<?php
/**
 * iframe Component
 *
 * @since 1.0.0
 */
class Amp_WP_iFrame_Component implements Amp_WP_Component_Interface {
	/**
	 * Store list of services that exclusively support
	 *
	 * @since 1.0.0
	 * @var array
	 */
    public $support_sites = array(
        'youtube',
        'twitter',
        'facebook',
        'vimeo',
        'soundcloud',
        'vine',
        'instagram',
        'instagr',
    );

	/**
	 * @see   Amp_WP_Component_Base::$enable_enqueue_scripts
	 *
	 * @var		bool
	 * @since		1.0.0
	 */
    public $enable_enqueue_scripts = false;

	/**
	 * Contract implementation
	 *
	 * @since 1.0.0
	 *
	 * @return array
	 */
    public function config() {
        return array(
            'scripts' => array(
                'amp-iframe' => 'https://cdn.ampproject.org/v0/amp-iframe-0.1.js'
            )
        );
    }
    
    public function head() {
        add_filter( 'embed_oembed_html', array( $this, 'amp_embedded' ), 8, 2 );
        add_action( 'wp_video_shortcode', array( $this, 'wp_video_shortcode' ), 8, 2 );
    }

	/**
	 * Change Popular Embedded Websites to AMP Version
	 *
	 * @param string $html
	 * @param string $url
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_embedded( $html, $url, $options = array() ) {
        if( !preg_match( '#https?://(?:www|m)?\.?([^\.]+)#', $url, $matched ) ) {
            return $html;
        }
        $provider = $matched[1];
        if( !in_array( $provider, $this->support_sites ) ) {
            return $html;
        }
        switch ( $provider ) {
            case 'youtube':
				if( $video_id = self::extract_youtube_video_id( $url ) ) {
					$dim = $this->get_iframe_dimension( $html, 'height', 'width', $options );
					// $dim[0] has Height whereas $dim[1] has width;
					return $this->amp_youtube_html( $video_id, '270', '480' );
				}
            break;
            case 'twitter':
				if( preg_match( '#https?://(?:www\.)?twitter\.com/\w{1,15}/status(?:es)?/(.*)#i', $url, $matched ) ) {
					$tweet_id = array_pop( $matched );
					$width = $this->get_iframe_dimension( $html, false, 'data-width', $options );
					return $this->amp_twitter_html( $tweet_id, $width );
				}
            break;
            case 'facebook':
				if( preg_match( '#https?://www\.facebook\.com/.*/posts/.*#i', $url ) ) {
					return $this->amp_facebook_html( $url );
				}
				if( preg_match( '#https?://www\.facebook\.com/.*/videos/.*#i', $url ) ) {
					return $this->amp_facebook_html( $url, true );
				}
            break;
            case 'vimeo':
				if( preg_match( '#https?://(?:.+\.)?vimeo\.com/.*?(\d+)$#i', $url, $matched ) ) {
					$video_id = array_pop( $matched );
					$dim = $this->get_iframe_dimension( $html, 'height', 'width', $options );
					return $this->amp_vimeo_html( $video_id, $dim[0], $dim[1] );
				}
            break;
            case 'soundcloud' :
				if( preg_match( '#https?://(www\.)?soundcloud\.com/.*#i', $url, $matched ) ) {
					if( $track_id = $this->get_soundcloud_track_id( $html ) ) {
						$dim = $this->get_iframe_dimension( $html, 'height', false, $options );
						return $this->amp_soundcloud_html( $track_id, $dim[0] );
					}
				}
            break;
            case 'vine':
				if( preg_match( '#https?://vine\.co/v/(.*)#i', $url, $matched ) ) {
					$vine_id = $matched[1];
					$dim = $this->get_iframe_dimension( $html, 'height', 'width', $options );
					return $this->amp_vine_html( $vine_id, $dim[0], $dim[1] );
				}
            break;
            case 'instagr':
            case 'instagram':
				if( preg_match( '#https?://(?:www\.)?instagr(?:\.am|am\.com)/p/([^\/]+)#i', $url, $matched ) ) {
					$shortcode = $matched[1];
					return $this->amp_instagram_html( $shortcode );
				}
            break;
        }
        return $html;
    }

