<?php
/* $Id: votingapi.module,v 1.46.2.6 2008-06-05 21:11:18 eaton Exp $ */

/**
 * VotingAPI 2.0
 *
 * A generalized voting API for Drupal. 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.
 */

/**
 * Implementation of hook_menu. Adds the url path for the votingapi settings
 * page.
 */
function votingapi_menu() {
  $items = array();
  $items['admin/settings/votingapi'] = array(
    'title' => 'Voting API',
    'description' => 'Global settings for the Voting API.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('votingapi_settings_form'),
    'access callback' => 'user_access',
    'access arguments' => array('administer voting api'),
    'type' => MENU_NORMAL_ITEM
  );
  return $items;
}

/**
 * Implementation of hook_perm. Exposes a permission to edit the module's
 * settings.
 */
function votingapi_perm() {
  return array('administer voting api');
}

/**
 * Implementation 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 = time();
    $last_cron = variable_get('votingapi_last_cron', 0);
    $result = db_query('SELECT DISTINCT content_type, content_id FROM {votingapi_vote} WHERE timestamp > %d', $last_cron);

    while ($content = db_fetch_object($result)) {
      votingapi_recalculate_results($content->content_type, $content->content_id, TRUE);
    }

    variable_set('votingapi_last_cron', $time);
  }
}

/**
 * Administrative settings for VotingAPI.
 */
function votingapi_settings_form($form_state) {
  $period = array(0 => t('Immediately')) + drupal_map_assoc(array(300, 900, 1800, 3600, 10800, 21600, 32400, 43200, 86400, 172800, 345600, 604800), 'format_interval') + array(-1 => t('Never'));

  $form['votingapi_anonymous_window'] = array(
    '#type' => 'select',
    '#title' => t('Anonymous vote rollover'),
    '#description' => t('The amount of time that must pass before two anonymous votes from the same computer are considered unique. Setting this to \'never\' will eliminate most double-voting, but will make it impossible for multiple anonymous on the same computer (like internet cafe customers) from casting votes.'),
    '#default_value' => variable_get('votingapi_anonymous_window', 86400),
    '#options' => $period
  );

  $form['votingapi_calculation_schedule'] = array(
    '#type' => 'radios',
    '#title' => t('Vote tallying'),
    '#description' => t('On high-traffic sites, administrators can use this setting to postpone the calculation of vote results.'),
    '#default_value' => variable_get('votingapi_calculation_schedule', 'immediate'),
    '#options' => array(
      'immediate' => t('Tally results whenever a vote is cast'),
      'cron' => t('Tally results at cron-time'),
      'manual' => t('Do not tally results automatically: I am using a module that manages its own vote results.')
    ),
  );

  return system_settings_form($form);
}


/**
 * Cast a vote on a particular piece of content. If a vote already exists, its
 * value is changed. In most cases, this is the function that should be used by
 * external modules.
 *
 * @param $votes
 *   An array of votes, each with the following structure:
 *   $vote['content_type']  (Optional, defaults to 'node')
 *   $vote['content_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 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 keyes are skipped)
 *   $criteria['content_type']
 *   $criteria['content_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 = $results[$content_type][$content_id][$tag][$value_type][$function]
 */
function votingapi_set_votes(&$votes, $criteria = NULL) {
  $touched = array();
  if (!empty($votes['content_type'])) {
    $votes = array($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 = votingapi_current_user_identifier();
      $tmp += $vote;
      votingapi_delete_votes(votingapi_select_votes($tmp));
    }
  }
  elseif (is_array($criteria)) {
    // The calling function passed in an explicit set of delete filters.
    if (!empty($criteria['content_type'])) {
      $criteria = array($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['content_type']][$vote['content_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;
}

/**
 * Save a collection of votes to the database.
 *
 * @param $votes
 *   A vote or array of votes, each with the following structure:
 *   $vote['content_type']  (Optional, defaults to 'node')
 *   $vote['content_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)
 *   $vote['timestamp']     (Optional, defaults to time())
 * @return
 *   The same votes, with vote_id keys populated.
 */
function votingapi_add_votes(&$votes) {
  if (!empty($votes['content_type'])) {
    $votes = array($votes);
  }
  foreach ($votes as $key => $vote) {
    _votingapi_prep_vote($vote);
    drupal_write_record('votingapi_vote', $vote);
    $votes[$key] = $vote;
  }
  module_invoke_all('votingapi_insert', $votes);
  return $votes;
}

