er.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for an existing day archive.
 */
function is_day() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_day();
}

/**
 * Determines whether the query is for a feed.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string|string[] $feeds Optional. Feed type or array of feed types
 *                                         to check against. Default empty.
 * @return bool Whether the query is for a feed.
 */
function is_feed( $feeds = '' ) {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_feed( $feeds );
}

/**
 * Is the query for a comments feed?
 *
 * @since 3.0.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a comments feed.
 */
function is_comment_feed() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_comment_feed();
}

/**
 * Determines whether the query is for the front page of the site.
 *
 * This is for what is displayed at your site's main URL.
 *
 * Depends on the site's "Front page displays" Reading Settings 'show_on_front' and 'page_on_front'.
 *
 * If you set a static page for the front page of your site, this function will return
 * true when viewing that page.
 *
 * Otherwise the same as @see is_home()
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for the front page of the site.
 */
function is_front_page() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_front_page();
}

/**
 * Determines whether the query is for the blog homepage.
 *
 * The blog homepage is the page that shows the time-based blog content of the site.
 *
 * is_home() is dependent on the site's "Front page displays" Reading Settings 'show_on_front'
 * and 'page_for_posts'.
 *
 * If a static page is set for the front page of the site, this function will return true only
 * on the page you set as the "Posts page".
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @see is_front_page()
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for the blog homepage.
 */
function is_home() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_home();
}

/**
 * Determines whether the query is for the Privacy Policy page.
 *
 * The Privacy Policy page is the page that shows the Privacy Policy content of the site.
 *
 * is_privacy_policy() is dependent on the site's "Change your Privacy Policy page" Privacy Settings 'wp_page_for_privacy_policy'.
 *
 * This function will return true only on the page you set as the "Privacy Policy page".
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 5.2.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for the Privacy Policy page.
 */
function is_privacy_policy() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_privacy_policy();
}

/**
 * Determines whether the query is for an existing month archive.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for an existing month archive.
 */
function is_month() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_month();
}

/**
 * Determines whether the query is for an existing single page.
 *
 * If the $page parameter is specified, this function will additionally
 * check if the query is for one of the pages specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @see is_single()
 * @see is_singular()
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param int|string|int[]|string[] $page Optional. Page ID, title, slug, or array of such
 *                                        to check against. Default empty.
 * @return bool Whether the query is for an existing single page.
 */
function is_page( $page = '' ) {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_page( $page );
}

/**
 * Determines whether the query is for a paged result and not for the first page.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a paged result.
 */
function is_paged() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_paged();
}

/**
 * Determines whether the query is for a post or page preview.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.0.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a post or page preview.
 */
function is_preview() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_preview();
}

/**
 * Is the query for the robots.txt file?
 *
 * @since 2.1.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for the robots.txt file.
 */
function is_robots() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_robots();
}

/**
 * Is the query for the favicon.ico file?
 *
 * @since 5.4.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for the favicon.ico file.
 */
function is_favicon() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_favicon();
}

/**
 * Determines whether the query is for a search.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a search.
 */
function is_search() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_search();
}

/**
 * Determines whether the query is for an existing single post.
 *
 * Works for any post type, except attachments and pages
 *
 * If the $post parameter is specified, this function will additionally
 * check if the query is for one of the Posts specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @see is_page()
 * @see is_singular()
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param int|string|int[]|string[] $post Optional. Post ID, title, slug, or array of such
 *                                        to check against. Default empty.
 * @return bool Whether the query is for an existing single post.
 */
function is_single( $post = '' ) {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_single( $post );
}

/**
 * Determines whether the query is for an existing single post of any post type
 * (post, attachment, page, custom post types).
 *
 * If the $post_types parameter is specified, this function will additionally
 * check if the query is for one of the Posts Types specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @see is_page()
 * @see is_single()
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string|string[] $post_types Optional. Post type or array of post types
 *                                    to check against. Default empty.
 * @return bool Whether the query is for an existing single post
 *              or any of the given post types.
 */
function is_singular( $post_types = '' ) {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_singular( $post_types );
}

