &&
                        $thismonth == gmdate( 'm', $ts ) &&
                        $thisyear == gmdate( 'Y', $ts ) ) {
                        $calendar_output .= '<td id="today">';
                } else {
                        $calendar_output .= '<td>';
                }

                if ( in_array( $day, $daywithpost ) ) {
                        // any posts today?
                        $date_format = date( _x( 'F j, Y', 'daily archives date format' ), strtotime( "{$thisyear}-{$thismonth}-{$day}" ) );
                        /* translators: Post calendar label. 1: Date */
                        $label = sprintf( __( 'Posts published on %s' ), $date_format );
                        $calendar_output .= sprintf(
                                '<a href="%s" aria-label="%s">%s</a>',
                                get_day_link( $thisyear, $thismonth, $day ),
                                esc_attr( $label ),
                                $day
                        );
                } else {
                        $calendar_output .= $day;
                }
                $calendar_output .= '</td>';

                if ( 6 == calendar_week_mod( date( 'w', mktime(0, 0 , 0, $thismonth, $day, $thisyear ) ) - $week_begins ) ) {
                        $newrow = true;
                }
        }

        $pad = 7 - calendar_week_mod( date( 'w', mktime( 0, 0 , 0, $thismonth, $day, $thisyear ) ) - $week_begins );
        if ( $pad != 0 && $pad != 7 ) {
                $calendar_output .= "\n\t\t".'<td class="pad" colspan="'. esc_attr( $pad ) .'">&nbsp;</td>';
        }
        $calendar_output .= "\n\t</tr>\n\t</tbody>\n\t</table>";

        $cache[ $key ] = $calendar_output;
        wp_cache_set( 'get_calendar', $cache, 'calendar' );

        if ( $echo ) {
                /**
                 * Filters the HTML calendar output.
                 *
                 * @since 3.0.0
                 *
                 * @param string $calendar_output HTML output of the calendar.
                 */
                echo apply_filters( 'get_calendar', $calendar_output );
                return;
        }
        /** This filter is documented in wp-includes/general-template.php */
        return apply_filters( 'get_calendar', $calendar_output );
}

/**
 * Purge the cached results of get_calendar.
 *
 * @see get_calendar
 * @since 2.1.0
 */
function delete_get_calendar_cache() {
        wp_cache_delete( 'get_calendar', 'calendar' );
}

/**
 * Display all of the allowed tags in HTML format with attributes.
 *
 * This is useful for displaying in the comment area, which elements and
 * attributes are supported. As well as any plugins which want to display it.
 *
 * @since 1.0.1
 *
 * @global array $allowedtags
 *
 * @return string HTML allowed tags entity encoded.
 */
function allowed_tags() {
        global $allowedtags;
        $allowed = '';
        foreach ( (array) $allowedtags as $tag => $attributes ) {
                $allowed .= '<'.$tag;
                if ( 0 < count($attributes) ) {
                        foreach ( $attributes as $attribute => $limits ) {
                                $allowed .= ' '.$attribute.'=""';
                        }
                }
                $allowed .= '> ';
        }
        return htmlentities( $allowed );
}

/***** Date/Time tags *****/

/**
 * Outputs the date in iso8601 format for xml files.
 *
 * @since 1.0.0
 */
function the_date_xml() {
        echo mysql2date( 'Y-m-d', get_post()->post_date, false );
}

/**
 * Display or Retrieve the date the current post was written (once per date)
 *
 * Will only output the date if the current post's date is different from the
 * previous one output.
 *
 * i.e. Only one date listing will show per day worth of posts shown in the loop, even if the
 * function is called several times for each post.
 *
 * HTML output can be filtered with 'the_date'.
 * Date string output can be filtered with 'get_the_date'.
 *
 * @since 0.71
 *
 * @global string|int|bool $currentday
 * @global string|int|bool $previousday
 *
 * @param string $d      Optional. PHP date format defaults to the date_format option if not specified.
 * @param string $before Optional. Output before the date.
 * @param string $after  Optional. Output after the date.
 * @param bool   $echo   Optional, default is display. Whether to echo the date or return it.
 * @return string|void String if retrieving.
 */
function the_date( $d = '', $before = '', $after = '', $echo = true ) {
        global $currentday, $previousday;

        if ( is_new_day() ) {
                $the_date = $before . get_the_date( $d ) . $after;
                $previousday = $currentday;

                /**
                 * Filters the date a post was published for display.
                 *
                 * @since 0.71
                 *
                 * @param string $the_date The formatted date string.
                 * @param string $d        PHP date format. Defaults to 'date_format' option
                 *                         if not specified.
                 * @param string $before   HTML output before the date.
                 * @param string $after    HTML output after the date.
                 */
                $the_date = apply_filters( 'the_date', $the_date, $d, $before, $after );

                if ( $echo )
                        echo $the_date;
                else
                        return $the_date;
        }
}

/**
 * Retrieve the date on which the post was written.
 *
 * Unlike the_date() this function will always return the date.
 * Modify output with the {@see 'get_the_date'} filter.
 *
 * @since 3.0.0
 *
 * @param  string      $d    Optional. PHP date format defaults to the date_format option if not specified.
 * @param  int|WP_Post $post Optional. Post ID or WP_Post object. Default current post.
 * @return false|string Date the current post was written. False on failure.
 */
function get_the_date( $d = '', $post = null ) {
        $post = get_post( $post );

        if ( ! $post ) {
                return false;
        }

        if ( '' == $d ) {
                $the_date = mysql2date( get_option( 'date_format' ), $post->post_date );
        } else {
                $the_date = mysql2date( $d, $post->post_date );
        }

        /**
         * Filters the date a post was published.
         *
         * @since 3.0.0
         *
         * @param string      $the_date The formatted date.
         * @param string      $d        PHP date format. Defaults to 'date_format' option
         *                              if not specified.
         * @param int|WP_Post $post     The post object or ID.
         */
        return apply_filters( 'get_the_date', $the_date, $d, $post );
}

/**
 * Display the date on which the post was last modified.
 *
 * @since 2.1.0
 *
 * @param string $d      Optional. PHP date format defaults to the date_format option if not specified.
 * @param string $before Optional. Output before the date.
 * @param string $after  Optional. Output after the date.
 * @param bool   $echo   Optional, default is display. Whether to echo the date or return it.
 * @return string|void String if retrieving.
 */
function the_modified_date( $d = '', $before = '', $after = '', $echo = true ) {
        $the_modified_date = $before . get_the_modified_date($d) . $after;

        /**
         * Filters the date a post was last modified for display.
         *
         * @since 2.1.0
         *
         * @param string $the_modified_date The last modified date.
         * @param string $d                 PHP date format. Defaults to 'date_format' option
         *                                  if not specified.
         * @param string $before            HTML output before the date.
         * @param string $after             HTML output after the date.
         */
        $the_modified_date = apply_filters( 'the_modified_date', $the_modified_date, $d, $before, $after );

        if ( $echo )
                echo $the_modified_date;
        else
                return $the_modified_date;

}

/**
 * Retrieve the date on which the post was last modified.
 *
 * @since 2.1.0
 * @since 4.6.0 Added the `$post` parameter.
 *
 * @param string      $d    Optional. PHP date format defaults to the date_format option if not specified.
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default current post.
 * @return false|string Date the current post was modified. False on failure.
 */
function get_the_modified_date( $d = '', $post = null ) {
        $post = get_post( $post );

        if ( ! $post ) {
                // For backward compatibility, failures go through the filter below.
                $the_time = false;
        } elseif ( empty( $d ) ) {
                $the_time = get_post_modified_time( get_option( 'date_format' ), false, $post, true );
        } else {
                $the_time = get_post_modified_time( $d, false, $post, true );
        }

        /**
         * Filters the date a post was last modified.
         *
         * @since 2.1.0
         * @since 4.6.0 Added the `$post` parameter.
         *
         * @param string|bool  $the_time The formatted date or false if no post is found.
         * @param string       $d        PHP date format. Defaults to value specified in
         *                               'date_format' option.
         * @param WP_Post|null $post     WP_Post object or null if no post is found.
         */
        return apply_filters( 'get_the_modified_date', $the_time, $d, $post );
}

/**
 * Display the time at which the post was written.
 *
 * @since 0.71
 *
 * @param string $d Either 'G', 'U', or php date format.
 */
function the_time( $d = '' ) {
        /**
         * Filters the time a post was written for display.
         *
         * @since 0.71
         *
         * @param string $get_the_time The formatted time.
         * @param string $d            The time format. Accepts 'G', 'U',
         *                             or php date format.
         */
        echo apply_filters( 'the_time', get_the_time( $d ), $d );
}

/**
 * Retrieve the time at which the post was written.
 *
 * @since 1.5.0
 *
 * @param string      $d    Optional. Format to use for retrieving the time the post
 *                          was written. Either 'G', 'U', or php date format defaults
 *                          to the value specified in the time_format option. Default empty.
 * @param int|WP_Post $post WP_Post object or ID. Default is global $post object.
 * @return string|int|false Formatted date string or Unix timestamp if `$id` is 'U' or 'G'. False on failure.
 */
function get_the_time( $d = '', $post = null ) {
        $post = get_post($post);

        if ( ! $post ) {
                return false;
        }

        if ( '' == $d )
                $the_time = get_post_time(get_option('time_format'), false, $post, true);
        else
                $the_time = get_post_time($d, false, $post, true);