	/**
	 * Get specific html attribute from html string
	 *
	 * @param string $html
	 * @param string $attr
	 * @param string $tag
	 *
	 * @return bool|string string attribute value on success or false on failure.
	 * @since 1.0.0
	 */
    public function get_html_attr( $html, $attr, $tag = 'iframe' ) {
        if ( preg_match( "'<$tag\s.*?$attr\s*=\s*
                                        ([\"\'])?
                                        (?(1) (.*?)\\1 | ([^\s\>]+))
                                        'isx", $html, $match ) ) {
            return array_pop( $match );
        }
        return false;
    }

	/**
	 * Generate iFrame Dimensions
	 *
	 * @param	string $string
	 * @param	string $height_attr
	 * @param	string $width_attr
	 * @param	array  $defaults
	 *
	 * @return	array
	 * @since		1.0.0
	 */
	public function get_iframe_dimension( $string, $height_attr = 'height', $width_attr = 'width', $defaults = array() ) {
		
		$width = !empty( $defaults['width'] ) ? $defaults['width'] : 480;
		
		if( $width_attr ) {
			if ( $_width = $this->get_html_attr( $string, $width_attr ) ) {
				$width = $_width;
			}
		}

		$height = !empty( $defaults['height'] ) ? $defaults['height'] : 480;
		if( $height_attr ) {
			if( $_height = $this->get_html_attr( $string, $height_attr ) ) {
				$height = $_height;
			}
		}
		return array( $height, $width );
    }

	/**
	 * Generate amp-twitter html
	 *
	 * @param string $tweet_id
	 * @param int    $width
	 *
	 * @return string
	 * @since 1.0.0
	 */
    public function amp_twitter_html( $tweet_id, $width ) {
        amp_wp_enqueue_script( 'amp-twitter', 'https://cdn.ampproject.org/v0/amp-twitter-0.1.js' );
        return sprintf( '<amp-twitter width="%d" height="%d" layout="responsive" data-tweetid="%s"></amp-twitter>', $width, $width, $tweet_id );
    }

	/**
	 * Generate amp-facebook html
	 *
	 * @param string $url
	 * @param bool   $is_video
	 *
	 * @return string
	 * @since 1.0.0
	 */
    public function amp_facebook_html( $url, $is_video = false ) {
        amp_wp_enqueue_script( 'amp-facebook', 'https://cdn.ampproject.org/v0/amp-facebook-0.1.js' );
        $atts = '';
        if( $is_video ) { $atts .= ' data-embed-as="video"'; }
        return sprintf( '<amp-facebook %s width="700" height="400" layout="responsive" data-href="%s">', $atts, esc_url( $url ) );
    }

	/**
	 * Generate amp-youtube html
	 *
	 * @param string $video_id
	 * @param int    $height
	 * @param int    $width
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_youtube_html( $video_id, $height = 270, $width = 480 ) {
        amp_wp_enqueue_script( 'amp-youtube', 'https://cdn.ampproject.org/v0/amp-youtube-0.1.js' );
        return sprintf( '<amp-youtube width="%d" height="%d" layout="responsive" data-videoid="%s"></amp-youtube>', $width, $height, $video_id );
    }

	/**
	 * Generate amp-vimeo html
	 *
	 * @param string $video_id
	 * @param int    $height
	 * @param int    $width
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_vimeo_html( $video_id, $height = 270, $width = 480 ) {
        amp_wp_enqueue_script( 'amp-vimeo', 'https://cdn.ampproject.org/v0/amp-vimeo-0.1.js' );
        return sprintf( '<amp-vimeo data-videoid="%s" layout="responsive" width="%d" height="%d"></amp-vimeo>', esc_attr( $video_id ), $width, $height );
    }

