<?php

/**
 * @file
 * A generalized voting API for Drupal.
 *
 * Maintains and provides an interface for a shared bin of vote and rating
 * data. Modules can cast votes with arbitrary properties and VotingAPI will
 * total them automatically. Support for basic anonymous voting by IP address,
 * multi-criteria voting, arbitrary aggregation functions, etc.
 */

/**
 * Implements of hook_menu().
 */
function votingapi_menu() {
  $items = array();
  $items['admin/config/search/votingapi'] = array(
    'title' => 'Voting API',
    'description' => 'Configure sitewide settings for user-generated ratings and votes.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('votingapi_settings_form'),
    'access callback' => 'user_access',
    'access arguments' => array('administer voting api'),
    'file' => 'votingapi.admin.inc',
    'type' => MENU_NORMAL_ITEM
  );

  if (module_exists('devel_generate')) {
    $items['admin/config/development/generate/votingapi'] = array(
      'title' => 'Generate votes',
      'description' => 'Generate a given number of votes on site content. Optionally delete existing votes.',
      'page callback' => 'drupal_get_form',
      'page arguments' => array('votingapi_generate_votes_form'),
      'access arguments' => array('administer voting api'),
      'file' => 'votingapi.admin.inc',
    );
  }

  return $items;
}

/**
 * Implements hook_permission().
 */
function votingapi_permission() {
  return array(
      'administer voting api' => array(
          'title' => t('Administer Voting API'),
      ),
  );
}

/**
 * Implements of hook_views_api().
 */
function votingapi_views_api() {
  return array(
    'api' => 3,
    'path' => drupal_get_path('module', 'votingapi') . '/views',
  );
}

/**
 * Implements of hook_cron().
 *
 * Allows db-intensive recalculations to be deferred until cron-time.
 */
function votingapi_cron() {
  if (variable_get('votingapi_calculation_schedule', 'immediate') == 'cron') {
    $time = REQUEST_TIME;
    $last_cron = variable_get('votingapi_last_cron', 0);
    $result = db_query('SELECT DISTINCT entity_type, entity_id FROM {votingapi_vote} WHERE timestamp > :timestamp', array(':timestamp' => $last_cron));
    foreach ($result as $content) {
      votingapi_recalculate_results($content->entity_type, $content->entity_id, TRUE);
    }

    variable_set('votingapi_last_cron', $time);
  }

  _votingapi_cron_delete_orphaned();
}

/**
 * Cast a vote on a particular piece of content.
 *
 * This function does most of the heavy lifting needed by third-party modules
 * based on VotingAPI. Handles clearing out old votes for a given piece of
 * content, saving the incoming votes, and re-tallying the results given the
 * new data.
 *
 * Modules that need more explicit control can call votingapi_add_votes() and
 * manage the deletion/recalculation tasks manually.
 *
 * @param $votes
 *   An array of votes, each with the following structure:
 *   $vote['entity_type']  (Optional, defaults to 'node')
 *   $vote['entity_id']    (Required)
 *   $vote['value_type']    (Optional, defaults to 'percent')
 *   $vote['value']         (Required)
 *   $vote['tag']           (Optional, defaults to 'vote')
 *   $vote['uid']           (Optional, defaults to current user)
 *   $vote['vote_source']   (Optional, defaults to current IP)
 *   $vote['timestamp']     (Optional, defaults to REQUEST_TIME)
 * @param $criteria
 *   A keyed array used to determine what votes will be deleted when the current
 *   vote is cast. If no value is specified, all votes for the current content
 *   by the current user will be reset. If an empty array is passed in, no votes
 *   will be reset and all incoming votes will be saved IN ADDITION to existing
 *   ones.
 *   $criteria['vote_id']     (If this is set, all other keys are skipped)
 *   $criteria['entity_type']
 *   $criteria['entity_type']
 *   $criteria['value_type']
 *   $criteria['tag']
 *   $criteria['uid']
 *   $criteria['vote_source']
 *   $criteria['timestamp']   (If this is set, records with timestamps
 *      GREATER THAN the set value will be selected.)
 * @return
 *   An array of vote result records affected by the vote. The values are
 *   contained in a nested array keyed thusly:
 *   $value = $results[$entity_type][$entity_id][$tag][$value_type][$function]
 *
 * @see votingapi_add_votes()
 * @see votingapi_recalculate_results()
 */
function votingapi_set_votes(&$votes, $criteria = NULL) {
  $touched = array();
  if (!empty($votes['entity_id'])) {
    $votes = array($votes);
  }

