<?php

/**
 * @file
 * This file contains the drupal hook implementations
 */

/**
 * Implementation of hook_user().
 */
function session_aggregator_user($op, &$edit, &$account, $category = NULL) {
  switch ($op) {
    case 'login':
      // Save the session start time
      $sid = session_id();
      $now = time();
        
      // Save the session id and creation timestamp. Used to handle session
      // collisions and hung sessions in hook_session_limit.
      $session_aggregator = variable_get('session_aggregator', array());
      $session_aggregator[$account->uid][$sid] = array('created' => $now) ;
      variable_set('session_aggregator', $session_aggregator);
      
      if (session_aggregator_user_exists($account->uid)) {
        db_query("UPDATE session_aggregator SET unique_sessions = unique_sessions + 1 WHERE uid = %d", $account->uid);
      }
      else {
        db_query("INSERT INTO session_aggregator (uid, unique_sessions, since) VALUES (%d, 1, %d)", $account->uid, $now);
      }
      break;

    case 'logout':
      // Update record
      if (session_aggregator_user_exists($account->uid)) {
        $session_time = time() - $account->login;
        db_query("UPDATE session_aggregator SET elapsed_time = elapsed_time + %d WHERE uid = %d", $session_time, $account->uid);
        
        // Remove the session data from variable table. There won't be a 
        // session collision or hung session since user is being logged out.
        $session_aggregator = variable_get('session_aggregator', array());
        unset($session_aggregator[$account->uid]);
        variable_set('session_aggregator', $session_aggregator);
      }
      break;
  }
}

/**
 * Determine if a user has records in the session_aggregator table
 * @param int $uid
 *   The id of the user to check
 * @return boolean
 */
function session_aggregator_user_exists($uid) {
  $sql = "SELECT COUNT(*) FROM {session_aggregator} sa WHERE sa.uid = %d";
  $result = db_result(db_query($sql, $uid));
  return $result ? TRUE : FALSE;
}

/**
 * Implementation of hook_views_api().
 */
function session_aggregator_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'session_aggregator') . '/views',
  );
}

/**
 * Implementation of hook_session_limit.
 */
function session_aggregator_session_limit($sid, $op) {
  // When a session is terminated, update the elapsed time from the old session.
  if ($op == 'disconnect') {
    global $user;
    $session_aggregator = variable_get('session_aggregator', array());
    $now = time();
    $sess_created = $session_aggregator[$user->uid][$sid]['created'];
    $session_length = $now - $sess_created;
    $timeout = variable_get('autologout_timeout', 1800);
    $timeout_padding = variable_get('autologout_padding', 10);

    // Determine how much time to append to elapsed time.
    $session_time = ($session_length > ($timeout + (int)$timeout_padding)) ? $timeout + $timeout_padding : $session_length;

    // Terminate the old session when a collision happens and append the time 
    // of the old session to the elapsed time.
    db_query("UPDATE session_aggregator SET elapsed_time = elapsed_time + %d WHERE uid = %d", $session_time, $user->uid);
  }
}