/**
 * Save a vote results to the database.
 *
 * @param vote_results
 *   An array of vote results, each with the following properties:
 *   $vote_result['content_type']
 *   $vote_result['content_id']
 *   $vote_result['value_type']
 *   $vote_result['value']
 *   $vote_result['tag']
 *   $vote_result['function']
 *   $vote_result['timestamp']   (Optional, defaults to time())
 */
function votingapi_add_results($vote_results = array()) {
  if (!empty($vote_results['content_type'])) {
    $vote_results = array($vote_results);
  }

  foreach ($vote_results as $vote_result) {
    $vote_result['timestamp'] = 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[] = $vote['vote_id'];
    }
    db_query("DELETE FROM {votingapi_vote} WHERE vote_id IN (". implode(',', array_fill(0, count($vids), '%d')) .")", $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[] = $vote['vote_cache_id'];
    }
    db_query("DELETE FROM {votingapi_cache} WHERE vote_cache_id IN (". implode(',', array_fill(0, count($vids), '%d')) .")", $vids);
  }
}

/**
 * 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 keyes are skipped)
 *   $criteria['content_id']
 *   $criteria['content_type']
 *   $criteria['value_type']
 *   $criteria['tag']
 *   $criteria['uid']
 *   $criteria['vote_source']
 *   $criteria['timestamp']   (If this is set, records with timestamps
 *      GREATER THAN the set value will be selected.)
 * @return
 *   An array of votes matching the criteria.
 */
function votingapi_select_votes($criteria = array()) {
  if (!empty($criteria['vote_source'])) {
    $criteria['timestamp'] = time() - variable_get('votingapi_anonymous_window', 3600);
  }
  $votes = array();
  $result = _votingapi_select('vote', $criteria);
  while ($vote = db_fetch_array($result)) {
    $votes[] = $vote;
  }
  return $votes;
}

/**
 * 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 keyes are skipped)
 *   $criteria['content_type']
 *   $criteria['content_type']
 *   $criteria['value_type']
 *   $criteria['tag']
 *   $criteria['uid']
 *   $criteria['vote_source']
 *   $criteria['timestamp']   (If this is set, records with timestamps
 *      GREATER THAN the set value will be selected.)
 * @return
 *   An array of vote results matching the criteria.
 */
function votingapi_select_results($criteria = array()) {
  $cached = array();
  $result = _votingapi_select('cache', $criteria);
  while ($cache = db_fetch_array($result)) {
    $cached[] = $cache;
  }
  return $cached;
}

/**
 * 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 $content_type
 *   A string identifying the type of content being rated. Node, comment,
 *   aggregator item, etc.
 * @param $content_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]
 */
function votingapi_recalculate_results($content_type, $content_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) {
    $criteria = array('content_type' => $content_type, 'content_id' => $content_id);
    _votingapi_delete('cache', $criteria);

    // Bulk query to pull the majority of the results we care about.
    $cache = _votingapi_get_standard_results($content_type, $content_id);

    // Give other modules a chance to alter the collection of votes.
    drupal_alter('votingapi_results', $cache, $content_type, $content_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(
            'content_type' => $content_type,
            'content_id' => $content_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, $content_type, $content_id);

    return $cached;
  }
}


/**
 * Internal function - builds the default set of VotingAPI results
 * for the three supported voting styles.
 */
function _votingapi_get_standard_results($content_type, $content_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.content_type = '%s' AND v.content_id = %d AND v.value_type IN ('points', 'percent') ";
  $sql .= "GROUP BY v.value_type, v.tag";
  $results = db_query($sql, $content_type, $content_id);

  while ($result = db_fetch_array($results)) {
    $cache[$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, COUNT(1) AS score ";
  $sql .= "FROM {votingapi_vote} v ";
  $sql .= "WHERE v.content_type = '%s' AND v.content_id = %d AND v.value_type = 'option' ";
  $sql .= "GROUP BY v.value, v.tag";
  $results = db_query($sql, $content_type, $content_id);
  while ($result = db_fetch_array($results)) {
    $cache[$result['tag']][$result['value_type']]['option-'. $result['value']] = $result['score'];
  }

  return $cache;
}

/**
 * Simple wrapper function for votingapi_select_votes. Returns the
 * value of the first vote matching the criteria passed in.
 */
function votingapi_select_single_vote_value($criteria = array()) {
  if ($votes = votingapi_select_votes($criteria) && !empty($votes)) {
    return $votes[0]['value'];
  }
}