  // Allow other modules to modify or unset/remove votes.
  // module_invoke_all does not allow passing variables by reference
  // http://api.drupal.org/api/drupal/includes%21module.inc/function/module_invoke_all/7#comment-35778
  drupal_alter(array('votingapi_preset_votes'), $votes);
  // Handle clearing out old votes if they exist.
  if (!isset($criteria)) {
    // If the calling function didn't explicitly set criteria for vote deletion,
    // build up the delete queries here.
    foreach ($votes as $vote) {
      $tmp = $vote + votingapi_current_user_identifier();
      if (isset($tmp['value'])) {
        unset($tmp['value']);
      }
      votingapi_delete_votes(votingapi_select_votes($tmp));
    }
  }
  elseif (is_array($criteria)) {
    // The calling function passed in an explicit set of delete filters.
    if (!empty($criteria['entity_id'])) {
      $criteria = array($criteria);
    }
    foreach ($criteria as $c) {
      votingapi_delete_votes(votingapi_select_votes($c));
    }
  }

  foreach ($votes as $key => $vote) {
    _votingapi_prep_vote($vote);
    $votes[$key] = $vote; // Is this needed? Check to see how PHP4 handles refs.
  }

  // Cast the actual votes, inserting them into the table.
  votingapi_add_votes($votes);

  foreach ($votes as $vote) {
    $touched[$vote['entity_type']][$vote['entity_id']] = TRUE;
  }

  if (variable_get('votingapi_calculation_schedule', 'immediate') != 'cron') {
    foreach ($touched as $type => $ids) {
      foreach ($ids as $id => $bool) {
        $touched[$type][$id] = votingapi_recalculate_results($type, $id);
      }
    }
  }
  return $touched;
}

/**
 * Generate a proper identifier for the current user: if they have an account,
 * return their UID. Otherwise, return their IP address.
 */
function votingapi_current_user_identifier() {
  global $user;
  $criteria = array('uid' => $user->uid);
  if (!$user->uid) {
    $criteria['vote_source'] = ip_address();
  }
  return $criteria;
}

/**
 * Implements of hook_votingapi_storage_add_vote().
 */
function votingapi_votingapi_storage_add_vote(&$vote) {
  drupal_write_record('votingapi_vote', $vote);
}

/**
 * Implements of hook_votingapi_storage_delete_votes().
 */
function votingapi_votingapi_storage_delete_votes($votes, $vids) {
  db_delete('votingapi_vote')->condition('vote_id', $vids, 'IN')->execute();
}

/**
 * Implements of hook_votingapi_storage_select_votes().
 */
function votingapi_votingapi_storage_select_votes($criteria, $limit) {
  $query = db_select('votingapi_vote')->fields('votingapi_vote');
  foreach ($criteria as $key => $value) {
    if ($key == 'timestamp') {
      $query->condition($key, $value, '>');
    }
    else {
      $query->condition($key, $value, is_array($value) ? 'IN' : '=');
    }
  }
  if (!empty($limit)) {
    $query->range(0, $limit);
  }
  return $query->execute()->fetchAll(PDO::FETCH_ASSOC);
}

/**
 * Save a collection of votes to the database.
 *
 * This function does most of the heavy lifting for VotingAPI the main
 * votingapi_set_votes() function, but does NOT automatically triger re-tallying
 * of results. As such, it's useful for modules that must insert their votes in
 * separate batches without triggering unecessary recalculation.
 *
 * Remember that any module calling this function implicitly assumes responsibility
 * for calling votingapi_recalculate_results() when all votes have been inserted.
 *
 * @param $votes
 *   A vote or array of votes, each with the following structure:
 *   $vote['entity_type']  (Optional, defaults to 'node')
 *   $vote['entity_id']    (Required)
 *   $vote['value_type']    (Optional, defaults to 'percent')
 *   $vote['value']         (Required)
 *   $vote['tag']           (Optional, defaults to 'vote')
 *   $vote['uid']           (Optional, defaults to current user)
 *   $vote['vote_source']   (Optional, defaults to current IP)
 *   $vote['timestamp']     (Optional, defaults to REQUEST_TIME)
 * @return
 *   The same votes, with vote_id keys populated.
 *
 * @see votingapi_set_votes()
 * @see votingapi_recalculate_results()
 */
function votingapi_add_votes(&$votes) {
  if (!empty($votes['entity_id'])) {
    $votes = array($votes);
  }
  $function = variable_get('votingapi_storage_module', 'votingapi') . '_votingapi_storage_add_vote';
  foreach ($votes as $key => $vote) {
    _votingapi_prep_vote($vote);
    $function($vote);
    $votes[$key] = $vote;
  }
  module_invoke_all('votingapi_insert', $votes);
  return $votes;
}

