<?php
/**
 * WordPress Post Thumbnail Template Functions.
 *
 * Support for post thumbnails.
 * Theme's functions.php must call add_theme_support( 'post-thumbnails' ) to use these.
 *
 * @package WordPress
 * @subpackage Template
 */

/**
 * Determines whether a post has an image attached.
 *
 * 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 2.9.0
 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return bool Whether the post has an image attached.
 */
function has_post_thumbnail( $post = null ) {
    $thumbnail_id  = get_post_thumbnail_id( $post );
    $has_thumbnail = (bool) $thumbnail_id;

    /**
     * Filters whether a post has a post thumbnail.
     *
     * @since 5.1.0
     *
     * @param bool             $has_thumbnail true if the post has a post thumbnail, otherwise false.
     * @param int|WP_Post|null $post          Post ID or WP_Post object. Default is global `$post`.
     * @param int|false        $thumbnail_id  Post thumbnail ID or false if the post does not exist.
     */
    return (bool) apply_filters( 'has_post_thumbnail', $has_thumbnail, $post, $thumbnail_id );
}

/**
 * Retrieves the post thumbnail ID.
 *
 * @since 2.9.0
 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
 * @since 5.5.0 The return value for a non-existing post
 *              was changed to false instead of an empty string.
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return int|false Post thumbnail ID (which can be 0 if the thumbnail is not set),
 *                   or false if the post does not exist.
 */
function get_post_thumbnail_id( $post = null ) {
    $post = get_post( $post );

    if ( ! $post ) {
        return false;
    }

    $thumbnail_id = (int) get_post_meta( $post->ID, '_thumbnail_id', true );

    /**
     * Filters the post thumbnail ID.
     *
     * @since 5.9.0
     *
     * @param int|false        $thumbnail_id Post thumbnail ID or false if the post does not exist.
     * @param int|WP_Post|null $post         Post ID or WP_Post object. Default is global `$post`.
     */
    return (int) apply_filters( 'post_thumbnail_id', $thumbnail_id, $post );
}

/**
 * Displays the post thumbnail.
 *
 * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
 * is registered, which differs from the 'thumbnail' image size managed via the
 * Settings > Media screen.
 *
 * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
 * size is used by default, though a different size can be specified instead as needed.
 *
 * @since 2.9.0
 *
 * @see get_the_post_thumbnail()
 *
 * @param string|int[] $size Optional. Image size. Accepts any registered image size name, or an array of
 *                           width and height values in pixels (in that order). Default 'post-thumbnail'.
 * @param string|array $attr Optional. Query string or array of attributes. Default empty.
 */
function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
    echo get_the_post_thumbnail( null, $size, $attr );
}

/**
 * Updates cache for thumbnails in the current loop.
 *
 * @since 3.2.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param WP_Query|null $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.
 */
function update_post_thumbnail_cache( $wp_query = null ) {
    if ( ! $wp_query ) {
        $wp_query = $GLOBALS['wp_query'];
    }

    if ( $wp_query->thumbnails_cached ) {
        return;
    }

    $thumb_ids = array();

    /*
     * $wp_query may contain an array of post objects or post IDs.
     *
     * This ensures the cache is primed for all post objects to avoid
     * `get_post()` calls in `get_the_post_thumbnail()` triggering an
     * additional database call for each post.
     */
    $parent_post_ids = array();
    foreach ( $wp_query->posts as $post ) {
        if ( $post instanceof WP_Post ) {
            $parent_post_ids[] = $post->ID;
        } elseif ( is_int( $post ) ) {
            $parent_post_ids[] = $post;
        }
    }
    _prime_post_caches( $parent_post_ids, false, true );

    foreach ( $wp_query->posts as $post ) {
        $id = get_post_thumbnail_id( $post );
        if ( $id ) {
            $thumb_ids[] = $id;
        }
    }

    if ( ! empty( $thumb_ids ) ) {
        _prime_post_caches( $thumb_ids, false, true );
    }

    $wp_query->thumbnails_cached = true;
}

/**
 * Retrieves the post thumbnail.
 *
 * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
 * is registered, which differs from the 'thumbnail' image size managed via the
 * Settings > Media screen.
 *
 * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
 * size is used by default, though a different size can be specified instead as needed.
 *
 * @since 2.9.0
 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object.  Default is global `$post`.
 * @param string|int[]     $size Optional. Image size. Accepts any registered image size name, or an array of
 *                               width and height values in pixels (in that order). Default 'post-thumbnail'.
 * @param string|array     $attr Optional. Query string or array of attributes. Default empty.
 * @return string The post thumbnail image tag.
 */
function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr = '' ) {
    $post = get_post( $post );

    if ( ! $post ) {
        return '';
    }

    $post_thumbnail_id = get_post_thumbnail_id( $post );