/**
 * Determines whether the query is for a specific time.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a specific time.
 */
function is_time() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_time();
}

/**
 * Determines whether the query is for a trackback endpoint call.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for a trackback endpoint call.
 */
function is_trackback() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_trackback();
}

/**
 * Determines whether the query is for an existing year archive.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for an existing year archive.
 */
function is_year() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_year();
}

/**
 * Determines whether the query has resulted in a 404 (returns no results).
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is a 404 error.
 */
function is_404() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_404();
}

/**
 * Is the query for an embedded post?
 *
 * @since 4.4.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is for an embedded post.
 */
function is_embed() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_embed();
}

/**
 * Determines whether the query is the main query.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 3.3.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool Whether the query is the main query.
 */
function is_main_query() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '6.1.0' );
		return false;
	}

	if ( 'pre_get_posts' === current_filter() ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: pre_get_posts, 2: WP_Query->is_main_query(), 3: is_main_query(), 4: Documentation URL. */
				__( 'In %1$s, use the %2$s method, not the %3$s function. See %4$s.' ),
				'<code>pre_get_posts</code>',
				'<code>WP_Query->is_main_query()</code>',
				'<code>is_main_query()</code>',
				__( 'https://developer.wordpress.org/reference/functions/is_main_query/' )
			),
			'3.7.0'
		);
	}

	return $wp_query->is_main_query();
}

/*
 * The Loop. Post loop control.
 */

/**
 * Determines whether current WordPress query has posts to loop over.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool True if posts are available, false if end of the loop.
 */
function have_posts() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return false;
	}

	return $wp_query->have_posts();
}

/**
 * Determines whether the caller is in the Loop.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.0.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool True if caller is within loop, false if loop hasn't started or ended.
 */
function in_the_loop() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return false;
	}

	return $wp_query->in_the_loop;
}

/**
 * Rewind the loop posts.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 */
function rewind_posts() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return;
	}

	$wp_query->rewind_posts();
}

/**
 * Iterate the post index in the loop.
 *
 * @since 1.5.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 */
function the_post() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return;
	}

	$wp_query->the_post();
}

/*
 * Comments loop.
 */

/**
 * Determines whether current WordPress query has comments to loop over.
 *
 * @since 2.2.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @return bool True if comments are available, false if no more comments.
 */
function have_comments() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return false;
	}

	return $wp_query->have_comments();
}

/**
 * Iterate comment index in the comment loop.
 *
 * @since 2.2.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 */
function the_comment() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		return;
	}

	$wp_query->the_comment();
}

/**
 * Redirect old slugs to the correct permalink.
 *
 * Attempts to find the current slug from the past slugs.
 *
 * @since 2.1.0
 */
function wp_old_slug_redirect() {
	if ( is_404() && '' !== get_query_var( 'name' ) ) {
		// Guess the current post type based on the query vars.
		if ( get_query_var( 'post_type' ) ) {
			$post_type = get_query_var( 'post_type' );
		} elseif ( get_query_var( 'attachment' ) ) {
			$post_type = 'attachment';
		} elseif ( get_query_var( 'pagename' ) ) {
			$post_type = 'page';
		} else {
			$post_type = 'post';
		}

		if ( is_array( $post_type ) ) {
			if ( count( $post_type ) > 1 ) {
				return;
			}
			$post_type = reset( $post_type );
		}

		// Do not attempt redirect for hierarchical post types.
		if ( is_post_type_hierarchical( $post_type ) ) {
			return;
		}