/**
 * Save a bundle of vote results to the database.
 *
 * This function is called by votingapi_recalculate_results() after tallying
 * the values of all cast votes on a piece of content. This function will be of
 * little use for most third-party modules, unless they manually insert their
 * own result data.
 *
 * @param vote_results
 *   An array of vote results, each with the following properties:
 *   $vote_result['entity_type']
 *   $vote_result['entity_id']
 *   $vote_result['value_type']
 *   $vote_result['value']
 *   $vote_result['tag']
 *   $vote_result['function']
 *   $vote_result['timestamp']   (Optional, defaults to REQUEST_TIME)
 */
function votingapi_add_results($vote_results = array()) {
  if (!empty($vote_results['entity_id'])) {
    $vote_results = array($vote_results);
  }

  foreach ($vote_results as $vote_result) {
    $vote_result['timestamp'] = REQUEST_TIME;
    drupal_write_record('votingapi_cache', $vote_result);
  }
}

/**
 * Delete votes from the database.
 *
 * @param $votes
 *   An array of votes to delete. Minimally, each vote must have the 'vote_id'
 *   key set.
 */
function votingapi_delete_votes($votes = array()) {
  if (!empty($votes)) {
    module_invoke_all('votingapi_delete', $votes);
    $vids = array();
    foreach ($votes as $vote) {
      $vids[] = $vote['vote_id'];
    }
    $function = variable_get('votingapi_storage_module', 'votingapi') . '_votingapi_storage_delete_votes';
    $function($votes, $vids);
  }
}

/**
 * Delete cached vote results from the database.
 *
 * @param $vote_results
 *   An array of vote results to delete. Minimally, each vote result must have
 *   the 'vote_cache_id' key set.
 */
function votingapi_delete_results($vote_results = array()) {
  if (!empty($vote_results)) {
    $vids = array();
    foreach ($vote_results as $vote) {
      $vids[] = $vote['vote_cache_id'];
    }
    db_delete('votingapi_cache')->condition('vote_cache_id', $vids, 'IN')->execute();
  }
}

/**
 * Select individual votes from the database.
 *
 * @param $criteria
 *   A keyed array used to build the select query. Keys can contain
 *   a single value or an array of values to be matched.
 *   $criteria['vote_id']       (If this is set, all other keys are skipped)
 *   $criteria['entity_id']
 *   $criteria['entity_type']
 *   $criteria['value_type']
 *   $criteria['tag']
 *   $criteria['uid']
 *   $criteria['vote_source']
 *   $criteria['timestamp']   (If this is set, records with timestamps
 *      GREATER THAN the set value will be selected.)
 * @param $limit
 *   An optional integer specifying the maximum number of votes to return.
 * @return
 *   An array of votes matching the criteria.
 */
function votingapi_select_votes($criteria = array(), $limit = 0) {
  $window = -1;
  if (empty($criteria['uid']) || $criteria['uid'] == 0) {
    if (!empty($criteria['vote_source'])) {
      $window = variable_get('votingapi_anonymous_window', 86400);
    }
  } else {
    $window = variable_get('votingapi_user_window', -1);
  }
  if ($window >= 0) {
    $criteria['timestamp'] = REQUEST_TIME - $window;
  }
  $function = variable_get('votingapi_storage_module', 'votingapi') . '_votingapi_storage_select_votes';
  return $function($criteria, $limit);
}

/**
 * Select cached vote results from the database.
 *
 * @param $criteria
 *   A keyed array used to build the select query. Keys can contain
 *   a single value or an array of values to be matched.
 *   $criteria['vote_cache_id']     (If this is set, all other keys are skipped)
 *   $criteria['entity_id']
 *   $criteria['entity_type']
 *   $criteria['value_type']
 *   $criteria['tag']
 *   $criteria['function']
 *   $criteria['timestamp']   (If this is set, records with timestamps
 *      GREATER THAN the set value will be selected.)
 * @param $limit
 *   An optional integer specifying the maximum number of votes to return.
 * @return
 *   An array of vote results matching the criteria.
 */
function votingapi_select_results($criteria = array(), $limit = 0) {
  $query = db_select('votingapi_cache')->fields('votingapi_cache');
  foreach ($criteria as $key => $value) {
    $query->condition($key, $value, is_array($value) ? 'IN' : '=');
  }
  if (!empty($limit)) {
    $query->range(0, $limit);
  }
  return $query->execute()->fetchAll(PDO::FETCH_ASSOC);
}