    /**
     * Filters the post thumbnail size.
     *
     * @since 2.9.0
     * @since 4.9.0 Added the `$post_id` parameter.
     *
     * @param string|int[] $size    Requested image size. Can be any registered image size name, or
     *                              an array of width and height values in pixels (in that order).
     * @param int          $post_id The post ID.
     */
    $size = apply_filters( 'post_thumbnail_size', $size, $post->ID );

    if ( $post_thumbnail_id ) {

        /**
         * Fires before fetching the post thumbnail HTML.
         *
         * Provides "just in time" filtering of all filters in wp_get_attachment_image().
         *
         * @since 2.9.0
         *
         * @param int          $post_id           The post ID.
         * @param int          $post_thumbnail_id The post thumbnail ID.
         * @param string|int[] $size              Requested image size. Can be any registered image size name, or
         *                                        an array of width and height values in pixels (in that order).
         */
        do_action( 'begin_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );

        if ( in_the_loop() ) {
            update_post_thumbnail_cache();
        }

        $html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );

        /**
         * Fires after fetching the post thumbnail HTML.
         *
         * @since 2.9.0
         *
         * @param int          $post_id           The post ID.
         * @param int          $post_thumbnail_id The post thumbnail ID.
         * @param string|int[] $size              Requested image size. Can be any registered image size name, or
         *                                        an array of width and height values in pixels (in that order).
         */
        do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );

    } else {
        $html = '';
    }

    /**
     * Filters the post thumbnail HTML.
     *
     * @since 2.9.0
     *
     * @param string       $html              The post thumbnail HTML.
     * @param int          $post_id           The post ID.
     * @param int          $post_thumbnail_id The post thumbnail ID, or 0 if there isn't one.
     * @param string|int[] $size              Requested image size. Can be any registered image size name, or
     *                                        an array of width and height values in pixels (in that order).
     * @param string|array $attr              Query string or array of attributes.
     */
    return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
}

/**
 * Returns the post thumbnail URL.
 *
 * @since 4.4.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object.  Default is global `$post`.
 * @param string|int[]     $size Optional. Registered image size to retrieve the source for or a flat array
 *                               of height and width dimensions. Default 'post-thumbnail'.
 * @return string|false Post thumbnail URL or false if no image is available. If `$size` does not match
 *                      any registered image size, the original image URL will be returned.
 */
function get_the_post_thumbnail_url( $post = null, $size = 'post-thumbnail' ) {
    $post_thumbnail_id = get_post_thumbnail_id( $post );

    if ( ! $post_thumbnail_id ) {
        return false;
    }

    $thumbnail_url = wp_get_attachment_image_url( $post_thumbnail_id, $size );

    /**
     * Filters the post thumbnail URL.
     *
     * @since 5.9.0
     *
     * @param string|false     $thumbnail_url Post thumbnail URL or false if the post does not exist.
     * @param int|WP_Post|null $post          Post ID or WP_Post object. Default is global `$post`.
     * @param string|int[]     $size          Registered image size to retrieve the source for or a flat array
     *                                        of height and width dimensions. Default 'post-thumbnail'.
     */
    return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
}

/**
 * Displays the post thumbnail URL.
 *
 * @since 4.4.0
 *
 * @param string|int[] $size Optional. Image size to use. Accepts any valid image size,
 *                           or an array of width and height values in pixels (in that order).
 *                           Default 'post-thumbnail'.
 */
function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
    $url = get_the_post_thumbnail_url( null, $size );

    if ( $url ) {
        echo esc_url( $url );
    }
}

/**
 * Returns the post thumbnail caption.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return string Post thumbnail caption.
 */
function get_the_post_thumbnail_caption( $post = null ) {
    $post_thumbnail_id = get_post_thumbnail_id( $post );

    if ( ! $post_thumbnail_id ) {
        return '';
    }

    $caption = wp_get_attachment_caption( $post_thumbnail_id );

    if ( ! $caption ) {
        $caption = '';
    }

    return $caption;
}

/**
 * Displays the post thumbnail caption.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 */
function the_post_thumbnail_caption( $post = null ) {
    /**
     * Filters the displayed post thumbnail caption.
     *
     * @since 4.6.0
     *
     * @param string $caption Caption for the given attachment.
     */
    echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
}