		$id = _find_post_by_old_slug( $post_type );

		if ( ! $id ) {
			$id = _find_post_by_old_date( $post_type );
		}

		/**
		 * Filters the old slug redirect post ID.
		 *
		 * @since 4.9.3
		 *
		 * @param int $id The redirect post ID.
		 */
		$id = apply_filters( 'old_slug_redirect_post_id', $id );

		if ( ! $id ) {
			return;
		}

		$link = get_permalink( $id );

		if ( get_query_var( 'paged' ) > 1 ) {
			$link = user_trailingslashit( trailingslashit( $link ) . 'page/' . get_query_var( 'paged' ) );
		} elseif ( is_embed() ) {
			$link = user_trailingslashit( trailingslashit( $link ) . 'embed' );
		}

		/**
		 * Filters the old slug redirect URL.
		 *
		 * @since 4.4.0
		 *
		 * @param string $link The redirect URL.
		 */
		$link = apply_filters( 'old_slug_redirect_url', $link );

		if ( ! $link ) {
			return;
		}

		wp_redirect( $link, 301 ); // Permanent redirect.
		exit;
	}
}

/**
 * Find the post ID for redirecting an old slug.
 *
 * @since 4.9.3
 * @access private
 *
 * @see wp_old_slug_redirect()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $post_type The current post type based on the query vars.
 * @return int The Post ID.
 */
function _find_post_by_old_slug( $post_type ) {
	global $wpdb;

	$query = $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta, $wpdb->posts WHERE ID = post_id AND post_type = %s AND meta_key = '_wp_old_slug' AND meta_value = %s", $post_type, get_query_var( 'name' ) );

	/*
	 * If year, monthnum, or day have been specified, make our query more precise
	 * just in case there are multiple identical _wp_old_slug values.
	 */
	if ( get_query_var( 'year' ) ) {
		$query .= $wpdb->prepare( ' AND YEAR(post_date) = %d', get_query_var( 'year' ) );
	}
	if ( get_query_var( 'monthnum' ) ) {
		$query .= $wpdb->prepare( ' AND MONTH(post_date) = %d', get_query_var( 'monthnum' ) );
	}
	if ( get_query_var( 'day' ) ) {
		$query .= $wpdb->prepare( ' AND DAYOFMONTH(post_date) = %d', get_query_var( 'day' ) );
	}

	$key          = md5( $query );
	$last_changed = wp_cache_get_last_changed( 'posts' );
	$cache_key    = "find_post_by_old_slug:$key:$last_changed";
	$cache        = wp_cache_get( $cache_key, 'post-queries' );
	if ( false !== $cache ) {
		$id = $cache;
	} else {
		$id = (int) $wpdb->get_var( $query );
		wp_cache_set( $cache_key, $id, 'post-queries' );
	}

	return $id;
}

/**
 * Find the post ID for redirecting an old date.
 *
 * @since 4.9.3
 * @access private
 *
 * @see wp_old_slug_redirect()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $post_type The current post type based on the query vars.
 * @return int The Post ID.
 */
function _find_post_by_old_date( $post_type ) {
	global $wpdb;

	$date_query = '';
	if ( get_query_var( 'year' ) ) {
		$date_query .= $wpdb->prepare( ' AND YEAR(pm_date.meta_value) = %d', get_query_var( 'year' ) );
	}
	if ( get_query_var( 'monthnum' ) ) {
		$date_query .= $wpdb->prepare( ' AND MONTH(pm_date.meta_value) = %d', get_query_var( 'monthnum' ) );
	}
	if ( get_query_var( 'day' ) ) {
		$date_query .= $wpdb->prepare( ' AND DAYOFMONTH(pm_date.meta_value) = %d', get_query_var( 'day' ) );
	}