/**
 * Recalculates the aggregate results of all votes for a piece of content.
 *
 * Loads all votes for a given piece of content, then calculates and caches the
 * aggregate vote results. This is only intended for modules that have assumed
 * responsibility for the full voting cycle: the votingapi_set_vote() function
 * recalculates automatically.
 *
 * @param $entity_type
 *   A string identifying the type of content being rated. Node, comment,
 *   aggregator item, etc.
 * @param $entity_id
 *   The key ID of the content being rated.
 * @return
 *   An array of the resulting votingapi_cache records, structured thusly:
 *   $value = $results[$ag][$value_type][$function]
 *
 * @see votingapi_set_votes()
 */
function votingapi_recalculate_results($entity_type, $entity_id, $force_calculation = FALSE) {
  // if we're operating in cron mode, and the 'force recalculation' flag is NOT set,
  // bail out. The cron run will pick up the results.

  if (variable_get('votingapi_calculation_schedule', 'immediate') != 'cron' || $force_calculation == TRUE) {
    $query = db_delete('votingapi_cache')
      ->condition('entity_type', $entity_type)
      ->condition('entity_id', $entity_id)
      ->execute();

    $function = variable_get('votingapi_storage_module', 'votingapi') . '_votingapi_storage_standard_results';
    // Bulk query to pull the majority of the results we care about.
    $cache = $function($entity_type, $entity_id);

    // Give other modules a chance to alter the collection of votes.
    drupal_alter('votingapi_results', $cache, $entity_type, $entity_id);

    // Now, do the caching. Woo.
    $cached = array();
    foreach ($cache as $tag => $types) {
      foreach ($types as $type => $functions) {
        foreach ($functions as $function => $value) {
          $cached[] = array(
            'entity_type' => $entity_type,
            'entity_id' => $entity_id,
            'value_type' => $type,
            'value' => $value,
            'tag' => $tag,
            'function' => $function,
          );
        }
      }
    }
    votingapi_add_results($cached);

    // Give other modules a chance to act on the results of the vote totaling.
    module_invoke_all('votingapi_results', $cached, $entity_type, $entity_id);

    return $cached;
  }
}


/**
 * Returns metadata about tags, value_types, and results defined by vote modules.
 *
 * If your module needs to determine what existing tags, value_types, etc., are
 * being supplied by other modules, call this function. Querying the votingapi
 * tables for this information directly is discouraged, as values may not appear
 * consistently. (For example, 'average' does not appear in the cache table until
 * votes have actually been cast in the cache table.)
 *
 * Three major bins of data are stored: tags, value_types, and functions. Each
 * entry in these bins is keyed by the value stored in the actual VotingAPI
 * tables, and contains an array with (minimally) 'name' and 'description' keys.
 * Modules can add extra keys to their entries if desired.
 *
 * This metadata can be modified or expanded using hook_votingapi_metadata_alter().
 *
 * @return
 *   An array of metadata defined by VotingAPI and altered by vote modules.
 *
 * @see hook_votingapi_metadata_alter()
 */
function votingapi_metadata($reset = FALSE) {
  static $data;
  if ($reset || !isset($data)) {
    $data = array(
      'tags' => array(
        'vote' => array(
          'name' => t('Normal vote'),
          'description' => t('The default tag for votes on content. If multiple votes with different tags are being cast on a piece of content, consider casting a "summary" vote with this tag as well.'),
        ),
      ),
      'value_types' => array(
        'percent' => array(
          'name' => t('Percent'),
          'description' => t('Votes in a specific range. Values are stored in a 1-100 range, but can be represented as any scale when shown to the user.'),
        ),
        'points' => array(
          'name' => t('Points'),
          'description' => t('Votes that contribute points/tokens/karma towards a total. May be positive or negative.'),
        ),
      ),
      'functions' => array(
        'count' => array(
          'name' => t('Number of votes'),
          'description' => t('The number of votes cast for a given piece of content.'),
        ),
        'average' => array(
          'name' => t('Average vote'),
          'description' => t('The average vote cast on a given piece of content.'),
        ),
        'sum' => array(
          'name' => t('Total score'),
          'description' => t('The sum of all votes for a given piece of content.'),
          'value_types' => array('points'),
        ),
      ),
    );

    drupal_alter('votingapi_metadata', $data);
  }

  return $data;
}

/**
 * Builds the default VotingAPI results for the three supported voting styles.
 */
function votingapi_votingapi_storage_standard_results($entity_type, $entity_id) {
  $cache = array();