        /**
         * Filters the time a post was written.
         *
         * @since 1.5.0
         *
         * @param string      $the_time The formatted time.
         * @param string      $d        Format to use for retrieving the time the post was written.
         *                              Accepts 'G', 'U', or php date format value specified
         *                              in 'time_format' option. Default empty.
         * @param int|WP_Post $post     WP_Post object or ID.
         */
        return apply_filters( 'get_the_time', $the_time, $d, $post );
}

/**
 * Retrieve the time at which the post was written.
 *
 * @since 2.0.0
 *
 * @param string      $d         Optional. Format to use for retrieving the time the post
 *                               was written. Either 'G', 'U', or php date format. Default 'U'.
 * @param bool        $gmt       Optional. Whether to retrieve the GMT time. Default false.
 * @param int|WP_Post $post      WP_Post object or ID. Default is global $post object.
 * @param bool        $translate Whether to translate the time string. Default false.
 * @return string|int|false Formatted date string or Unix timestamp if `$id` is 'U' or 'G'. False on failure.
 */
function get_post_time( $d = 'U', $gmt = false, $post = null, $translate = false ) {
        $post = get_post($post);

        if ( ! $post ) {
                return false;
        }

        if ( $gmt )
                $time = $post->post_date_gmt;
        else
                $time = $post->post_date;

        $time = mysql2date($d, $time, $translate);

        /**
         * Filters the localized time a post was written.
         *
         * @since 2.6.0
         *
         * @param string $time The formatted time.
         * @param string $d    Format to use for retrieving the time the post was written.
         *                     Accepts 'G', 'U', or php date format. Default 'U'.
         * @param bool   $gmt  Whether to retrieve the GMT time. Default false.
         */
        return apply_filters( 'get_post_time', $time, $d, $gmt );
}

/**
 * Display the time at which the post was last modified.
 *
 * @since 2.0.0
 *
 * @param string $d Optional Either 'G', 'U', or php date format defaults to the value specified in the time_format option.
 */
function the_modified_time($d = '') {
        /**
         * Filters the localized time a post was last modified, for display.
         *
         * @since 2.0.0
         *
         * @param string $get_the_modified_time The formatted time.
         * @param string $d                     The time format. Accepts 'G', 'U',
         *                                      or php date format. Defaults to value
         *                                      specified in 'time_format' option.
         */
        echo apply_filters( 'the_modified_time', get_the_modified_time($d), $d );
}

/**
 * Retrieve the time at which the post was last modified.
 *
 * @since 2.0.0
 * @since 4.6.0 Added the `$post` parameter.
 *
 * @param string      $d     Optional. Format to use for retrieving the time the post
 *                           was modified. Either 'G', 'U', or php date format defaults
 *                           to the value specified in the time_format option. Default empty.
 * @param int|WP_Post $post  Optional. Post ID or WP_Post object. Default current post.
 * @return false|string Formatted date string or Unix timestamp. False on failure.
 */
function get_the_modified_time( $d = '', $post = null ) {
        $post = get_post( $post );

        if ( ! $post ) {
                // For backward compatibility, failures go through the filter below.
                $the_time = false;
        } elseif ( empty( $d ) ) {
                $the_time = get_post_modified_time( get_option( 'time_format' ), false, $post, true );
        } else {
                $the_time = get_post_modified_time( $d, false, $post, true );
        }

        /**
         * Filters the localized time a post was last modified.
         *
         * @since 2.0.0
         * @since 4.6.0 Added the `$post` parameter.
         *
         * @param string|bool  $the_time The formatted time or false if no post is found.
         * @param string       $d        Format to use for retrieving the time the post was
         *                               written. Accepts 'G', 'U', or php date format. Defaults
         *                               to value specified in 'time_format' option.
         * @param WP_Post|null $post     WP_Post object or null if no post is found.
         */
        return apply_filters( 'get_the_modified_time', $the_time, $d, $post );
}

/**
 * Retrieve the time at which the post was last modified.
 *
 * @since 2.0.0
 *
 * @param string      $d         Optional. Format to use for retrieving the time the post
 *                               was modified. Either 'G', 'U', or php date format. Default 'U'.
 * @param bool        $gmt       Optional. Whether to retrieve the GMT time. Default false.
 * @param int|WP_Post $post      WP_Post object or ID. Default is global $post object.
 * @param bool        $translate Whether to translate the time string. Default false.
 * @return string|int|false Formatted date string or Unix timestamp if `$id` is 'U' or 'G'. False on failure.
 */
function get_post_modified_time( $d = 'U', $gmt = false, $post = null, $translate = false ) {
        $post = get_post($post);

        if ( ! $post ) {
                return false;
        }

        if ( $gmt )
                $time = $post->post_modified_gmt;
        else
                $time = $post->post_modified;
        $time = mysql2date($d, $time, $translate);

        /**
         * Filters the localized time a post was last modified.
         *
         * @since 2.8.0
         *
         * @param string $time The formatted time.
         * @param string $d    The date format. Accepts 'G', 'U', or php date format. Default 'U'.
         * @param bool   $gmt  Whether to return the GMT time. Default false.
         */
        return apply_filters( 'get_post_modified_time', $time, $d, $gmt );
}

/**
 * Display the weekday on which the post was written.
 *
 * @since 0.71
 *
 * @global WP_Locale $wp_locale
 */
function the_weekday() {
        global $wp_locale;
        $the_weekday = $wp_locale->get_weekday( mysql2date( 'w', get_post()->post_date, false ) );

        /**
         * Filters the weekday on which the post was written, for display.
         *
         * @since 0.71
         *
         * @param string $the_weekday
         */
        echo apply_filters( 'the_weekday', $the_weekday );
}

/**
 * Display the weekday on which the post was written.
 *
 * Will only output the weekday if the current post's weekday is different from
 * the previous one output.
 *
 * @since 0.71
 *
 * @global WP_Locale       $wp_locale
 * @global string|int|bool $currentday
 * @global string|int|bool $previousweekday
 *
 * @param string $before Optional Output before the date.
 * @param string $after Optional Output after the date.
 */
function the_weekday_date($before='',$after='') {
        global $wp_locale, $currentday, $previousweekday;
        $the_weekday_date = '';
        if ( $currentday != $previousweekday ) {
                $the_weekday_date .= $before;
                $the_weekday_date .= $wp_locale->get_weekday( mysql2date( 'w', get_post()->post_date, false ) );
                $the_weekday_date .= $after;
                $previousweekday = $currentday;
        }

        /**
         * Filters the localized date on which the post was written, for display.
         *
         * @since 0.71
         *
         * @param string $the_weekday_date
         * @param string $before           The HTML to output before the date.
         * @param string $after            The HTML to output after the date.
         */
        $the_weekday_date = apply_filters( 'the_weekday_date', $the_weekday_date, $before, $after );
        echo $the_weekday_date;
}

/**
 * Fire the wp_head action.
 *
 * See {@see 'wp_head'}.
 *
 * @since 1.2.0
 */
function wp_head() {
        /**
         * Prints scripts or data in the head tag on the front end.
         *
         * @since 1.5.0
         */
        do_action( 'wp_head' );
}

/**
 * Fire the wp_footer action.
 *
 * See {@see 'wp_footer'}.
 *
 * @since 1.5.1
 */
function wp_footer() {
        /**
         * Prints scripts or data before the closing body tag on the front end.
         *
         * @since 1.5.1
         */
        do_action( 'wp_footer' );
}

/**
 * Display the links to the general feeds.
 *
 * @since 2.8.0
 *
 * @param array $args Optional arguments.
 */
function feed_links( $args = array() ) {
        if ( !current_theme_supports('automatic-feed-links') )
                return;

        $defaults = array(
                /* translators: Separator between blog name and feed type in feed links */
                'separator'     => _x('&raquo;', 'feed link'),
                /* translators: 1: blog title, 2: separator (raquo) */
                'feedtitle'     => __('%1$s %2$s Feed'),
                /* translators: 1: blog title, 2: separator (raquo) */
                'comstitle'     => __('%1$s %2$s Comments Feed'),
        );

        $args = wp_parse_args( $args, $defaults );

        /**
         * Filters whether to display the posts feed link.
         *
         * @since 4.4.0
         *
         * @param bool $show Whether to display the posts feed link. Default true.
         */
        if ( apply_filters( 'feed_links_show_posts_feed', true ) ) {
                echo '<link rel="alternate" type="' . feed_content_type() . '" title="' . esc_attr( sprintf( $args['feedtitle'], get_bloginfo( 'name' ), $args['separator'] ) ) . '" href="' . esc_url( get_feed_link() ) . "\" />\n";
        }

        /**
         * Filters whether to display the comments feed link.
         *
         * @since 4.4.0
         *
         * @param bool $show Whether to display the comments feed link. Default true.
         */
        if ( apply_filters( 'feed_links_show_comments_feed', true ) ) {
                echo '<link rel="alternate" type="' . feed_content_type() . '" title="' . esc_attr( sprintf( $args['comstitle'], get_bloginfo( 'name' ), $args['separator'] ) ) . '" href="' . esc_url( get_feed_link( 'comments_' . get_default_feed() ) ) . "\" />\n";
        }
}