	$id = 0;
	if ( $date_query ) {
		$query        = $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta AS pm_date, $wpdb->posts WHERE ID = post_id AND post_type = %s AND meta_key = '_wp_old_date' AND post_name = %s" . $date_query, $post_type, get_query_var( 'name' ) );
		$key          = md5( $query );
		$last_changed = wp_cache_get_last_changed( 'posts' );
		$cache_key    = "find_post_by_old_date:$key:$last_changed";
		$cache        = wp_cache_get( $cache_key, 'post-queries' );
		if ( false !== $cache ) {
			$id = $cache;
		} else {
			$id = (int) $wpdb->get_var( $query );
			if ( ! $id ) {
				// Check to see if an old slug matches the old date.
				$id = (int) $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts, $wpdb->postmeta AS pm_slug, $wpdb->postmeta AS pm_date WHERE ID = pm_slug.post_id AND ID = pm_date.post_id AND post_type = %s AND pm_slug.meta_key = '_wp_old_slug' AND pm_slug.meta_value = %s AND pm_date.meta_key = '_wp_old_date'" . $date_query, $post_type, get_query_var( 'name' ) ) );
			}
			wp_cache_set( $cache_key, $id, 'post-queries' );
		}
	}

	return $id;
}

/**
 * Set up global post data.
 *
 * @since 1.5.0
 * @since 4.4.0 Added the ability to pass a post ID to `$post`.
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
 * @return bool True when finished.
 */
function setup_postdata( $post ) {
	global $wp_query;

	if ( ! empty( $wp_query ) && $wp_query instanceof WP_Query ) {
		return $wp_query->setup_postdata( $post );
	}

	return false;
}

/**
 * Generates post data.
 *
 * @since 5.2.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
 * @return array|false Elements of post, or false on failure.
 */
function generate_postdata( $post ) {
	global $wp_query;

	if ( ! empty( $wp_query ) && $wp_query instanceof WP_Query ) {
		return $wp_query->generate_postdata( $post );
	}

	return false;
}
$timestamp ] );
		}
	}

	/*
	 * If the results are empty (zero events to unschedule), no attempt
	 * to update the cron array is required.
	 */
	if ( empty( $results ) ) {
		return 0;
	}

	$set = _set_cron_array( $crons, $wp_error );

	if ( true === $set ) {
		return array_sum( $results );
	}

	return $set;
}

/**
 * Retrieves a scheduled event.
 *
 * Retrieves the full event object for a given event, if no timestamp is specified the next
 * scheduled event is returned.
 *
 * @since 5.1.0
 *
 * @param string   $hook      Action hook of the event.
 * @param array    $args      Optional. Array containing each separate argument to pass to the hook's callback function.
 *                            Although not passed to a callback, these arguments are used to uniquely identify the
 *                            event, so they should be the same as those used when originally scheduling the event.
 *                            Default empty array.
 * @param int|null $timestamp Optional. Unix timestamp (UTC) of the event. If not specified, the next scheduled event
 *                            is returned. Default null.
 * @return object|false {
 *     The event object. False if the event does not exist.
 *
 *     @type string       $hook      Action hook to execute when the event is run.
 *     @type int          $timestamp Unix timestamp (UTC) for when to next run the event.
 *     @type string|false $schedule  How often the event should subsequently recur.
 *     @type array        $args      Array containing each separate argument to pass to the hook's callback function.
 *     @type int          $interval  Optional. The interval time in seconds for the schedule. Only present for recurring events.
 * }
 */
function wp_get_scheduled_event( $hook, $args = array(), $timestamp = null ) {
	/**
	 * Filter to preflight or hijack retrieving a scheduled event.
	 *
	 * Returning a non-null value will short-circuit the normal process,
	 * returning the filtered value instead.
	 *
	 * Return false if the event does not exist, otherwise an event object
	 * should be returned.
	 *
	 * @since 5.1.0
	 *
	 * @param null|false|object $pre  Value to return instead. Default null to continue retrieving the event.
	 * @param string            $hook Action hook of the event.
	 * @param array             $args Array containing each separate argument to pass to the hook's callback function.
	 *                                Although not passed to a callback, these arguments are used to uniquely identify
	 *                                the event.
	 * @param int|null  $timestamp Unix timestamp (UTC) of the event. Null to retrieve next scheduled event.
	 */
	$pre = apply_filters( 'pre_get_scheduled_event', null, $hook, $args, $timestamp );
	if ( null !== $pre ) {
		return $pre;
	}

	if ( null !== $timestamp && ! is_numeric( $timestamp ) ) {
		return false;
	}

	$crons = _get_cron_array();
	if ( empty( $crons ) ) {
		return false;
	}

	$key = md5( serialize( $args ) );

	if ( ! $timestamp ) {
		// Get next event.
		$next = false;
		foreach ( $crons as $timestamp => $cron ) {
			if ( isset( $cron[ $hook ][ $key ] ) ) {
				$next = $timestamp;
				break;
			}
		}
		if ( ! $next ) {
			return false;
		}

