<?php
/*
 Plugin Name: Open Graph
 Plugin URI: http://wordpress.org/plugins/opengraph
 Description: Adds Open Graph metadata to your pages
 Author: Will Norris
 Author URI: http://willnorris.com/
 Version: 1.6
 License: Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html)
 Text Domain: opengraph
 */


// If you have the opengraph plugin running alongside jetpack, we assume you'd
// rather use our opengraph support, so disable jetpack's opengraph functionality.
add_filter('jetpack_enable_opengraph', '__return_false');
add_filter('jetpack_enable_open_graph', '__return_false');


/**
 * Add Open Graph XML prefix to <html> element.
 *
 * @uses apply_filters calls 'opengraph_prefixes' filter on RDFa prefix array
 */
function opengraph_add_prefix( $output ) {
  $prefixes = array(
    'og' => 'http://ogp.me/ns#'
  );
  $prefixes = apply_filters('opengraph_prefixes', $prefixes);

  $prefix_str = '';
  foreach ( $prefixes as $k => $v ) {
    $prefix_str .= $k . ': ' . $v . ' ';
  }
  $prefix_str = trim($prefix_str);

  if (preg_match('/(prefix\s*=\s*[\"|\'])/i', $output)) {
    $output = preg_replace('/(prefix\s*=\s*[\"|\'])/i', '${1}' . $prefix_str, $output);
  } else {
    $output .= ' prefix="' . $prefix_str . '"';
  }
  return $output;
}
add_filter('language_attributes', 'opengraph_add_prefix');


/**
 * Add additional prefix namespaces that are supported by the opengraph plugin.
 */
function opengraph_additional_prefixes( $prefixes ) {
  if ( is_author() ) {
    $prefixes['profile'] = 'http://ogp.me/ns/profile#';
  }
  if ( is_singular() ) {
    $prefixes['article'] = 'http://ogp.me/ns/article#';
  }
  return $prefixes;
}


/**
 * Get the Open Graph metadata for the current page.
 *
 * @uses apply_filters() Calls 'opengraph_{$name}' for each property name
 * @uses apply_filters() Calls 'twitter_{$name}' for each property name
 * @uses apply_filters() Calls 'opengraph_metadata' before returning metadata array
 */
function opengraph_metadata() {
  $metadata = array();

   // defualt properties defined at http://ogp.me/
  $properties = array(
    // required
    'title', 'type', 'image', 'url',

    // optional
    'audio', 'description', 'determiner', 'locale', 'site_name', 'video',
  );

  foreach ( $properties as $property ) {
    $filter = 'opengraph_' . $property;
    $metadata["og:$property"] = apply_filters($filter, '');
  }

  $twitter_properties = array('card');

  foreach ( $twitter_properties as $property ) {
    $filter = 'twitter_' . $property;
    $metadata["twitter:$property"] = apply_filters($filter, '');
  }

  return apply_filters('opengraph_metadata', $metadata);
}


/**
 * Register filters for default Open Graph metadata.
 */
function opengraph_default_metadata() {
  // core metadata attributes
  add_filter('opengraph_title', 'opengraph_default_title', 5);
  add_filter('opengraph_type', 'opengraph_default_type', 5);
  add_filter('opengraph_image', 'opengraph_default_image', 5);
  add_filter('opengraph_url', 'opengraph_default_url', 5);

  add_filter('opengraph_description', 'opengraph_default_description', 5);
  add_filter('opengraph_locale', 'opengraph_default_locale', 5);
  add_filter('opengraph_site_name', 'opengraph_default_sitename', 5);

  // additional prefixes
  add_filter('opengraph_prefixes', 'opengraph_additional_prefixes');

  // additional profile metadata
  add_filter('opengraph_metadata', 'opengraph_profile_metadata');

  // additional article metadata
  add_filter('opengraph_metadata', 'opengraph_article_metadata');

  // twitter card metadata
  add_filter('twitter_card', 'twitter_default_card', 5);
}
add_filter('wp', 'opengraph_default_metadata');


/**
 * Default title property, using the page title.
 */
function opengraph_default_title( $title ) {
  if ( empty($title) ) {
    if ( is_singular() ) {
      $title = get_the_title( get_queried_object_id() );
    } else if ( is_author() ) {
      $author = get_queried_object();
      $title = $author->display_name;
    } else if ( is_category() && single_cat_title( '', false ) ) {
      $title = single_cat_title( '', false );
    } else if ( is_tag() && single_tag_title( '', false ) ) {
      $title = single_tag_title( '', false );
    } else if ( is_archive() && get_post_format()) {
      $title = get_post_format_string( get_post_format() );
    } else if ( is_archive() && function_exists ("get_the_archive_title") && get_the_archive_title() ) { // new in version 4.1 to get all other archive titles
      $title = get_the_archive_title();
    }
  }
  return $title;
}


/**
 * Default type property.
 */
function opengraph_default_type( $type ) {
  if ( empty($type) ) {
    if ( is_singular( array('post', 'page') ) ) {
      $type = 'article';
    } else if ( is_author() ) {
      $type = 'profile';
    } else {
      $type = 'website';
    }
  }
  return $type;
}


/**
 * Default image property, using the post-thumbnail and any attached images.
 */
function opengraph_default_image( $image ) {
  if ( empty($image) && is_singular() ) {
    $id = get_queried_object_id();
    $image_ids = array();