/**
 * Display the links to the extra feeds such as category feeds.
 *
 * @since 2.8.0
 *
 * @param array $args Optional arguments.
 */
function feed_links_extra( $args = array() ) {
        $defaults = array(
                /* translators: Separator between blog name and feed type in feed links */
                'separator'   => _x('&raquo;', 'feed link'),
                /* translators: 1: blog name, 2: separator(raquo), 3: post title */
                'singletitle' => __('%1$s %2$s %3$s Comments Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: category name */
                'cattitle'    => __('%1$s %2$s %3$s Category Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: tag name */
                'tagtitle'    => __('%1$s %2$s %3$s Tag Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: term name, 4: taxonomy singular name */
                'taxtitle'    => __('%1$s %2$s %3$s %4$s Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: author name  */
                'authortitle' => __('%1$s %2$s Posts by %3$s Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: search phrase */
                'searchtitle' => __('%1$s %2$s Search Results for &#8220;%3$s&#8221; Feed'),
                /* translators: 1: blog name, 2: separator(raquo), 3: post type name */
                'posttypetitle' => __('%1$s %2$s %3$s Feed'),
        );

        $args = wp_parse_args( $args, $defaults );

        if ( is_singular() ) {
                $id = 0;
                $post = get_post( $id );

                if ( comments_open() || pings_open() || $post->comment_count > 0 ) {
                        $title = sprintf( $args['singletitle'], get_bloginfo('name'), $args['separator'], the_title_attribute( array( 'echo' => false ) ) );
                        $href = get_post_comments_feed_link( $post->ID );
                }
        } elseif ( is_post_type_archive() ) {
                $post_type = get_query_var( 'post_type' );
                if ( is_array( $post_type ) )
                        $post_type = reset( $post_type );

                $post_type_obj = get_post_type_object( $post_type );
                $title = sprintf( $args['posttypetitle'], get_bloginfo( 'name' ), $args['separator'], $post_type_obj->labels->name );
                $href = get_post_type_archive_feed_link( $post_type_obj->name );
        } elseif ( is_category() ) {
                $term = get_queried_object();

                if ( $term ) {
                        $title = sprintf( $args['cattitle'], get_bloginfo('name'), $args['separator'], $term->name );
                        $href = get_category_feed_link( $term->term_id );
                }
        } elseif ( is_tag() ) {
                $term = get_queried_object();

                if ( $term ) {
                        $title = sprintf( $args['tagtitle'], get_bloginfo('name'), $args['separator'], $term->name );
                        $href = get_tag_feed_link( $term->term_id );
                }
        } elseif ( is_tax() ) {
                $term = get_queried_object();
                $tax = get_taxonomy( $term->taxonomy );
                $title = sprintf( $args['taxtitle'], get_bloginfo('name'), $args['separator'], $term->name, $tax->labels->singular_name );
                $href = get_term_feed_link( $term->term_id, $term->taxonomy );
        } elseif ( is_author() ) {
                $author_id = intval( get_query_var('author') );

                $title = sprintf( $args['authortitle'], get_bloginfo('name'), $args['separator'], get_the_author_meta( 'display_name', $author_id ) );
                $href = get_author_feed_link( $author_id );
        } elseif ( is_search() ) {
                $title = sprintf( $args['searchtitle'], get_bloginfo('name'), $args['separator'], get_search_query( false ) );
                $href = get_search_feed_link();
        } elseif ( is_post_type_archive() ) {
                $title = sprintf( $args['posttypetitle'], get_bloginfo('name'), $args['separator'], post_type_archive_title( '', false ) );
                $post_type_obj = get_queried_object();
                if ( $post_type_obj )
                        $href = get_post_type_archive_feed_link( $post_type_obj->name );
        }

        if ( isset($title) && isset($href) )
                echo '<link rel="alternate" type="' . feed_content_type() . '" title="' . esc_attr( $title ) . '" href="' . esc_url( $href ) . '" />' . "\n";
}

/**
 * Display the link to the Really Simple Discovery service endpoint.
 *
 * @link http://archipelago.phrasewise.com/rsd
 * @since 2.0.0
 */
function rsd_link() {
        echo '<link rel="EditURI" type="application/rsd+xml" title="RSD" href="' . esc_url( site_url( 'xmlrpc.php?rsd', 'rpc' ) ) . '" />' . "\n";
}

/**
 * Display the link to the Windows Live Writer manifest file.
 *
 * @link https://msdn.microsoft.com/en-us/library/bb463265.aspx
 * @since 2.3.1
 */
function wlwmanifest_link() {
        echo '<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="',
                includes_url( 'wlwmanifest.xml' ), '" /> ', "\n";
}

/**
 * Displays a noindex meta tag if required by the blog configuration.
 *
 * If a blog is marked as not being public then the noindex meta tag will be
 * output to tell web robots not to index the page content. Add this to the
 * {@see 'wp_head'} action.
 *
 * Typical usage is as a {@see 'wp_head'} callback:
 *
 *     add_action( 'wp_head', 'noindex' );
 *
 * @see wp_no_robots
 *
 * @since 2.1.0
 */
function noindex() {
        // If the blog is not public, tell robots to go away.
        if ( '0' == get_option('blog_public') )
                wp_no_robots();
}

/**
 * Display a noindex meta tag.
 *
 * Outputs a noindex meta tag that tells web robots not to index the page content.
 * Typical usage is as a wp_head callback. add_action( 'wp_head', 'wp_no_robots' );
 *
 * @since 3.3.0
 */
function wp_no_robots() {
        echo "<meta name='robots' content='noindex,follow' />\n";
}

/**
 * Display site icon meta tags.
 *
 * @since 4.3.0
 *
 * @link https://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#rel-icon HTML5 specification link icon.
 */
function wp_site_icon() {
        if ( ! has_site_icon() && ! is_customize_preview() ) {
                return;
        }

        $meta_tags = array();
        $icon_32 = get_site_icon_url( 32 );
        if ( empty( $icon_32 ) && is_customize_preview() ) {
                $icon_32 = '/favicon.ico'; // Serve default favicon URL in customizer so element can be updated for preview.
        }
        if ( $icon_32 ) {
                $meta_tags[] = sprintf( '<link rel="icon" href="%s" sizes="32x32" />', esc_url( $icon_32 ) );
        }
        $icon_192 = get_site_icon_url( 192 );
        if ( $icon_192 ) {
                $meta_tags[] = sprintf( '<link rel="icon" href="%s" sizes="192x192" />', esc_url( $icon_192 ) );
        }
        $icon_180 = get_site_icon_url( 180 );
        if ( $icon_180 ) {
                $meta_tags[] = sprintf( '<link rel="apple-touch-icon-precomposed" href="%s" />', esc_url( $icon_180 ) );
        }
        $icon_270 = get_site_icon_url( 270 );
        if ( $icon_270 ) {
                $meta_tags[] = sprintf( '<meta name="msapplication-TileImage" content="%s" />', esc_url( $icon_270 ) );
        }

        /**
         * Filters the site icon meta tags, so Plugins can add their own.
         *
         * @since 4.3.0
         *
         * @param array $meta_tags Site Icon meta elements.
         */
        $meta_tags = apply_filters( 'site_icon_meta_tags', $meta_tags );
        $meta_tags = array_filter( $meta_tags );

        foreach ( $meta_tags as $meta_tag ) {
                echo "$meta_tag\n";
        }
}

/**
 * Prints resource hints to browsers for pre-fetching, pre-rendering
 * and pre-connecting to web sites.
 *
 * Gives hints to browsers to prefetch specific pages or render them
 * in the background, to perform DNS lookups or to begin the connection
 * handshake (DNS, TCP, TLS) in the background.
 *
 * These performance improving indicators work by using `<link rel"…">`.
 *
 * @since 4.6.0
 */
function wp_resource_hints() {
        $hints = array(
                'dns-prefetch' => wp_dependencies_unique_hosts(),
                'preconnect'   => array(),
                'prefetch'     => array(),
                'prerender'    => array(),
        );

        /*
         * Add DNS prefetch for the Emoji CDN.
         * The path is removed in the foreach loop below.
         */
        /** This filter is documented in wp-includes/formatting.php */
        $hints['dns-prefetch'][] = apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/2.4/svg/' );

        foreach ( $hints as $relation_type => $urls ) {
                $unique_urls = array();

                /**
                 * Filters domains and URLs for resource hints of relation type.
                 *
                 * @since 4.6.0
                 *
                 * @param array  $urls          URLs to print for resource hints.
                 * @param string $relation_type The relation type the URLs are printed for, e.g. 'preconnect' or 'prerender'.
                 */
                $urls = apply_filters( 'wp_resource_hints', $urls, $relation_type );

                foreach ( $urls as $key => $url ) {
                        $atts = array();

                        if ( is_array( $url ) ) {
                                if ( isset( $url['href'] ) ) {
                                        $atts = $url;
                                        $url  = $url['href'];
                                } else {
                                        continue;
                                }
                        }

                        $url = esc_url( $url, array( 'http', 'https' ) );

                        if ( ! $url ) {
                                continue;
                        }

                        if ( isset( $unique_urls[ $url ] ) ) {
                                continue;
                        }

                        if ( in_array( $relation_type, array( 'preconnect', 'dns-prefetch' ) ) ) {
                                $parsed = wp_parse_url( $url );

                                if ( empty( $parsed['host'] ) ) {
                                        continue;
                                }