		$timestamp = $next;
	} elseif ( ! isset( $crons[ $timestamp ][ $hook ][ $key ] ) ) {
		return false;
	}

	$event = (object) array(
		'hook'      => $hook,
		'timestamp' => $timestamp,
		'schedule'  => $crons[ $timestamp ][ $hook ][ $key ]['schedule'],
		'args'      => $args,
	);

	if ( isset( $crons[ $timestamp ][ $hook ][ $key ]['interval'] ) ) {
		$event->interval = $crons[ $timestamp ][ $hook ][ $key ]['interval'];
	}

	return $event;
}

/**
 * Retrieves the next timestamp for an event.
 *
 * @since 2.1.0
 *
 * @param string $hook Action hook of the event.
 * @param array  $args Optional. Array containing each separate argument to pass to the hook's callback function.
 *                     Although not passed to a callback, these arguments are used to uniquely identify the
 *                     event, so they should be the same as those used when originally scheduling the event.
 *                     Default empty array.
 * @return int|false The Unix timestamp of the next time the event will occur. False if the event doesn't exist.
 */
function wp_next_scheduled( $hook, $args = array() ) {
	$next_event = wp_get_scheduled_event( $hook, $args );
	if ( ! $next_event ) {
		return false;
	}

	return $next_event->timestamp;
}

/**
 * Sends a request to run cron through HTTP request that doesn't halt page loading.
 *
 * @since 2.1.0
 * @since 5.1.0 Return values added.
 *
 * @param int $gmt_time Optional. Unix timestamp (UTC). Default 0 (current time is used).
 * @return bool True if spawned, false if no events spawned.
 */
function spawn_cron( $gmt_time = 0 ) {
	if ( ! $gmt_time ) {
		$gmt_time = microtime( true );
	}

	if ( defined( 'DOING_CRON' ) || isset( $_GET['doing_wp_cron'] ) ) {
		return false;
	}

	/*
	 * Get the cron lock, which is a Unix timestamp of when the last cron was spawned
	 * and has not finished running.
	 *
	 * Multiple processes on multiple web servers can run this code concurrently,
	 * this lock attempts to make spawning as atomic as possible.
	 */
	$lock = get_transient( 'doing_cron' );

	if ( $lock > $gmt_time + 10 * MINUTE_IN_SECONDS ) {
		$lock = 0;
	}

	// Don't run if another process is currently running it or more than once every 60 sec.
	if ( $lock + WP_CRON_LOCK_TIMEOUT > $gmt_time ) {
		return false;
	}

	// Sanity check.
	$crons = wp_get_ready_cron_jobs();
	if ( empty( $crons ) ) {
		return false;
	}

	$keys = array_keys( $crons );
	if ( isset( $keys[0] ) && $keys[0] > $gmt_time ) {
		return false;
	}

	if ( defined( 'ALTERNATE_WP_CRON' ) && ALTERNATE_WP_CRON ) {
		if ( 'GET' !== $_SERVER['REQUEST_METHOD'] || defined( 'DOING_AJAX' ) || defined( 'XMLRPC_REQUEST' ) ) {
			return false;
		}

		$doing_wp_cron = sprintf( '%.22F', $gmt_time );
		set_transient( 'doing_cron', $doing_wp_cron );

		ob_start();
		wp_redirect( add_query_arg( 'doing_wp_cron', $doing_wp_cron, wp_unslash( $_SERVER['REQUEST_URI'] ) ) );
		echo ' ';

