<?php

/**
 * @author Janis Elsts
 * @copyright 2010
 */

if ( ! class_exists( 'blcEmbedParserBase' ) ) :

	/**
	 * Base class for embedded video/audio parsers.
	 *
	 * Sub-classes should override the link_url_from_src() method and set the $url_search_string,
	 * $short_title and $long_title properties to meaningful values.
	 *
	 * @package Broken Link Checker
	 * @author Janis Elsts
	 * @access public
	 */
	class blcEmbedParserBase extends blcParser {
		var $supported_formats = array( 'html' );

		var $short_title       = '';      //Short desc. of embeds handled by this parser, singular. Example: "YouTube Video".
		var $long_title        = '';       //Longer version of the above, e.g. "Embedded YouTube video".
		var $url_search_string = '';//Only consider embeds where the SRC contains this string. Example: "youtube.com/v/"

		/**
		 * Parse a string for embed codes.
		 *
		 * @param string $content The text to parse.
		 * @param string $base_url The base URL. Ignored.
		 * @param string $default_link_text Default link text. Ignored.
		 * @return array An array of new blcLinkInstance objects. The objects will include info about the embeds found, but not about the corresponding container entity.
		 */
		function parse( $content, $base_url = '', $default_link_text = '' ) {
			$instances = array();

			//Find likely-looking <embed> elements
			$embeds = $this->extract_embeds( $content );
			foreach ( $embeds as $embed ) {
				//Do we know how to handle this embed? (first-pass verification)
				if ( strpos( $embed['attributes']['src'], $this->url_search_string ) === false ) {
					continue;
				}

				//Get the original URL of the embedded object (may perform more complex verification)
				$url = $this->link_url_from_src( $embed['attributes']['src'] );
				if ( empty( $url ) ) {
					continue;
				}

				//Create a new link instance.
				$instance = new blcLinkInstance();

				$instance->set_parser( $this );
				$instance->raw_url   = $embed['embed_code'];
				$instance->link_text = '[' . $this->short_title . ']';

				$link_obj = new blcLink( $url ); //Creates or loads the link
				$instance->set_link( $link_obj );

				$instances[] = $instance;
			}

			return $instances;
		}

		/**
		 * Extract embedded elements from a HTML string.
		 *
		 * This function returns an array of <embed> elements found in the input
		 * string. Embeds without a 'src' attribute are skipped.
		 *
		 * Each array item has the same basic structure as the array items
		 * returned by blcUtility::extract_tags(), plus an additional 'embed_code' key
		 * that contains the HTML code for the element. If the embed element is wrapped
		 * in an <object>, the 'embed_code' key contains the full HTML for the entire
		 * <object> + <embed> structure.
		 *
		 * @uses blcUtility::extract_tags() This function is a simple wrapper around extract_tags()
		 *
		 * @param string $html
		 * @return array
		 */
		function extract_embeds( $html ) {
			$results = array();

			//remove all <code></code> blocks first
			$html = preg_replace( '/<code[^>]*>.+?<\/code>/si', ' ', $html );

			//Find likely-looking <object> elements
			$objects = blcUtility::extract_tags( $html, 'object', false, true );
			foreach ( $objects as $candidate ) {
				//Find the <embed> tag
				$embed = blcUtility::extract_tags( $candidate['full_tag'], 'embed', true );
				if ( empty( $embed ) ) {
					continue;
				}
				$embed = reset( $embed ); //Take the first (and only) found <embed> element

				if ( empty( $embed['attributes']['src'] ) ) {
					continue;
				}

				$embed['embed_code'] = $candidate['full_tag'];

				$results[] = $embed;

				//Remove the element so it doesn't come up when we search for plain <embed> elements.
				$html = str_replace( $candidate['full_tag'], ' ', $html );
			}

			//Find <embed> elements not wrapped in an <object> element.
			$embeds = blcUtility::extract_tags( $html, 'embed', true, true );
			foreach ( $embeds as $embed ) {
				if ( ! empty( $embed['attributes']['src'] ) ) {
					$embed['embed_code'] = $embed['full_tag'];
					$results[]           = $embed;
				}
			}

			return $results;
		}

		/**
		 * Remove all occurrences of the specified embed from a string.
		 *
		 * @param string $content Look for embeds in this string.
		 * @param string $url Ignored.
		 * @param string $embed_code The full embed code to look for.
		 * @return string Input string with all matching embeds removed.
		 */
		function unlink( $content, $url, $embed_code ) {
			if ( empty( $embed_code ) ) {
				return $content;
			}

			return str_replace( $embed_code, '', $content ); //Super-simple.
		}

		/**
		 * Get the link text for printing in the "Broken Links" table.
		 *
		 * @param blcLinkInstance $instance
		 * @param string $context
		 * @return string HTML
		 */
		function ui_get_link_text( $instance, $context = 'display' ) {
			$image_url = sprintf(
				'/images/%s.png',
				$this->parser_type
			);

			$image_html = sprintf(
				'<img src="%s" class="blc-small-image" title="%2$s" alt="%2$s"> ',
				esc_attr( plugins_url( $image_url, BLC_PLUGIN_FILE_LEGACY ) ),
				$this->long_title
			);

			$field_html = sprintf(
				'%s',
				$this->short_title
			);

			if ( 'email' != $context ) {
				$field_html = $image_html . $field_html;
			}

			return $field_html;
		}

		/**
		 * Determine the original URL of an embedded object by analysing its SRC attribute.
		 *
		 * For example, if the object in question is an embedded YouTube video, this
		 * method should return the URL of the original video; e.g. 'http://www.youtube.com/watch?v=example1234'
		 *
		 * Should be overridden in a sub-class.
		 *
		 * @param string $src
		 * @return string The URL of the embedded object, or an empty string if the URL can't be determined.
		 */
		function link_url_from_src( $src ) {
			return '';
		}

		/**
		 * Editing is disabled in embed parsers. Calling this function will yield an instance of WP_Error.
		 *
		 * @param string $content
		 * @param string $new_url
		 * @param string $old_url
		 * @param string $old_raw_url
		 * @return WP_Error
		 */
		function edit( $content, $new_url, $old_url, $old_raw_url ) {
			return new WP_Error(
				'not_implemented',
				sprintf( __( "Embedded videos can't be edited using Broken Link Checker. Please edit or replace the video in question manually.", 'broken-link-checker' ), $this->parser_type )
			);
		}

		public function is_url_editable() {
			return false;
		}

	}

endif;