                                if ( 'preconnect' === $relation_type && ! empty( $parsed['scheme'] ) ) {
                                        $url = $parsed['scheme'] . '://' . $parsed['host'];
                                } else {
                                        // Use protocol-relative URLs for dns-prefetch or if scheme is missing.
                                        $url = '//' . $parsed['host'];
                                }
                        }

                        $atts['rel'] = $relation_type;
                        $atts['href'] = $url;

                        $unique_urls[ $url ] = $atts;
                }

                foreach ( $unique_urls as $atts ) {
                        $html = '';

                        foreach ( $atts as $attr => $value ) {
                                if ( ! is_scalar( $value ) ||
                                     ( ! in_array( $attr, array( 'as', 'crossorigin', 'href', 'pr', 'rel', 'type' ), true ) && ! is_numeric( $attr ))
                                ) {
                                        continue;
                                }

                                $value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );

                                if ( ! is_string( $attr ) ) {
                                        $html .= " $value";
                                } else {
                                        $html .= " $attr='$value'";
                                }
                        }

                        $html = trim( $html );

                        echo "<link $html />\n";
                }
        }
}

/**
 * Retrieves a list of unique hosts of all enqueued scripts and styles.
 *
 * @since 4.6.0
 *
 * @return array A list of unique hosts of enqueued scripts and styles.
 */
function wp_dependencies_unique_hosts() {
        global $wp_scripts, $wp_styles;

        $unique_hosts = array();

        foreach ( array( $wp_scripts, $wp_styles ) as $dependencies ) {
                if ( $dependencies instanceof WP_Dependencies && ! empty( $dependencies->queue ) ) {
                        foreach ( $dependencies->queue as $handle ) {
                                if ( ! isset( $dependencies->registered[ $handle ] ) ) {
                                        continue;
                                }

                                /* @var _WP_Dependency $dependency */
                                $dependency = $dependencies->registered[ $handle ];
                                $parsed     = wp_parse_url( $dependency->src );

                                if ( ! empty( $parsed['host'] ) && ! in_array( $parsed['host'], $unique_hosts ) && $parsed['host'] !== $_SERVER['SERVER_NAME'] ) {
                                        $unique_hosts[] = $parsed['host'];
                                }
                        }
                }
        }

        return $unique_hosts;
}

/**
 * Whether the user can access the visual editor.
 *
 * Checks if the user can access the visual editor and that it's supported by the user's browser.
 *
 * @since 2.0.0
 *
 * @global bool $wp_rich_edit Whether the user can access the visual editor.
 * @global bool $is_gecko     Whether the browser is Gecko-based.
 * @global bool $is_opera     Whether the browser is Opera.
 * @global bool $is_safari    Whether the browser is Safari.
 * @global bool $is_chrome    Whether the browser is Chrome.
 * @global bool $is_IE        Whether the browser is Internet Explorer.
 * @global bool $is_edge      Whether the browser is Microsoft Edge.
 *
 * @return bool True if the user can access the visual editor, false otherwise.
 */
function user_can_richedit() {
        global $wp_rich_edit, $is_gecko, $is_opera, $is_safari, $is_chrome, $is_IE, $is_edge;

        if ( !isset($wp_rich_edit) ) {
                $wp_rich_edit = false;

                if ( get_user_option( 'rich_editing' ) == 'true' || ! is_user_logged_in() ) { // default to 'true' for logged out users
                        if ( $is_safari ) {
                                $wp_rich_edit = ! wp_is_mobile() || ( preg_match( '!AppleWebKit/(\d+)!', $_SERVER['HTTP_USER_AGENT'], $match ) && intval( $match[1] ) >= 534 );
                        } elseif ( $is_IE ) {
                                $wp_rich_edit = ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Trident/7.0;' ) !== false );
                        } elseif ( $is_gecko || $is_chrome || $is_edge || ( $is_opera && !wp_is_mobile() ) ) {
                                $wp_rich_edit = true;
                        }
                }
        }

        /**
         * Filters whether the user can access the visual editor.
         *
         * @since 2.1.0
         *
         * @param bool $wp_rich_edit Whether the user can access the visual editor.
         */
        return apply_filters( 'user_can_richedit', $wp_rich_edit );
}

/**
 * Find out which editor should be displayed by default.
 *
 * Works out which of the two editors to display as the current editor for a
 * user. The 'html' setting is for the "Text" editor tab.
 *
 * @since 2.5.0
 *
 * @return string Either 'tinymce', or 'html', or 'test'
 */
function wp_default_editor() {
        $r = user_can_richedit() ? 'tinymce' : 'html'; // defaults
        if ( wp_get_current_user() ) { // look for cookie
                $ed = get_user_setting('editor', 'tinymce');
                $r = ( in_array($ed, array('tinymce', 'html', 'test') ) ) ? $ed : $r;
        }

        /**
         * Filters which editor should be displayed by default.
         *
         * @since 2.5.0
         *
         * @param string $r Which editor should be displayed by default. Either 'tinymce', 'html', or 'test'.
         */
        return apply_filters( 'wp_default_editor', $r );
}

/**
 * Renders an editor.
 *
 * Using this function is the proper way to output all needed components for both TinyMCE and Quicktags.
 * _WP_Editors should not be used directly. See https://core.trac.wordpress.org/ticket/17144.
 *
 * NOTE: Once initialized the TinyMCE editor cannot be safely moved in the DOM. For that reason
 * running wp_editor() inside of a meta box is not a good idea unless only Quicktags is used.
 * On the post edit screen several actions can be used to include additional editors
 * containing TinyMCE: 'edit_page_form', 'edit_form_advanced' and 'dbx_post_sidebar'.
 * See https://core.trac.wordpress.org/ticket/19173 for more information.
 *
 * @see _WP_Editors::editor()
 * @since 3.3.0
 *
 * @param string $content   Initial content for the editor.
 * @param string $editor_id HTML ID attribute value for the textarea and TinyMCE. Can only be /[a-z]+/.
 * @param array  $settings  See _WP_Editors::editor().
 */
function wp_editor( $content, $editor_id, $settings = array() ) {
        if ( ! class_exists( '_WP_Editors', false ) )
                require( ABSPATH . WPINC . '/class-wp-editor.php' );
        _WP_Editors::editor($content, $editor_id, $settings);
}

/**
 * Outputs the editor scripts, stylesheets, and default settings.
 *
 * The editor can be initialized when needed after page load.
 * See wp.editor.initialize() in wp-admin/js/editor.js for initialization options.
 *
 * @uses _WP_Editors
 * @since 4.8.0
 */
function wp_enqueue_editor() {
        if ( ! class_exists( '_WP_Editors', false ) ) {
                require( ABSPATH . WPINC . '/class-wp-editor.php' );
        }

        _WP_Editors::enqueue_default_editor();
}

/**
 * Enqueue assets needed by the code editor for the given settings.
 *
 * @since 4.9.0
 *
 * @see wp_enqueue_editor()
 * @see _WP_Editors::parse_settings()
 * @param array $args {
 *     Args.
 *
 *     @type string   $type       The MIME type of the file to be edited.
 *     @type string   $file       Filename to be edited. Extension is used to sniff the type. Can be supplied as alternative to `$type` param.
 *     @type WP_Theme $theme      Theme being edited when on theme editor.
 *     @type string   $plugin     Plugin being edited when on plugin editor.
 *     @type array    $codemirror Additional CodeMirror setting overrides.
 *     @type array    $csslint    CSSLint rule overrides.
 *     @type array    $jshint     JSHint rule overrides.
 *     @type array    $htmlhint   JSHint rule overrides.
 * }
 * @returns array|false Settings for the enqueued code editor, or false if the editor was not enqueued .
 */
function wp_enqueue_code_editor( $args ) {
        if ( is_user_logged_in() && 'false' === wp_get_current_user()->syntax_highlighting ) {
                return false;
        }

        $settings = array(
                'codemirror' => array(
                        'indentUnit' => 4,
                        'indentWithTabs' => true,
                        'inputStyle' => 'contenteditable',
                        'lineNumbers' => true,
                        'lineWrapping' => true,
                        'styleActiveLine' => true,
                        'continueComments' => true,
                        'extraKeys' => array(
                                'Ctrl-Space' => 'autocomplete',
                                'Ctrl-/' => 'toggleComment',
                                'Cmd-/' => 'toggleComment',
                                'Alt-F' => 'findPersistent',
                                'Ctrl-F'     => 'findPersistent',
                                'Cmd-F'      => 'findPersistent',
                        ),
                        'direction' => 'ltr', // Code is shown in LTR even in RTL languages.
                        'gutters' => array(),
                ),
                'csslint' => array(
                        'errors' => true, // Parsing errors.
                        'box-model' => true,
                        'display-property-grouping' => true,
                        'duplicate-properties' => true,
                        'known-properties' => true,
                        'outline-none' => true,
                ),
                'jshint' => array(
                        // The following are copied from <https://github.com/WordPress/wordpress-develop/blob/4.8.1/.jshintrc>.
                        'boss' => true,
                        'curly' => true,
                        'eqeqeq' => true,
                        'eqnull' => true,
                        'es3' => true,
                        'expr' => true,
                        'immed' => true,
                        'noarg' => true,
                        'nonbsp' => true,
                        'onevar' => true,
                        'quotmark' => 'single',
                        'trailing' => true,
                        'undef' => true,
                        'unused' => true,