		// Flush any buffers and send the headers.
		wp_ob_end_flush_all();
		flush();

		require_once ABSPATH . 'wp-cron.php';
		return true;
	}

	// Set the cron lock with the current unix timestamp, when the cron is being spawned.
	$doing_wp_cron = sprintf( '%.22F', $gmt_time );
	set_transient( 'doing_cron', $doing_wp_cron );

	/**
	 * Filters the cron request arguments.
	 *
	 * @since 3.5.0
	 * @since 4.5.0 The `$doing_wp_cron` parameter was added.
	 *
	 * @param array $cron_request_array {
	 *     An array of cron request URL arguments.
	 *
	 *     @type string $url  The cron request URL.
	 *     @type int    $key  The 22 digit GMT microtime.
	 *     @type array  $args {
	 *         An array of cron request arguments.
	 *
	 *         @type int  $timeout   The request timeout in seconds. Default .01 seconds.
	 *         @type bool $blocking  Whether to set blocking for the request. Default false.
	 *         @type bool $sslverify Whether SSL should be verified for the request. Default false.
	 *     }
	 * }
	 * @param string $doing_wp_cron The unix timestamp of the cron lock.
	 */
	$cron_request = apply_filters(
		'cron_request',
		array(
			'url'  => add_query_arg( 'doing_wp_cron', $doing_wp_cron, site_url( 'wp-cron.php' ) ),
			'key'  => $doing_wp_cron,
			'args' => array(
				'timeout'   => 0.01,
				'blocking'  => false,
				/** This filter is documented in wp-includes/class-wp-http-streams.php */
				'sslverify' => apply_filters( 'https_local_ssl_verify', false ),
			),
		),
		$doing_wp_cron
	);

	$result = wp_remote_post( $cron_request['url'], $cron_request['args'] );
	return ! is_wp_error( $result );
}

/**
 * Registers _wp_cron() to run on the {@see 'wp_loaded'} action.
 *
 * If the {@see 'wp_loaded'} action has already fired, this function calls
 * _wp_cron() directly.
 *
 * Warning: This function may return Boolean FALSE, but may also return a non-Boolean
 * value which evaluates to FALSE. For information about casting to booleans see the
 * {@link https://www.php.net/manual/en/language.types.boolean.php PHP documentation}. Use
 * the `===` operator for testing the return value of this function.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value added to indicate success or failure.
 * @since 5.7.0 Functionality moved to _wp_cron() to which this becomes a wrapper.
 *
 * @return bool|int|void On success an integer indicating number of events spawned (0 indicates no
 *                       events needed to be spawned), false if spawning fails for one or more events or
 *                       void if the function registered _wp_cron() to run on the action.
 */
function wp_cron() {
	if ( did_action( 'wp_loaded' ) ) {
		return _wp_cron();
	}

	add_action( 'wp_loaded', '_wp_cron', 20 );
}

/**
 * Runs scheduled callbacks or spawns cron for all scheduled events.
 *
 * Warning: This function may return Boolean FALSE, but may also return a non-Boolean
 * value which evaluates to FALSE. For information about casting to booleans see the
 * {@link https://www.php.net/manual/en/language.types.boolean.php PHP documentation}. Use
 * the `===` operator for testing the return value of this function.
 *
 * @since 5.7.0
 * @access private
 *
 * @return int|false On success an integer indicating number of events spawned (0 indicates no
 *                   events needed to be spawned), false if spawning fails for one or more events.
 */
function _wp_cron() {
	// Prevent infinite loops caused by lack of wp-cron.php.
	if ( str_contains( $_SERVER['REQUEST_URI'], '/wp-cron.php' ) || ( defined( 'DISABLE_WP_CRON' ) && DISABLE_WP_CRON ) ) {
		return 0;
	}