    // As of July 2014, Facebook seems to only let you select from the first 3 images
    $max_images = apply_filters('opengraph_max_images', 3);

    // list post thumbnail first if this post has one
    if ( function_exists('has_post_thumbnail') ) {
      if ( is_singular() && has_post_thumbnail($id) ) {
        $image_ids[] = get_post_thumbnail_id($id);
      }
    }

    // then list any image attachments
    $attachments = get_children( array('post_parent' => $id, 'post_status' => 'inherit',
      'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC',
      'orderby' => 'menu_order ID') );
    foreach ( $attachments as $attachment ) {
      if ( !in_array($attachment->ID, $image_ids) ) {
        $image_ids[] = $attachment->ID;
        if (sizeof($image_ids) >= $max_images) {
          break;
        }
      }
    }

    // get URLs for each image
    $image = array();
    foreach ( $image_ids as $id ) {
      $thumbnail = wp_get_attachment_image_src( $id, 'medium');
      if ($thumbnail) {
        $image[] = $thumbnail[0];
      }
    }
  }
  return $image;
}


/**
 * Default url property, using the permalink for the page.
 */
function opengraph_default_url( $url ) {
  if ( empty($url) ) {
    if ( is_singular() ) {
      $url = get_permalink();
    } else if ( is_author() ) {
      $url = get_author_posts_url( get_queried_object_id() );
    }
  }
  return $url;
}


/**
 * Default site_name property, using the bloginfo name.
 */
function opengraph_default_sitename( $name ) {
  if ( empty($name) ) {
    $name = get_bloginfo('name');
  }
  return $name;
}


/**
 * Default description property, using the excerpt or content for posts, or the
 * bloginfo description.
 */
function opengraph_default_description( $description ) {
  if ( empty($description) ) {
    if ( is_singular() ) {
      $post = get_queried_object();
      if ( !empty($post->post_excerpt) ) {
        $description = $post->post_excerpt;
      } else {
        $description = $post->post_content;
      }
    } else if ( is_author() ) {
      $id = get_queried_object_id();
      $description = get_user_meta($id, 'description', true);
    } else if ( is_category() && category_description() ) {
      $description = category_description();
    } else if ( is_tag() && tag_description() ) {
      $description = tag_description();
    } else if ( is_archive() && function_exists("get_the_archive_description") && get_the_archive_description() ) { // new in version 4.1 to get all other archive descriptions
      $description = get_the_archive_description();
    } else {
      $description = get_bloginfo('description');
    }
  }

  // strip description to first 55 words.
  $description = strip_tags(strip_shortcodes($description));
  $description = __opengraph_trim_text($description);

  return $description;
}


/**
 * Default locale property, using the WordPress locale.
 */
function opengraph_default_locale( $locale ) {
  if ( empty($locale) ) {
    $locale = get_locale();
  }
  return $locale;
}


/**
 * Default twitter-card type.
 */
function twitter_default_card( $card ) {
  $post_type = apply_filters('opengraph_type', null);
  if ( $post_type == 'article' ) {
    return "summary";
  }

  return '';
}


/**
 * Output Open Graph <meta> tags in the page header.
 */
function opengraph_meta_tags() {
  $metadata = opengraph_metadata();
  foreach ( $metadata as $key => $value ) {
    if ( empty($key) || empty($value) ) {
      continue;
    }
    $value = (array) $value;
    foreach ( $value as $v ) {
      printf('<meta property="%1$s" name="%1$s" content="%2$s" />' . "\n",
        esc_attr($key), esc_attr($v));
    }
  }
}
add_action('wp_head', 'opengraph_meta_tags');


/**
 * Include profile metadata for author pages.
 */
function opengraph_profile_metadata( $metadata ) {
  if ( is_author() ) {
    $id = get_queried_object_id();
    $metadata['profile:first_name'] = get_the_author_meta('first_name', $id);
    $metadata['profile:last_name'] = get_the_author_meta('last_name', $id);
    $metadata['profile:username'] = get_the_author_meta('nicename', $id);
  }
  return $metadata;
}


/**
 * Include profile metadata for author pages.
 *
 * @link http://ogp.me/#type_article
 */
function opengraph_article_metadata( $metadata ) {
  if ( is_singular() ) {
    $post = get_queried_object();

    $tags = wp_get_post_tags($post->ID);

    // check if page/post has tags
    if ( $tags ) {
      foreach ( $tags as $tag ) {
        $metadata['article:tag'][] = $tag->name;
      }
    }

    $metadata['article:published_time'] = get_the_time( 'c', $post->ID );
    $metadata['article:author:first_name'] = get_the_author_meta('first_name', $post->post_author);
    $metadata['article:author:last_name'] = get_the_author_meta('last_name', $post->post_author);
    $metadata['article:author:username'] = get_the_author_meta('nicename', $post->post_author);
  }

  return $metadata;
}


/**
 * Helper function to trim text using the same default values for length and
 * 'more' text as wp_trim_excerpt.
 */
function __opengraph_trim_text( $text ) {
  $excerpt_length = apply_filters('excerpt_length', 55);
  $excerpt_more = apply_filters('excerpt_more', ' ' . '[...]');
  return wp_trim_words($text, $excerpt_length, $excerpt_more);
}