                        'browser' => true,

                        'globals' => array(
                                '_' => false,
                                'Backbone' => false,
                                'jQuery' => false,
                                'JSON' => false,
                                'wp' => false,
                        ),
                ),
                'htmlhint' => array(
                        'tagname-lowercase' => true,
                        'attr-lowercase' => true,
                        'attr-value-double-quotes' => false,
                        'doctype-first' => false,
                        'tag-pair' => true,
                        'spec-char-escape' => true,
                        'id-unique' => true,
                        'src-not-empty' => true,
                        'attr-no-duplication' => true,
                        'alt-require' => true,
                        'space-tab-mixed-disabled' => 'tab',
                        'attr-unsafe-chars' => true,
                ),
        );

        $type = '';
        if ( isset( $args['type'] ) ) {
                $type = $args['type'];

                // Remap MIME types to ones that CodeMirror modes will recognize.
                if ( 'application/x-patch' === $type || 'text/x-patch' === $type ) {
                        $type = 'text/x-diff';
                }
        } elseif ( isset( $args['file'] ) && false !== strpos( basename( $args['file'] ), '.' ) ) {
                $extension = strtolower( pathinfo( $args['file'], PATHINFO_EXTENSION ) );
                foreach ( wp_get_mime_types() as $exts => $mime ) {
                        if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
                                $type = $mime;
                                break;
                        }
                }

                // Supply any types that are not matched by wp_get_mime_types().
                if ( empty( $type ) ) {
                        switch ( $extension ) {
                                case 'conf':
                                        $type = 'text/nginx';
                                        break;
                                case 'css':
                                        $type = 'text/css';
                                        break;
                                case 'diff':
                                case 'patch':
                                        $type = 'text/x-diff';
                                        break;
                                case 'html':
                                case 'htm':
                                        $type = 'text/html';
                                        break;
                                case 'http':
                                        $type = 'message/http';
                                        break;
                                case 'js':
                                        $type = 'text/javascript';
                                        break;
                                case 'json':
                                        $type = 'application/json';
                                        break;
                                case 'jsx':
                                        $type = 'text/jsx';
                                        break;
                                case 'less':
                                        $type = 'text/x-less';
                                        break;
                                case 'md':
                                        $type = 'text/x-gfm';
                                        break;
                                case 'php':
                                case 'phtml':
                                case 'php3':
                                case 'php4':
                                case 'php5':
                                case 'php7':
                                case 'phps':
                                        $type = 'application/x-httpd-php';
                                        break;
                                case 'scss':
                                        $type = 'text/x-scss';
                                        break;
                                case 'sass':
                                        $type = 'text/x-sass';
                                        break;
                                case 'sh':
                                case 'bash':
                                        $type = 'text/x-sh';
                                        break;
                                case 'sql':
                                        $type = 'text/x-sql';
                                        break;
                                case 'svg':
                                        $type = 'application/svg+xml';
                                        break;
                                case 'xml':
                                        $type = 'text/xml';
                                        break;
                                case 'yml':
                                case 'yaml':
                                        $type = 'text/x-yaml';
                                        break;
                                case 'txt':
                                default:
                                        $type = 'text/plain';
                                        break;
                        }
                }
        }

        if ( 'text/css' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'css',
                        'lint' => true,
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
        } elseif ( 'text/x-scss' === $type || 'text/x-less' === $type || 'text/x-sass' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => $type,
                        'lint' => false,
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
        } elseif ( 'text/x-diff' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'diff',
                ) );
        } elseif ( 'text/html' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'htmlmixed',
                        'lint' => true,
                        'autoCloseBrackets' => true,
                        'autoCloseTags' => true,
                        'matchTags' => array(
                                'bothTags' => true,
                        ),
                ) );

                if ( ! current_user_can( 'unfiltered_html' ) ) {
                        $settings['htmlhint']['kses'] = wp_kses_allowed_html( 'post' );
                }
        } elseif ( 'text/x-gfm' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'gfm',
                        'highlightFormatting' => true,
                ) );
        } elseif ( 'application/javascript' === $type || 'text/javascript' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'javascript',
                        'lint' => true,
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
        } elseif ( false !== strpos( $type, 'json' ) ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => array(
                                'name' => 'javascript',
                        ),
                        'lint' => true,
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
                if ( 'application/ld+json' === $type ) {
                        $settings['codemirror']['mode']['jsonld'] = true;
                } else {
                        $settings['codemirror']['mode']['json'] = true;
                }
        } elseif ( false !== strpos( $type, 'jsx' ) ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'jsx',
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
        } elseif ( 'text/x-markdown' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'markdown',
                        'highlightFormatting' => true,
                ) );
        } elseif ( 'text/nginx' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'nginx',
                ) );
        } elseif ( 'application/x-httpd-php' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'php',
                        'autoCloseBrackets' => true,
                        'autoCloseTags' => true,
                        'matchBrackets' => true,
                        'matchTags' => array(
                                'bothTags' => true,
                        ),
                ) );
        } elseif ( 'text/x-sql' === $type || 'text/x-mysql' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'sql',
                        'autoCloseBrackets' => true,
                        'matchBrackets' => true,
                ) );
        } elseif ( false !== strpos( $type, 'xml' ) ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'xml',
                        'autoCloseBrackets' => true,
                        'autoCloseTags' => true,
                        'matchTags' => array(
                                'bothTags' => true,
                        ),
                ) );
        } elseif ( 'text/x-yaml' === $type ) {
                $settings['codemirror'] = array_merge( $settings['codemirror'], array(
                        'mode' => 'yaml',
                ) );
        } else {
                $settings['codemirror']['mode'] = $type;
        }

        if ( ! empty( $settings['codemirror']['lint'] ) ) {
                $settings['codemirror']['gutters'][] = 'CodeMirror-lint-markers';
        }

        // Let settings supplied via args override any defaults.
        foreach ( wp_array_slice_assoc( $args, array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ) ) as $key => $value ) {
                $settings[ $key ] = array_merge(
                        $settings[ $key ],
                        $value
                );
        }

        /**
         * Filters settings that are passed into the code editor.
         *
         * Returning a falsey value will disable the syntax-highlighting code editor.
         *
         * @since 4.9.0
         *
         * @param array $settings The array of settings passed to the code editor. A falsey value disables the editor.
         * @param array $args {
         *     Args passed when calling `wp_enqueue_code_editor()`.
         *
         *     @type string   $type       The MIME type of the file to be edited.
         *     @type string   $file       Filename being edited.
         *     @type WP_Theme $theme      Theme being edited when on theme editor.
         *     @type string   $plugin     Plugin being edited when on plugin editor.
         *     @type array    $codemirror Additional CodeMirror setting overrides.
         *     @type array    $csslint    CSSLint rule overrides.
         *     @type array    $jshint     JSHint rule overrides.
         *     @type array    $htmlhint   JSHint rule overrides.
         * }
         */
        $settings = apply_filters( 'wp_code_editor_settings', $settings, $args );

        if ( empty( $settings ) || empty( $settings['codemirror'] ) ) {
                return false;
        }

        wp_enqueue_script( 'code-editor' );
        wp_enqueue_style( 'code-editor' );

        if ( isset( $settings['codemirror']['mode'] ) ) {
                $mode = $settings['codemirror']['mode'];
                if ( is_string( $mode ) ) {
                        $mode = array(
                                'name' => $mode,
                        );
                }

                if ( ! empty( $settings['codemirror']['lint'] ) ) {
                        switch ( $mode['name'] ) {
                                case 'css':
                                case 'text/css':
                                case 'text/x-scss':
                                case 'text/x-less':
                                        wp_enqueue_script( 'csslint' );
                                        break;
                                case 'htmlmixed':
                                case 'text/html':
                                case 'php':
                                case 'application/x-httpd-php':
                                case 'text/x-php':
                                        wp_enqueue_script( 'htmlhint' );
                                        wp_enqueue_script( 'csslint' );
                                        wp_enqueue_script( 'jshint' );
                                        if ( ! current_user_can( 'unfiltered_html' ) ) {
                                                wp_enqueue_script( 'htmlhint-kses' );
                                        }
                                        break;
                                case 'javascript':
                                case 'application/ecmascript':
                                case 'application/json':
                                case 'application/javascript':
                                case 'application/ld+json':
                                case 'text/typescript':
                                case 'application/typescript':
                                        wp_enqueue_script( 'jshint' );
                                        wp_enqueue_script( 'jsonlint' );
                                        break;
                        }
                }
        }

        wp_add_inline_script( 'code-editor', sprintf( 'jQuery.extend( wp.codeEditor.defaultSettings, %s );', wp_json_encode( $settings ) ) );

        /**
         * Fires when scripts and styles are enqueued for the code editor.
         *
         * @since 4.9.0
         *
         * @param array $settings Settings for the enqueued code editor.
         */
        do_action( 'wp_enqueue_code_editor', $settings );

        return $settings;
}

/**
 * Retrieves the contents of the search WordPress query variable.
 *
 * The search query string is passed through esc_attr() to ensure that it is safe
 * for placing in an html attribute.
 *
 * @since 2.3.0
 *
 * @param bool $escaped Whether the result is escaped. Default true.
 *                          Only use when you are later escaping it. Do not use unescaped.
 * @return string
 */
function get_search_query( $escaped = true ) {
        /**
         * Filters the contents of the search query variable.
         *
         * @since 2.3.0
         *
         * @param mixed $search Contents of the search query variable.
         */
        $query = apply_filters( 'get_search_query', get_query_var( 's' ) );

        if ( $escaped )
                $query = esc_attr( $query );
        return $query;
}

