<?php

/**

 * @file

 * Parser functions for the aggregator module.

 */

/**

 * Implements hook_aggregator_parse_info().

 */

function aggregator_aggregator_parse_info() {

  return array(

    'title' => t('Default parser'),

    'description' => t('Parses RSS, Atom and RDF feeds.'),

  );

}

/**

 * Implements hook_aggregator_parse().

 */

function aggregator_aggregator_parse($feed) {

  global $channel, $image;

  // Filter the input data.

  if (aggregator_parse_feed($feed->source_string, $feed)) {

    $modified = empty($feed->http_headers['last-modified']) ? 0 : strtotime($feed->http_headers['last-modified']);

    // Prepare the channel data.

    foreach ($channel as $key => $value) {

      $channel[$key] = trim($value);

    }

    // Prepare the image data (if any).

    foreach ($image as $key => $value) {

      $image[$key] = trim($value);

    }

    $etag = empty($feed->http_headers['etag']) ? '' : $feed->http_headers['etag'];

    // Add parsed data to the feed object.

    $feed->link = !empty($channel['link']) ? $channel['link'] : '';

    $feed->description = !empty($channel['description']) ? $channel['description'] : '';

    $feed->image = !empty($image['url']) ? $image['url'] : '';

    $feed->etag = $etag;

    $feed->modified = $modified;

    // Clear the cache.

    cache_clear_all();

    return TRUE;

  }

  return FALSE;

}

/**

 * Parses a feed and stores its items.

 *

 * @param $data

 *   The feed data.

 * @param $feed

 *   An object describing the feed to be parsed.

 *

 * @return

 *   FALSE on error, TRUE otherwise.

 */

function aggregator_parse_feed(&$data, $feed) {

  global $items, $image, $channel;

  // Unset the global variables before we use them.

  unset($GLOBALS['element'], $GLOBALS['item'], $GLOBALS['tag']);

  $items = array();

  $image = array();

  $channel = array();

  // Parse the data.

  $xml_parser = drupal_xml_parser_create($data);

  xml_set_element_handler($xml_parser, 'aggregator_element_start', 'aggregator_element_end');

  xml_set_character_data_handler($xml_parser, 'aggregator_element_data');

  if (!xml_parse($xml_parser, $data, 1)) {

    watchdog('aggregator', 'The feed from %site seems to be broken, due to an error "%error" on line %line.', array('%site' => $feed->title, '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser)), WATCHDOG_WARNING);

    drupal_set_message(t('The feed from %site seems to be broken, because of error "%error" on line %line.', array('%site' => $feed->title, '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser))), 'error');

    return FALSE;

  }

  xml_parser_free($xml_parser);

  // We reverse the array such that we store the first item last, and the last

  // item first. In the database, the newest item should be at the top.

  $items = array_reverse($items);

  // Initialize items array.

  $feed->items = array();

  foreach ($items as $item) {

    // Prepare the item:

    foreach ($item as $key => $value) {

      $item[$key] = trim($value);

    }

    // Resolve the item's title. If no title is found, we use up to 40

    // characters of the description ending at a word boundary, but not

    // splitting potential entities.

    if (!empty($item['title'])) {

      $item['title'] = $item['title'];

    }

    elseif (!empty($item['description'])) {

      $item['title'] = preg_replace('/^(.*)[^\w;&].*?$/', "\\1", truncate_utf8($item['description'], 40));

    }

    else {

      $item['title'] = '';

    }

    // Resolve the items link.

    if (!empty($item['link'])) {

      $item['link'] = $item['link'];

    }

    else {

      $item['link'] = $feed->link;

    }

    // Atom feeds have an ID tag instead of a GUID tag.

    if (!isset($item['guid'])) {

      $item['guid'] = isset($item['id']) ? $item['id'] : '';

    }

    // Atom feeds have a content and/or summary tag instead of a description tag.

    if (!empty($item['content:encoded'])) {

      $item['description'] = $item['content:encoded'];

    }

    elseif (!empty($item['summary'])) {

      $item['description'] = $item['summary'];

    }

    elseif (!empty($item['content'])) {

      $item['description'] = $item['content'];

    }

    // Try to resolve and parse the item's publication date.

    $date = '';

    foreach (array('pubdate', 'dc:date', 'dcterms:issued', 'dcterms:created', 'dcterms:modified', 'issued', 'created', 'modified', 'published', 'updated') as $key) {

      if (!empty($item[$key])) {

        $date = $item[$key];

        break;

      }

    }

    $item['timestamp'] = strtotime($date);

    if ($item['timestamp'] === FALSE) {

      $item['timestamp'] = aggregator_parse_w3cdtf($date); // Aggregator_parse_w3cdtf() returns FALSE on failure.