	$crons = wp_get_ready_cron_jobs();
	if ( empty( $crons ) ) {
		return 0;
	}

	$gmt_time = microtime( true );
	$keys     = array_keys( $crons );
	if ( isset( $keys[0] ) && $keys[0] > $gmt_time ) {
		return 0;
	}

	$schedules = wp_get_schedules();
	$results   = array();
	foreach ( $crons as $timestamp => $cronhooks ) {
		if ( $timestamp > $gmt_time ) {
			break;
		}
		foreach ( (array) $cronhooks as $hook => $args ) {
			if ( isset( $schedules[ $hook ]['callback'] ) && ! call_user_func( $schedules[ $hook ]['callback'] ) ) {
				continue;
			}
			$results[] = spawn_cron( $gmt_time );
			break 2;
		}
	}

	if ( in_array( false, $results, true ) ) {
		return false;
	}
	return count( $results );
}

/**
 * Retrieves supported event recurrence schedules.
 *
 * The default supported recurrences are 'hourly', 'twicedaily', 'daily', and 'weekly'.
 * A plugin may add more by hooking into the {@see 'cron_schedules'} filter.
 * The filter accepts an array of arrays. The outer array has a key that is the name
 * of the schedule, for example 'monthly'. The value is an array with two keys,
 * one is 'interval' and the other is 'display'.
 *
 * The 'interval' is a number in seconds of when the cron job should run.
 * So for 'hourly' the time is `HOUR_IN_SECONDS` (60 * 60 or 3600). For 'monthly',
 * the value would be `MONTH_IN_SECONDS` (30 * 24 * 60 * 60 or 2592000).
 *
 * The 'display' is the description. For the 'monthly' key, the 'display'
 * would be `__( 'Once Monthly' )`.
 *
 * For your plugin, you will be passed an array. You can easily add your
 * schedule by doing the following.
 *
 *     // Filter parameter variable name is 'array'.
 *     $array['monthly'] = array(
 *         'interval' => MONTH_IN_SECONDS,
 *         'display'  => __( 'Once Monthly' )
 *     );
 *
 * @since 2.1.0
 * @since 5.4.0 The 'weekly' schedule was added.
 *
 * @return array {
 *     The array of cron schedules keyed by the schedule name.
 *
 *     @type array ...$0 {
 *         Cron schedule information.
 *
 *         @type int    $interval The schedule interval in seconds.
 *         @type string $display  The schedule display name.
 *     }
 * }
 */
function wp_get_schedules() {
	$schedules = array(
		'hourly'     => array(
			'interval' => HOUR_IN_SECONDS,
			'display'  => __( 'Once Hourly' ),
		),
		'twicedaily' => array(
			'interval' => 12 * HOUR_IN_SECONDS,
			'display'  => __( 'Twice Daily' ),
		),
		'daily'      => array(
			'interval' => DAY_IN_SECONDS,
			'display'  => __( 'Once Daily' ),
		),
		'weekly'     => array(
			'interval' => WEEK_IN_SECONDS,
			'display'  => __( 'Once Weekly' ),
		),
	);

	/**
	 * Filters the non-default cron schedules.
	 *
	 * @since 2.1.0
	 *
	 * @param array $new_schedules {
	 *     An array of non-default cron schedules keyed by the schedule name. Default empty array.
	 *
	 *     @type array ...$0 {
	 *         Cron schedule information.
	 *
	 *         @type int    $interval The schedule interval in seconds.
	 *         @type string $display  The schedule display name.
	 *     }
	 * }
	 */
	return array_merge( apply_filters( 'cron_schedules', array() ), $schedules );
}