/**
 * Displays the contents of the search query variable.
 *
 * The search query string is passed through esc_attr() to ensure that it is safe
 * for placing in an html attribute.
 *
 * @since 2.1.0
 */
function the_search_query() {
        /**
         * Filters the contents of the search query variable for display.
         *
         * @since 2.3.0
         *
         * @param mixed $search Contents of the search query variable.
         */
        echo esc_attr( apply_filters( 'the_search_query', get_search_query( false ) ) );
}

/**
 * Gets the language attributes for the html tag.
 *
 * Builds up a set of html attributes containing the text direction and language
 * information for the page.
 *
 * @since 4.3.0
 *
 * @param string $doctype Optional. The type of html document. Accepts 'xhtml' or 'html'. Default 'html'.
 */
function get_language_attributes( $doctype = 'html' ) {
        $attributes = array();

        if ( function_exists( 'is_rtl' ) && is_rtl() )
                $attributes[] = 'dir="rtl"';

        if ( $lang = get_bloginfo( 'language' ) ) {
                if ( get_option( 'html_type' ) == 'text/html' || $doctype == 'html' ) {
                        $attributes[] = 'lang="' . esc_attr( $lang ) . '"';
                }

                if ( get_option( 'html_type' ) != 'text/html' || $doctype == 'xhtml' ) {
                        $attributes[] = 'xml:lang="' . esc_attr( $lang ) . '"';
                }
        }

        $output = implode(' ', $attributes);

        /**
         * Filters the language attributes for display in the html tag.
         *
         * @since 2.5.0
         * @since 4.3.0 Added the `$doctype` parameter.
         *
         * @param string $output A space-separated list of language attributes.
         * @param string $doctype The type of html document (xhtml|html).
         */
        return apply_filters( 'language_attributes', $output, $doctype );
}

/**
 * Displays the language attributes for the html tag.
 *
 * Builds up a set of html attributes containing the text direction and language
 * information for the page.
 *
 * @since 2.1.0
 * @since 4.3.0 Converted into a wrapper for get_language_attributes().
 *
 * @param string $doctype Optional. The type of html document. Accepts 'xhtml' or 'html'. Default 'html'.
 */
function language_attributes( $doctype = 'html' ) {
        echo get_language_attributes( $doctype );
}

/**
 * Retrieve paginated link for archive post pages.
 *
 * Technically, the function can be used to create paginated link list for any
 * area. The 'base' argument is used to reference the url, which will be used to
 * create the paginated links. The 'format' argument is then used for replacing
 * the page number. It is however, most likely and by default, to be used on the
 * archive post pages.
 *
 * The 'type' argument controls format of the returned value. The default is
 * 'plain', which is just a string with the links separated by a newline
 * character. The other possible values are either 'array' or 'list'. The
 * 'array' value will return an array of the paginated link list to offer full
 * control of display. The 'list' value will place all of the paginated links in
 * an unordered HTML list.
 *
 * The 'total' argument is the total amount of pages and is an integer. The
 * 'current' argument is the current page number and is also an integer.
 *
 * An example of the 'base' argument is "http://example.com/all_posts.php%_%"
 * and the '%_%' is required. The '%_%' will be replaced by the contents of in
 * the 'format' argument. An example for the 'format' argument is "?page=%#%"
 * and the '%#%' is also required. The '%#%' will be replaced with the page
 * number.
 *
 * You can include the previous and next links in the list by setting the
 * 'prev_next' argument to true, which it is by default. You can set the
 * previous text, by using the 'prev_text' argument. You can set the next text
 * by setting the 'next_text' argument.
 *
 * If the 'show_all' argument is set to true, then it will show all of the pages
 * instead of a short list of the pages near the current page. By default, the
 * 'show_all' is set to false and controlled by the 'end_size' and 'mid_size'
 * arguments. The 'end_size' argument is how many numbers on either the start
 * and the end list edges, by default is 1. The 'mid_size' argument is how many
 * numbers to either side of current page, but not including current page.
 *
 * It is possible to add query vars to the link by using the 'add_args' argument
 * and see add_query_arg() for more information.
 *
 * The 'before_page_number' and 'after_page_number' arguments allow users to
 * augment the links themselves. Typically this might be to add context to the
 * numbered links so that screen reader users understand what the links are for.
 * The text strings are added before and after the page number - within the
 * anchor tag.
 *
 * @since 2.1.0
 * @since 4.9.0 Added the `aria_current` argument.
 *
 * @global WP_Query   $wp_query
 * @global WP_Rewrite $wp_rewrite
 *
 * @param string|array $args {
 *     Optional. Array or string of arguments for generating paginated links for archives.
 *
 *     @type string $base               Base of the paginated url. Default empty.
 *     @type string $format             Format for the pagination structure. Default empty.
 *     @type int    $total              The total amount of pages. Default is the value WP_Query's
 *                                      `max_num_pages` or 1.
 *     @type int    $current            The current page number. Default is 'paged' query var or 1.
 *     @type string $aria_current       The value for the aria-current attribute. Possible values are 'page',
 *                                      'step', 'location', 'date', 'time', 'true', 'false'. Default is 'page'.
 *     @type bool   $show_all           Whether to show all pages. Default false.
 *     @type int    $end_size           How many numbers on either the start and the end list edges.
 *                                      Default 1.
 *     @type int    $mid_size           How many numbers to either side of the current pages. Default 2.
 *     @type bool   $prev_next          Whether to include the previous and next links in the list. Default true.
 *     @type bool   $prev_text          The previous page text. Default '&laquo; Previous'.
 *     @type bool   $next_text          The next page text. Default 'Next &raquo;'.
 *     @type string $type               Controls format of the returned value. Possible values are 'plain',
 *                                      'array' and 'list'. Default is 'plain'.
 *     @type array  $add_args           An array of query args to add. Default false.
 *     @type string $add_fragment       A string to append to each link. Default empty.
 *     @type string $before_page_number A string to appear before the page number. Default empty.
 *     @type string $after_page_number  A string to append after the page number. Default empty.
 * }
 * @return array|string|void String of page links or array of page links.
 */
function paginate_links( $args = '', $merge_args = true ) {
        global $wp_query, $wp_rewrite;

        // Setting up default values based on the current URL.
        $pagenum_link = html_entity_decode( get_pagenum_link() );
        $url_parts    = explode( '?', $pagenum_link );

        // Get max pages and current page out of the current query, if available.
        $total   = isset( $wp_query->max_num_pages ) ? $wp_query->max_num_pages : 1;
        $current = get_query_var( 'paged' ) ? intval( get_query_var( 'paged' ) ) : 1;

        // Append the format placeholder to the base URL.
        $pagenum_link = trailingslashit( $url_parts[0] ) . '%_%';

        // URL base depends on permalink settings.
        $format  = $wp_rewrite->using_index_permalinks() && ! strpos( $pagenum_link, 'index.php' ) ? 'index.php/' : '';
        $format .= $wp_rewrite->using_permalinks() ? user_trailingslashit( $wp_rewrite->pagination_base . '/%#%', 'paged' ) : '?paged=%#%';

        $defaults = array(
                'base'               => $pagenum_link, // http://example.com/all_posts.php%_% : %_% is replaced by format (below)
                'format'             => $format, // ?page=%#% : %#% is replaced by the page number
                'total'              => $total,
                'current'            => $current,
                'aria_current'       => 'page',
                'show_all'           => false,
                'prev_next'          => true,
                'prev_text'          => __( '&laquo; Previous' ),
                'next_text'          => __( 'Next &raquo;' ),
                'end_size'           => 1,
                'mid_size'           => 2,
                'type'               => 'plain',
                'add_args'           => array(), // array of query args to add
                'add_fragment'       => '',
                'before_page_number' => '',
                'after_page_number'  => '',
        );

        $args = wp_parse_args( $args, $defaults );

        if ( ! is_array( $args['add_args'] ) ) {
                $args['add_args'] = array();
        }

        // Merge additional query vars found in the original URL into 'add_args' array.
        if ( isset( $url_parts[1] ) ) {
                // Find the format argument.
                $format = explode( '?', str_replace( '%_%', $args['format'], $args['base'] ) );
                $format_query = isset( $format[1] ) ? $format[1] : '';
                wp_parse_str( $format_query, $format_args );

                // Find the query args of the requested URL.
                wp_parse_str( $url_parts[1], $url_query_args );

                // Remove the format argument from the array of query arguments, to avoid overwriting custom format.
                foreach ( $format_args as $format_arg => $format_arg_value ) {
                        unset( $url_query_args[ $format_arg ] );
                }

                if($merge_args)
                {
                        $args['add_args'] = array_merge( $args['add_args'], urlencode_deep( $url_query_args ) );
                }
        }

