<?php



function has_post_thumbnail( $post = null ) {
	$thumbnail_id  = get_post_thumbnail_id( $post );
	$has_thumbnail = (bool) $thumbnail_id;

	
	return (bool) apply_filters( 'has_post_thumbnail', $has_thumbnail, $post, $thumbnail_id );
}


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 );

	
	return (int) apply_filters( 'post_thumbnail_id', $thumbnail_id, $post );
}


function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
	echo get_the_post_thumbnail( null, $size, $attr );
}


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;
}


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 );

	
	$size = apply_filters( 'post_thumbnail_size', $size, $post->ID );

	if ( $post_thumbnail_id ) {

		
		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 );

		
		do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );

	} else {
		$html = '';
	}

	
	return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
}


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 );

	
	return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
}


function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
	$url = get_the_post_thumbnail_url( null, $size );

	if ( $url ) {
		echo esc_url( $url );
	}
}


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;
}


function the_post_thumbnail_caption( $post = null ) {
	
	echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
}