    }

    // Resolve dc:creator tag as the item author if author tag is not set.

    if (empty($item['author']) && !empty($item['dc:creator'])) {

      $item['author'] = $item['dc:creator'];

    }

    $item += array('author' => '', 'description' => '');

    // Store on $feed object. This is where processors will look for parsed items.

    $feed->items[] = $item;

  }

  return TRUE;

}

/**

 * Performs an action when an opening tag is encountered.

 *

 * Callback function used by xml_parse() within aggregator_parse_feed().

 */

function aggregator_element_start($parser, $name, $attributes) {

  global $item, $element, $tag, $items, $channel;

  $name = strtolower($name);

  switch ($name) {

    case 'image':

    case 'textinput':

    case 'summary':

    case 'tagline':

    case 'subtitle':

    case 'logo':

    case 'info':

      $element = $name;

      break;

    case 'id':

    case 'content':

      if ($element != 'item') {

        $element = $name;

      }

    case 'link':

      // According to RFC 4287, link elements in Atom feeds without a 'rel'

      // attribute should be interpreted as though the relation type is

      // "alternate".

      if (!empty($attributes['HREF']) && (empty($attributes['REL']) || $attributes['REL'] == 'alternate')) {

        if ($element == 'item') {

          $items[$item]['link'] = $attributes['HREF'];

        }

        else {

          $channel['link'] = $attributes['HREF'];

        }

      }

      break;

    case 'item':

      $element = $name;

      $item += 1;

      break;

    case 'entry':

      $element = 'item';

      $item += 1;

      break;

  }

  $tag = $name;

}

/**

 * Performs an action when a closing tag is encountered.

 *

 * Callback function used by xml_parse() within aggregator_parse_feed().

 */

function aggregator_element_end($parser, $name) {

  global $element;

  switch ($name) {

    case 'image':

    case 'textinput':

    case 'item':

    case 'entry':

    case 'info':

      $element = '';

      break;

    case 'id':

    case 'content':

      if ($element == $name) {

        $element = '';

      }

  }

}

/**

 * Performs an action when data is encountered.

 *

 * Callback function used by xml_parse() within aggregator_parse_feed().

 */

function aggregator_element_data($parser, $data) {

  global $channel, $element, $items, $item, $image, $tag;

  $items += array($item => array());

  switch ($element) {

    case 'item':

      $items[$item] += array($tag => '');

      $items[$item][$tag] .= $data;

      break;

    case 'image':

    case 'logo':

      $image += array($tag => '');

      $image[$tag] .= $data;

      break;

    case 'link':

      if ($data) {

        $items[$item] += array($tag => '');

        $items[$item][$tag] .= $data;

      }

      break;

    case 'content':

      $items[$item] += array('content' => '');

      $items[$item]['content'] .= $data;

      break;

    case 'summary':

      $items[$item] += array('summary' => '');

      $items[$item]['summary'] .= $data;

      break;

    case 'tagline':

    case 'subtitle':

      $channel += array('description' => '');

      $channel['description'] .= $data;

      break;

    case 'info':

    case 'id':

    case 'textinput':

      // The sub-element is not supported. However, we must recognize

      // it or its contents will end up in the item array.

      break;

    default:

      $channel += array($tag => '');

      $channel[$tag] .= $data;

  }

}

/**

 * Parses the W3C date/time format, a subset of ISO 8601.

 *

 * PHP date parsing functions do not handle this format. See

 * http://www.w3.org/TR/NOTE-datetime for more information. Originally from

 * MagpieRSS (http://magpierss.sourceforge.net/).

 *

 * @param $date_str

 *   A string with a potentially W3C DTF date.

 *

 * @return

 *   A timestamp if parsed successfully or FALSE if not.

 */

function aggregator_parse_w3cdtf($date_str) {

  if (preg_match('/(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})(:(\d{2}))?(?:([-+])(\d{2}):?(\d{2})|(Z))?/', $date_str, $match)) {

    list($year, $month, $day, $hours, $minutes, $seconds) = array($match[1], $match[2], $match[3], $match[4], $match[5], $match[6]);

    // Calculate the epoch for current date assuming GMT.

    $epoch = gmmktime($hours, $minutes, $seconds, $month, $day, $year);

    if ($match[10] != 'Z') { // Z is zulu time, aka GMT

      list($tz_mod, $tz_hour, $tz_min) = array($match[8], $match[9], $match[10]);

      // Zero out the variables.

      if (!$tz_hour) {

        $tz_hour = 0;

      }

      if (!$tz_min) {

        $tz_min = 0;

      }

      $offset_secs = (($tz_hour * 60) + $tz_min) * 60;

      // Is timezone ahead of GMT?  If yes, subtract offset.

      if ($tz_mod == '+') {

        $offset_secs *= -1;

      }

      $epoch += $offset_secs;

    }

    return $epoch;

  }

  else {

    return FALSE;

  }

}