<?php

/**
 * @file
 * Provides logic for page cache expiration
 */

define('EXPIRE_FLUSH_NODE_TERMS', TRUE);
define('EXPIRE_FLUSH_MENU_ITEMS', 1);
define('EXPIRE_FLUSH_CCK_REFERENCES', TRUE);


/**
 * Implementation of hook_comment(). Acts on comment modification.
 */
function expire_comment($comment, $op) {

  switch ($op) {
    case 'insert':
    case 'update':
      // Expire the relevant node page from the static page cache to prevent serving stale content:
      if (!empty($comment['nid'])) {
        $node = node_load($comment['nid']);
        $node->nid = $comment['nid'];
        expire_node($node);
      }
      break;
    case 'publish':
    case 'unpublish':
    case 'delete':
      if (!empty($comment->nid)) {
        $node = node_load($comment->nid);
        $node->nid = $comment->nid;
        expire_node($node);
      }
      break;
  }
}

/**
 * Implementation of hook_nodeapi(). Acts on nodes defined by other modules.
 */
function expire_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {

  switch ($op) {
    case 'insert':
      expire_node($node);
      break;
    case 'update':
      expire_node($node);
      break;
    case 'delete':
      expire_node($node);
      break;
  }
}

/**
 * Implementation of hook_votingapi_insert().
 *
 * @param $votes
 *  array of votes
 */
function expire_votingapi_insert($votes) {
  if (!BOOST_ENABLED) return;

  foreach ($votes as $vote) {
    $node = node_load($vote['content_id']);
    $node->nid = $vote['content_id'];
    expire_node($node);
  }
}

/**
 * Implementation of hook_votingapi_delete().
 *
 * @param $votes
 *  array of votes
 */
function expire_votingapi_delete($votes) {
  if (!BOOST_ENABLED) return;

  foreach ($votes as $vote) {
    $node = node_load($vote['content_id']);
    $node->nid = $vote['content_id'];
    boost_expire_node($node);
  }
}

/**
 * Implementation of hook_user(). Acts on user account actions.
 */
function expire_user($op, &$edit, &$account, $category = NULL) {

  global $user;
  switch ($op) {
    case 'delete':
      // Expire the relevant user page from the static page cache to prevent serving stale content:
      if (!empty($account->uid)) {
        $paths[] = 'user/' . $account->uid;
        $flushed = expire_cache_derivative($paths, TRUE, TRUE);
        watchdog('boost', 'expire_user() <br />User !uid was deleted resulting in !flushed pages being expired from the cache',  array('!uid' => $account->uid, '!flushed' => $flushed));
      }
      break;
  }
}

/**
 * Expires a node from the cache; including related pages.
 *
 * Expires front page if promoted, taxonomy terms,
 *
 * @param $node
 *  node object
 * @param $nid
 *  node id
 */
function expire_node($node) {
  $data = array();
  $paths = array();

  // Check node object
  if (empty($node->nid)) {
    return FALSE;
  }

  // Expire this node
  $paths['node'] = 'node/' . $node->nid;

  // If promoted to front page, expire front page
  if ($node->promote == 1) {
    $paths['front'] = '<front>';
  }

  // Get taxonomy terms and flush
  if (module_exists('taxonomy') && EXPIRE_FLUSH_NODE_TERMS) {
    $tids = boost_taxonomy_node_get_tids($node->nid);
    $filenames = array();
    foreach ($tids as $tid) {
      if (is_int($tid)) {
        $paths['term' . $tid] = 'taxonomy/term/' . $tid;
      }
    }
  }

  // Get menu and flush related items in the menu.
  if (EXPIRE_FLUSH_MENU_ITEMS !=0) {
    if (!isset($node->menu['menu_name'])) {
      menu_nodeapi($node, 'prepare');
    }
    $menu = menu_tree_all_data($node->menu['menu_name']);
    if (EXPIRE_FLUSH_MENU_ITEMS == 1) {
      $links = expire_get_menu_structure($menu, FALSE, 'node/' . $node->nid);
    }
    elseif (EXPIRE_FLUSH_MENU_ITEMS == 2) {
      $links = expire_get_menu_structure($menu);
    }
    $paths = array_merge($links, $paths);
  }

  // Get CCK References and flush.
  if (EXPIRE_FLUSH_CCK_REFERENCES && module_exists('nodereference')) {
    $nids = array();
    $type = content_types($node->type);
    if ($type) {
      foreach ($type['fields'] as $field) {
        // Add referenced nodes to nids. This will clean up nodereferrer fields
        // when the referencing node is updated.
        if ($field['type'] == 'nodereference') {
          $node_field = isset($node->$field['field_name']) ? $node->$field['field_name'] : array();
          foreach ($node_field as $delta => $item) {
            $nids[$item['nid']] = $item['nid'];
          }
        }
      }
      foreach ($nids as $nid) {
        if (is_int($nid)) {
          $paths['reference' . $nid] = 'node/' . $nid;
        }
      }
    }

    // Get CCK references pointing to this node and flush.
    if (module_exists('nodereferrer')) {
      $nids = nodereferrer_referrers($node->nid);
      foreach ($nids as $nid) {
        if (is_int($nid['nid'])) {
          $paths['referrer' . $nid['nid']] = 'node/' . $nid['nid'];
        }
      }
    }
  }

  // Flush array of paths
  if (!empty($paths)) {
    $flushed = expire_cache_derivative($paths, TRUE);
    watchdog('expire', 'expire_node() <br />Node !nid was flushed resulting in !flushed pages being expired from the cache',  array('!nid' => $node->nid, '!flushed' => $flushed));
  }
}