/**
 * Simple wrapper function for votingapi_select_results. Returns the
 * value of the first result matching the criteria passed in.
 */
function votingapi_select_single_result_value($criteria = array()) {
  return db_result(_votingapi_query('cache', $criteria, 1));
}

/**
 * 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(
      'content_type' => 'node',
      'value_type' => 'percent',
      'tag' => 'vote',
      'uid' => $user->uid,
      'timestamp' => time(),
      'vote_source' => ip_address(),
      'prepped' => TRUE
    );
  }
}


/**
 * Internal helper function constructs SELECT queries. Don't use unless you're me.
 */
function _votingapi_select($table = 'vote', $criteria = array(), $limit = 0) {
  $query = "SELECT * FROM {votingapi_". $table ."} v WHERE 1 = 1";
  $details = _votingapi_query('vote', $criteria);

  $query .= $details['query'];
  return $limit ? db_query_range($query, $details['args'], 0, $limit) : db_query($query, $details['args']);
}

/**
 * Internal helper function constructs DELETE queries. Don't use unless you're me.
 */
function _votingapi_delete($table = 'vote', $criteria = array(), $limit = 0) {
  $query = "DELETE FROM {votingapi_". $table ."} WHERE 1 = 1";
  $details = _votingapi_query('vote', $criteria, '');

  $query .= $details['query'];
  db_query($query, $details['args']);
}

/**
 * Internal helper function constructs WHERE clauses. Don't use unless you're me.
 */
function _votingapi_query($table = 'vote', $criteria = array(), $alias = 'v.') {
  $criteria += array(
    'vote_id' => NULL,
    'vote_cache_id' => NULL,
    'content_id' => NULL,
    'content_type' => NULL,
    'value_type' => NULL,
    'value' => NULL,
    'tag' => NULL,
    'uid' => NULL,
    'timestamp' => NULL,
    'vote_source' => NULL,
    'function' => NULL,
  );

  $query = '';
  $args = array();
  if (!empty($criteria['vote_id'])) {
    _votingapi_query_builder($alias . 'vote_id', $criteria['vote_id'], $query, $args);
  } elseif (!empty($criteria['vote_cache_id'])) {
    _votingapi_query_builder($alias . 'vote_cache_id', $criteria['vote_cache_id'], $query, $args);
  } else {
    _votingapi_query_builder($alias . 'content_type', $criteria['content_type'], $query, $args, TRUE);
    _votingapi_query_builder($alias . 'content_id', $criteria['content_id'], $query, $args);
    _votingapi_query_builder($alias . 'value_type', $criteria['value_type'], $query, $args, TRUE);
    _votingapi_query_builder($alias . 'tag', $criteria['tag'], $query, $args, TRUE);
    _votingapi_query_builder($alias . 'function', $criteria['function'], $query, $args);
    _votingapi_query_builder($alias . 'uid', $criteria['uid'], $query, $args);
    _votingapi_query_builder($alias . 'vote_source', $criteria['vote_source'], $query, $args, TRUE);
    _votingapi_query_builder($alias . 'timestamp', $criteria['timestamp'], $query, $args);
  }
  return array('query' => $query, 'args' => $args);
}

/**
 * Internal helper function constructs individual elements of WHERE clauses.
 * Don't use unless you're me.
 */
function _votingapi_query_builder($name, $value, &$query, &$args, $col_is_string = FALSE) {
  if (!isset($value)) {
    // Do nothing
  }
  elseif ($name === 'timestamp') {
    $query .= " AND timestamp >= %d";
    $args[] = $value;
  }
  elseif ($name === 'v.timestamp') {
    $query .= " AND v.timestamp >= %d";
    $args[] = $value;
  }
  else {
    if (is_array($value)) {
      if ($col_is_string) {
        $query .= " AND $name IN ('". array_fill(1, count($value), "'%s'") ."')";
        $args += $value;
      }
      else {
        $query .= " AND $name IN (". array_fill(1, count($value), "%d") .")";
        $args += $value;
      }
    } else {
      if ($col_is_string) {
        $query .= " AND $name = '%s'";
        $args[] = $value;
      }
      else {
        $query .= " AND $name = %d";
        $args[] = $value;
      }
    }
  }
}