<?php
/**
 * Facebook embeds
 */

define( 'JETPACK_FACEBOOK_EMBED_REGEX', '#^https?://(www.)?facebook\.com/([^/]+)/(posts|photos)/([^/]+)?#' );
define( 'JETPACK_FACEBOOK_ALTERNATE_EMBED_REGEX', '#^https?://(www.)?facebook\.com/permalink.php\?([^\s]+)#' );
define( 'JETPACK_FACEBOOK_PHOTO_EMBED_REGEX', '#^https?://(www.)?facebook\.com/photo.php\?([^\s]+)#' );
define( 'JETPACK_FACEBOOK_PHOTO_ALTERNATE_EMBED_REGEX', '#^https?://(www.)?facebook\.com/([^/]+)/photos/([^/]+)?#' );
define( 'JETPACK_FACEBOOK_VIDEO_EMBED_REGEX', '#^https?://(www.)?facebook\.com/video.php\?([^\s]+)#' );
define( 'JETPACK_FACEBOOK_VIDEO_ALTERNATE_EMBED_REGEX', '#^https?://(www.)?facebook\.com/([^/]+)/videos/([^/]+)?#' );


// Example URL: https://www.facebook.com/VenusWilliams/posts/10151647007373076
wp_embed_register_handler( 'facebook', JETPACK_FACEBOOK_EMBED_REGEX, 'jetpack_facebook_embed_handler' );

// Example URL: https://www.facebook.com/permalink.php?id=222622504529111&story_fbid=559431180743788
wp_embed_register_handler( 'facebook-alternate', JETPACK_FACEBOOK_ALTERNATE_EMBED_REGEX, 'jetpack_facebook_embed_handler' );

// Photos are handled on a different endpoint; e.g. https://www.facebook.com/photo.php?fbid=10151609960150073&set=a.398410140072.163165.106666030072&type=1
wp_embed_register_handler( 'facebook-photo', JETPACK_FACEBOOK_PHOTO_EMBED_REGEX, 'jetpack_facebook_embed_handler' );

// Photos (from pages for example) can be at
wp_embed_register_handler( 'facebook-alternate-photo', JETPACK_FACEBOOK_PHOTO_ALTERNATE_EMBED_REGEX, 'jetpack_facebook_embed_handler' );

// Videos e.g. https://www.facebook.com/video.php?v=772471122790796
wp_embed_register_handler( 'facebook-video', JETPACK_FACEBOOK_VIDEO_EMBED_REGEX, 'jetpack_facebook_embed_handler' );
// Videos  https://www.facebook.com/WhiteHouse/videos/10153398464269238/
wp_embed_register_handler( 'facebook-alternate-video', JETPACK_FACEBOOK_VIDEO_ALTERNATE_EMBED_REGEX, 'jetpack_facebook_embed_handler' );

function jetpack_facebook_embed_handler( $matches, $attr, $url ) {
	if ( false !== strpos( $url, 'video.php' ) || false !== strpos( $url, '/videos/' ) ) {
		$embed = sprintf( '<div class="fb-video" data-allowfullscreen="true" data-href="%s"></div>', esc_url( $url ) );
	} else {
		$width = 552; // As of 01/2017, the default width of Facebook embeds when no width attribute provided

		global $content_width;
		if ( isset( $content_width ) ) {
			$width = min( $width, $content_width );
		}

		$embed = sprintf( '<fb:post href="%s" data-width="%s"></fb:post>', esc_url( $url ), esc_attr( $width ) );
	}

	// since Facebook is a faux embed, we need to load the JS SDK in the wpview embed iframe
	if ( defined( 'DOING_AJAX' ) && DOING_AJAX && ! empty( $_POST['action'] ) && 'parse-embed' == $_POST['action'] ) {
		ob_start();
		wp_scripts()->do_items( array( 'jetpack-facebook-embed' ) );
		$scripts = ob_get_clean();
		return $embed . $scripts;
	} else {
		wp_enqueue_script( 'jetpack-facebook-embed' );
		return $embed;
	}
}

add_shortcode( 'facebook', 'jetpack_facebook_shortcode_handler' );

function jetpack_facebook_shortcode_handler( $atts ) {
	global $wp_embed;

	if ( empty( $atts['url'] ) )
		return;

	if ( ! preg_match( JETPACK_FACEBOOK_EMBED_REGEX, $atts['url'] )
	&& ! preg_match( JETPACK_FACEBOOK_PHOTO_EMBED_REGEX, $atts['url'] )
	&& ! preg_match( JETPACK_FACEBOOK_VIDEO_EMBED_REGEX, $atts['url'] )
	&& ! preg_match( JETPACK_FACEBOOK_VIDEO_ALTERNATE_EMBED_REGEX, $atts['url'] )  ) {
		return;
	}

	return $wp_embed->shortcode( $atts, $atts['url'] );
}