	/**
	 * Generate amp-soundcloud html
	 *
	 * @param string $track_id
	 * @param int    $height
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_soundcloud_html( $track_id, $height = 270 ) {
        amp_wp_enqueue_script( 'amp-soundcloud', 'https://cdn.ampproject.org/v0/amp-soundcloud-0.1.js' );
        return sprintf( '<amp-soundcloud height="%d" layout="fixed-height" data-trackid="%s" data-visual="true"></amp-soundcloud>', $height, esc_attr( $track_id ) );
    }

	/**
	 * Generate amp-soundcloud html
	 *
	 * @param string $vine_id
	 * @param int    $height
	 * @param int    $width
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_vine_html( $vine_id, $height = 1, $width = 1 ) {
        amp_wp_enqueue_script( 'amp-vine', 'https://cdn.ampproject.org/v0/amp-vine-0.1.js' );
        return sprintf( '<amp-vine width="%d" height="%d" layout="responsive" data-vineid="%s"></amp-vine>', $width, $height, esc_attr( $vine_id ) );
    }

	/**
	 * Generate amp-instagram html
	 *
	 * @param string $shortcode
	 *
	 * @since 1.0.0
	 * @return string
	 */
    public function amp_instagram_html( $shortcode ) {
        amp_wp_enqueue_script( 'amp-instagram', 'https://cdn.ampproject.org/v0/amp-instagram-0.1.js' );
        return sprintf( '<amp-instagram data-shortcode="%s" width="1" height="1" layout="responsive"></amp-instagram>', esc_attr( $shortcode ) );
    }

	/**
	 * Retrieve soundcloud track-id from embed html code
	 *
	 * @param string $html
	 *
	 * @since 1.0.0
	 * @return string|bool  track id on success or false on failure.
	 */
    public function get_soundcloud_track_id( $html ) {
        parse_str( urldecode( $this->get_html_attr( $html, 'src' ) ), $vars );
        if( !empty( $vars['url'] ) ) {
            if( preg_match( '#soundcloud.com/tracks/(.+)$#i', $vars['url'], $matched ) ) {
                return $matched[1];
            }
        }
        return false;
    }

	/**
	 * Transform <iframe> tags to <img-iframe> tags
	 *
	 * @param	Amp_WP_Html_Util $instance
	 * @since		1.0.0
	 *
	 * @return	Amp_WP_Html_Util
	 */
    public function transform( Amp_WP_Html_Util $instance ) {
		$elements = $instance->getElementsByTagName( 'iframe' );

		/**
		 * @var DOMElement $element
		 */
		if( $nodes_count = $elements->length ) {
			$this->enable_enqueue_scripts = true;
			for( $i = $nodes_count - 1; $i >= 0; $i -- ) {
				if( !$element = $elements->item( $i ) ) {
					continue;
				}
				$attributes = $instance->filter_attributes( $instance->get_node_attributes( $element ) );
				$attributes = $this->filter_attributes( $attributes );
				if( !empty( $attributes['src'] ) && ( $embedded = $this->amp_embedded( '', $attributes['src'], $attributes ) ) ) {
					$instance->set_outer_HTML( $element, $embedded );
				} else {
					$instance->replace_node( $element, 'amp-iframe', $attributes );
				}
			}
		}
		return $instance;
    }

	/**
	 * This is our workaround to enforce max sizing with layout=responsive.
	 *
	 * We want elements to not grow beyond their width and shrink to fill the screen on viewports smaller than their
	 * width.
	 *
	 * See https://github.com/ampproject/amphtml/issues/1280#issuecomment-171533526
	 * See https://github.com/Automattic/amp-wp/issues/101
	 *
	 * @copyright credit goes to automattic amp - github.com/Automattic/amp-wp
	 *
	 * @since     1.0.0
	 */
    public function enforce_sizes_attribute( $attributes ) {
        if( !isset( $attributes['width'], $attributes['height'] ) ) {
            return $attributes;
        }
        $max_width = $attributes['width'];
        if( ( $_max_width = amp_wp_get_container_width() ) && $max_width > $_max_width ) {
            $max_width = $_max_width;
        }
        $attributes['sizes'] = sprintf( '(min-width: %1$dpx) %1$dpx, 100vw', absint( $max_width ) );
        return $attributes;
    }