        // Who knows what else people pass in $args
        $total = (int) $args['total'];
        if ( $total < 2 ) {
                return;
        }
        $current  = (int) $args['current'];
        $end_size = (int) $args['end_size']; // Out of bounds?  Make it the default.
        if ( $end_size < 1 ) {
                $end_size = 1;
        }
        $mid_size = (int) $args['mid_size'];
        if ( $mid_size < 0 ) {
                $mid_size = 2;
        }
        $add_args = $args['add_args'];
        $r = '';
        $page_links = array();
        $dots = false;

        if ( $args['prev_next'] && $current && 1 < $current ) :
                $link = str_replace( '%_%', 2 == $current ? '' : $args['format'], $args['base'] );
                $link = str_replace( '%#%', $current - 1, $link );
                if ( $add_args )
                        $link = add_query_arg( $add_args, $link );
                $link .= $args['add_fragment'];

                /**
                 * Filters the paginated links for the given archive pages.
                 *
                 * @since 3.0.0
                 *
                 * @param string $link The paginated link URL.
                 */
                $page_links[] = '<a class="prev page-numbers" href="' . esc_url( apply_filters( 'paginate_links', $link ) ) . '">' . $args['prev_text'] . '</a>';
        endif;
        for ( $n = 1; $n <= $total; $n++ ) :
                if ( $n == $current ) :
                        $page_links[] = "<span aria-current='" . esc_attr( $args['aria_current'] ) . "' class='page-numbers current'>" . $args['before_page_number'] . number_format_i18n( $n ) . $args['after_page_number'] . "</span>";
                        $dots = true;
                else :
                        if ( $args['show_all'] || ( $n <= $end_size || ( $current && $n >= $current - $mid_size && $n <= $current + $mid_size ) || $n > $total - $end_size ) ) :
                                $link = str_replace( '%_%', 1 == $n ? '' : $args['format'], $args['base'] );
                                $link = str_replace( '%#%', $n, $link );
                                if ( $add_args )
                                        $link = add_query_arg( $add_args, $link );
                                $link .= $args['add_fragment'];

                                /** This filter is documented in wp-includes/general-template.php */
                                $page_links[] = "<a class='page-numbers' href='" . esc_url( apply_filters( 'paginate_links', $link ) ) . "'>" . $args['before_page_number'] . number_format_i18n( $n ) . $args['after_page_number'] . "</a>";
                                $dots = true;
                        elseif ( $dots && ! $args['show_all'] ) :
                                $page_links[] = '<span class="page-numbers dots">' . __( '&hellip;' ) . '</span>';
                                $dots = false;
                        endif;
                endif;
        endfor;
        if ( $args['prev_next'] && $current && $current < $total ) :
                $link = str_replace( '%_%', $args['format'], $args['base'] );
                $link = str_replace( '%#%', $current + 1, $link );
                if ( $add_args )
                        $link = add_query_arg( $add_args, $link );
                $link .= $args['add_fragment'];

                /** This filter is documented in wp-includes/general-template.php */
                $page_links[] = '<a class="next page-numbers" href="' . esc_url( apply_filters( 'paginate_links', $link ) ) . '">' . $args['next_text'] . '</a>';
        endif;
        switch ( $args['type'] ) {
                case 'array' :
                        return $page_links;

                case 'list' :
                        $r .= "<ul class='page-numbers'>\n\t<li>";
                        $r .= join("</li>\n\t<li>", $page_links);
                        $r .= "</li>\n</ul>\n";
                        break;

                default :
                        $r = join("\n", $page_links);
                        break;
        }
        return $r;
}

/**
 * Registers an admin colour scheme css file.
 *
 * Allows a plugin to register a new admin colour scheme. For example:
 *
 *     wp_admin_css_color( 'classic', __( 'Classic' ), admin_url( "css/colors-classic.css" ), array(
 *         '#07273E', '#14568A', '#D54E21', '#2683AE'
 *     ) );
 *
 * @since 2.5.0
 *
 * @global array $_wp_admin_css_colors
 *
 * @param string $key    The unique key for this theme.
 * @param string $name   The name of the theme.
 * @param string $url    The URL of the CSS file containing the color scheme.
 * @param array  $colors Optional. An array of CSS color definition strings which are used
 *                       to give the user a feel for the theme.
 * @param array  $icons {
 *     Optional. CSS color definitions used to color any SVG icons.
 *
 *     @type string $base    SVG icon base color.
 *     @type string $focus   SVG icon color on focus.
 *     @type string $current SVG icon color of current admin menu link.
 * }
 */
function wp_admin_css_color( $key, $name, $url, $colors = array(), $icons = array() ) {
        global $_wp_admin_css_colors;

        if ( !isset($_wp_admin_css_colors) )
                $_wp_admin_css_colors = array();

        $_wp_admin_css_colors[$key] = (object) array(
                'name' => $name,
                'url' => $url,
                'colors' => $colors,
                'icon_colors' => $icons,
        );
}

/**
 * Registers the default Admin color schemes
 *
 * @since 3.0.0
 */
function register_admin_color_schemes() {
        $suffix = is_rtl() ? '-rtl' : '';
        $suffix .= SCRIPT_DEBUG ? '' : '.min';

        wp_admin_css_color( 'fresh', _x( 'Default', 'admin color scheme' ),
                false,
                array( '#222', '#333', '#0073aa', '#00a0d2' ),
                array( 'base' => '#82878c', 'focus' => '#00a0d2', 'current' => '#fff' )
        );

        // Other color schemes are not available when running out of src
        if ( false !== strpos( get_bloginfo( 'version' ), '-src' ) ) {
                return;
        }

        wp_admin_css_color( 'light', _x( 'Light', 'admin color scheme' ),
                admin_url( "css/colors/light/colors$suffix.css" ),
                array( '#e5e5e5', '#999', '#d64e07', '#04a4cc' ),
                array( 'base' => '#999', 'focus' => '#ccc', 'current' => '#ccc' )
        );

        wp_admin_css_color( 'blue', _x( 'Blue', 'admin color scheme' ),
                admin_url( "css/colors/blue/colors$suffix.css" ),
                array( '#096484', '#4796b3', '#52accc', '#74B6CE' ),
                array( 'base' => '#e5f8ff', 'focus' => '#fff', 'current' => '#fff' )
        );

        wp_admin_css_color( 'midnight', _x( 'Midnight', 'admin color scheme' ),
                admin_url( "css/colors/midnight/colors$suffix.css" ),
                array( '#25282b', '#363b3f', '#69a8bb', '#e14d43' ),
                array( 'base' => '#f1f2f3', 'focus' => '#fff', 'current' => '#fff' )
        );

        wp_admin_css_color( 'sunrise', _x( 'Sunrise', 'admin color scheme' ),
                admin_url( "css/colors/sunrise/colors$suffix.css" ),
                array( '#b43c38', '#cf4944', '#dd823b', '#ccaf0b' ),
                array( 'base' => '#f3f1f1', 'focus' => '#fff', 'current' => '#fff' )
        );

        wp_admin_css_color( 'ectoplasm', _x( 'Ectoplasm', 'admin color scheme' ),
                admin_url( "css/colors/ectoplasm/colors$suffix.css" ),
                array( '#413256', '#523f6d', '#a3b745', '#d46f15' ),
                array( 'base' => '#ece6f6', 'focus' => '#fff', 'current' => '#fff' )
        );

        wp_admin_css_color( 'ocean', _x( 'Ocean', 'admin color scheme' ),
                admin_url( "css/colors/ocean/colors$suffix.css" ),
                array( '#627c83', '#738e96', '#9ebaa0', '#aa9d88' ),
                array( 'base' => '#f2fcff', 'focus' => '#fff', 'current' => '#fff' )
        );

        wp_admin_css_color( 'coffee', _x( 'Coffee', 'admin color scheme' ),
                admin_url( "css/colors/coffee/colors$suffix.css" ),
                array( '#46403c', '#59524c', '#c7a589', '#9ea476' ),
                array( 'base' => '#f3f2f1', 'focus' => '#fff', 'current' => '#fff' )
        );

}

/**
 * Displays the URL of a WordPress admin CSS file.
 *
 * @see WP_Styles::_css_href and its {@see 'style_loader_src'} filter.
 *
 * @since 2.3.0
 *
 * @param string $file file relative to wp-admin/ without its ".css" extension.
 * @return string
 */
function wp_admin_css_uri( $file = 'wp-admin' ) {
        if ( defined('WP_INSTALLING') ) {
                $_file = "./$file.css";
        } else {
                $_file = admin_url("$file.css");
        }
        $_file = add_query_arg( 'version', get_bloginfo( 'version' ),  $_file );

        /**
         * Filters the URI of a WordPress admin CSS file.
         *
         * @since 2.3.0
         *
         * @param string $_file Relative path to the file with query arguments attached.
         * @param string $file  Relative path to the file, minus its ".css" extension.
         */
        return apply_filters( 'wp_admin_css_uri', $_file, $file );
}

/**
 * Enqueues or directly prints a stylesheet link to the specified CSS file.
 *
 * "Intelligently" decides to enqueue or to print the CSS file. If the
 * {@see 'wp_print_styles'} action has *not* yet been called, the CSS file will be
 * enqueued. If the {@see 'wp_print_styles'} action has been called, the CSS link will
 * be printed. Printing may be forced by passing true as the $force_echo
 * (second) parameter.
 *
 * For backward compatibility with WordPress 2.3 calling method: If the $file
 * (first) parameter does not correspond to a registered CSS file, we assume
 * $file is a file relative to wp-admin/ without its ".css" extension. A
 * stylesheet link to that generated URL is printed.
 *
 * @since 2.3.0
 *
 * @param string $file       Optional. Style handle name or file name (without ".css" extension) relative
 *                               to wp-admin/. Defaults to 'wp-admin'.
 * @param bool   $force_echo Optional. Force the stylesheet link to be printed rather than enqueued.
 */
function wp_admin_css( $file = 'wp-admin', $force_echo = false ) {
        // For backward compatibility
        $handle = 0 === strpos( $file, 'css/' ) ? substr( $file, 4 ) : $file;

        if ( wp_styles()->query( $handle ) ) {
                if ( $force_echo || did_action( 'wp_print_styles' ) ) // we already printed the style queue. Print this one immediately
                        wp_print_styles( $handle );
                else // Add to style queue
                        wp_enqueue_style( $handle );
                return;
        }