  $sql  = "SELECT v.value_type, v.tag, ";
  $sql .= "COUNT(v.value) as value_count, SUM(v.value) as value_sum  ";
  $sql .= "FROM {votingapi_vote} v ";
  $sql .= "WHERE v.entity_type = :type AND v.entity_id = :id AND v.value_type IN ('points', 'percent') ";
  $sql .= "GROUP BY v.value_type, v.tag";
  $results = db_query($sql, array(':type' => $entity_type, ':id' => $entity_id));

  foreach ($results as $result) {
    $cache[$result->tag][$result->value_type]['count'] = $result->value_count;
    $cache[$result->tag][$result->value_type]['average'] = $result->value_sum / $result->value_count;
    if ($result->value_type == 'points') {
      $cache[$result->tag][$result->value_type]['sum'] = $result->value_sum;
    }
  }

  $sql  = "SELECT v.tag, v.value, v.value_type, COUNT(1) AS score ";
  $sql .= "FROM {votingapi_vote} v ";
  $sql .= "WHERE v.entity_type = :type AND v.entity_id = :id AND v.value_type = 'option' ";
  $sql .= "GROUP BY v.value, v.tag, v.value_type";
  $results = db_query($sql, array(':type' => $entity_type, ':id' => $entity_id));

  foreach ($results as $result) {
    $cache[$result->tag][$result->value_type]['option-' . $result->value] = $result->score;
  }

  return $cache;
}

/**
 * Retrieve the value of the first vote matching the criteria passed in.
 */
function votingapi_select_single_vote_value($criteria = array()) {
  if ($results = votingapi_select_votes($criteria, 1)) {
    return $results[0]['value'];
  }
}

/**
 * Retrieve the value of the first result matching the criteria passed in.
 */
function votingapi_select_single_result_value($criteria = array()) {
  if ($results = votingapi_select_results($criteria, 1)) {
    return $results[0]['value'];
  }
}

/**
 * Populate the value of any unset vote properties.
 *
 * @param $vote
 *   A single vote.
 * @return
 *   A vote object with all required properties filled in with
 *   their default values.
 */
function _votingapi_prep_vote(&$vote) {
  global $user;
  if (empty($vote['prepped'])) {
    $vote += array(
      'entity_type' => 'node',
      'value_type' => 'percent',
      'tag' => 'vote',
      'uid' => $user->uid,
      'timestamp' => REQUEST_TIME,
      'vote_source' => ip_address(),
      'prepped' => TRUE
    );
  }
}

/**
 * Implements hook_entity_delete().
 *
 * Delete all votes and cache entries for the deleted entities
 */
function votingapi_entity_delete($entity, $type) {
  $ids = entity_extract_ids($type, $entity);
  $id = array($ids[0]);
  _votingapi_delete_cache_by_entity($id, $type);
  _votingapi_delete_votes_by_entity($id, $type);
}

/**
 * Helper function to delete all cache entries on given entities.
 *
 * @param array entity ids
 * @param string entity type
 */
function _votingapi_delete_cache_by_entity($entity_ids, $type) {
  $result = db_select('votingapi_cache', 'v')
    ->fields('v', array('vote_cache_id'))
    ->condition('entity_type', $type)
    ->condition('entity_id', $entity_ids)
    ->execute();
  $votes = array();
  foreach ($result as $row) {
    $votes[]['vote_cache_id'] = $row->vote_cache_id;
  }
  votingapi_delete_results($votes);
}

/**
 * Helper function to delete all votes on given entities.
 *
 * @param array entity ids
 * @param string entity type
 */
function _votingapi_delete_votes_by_entity($entity_ids, $type) {
  $result = db_select('votingapi_vote', 'v')
    ->fields('v', array('vote_id', 'entity_type', 'entity_id'))
    ->condition('entity_type', $type)
    ->condition('entity_id', $entity_ids)
    ->execute();
  $votes = array();
  foreach ($result as $row) {
    $votes[] = (array) $row;
  }
  votingapi_delete_votes($votes);
}

/**
 * Delete votes and cache entries for a number of entities in the queue.
 */
function _votingapi_cron_delete_orphaned() {
  $queue = DrupalQueue::get('VotingAPIOrphaned');
  $limit = variable_get('votingapi_cron_orphaned_max', 50);
  $done = 0;
  while (($item = $queue->claimItem()) && $done++ < $limit) {
    _votingapi_delete_cache_by_entity(array($item->data['entity_id']), $item->data['entity_type']);
    _votingapi_delete_votes_by_entity(array($item->data['entity_id']), $item->data['entity_type']);
    $queue->deleteItem($item);
  }
}