/**
 * Finds parent, siblings and children of the menu item. UGLY CODE...
 *
 * @param array $menu
 *  Output from menu_tree_all_data()
 * @param bool $found
 *  Signal for when the needle was found in the menu array.
 *  Set TRUE to get entire menu
 * @param string $needle
 *  Name of menu link. Example 'node/21'
 * @param bool $first
 *  Keep track of the first call; this is a recursive function.
 * @param bool &$found_global
 *  Used to signal the parent item was found in one of it's children
 * @param bool &$menu_out
 *  Output array of parent, siblings and children menu links
 *
 * TODO: Use page_callback and page_arguments instead of link_path.
 *  Can use boost_cache_expire_router() then.
 */
function expire_get_menu_structure($menu, $found = TRUE, $needle = '', $first = TRUE, &$found_global = FALSE, &$menu_out = array()) {
  $found_global = FALSE;
  // Get Siblings
  foreach ($menu as $item) {
    if ($item['link']['hidden'] == 0 && $item['link']['page_callback'] != '' && ($item['link']['link_path'] == $needle || $found)) {
      $menu_out[] = $item['link']['link_path'];
      $found = TRUE;
    }
  }
  // Get Children
  foreach ($menu as $item) {
    if ($item['link']['hidden'] != 0) {
      continue;
    }
    if ($item['link']['page_callback'] != '' && ($item['link']['link_path'] == $needle || $found)) {
      $menu_out[] = $item['link']['link_path'];
      $found = TRUE;
    }
    // Get Grandkids
    if (!empty($item['below'])) {
      $sub_menu = array();
      foreach ($item['below'] as $below) {
        if ($below['link']['hidden'] == 0) {
          $sub_menu[] = $below;
        }
      }
      expire_get_menu_structure($sub_menu, $needle, $found, FALSE, $found_global, $menu_out);
      $structure[$item['link']['link_path']][] = $sub;
      if ($item['link']['page_callback'] != '' && $found_global) {
        // Get Parent of kid
        $menu_out[] = $item['link']['link_path'];
      }
    }
    else {
      $structure[$item['link']['link_path']] = '';
    }
  }

  // Clean up
  if (is_array($structure)) {
    $structure = array_unique($structure);
  }
  $found_global = $found;
  if ($first) {
    $menu_out = array_unique($menu_out);
    sort($menu_out);
    return $menu_out;
  }
  else {
    return $structure;
  }
}

/**
 * Return taxonomy terms given a nid.
 *
 * Needed because of a weird bug with CCK & node_load()
 *  http://drupal.org/node/545922
 */
function expire_taxonomy_node_get_tids($nid) {
  $vid = db_result(db_query('SELECT vid FROM {node} WHERE nid = %d', $nid));
  $result = db_query(db_rewrite_sql('SELECT t.tid FROM {term_node} r INNER JOIN {term_data} t ON r.tid = t.tid INNER JOIN {vocabulary} v ON t.vid = v.vid WHERE r.vid = %d ORDER BY v.weight, t.weight, t.name', 't', 'tid'), $vid);
  $tids = array();
  while ($term = db_result($result)) {
    $tids[] = $term;
  }
  return $tids;
}

/**
 * Finds all possible paths/redirects/aliases given the root path.
 *
 * @param $paths
 *   Array of current URLs
 * @param $both
 *   Expire database & file
 * @param $force_flush
 *   Override the settings and kill the file
 */
function expire_cache_derivative($paths, $both = FALSE, $force_flush = FALSE) {
  global $base_path;
  $expire = array();

  if (empty($paths)) {
    return FALSE;
  }
  foreach ($paths as $path) {
    // Given path
    $expire[] = $path;

    // Special front page feed handling
    if ($path == '' || $path == '<front>') {
      $expire[] = 'rss.xml';
    }

    // Path alias
    $path_alias = url($path, array('absolute' => FALSE));
    if ($base_path != '/') {
      $path_alias = implode('/', array_diff_assoc(array_filter(explode('/', $path_alias)), array_filter(explode('/', $base_path))));
    }
    $expire[] = $path_alias;

    // Path redirects
    if (module_exists('path_redirect')) {
      $path_redirects = expire_path_redirect_load(array('redirect' => $path));
      if (isset($path_redirects)) {
        foreach ($path_redirects as $path_redirect) {
          $expire[] = $path_redirect['path'];
        }
      }
    }
  }

  // Expire cached files
  if (empty($expire)) {
    return FALSE;
  }
  $expire = array_unique($expire);
  watchdog('expire','<pre><tt>' .  print_r($expire, TRUE) . '</tt></pre>');
  // hook_expire_cache
  foreach (module_implements('expire_cache') as $module) {
    module_invoke($module, 'expire_cache', $expire);
  }
  return count($expire);
}

/**
 * Retrieve a specific URL redirect from the database.
 * http://drupal.org/node/451790
 *
 * @param $where
 *   Array containing 'redirect' => $path
 */
function expire_path_redirect_load($where = array(), $args = array(), $sort = array()) {
  $redirects = array();
  if (is_numeric($where)) {
    $where = array('rid' => $where);
  }

  foreach ($where as $key => $value) {
    if (is_string($key)) {
      $args[] = $value;
      $where[$key] = $key .' = '. (is_numeric($value) ? '%d' : "'%s'");
    }
  }

  if ($where && $args) {
    $sql = "SELECT * FROM {path_redirect} WHERE ". implode(' AND ', $where);
    if ($sort) {
      $sql .= ' ORDER BY '. implode(' ,', $sort);
    }
    $result = db_query($sql, $args);
    while ($redirect = db_fetch_array($result)) {
      $redirects[] = $redirect;
    }
    return $redirects;
  }
}