        /**
         * Filters the stylesheet link to the specified CSS file.
         *
         * If the site is set to display right-to-left, the RTL stylesheet link
         * will be used instead.
         *
         * @since 2.3.0
         * @param string $stylesheet_link HTML link element for the stylesheet.
         * @param string $file            Style handle name or filename (without ".css" extension)
         *                                relative to wp-admin/. Defaults to 'wp-admin'.
         */
        echo apply_filters( 'wp_admin_css', "<link rel='stylesheet' href='" . esc_url( wp_admin_css_uri( $file ) ) . "' type='text/css' />\n", $file );

        if ( function_exists( 'is_rtl' ) && is_rtl() ) {
                /** This filter is documented in wp-includes/general-template.php */
                echo apply_filters( 'wp_admin_css', "<link rel='stylesheet' href='" . esc_url( wp_admin_css_uri( "$file-rtl" ) ) . "' type='text/css' />\n", "$file-rtl" );
        }
}

/**
 * Enqueues the default ThickBox js and css.
 *
 * If any of the settings need to be changed, this can be done with another js
 * file similar to media-upload.js. That file should
 * require array('thickbox') to ensure it is loaded after.
 *
 * @since 2.5.0
 */
function add_thickbox() {
        wp_enqueue_script( 'thickbox' );
        wp_enqueue_style( 'thickbox' );

        if ( is_network_admin() )
                add_action( 'admin_head', '_thickbox_path_admin_subfolder' );
}

/**
 * Displays the XHTML generator that is generated on the wp_head hook.
 *
 * See {@see 'wp_head'}.
 *
 * @since 2.5.0
 */
function wp_generator() {
        /**
         * Filters the output of the XHTML generator tag.
         *
         * @since 2.5.0
         *
         * @param string $generator_type The XHTML generator.
         */
        the_generator( apply_filters( 'wp_generator_type', 'xhtml' ) );
}

/**
 * Display the generator XML or Comment for RSS, ATOM, etc.
 *
 * Returns the correct generator type for the requested output format. Allows
 * for a plugin to filter generators overall the {@see 'the_generator'} filter.
 *
 * @since 2.5.0
 *
 * @param string $type The type of generator to output - (html|xhtml|atom|rss2|rdf|comment|export).
 */
function the_generator( $type ) {
        /**
         * Filters the output of the XHTML generator tag for display.
         *
         * @since 2.5.0
         *
         * @param string $generator_type The generator output.
         * @param string $type           The type of generator to output. Accepts 'html',
         *                               'xhtml', 'atom', 'rss2', 'rdf', 'comment', 'export'.
         */
        echo apply_filters( 'the_generator', get_the_generator($type), $type ) . "\n";
}

/**
 * Creates the generator XML or Comment for RSS, ATOM, etc.
 *
 * Returns the correct generator type for the requested output format. Allows
 * for a plugin to filter generators on an individual basis using the
 * {@see 'get_the_generator_$type'} filter.
 *
 * @since 2.5.0
 *
 * @param string $type The type of generator to return - (html|xhtml|atom|rss2|rdf|comment|export).
 * @return string|void The HTML content for the generator.
 */
function get_the_generator( $type = '' ) {
        if ( empty( $type ) ) {

                $current_filter = current_filter();
                if ( empty( $current_filter ) )
                        return;

                switch ( $current_filter ) {
                        case 'rss2_head' :
                        case 'commentsrss2_head' :
                                $type = 'rss2';
                                break;
                        case 'rss_head' :
                        case 'opml_head' :
                                $type = 'comment';
                                break;
                        case 'rdf_header' :
                                $type = 'rdf';
                                break;
                        case 'atom_head' :
                        case 'comments_atom_head' :
                        case 'app_head' :
                                $type = 'atom';
                                break;
                }
        }

        switch ( $type ) {
                case 'html':
                        $gen = '<meta name="generator" content="WordPress ' . esc_attr( get_bloginfo( 'version' ) ) . '">';
                        break;
                case 'xhtml':
                        $gen = '<meta name="generator" content="WordPress ' . esc_attr( get_bloginfo( 'version' ) ) . '" />';
                        break;
                case 'atom':
                        $gen = '<generator uri="https://wordpress.org/" version="' . esc_attr( get_bloginfo_rss( 'version' ) ) . '">WordPress</generator>';
                        break;
                case 'rss2':
                        $gen = '<generator>' . esc_url_raw( 'https://wordpress.org/?v=' . get_bloginfo_rss( 'version' ) ) . '</generator>';
                        break;
                case 'rdf':
                        $gen = '<admin:generatorAgent rdf:resource="' . esc_url_raw( 'https://wordpress.org/?v=' . get_bloginfo_rss( 'version' ) ) . '" />';
                        break;
                case 'comment':
                        $gen = '<!-- generator="WordPress/' . esc_attr( get_bloginfo( 'version' ) ) . '" -->';
                        break;
                case 'export':
                        $gen = '<!-- generator="WordPress/' . esc_attr( get_bloginfo_rss( 'version' ) ) . '" created="' . date( 'Y-m-d H:i' ) . '" -->';
                        break;
        }

        /**
         * Filters the HTML for the retrieved generator type.
         *
         * The dynamic portion of the hook name, `$type`, refers to the generator type.
         *
         * @since 2.5.0
         *
         * @param string $gen  The HTML markup output to wp_head().
         * @param string $type The type of generator. Accepts 'html', 'xhtml', 'atom',
         *                     'rss2', 'rdf', 'comment', 'export'.
         */
        return apply_filters( "get_the_generator_{$type}", $gen, $type );
}

/**
 * Outputs the html checked attribute.
 *
 * Compares the first two arguments and if identical marks as checked
 *
 * @since 1.0.0
 *
 * @param mixed $checked One of the values to compare
 * @param mixed $current (true) The other value to compare if not just true
 * @param bool  $echo    Whether to echo or just return the string
 * @return string html attribute or empty string
 */
function checked( $checked, $current = true, $echo = true ) {
        return __checked_selected_helper( $checked, $current, $echo, 'checked' );
}

/**
 * Outputs the html selected attribute.
 *
 * Compares the first two arguments and if identical marks as selected
 *
 * @since 1.0.0
 *
 * @param mixed $selected One of the values to compare
 * @param mixed $current  (true) The other value to compare if not just true
 * @param bool  $echo     Whether to echo or just return the string
 * @return string html attribute or empty string
 */
function selected( $selected, $current = true, $echo = true ) {
        return __checked_selected_helper( $selected, $current, $echo, 'selected' );
}

/**
 * Outputs the html disabled attribute.
 *
 * Compares the first two arguments and if identical marks as disabled
 *
 * @since 3.0.0
 *
 * @param mixed $disabled One of the values to compare
 * @param mixed $current  (true) The other value to compare if not just true
 * @param bool  $echo     Whether to echo or just return the string
 * @return string html attribute or empty string
 */
function disabled( $disabled, $current = true, $echo = true ) {
        return __checked_selected_helper( $disabled, $current, $echo, 'disabled' );
}

/**
 * Outputs the html readonly attribute.
 *
 * Compares the first two arguments and if identical marks as readonly
 *
 * @since 4.9.0
 *
 * @param mixed $readonly One of the values to compare
 * @param mixed $current  (true) The other value to compare if not just true
 * @param bool  $echo     Whether to echo or just return the string
 * @return string html attribute or empty string
 */
function readonly( $readonly, $current = true, $echo = true ) {
        return __checked_selected_helper( $readonly, $current, $echo, 'readonly' );
}

/**
 * Private helper function for checked, selected, disabled and readonly.
 *
 * Compares the first two arguments and if identical marks as $type
 *
 * @since 2.8.0
 * @access private
 *
 * @param mixed  $helper  One of the values to compare
 * @param mixed  $current (true) The other value to compare if not just true
 * @param bool   $echo    Whether to echo or just return the string
 * @param string $type    The type of checked|selected|disabled|readonly we are doing
 * @return string html attribute or empty string
 */
function __checked_selected_helper( $helper, $current, $echo, $type ) {
        if ( (string) $helper === (string) $current )
                $result = " $type='$type'";
        else
                $result = '';

        if ( $echo )
                echo $result;

        return $result;
}

/**
 * Default settings for heartbeat
 *
 * Outputs the nonce used in the heartbeat XHR
 *
 * @since 3.6.0
 *
 * @param array $settings
 * @return array $settings
 */
function wp_heartbeat_settings( $settings ) {
        if ( ! is_admin() )
                $settings['ajaxurl'] = admin_url( 'admin-ajax.php', 'relative' );

        if ( is_user_logged_in() )
                $settings['nonce'] = wp_create_nonce( 'heartbeat-nonce' );

        return $settings;
}