/**
 * Retrieves the name of the recurrence schedule for an event.
 *
 * @see wp_get_schedules() for available schedules.
 *
 * @since 2.1.0
 * @since 5.1.0 {@see 'get_schedule'} filter added.
 *
 * @param string $hook Action hook to identify the event.
 * @param array  $args Optional. Arguments passed to the event's callback function.
 *                     Default empty array.
 * @return string|false Schedule name on success, false if no schedule.
 */
function wp_get_schedule( $hook, $args = array() ) {
	$schedule = false;
	$event    = wp_get_scheduled_event( $hook, $args );

	if ( $event ) {
		$schedule = $event->schedule;
	}

	/**
	 * Filters the schedule name for a hook.
	 *
	 * @since 5.1.0
	 *
	 * @param string|false $schedule Schedule for the hook. False if not found.
	 * @param string       $hook     Action hook to execute when cron is run.
	 * @param array        $args     Arguments to pass to the hook's callback function.
	 */
	return apply_filters( 'get_schedule', $schedule, $hook, $args );
}

/**
 * Retrieves cron jobs ready to be run.
 *
 * Returns the results of _get_cron_array() limited to events ready to be run,
 * ie, with a timestamp in the past.
 *
 * @since 5.1.0
 *
 * @return array[] Array of cron job arrays ready to be run.
 */
function wp_get_ready_cron_jobs() {
	/**
	 * Filter to preflight or hijack retrieving ready cron jobs.
	 *
	 * Returning an array will short-circuit the normal retrieval of ready
	 * cron jobs, causing the function to return the filtered value instead.
	 *
	 * @since 5.1.0
	 *
	 * @param null|array[] $pre Array of ready cron tasks to return instead. Default null
	 *                          to continue using results from _get_cron_array().
	 */
	$pre = apply_filters( 'pre_get_ready_cron_jobs', null );

	if ( null !== $pre ) {
		return $pre;
	}

	$crons    = _get_cron_array();
	$gmt_time = microtime( true );
	$results  = array();

	foreach ( $crons as $timestamp => $cronhooks ) {
		if ( $timestamp > $gmt_time ) {
			break;
		}

		$results[ $timestamp ] = $cronhooks;
	}

	return $results;
}

//
// Private functions.
//

/**
 * Retrieves cron info array option.
 *
 * @since 2.1.0
 * @since 6.1.0 Return type modified to consistently return an array.
 * @access private
 *
 * @return array[] Array of cron events.
 */
function _get_cron_array() {
	$cron = get_option( 'cron' );
	if ( ! is_array( $cron ) ) {
		return array();
	}

	if ( ! isset( $cron['version'] ) ) {
		$cron = _upgrade_cron_array( $cron );
	}

	unset( $cron['version'] );

	return $cron;
}

/**
 * Updates the cron option with the new cron array.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to outcome of update_option().
 * @since 5.7.0 The `$wp_error` parameter was added.
 *
 * @access private
 *
 * @param array[] $cron     Array of cron info arrays from _get_cron_array().
 * @param bool    $wp_error Optional. Whether to return a WP_Error on failure. Default false.
 * @return bool|WP_Error True if cron array updated. False or WP_Error on failure.
 */
function _set_cron_array( $cron, $wp_error = false ) {
	if ( ! is_array( $cron ) ) {
		$cron = array();
	}

	$cron['version'] = 2;
	$result          = update_option( 'cron', $cron );

	if ( $wp_error && ! $result ) {
		return new WP_Error(
			'could_not_set',
			__( 'The cron event list could not be saved.' )
		);
	}

	return $result;
}

/**
 * Upgrades a cron info array.
 *
 * This function upgrades the cron info array to version 2.
 *
 * @since 2.1.0
 * @access private
 *
 * @param array $cron Cron info array from _get_cron_array().
 * @return array An upgraded cron info array.
 */
function _upgrade_cron_array( $cron ) {
	if ( isset( $cron['version'] ) && 2 == $cron['version'] ) {
		return $cron;
	}

	$new_cron = array();

	foreach ( (array) $cron as $timestamp => $hooks ) {
		foreach ( (array) $hooks as $hook => $args ) {
			$key                                     = md5( serialize( $args['args'] ) );
			$new_cron[ $timestamp ][ $hook ][ $key ] = $args;
		}
	}

	$new_cron['version'] = 2;
	update_option( 'cron', $new_cron );
	return $new_cron;
}