	/**
	 * Filter iFrame attributes
	 *
	 * @param array $attributes
	 *
	 * @since 1.0.0
	 *
	 * @return array
	 */
    protected function filter_attributes( $attributes ) {
        $results = array();
        foreach ( $attributes as $key => $value ) {
            switch ( $key ) {
                case 'frameborder':
                    if( $value === 'no' ) {
                        $value = '0';
                    } else if ( '0' !== $value && '1' !== $value ) {
                        $value = '0';
                    }
                    if( $value !== '0' ) { $results[ $key ] = $value; }
                break;

                case 'allowfullscreen':
                case 'allowtransparency':
                case 'class':
                case 'sandbox':
                case 'src':
                case 'sizes':
                    if( $value !== '0' ) { $results[ $key ] = $value; }
                break;
            }
        }

        if( !isset( $results['sandbox'] ) ) {
            $results['sandbox'] = 'allow-scripts allow-same-origin';
        }
        if( empty( $results['height'] ) && isset( $attributes['src'] ) ) { // height is required
            if( !empty( $attributes['amp-height'] ) ) {
                $results['height'] = $attributes['amp-height'];
            } elseif ( ! empty( $attributes['height'] ) ) {
                $results['height'] = $attributes['height'];
            } else {
                $results['height'] = $this->get_frame_height( $attributes['src'] );
            }
        }

        return $results;
    }

	/**
	 * Returns appropriate frame height
	 *
	 * @param $url
	 *
	 * @since 1.0.0
	 *
	 * @return int
	 */
    protected function get_frame_height( $url ) {
        $height = 400;  // default height
        if ( preg_match( '#^https?://.*?\.soundcloud\.com#i', $url ) ) {
            $height = 156;
        }
        return $height;
    }
	
	/**
	 * Builds the Video Shortcode Output.
	 *
	 * This implements the functionality of the Video Shortcode for displaying
	 * WordPress mp4s in a post.
	 *
	 * @since		1.0.0
	 *
	 * @global	int	$content_width
	 * @staticvar	int	$instance
	 *
	 * @param array  $attr {
	 *     Attributes of the shortcode.
	 *     @type string $src      URL to the source of the video file. Default empty.
	 * }
	 * @param	string $content Shortcode content.
	 * @return	string|void HTML content to display video.
	 */
    public function wp_video_shortcode( $output, $atts ) {
        if( !empty( $atts['src'] ) ) {
            $url = trim( $atts['src'] );
            if( $_output = $this->amp_embedded( '', $url ) ) {
                return $_output;
            }
            if( substr( $url, 0, 8 ) === 'https://' ) {
                $width  = $this->get_html_attr( $output, 'width', 'video' );
                $height = $this->get_html_attr( $output, 'height', 'video' );
                amp_wp_enqueue_script( 'amp-video', 'https://cdn.ampproject.org/v0/amp-video-0.1.js' );
                return sprintf( '<amp-video width="%s" height="%s" src="%s" layout="responsive" controls></amp-video>', $width, $height, $url );
            }
        }
        return $output;
    }
	
	/**
	 * Grab YouTube Video ID from Given URL.
	 *
	 * @param	string	$url
	 *
	 * @since		1.2.1
	 * @return	string	video id on success or empty string on failure.
	 */
	public static function extract_youtube_video_id( $url ) {
		$video_id = '';
		if ( preg_match( '#https?://(?:(?:m|www)\.)?youtube\.com/watch\?(.*)#i', $url, $matched ) ) {
			parse_str( $matched[1], $vars );
			if( !empty( $vars['v'] ) ) {
				$video_id = $vars['v'];
			}
		} elseif ( preg_match( '#https?://(?:(?:m|www)\.)?youtube\.com/embed/([^\/\?\&]+)#i', $url, $matched ) ) {
			$video_id = $matched[1];
		} elseif ( preg_match( '#https?://(?:(?:m|www)\.)?youtu\.be/([^\/\?\&]+)#i', $url, $matched ) ) {
			$video_id = $matched[1];
		}
		return $video_id;
	}
}

// Register component class
amp_wp_register_component( 'Amp_WP_iFrame_Component' );