<?php defined("SYSPATH") or die("No direct script access.");
/**
 * Gallery - a web based photo album viewer and editor
 * Copyright (C) 2000-2009 Bharat Mediratta
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA  02110-1301, USA.
 */

/**
 * Provides a driver-based interface for managing users and groups.
 */
class Identity_Core {
  protected static $instance;

  // Configuration
  protected $config;

  // Driver object
  protected $driver;

  /**
   * Returns a singleton instance of Identity.
   * There can only be one Identity driver configured at a given point
   *
   * @param   string  configuration
   * @return  Identity_Core
   */
  static function & instance($config="default") {
   if (!isset(Identity::$instance)) {
      // Create a new instance
      Identity::$instance = new Identity($config);
    }

    return Identity::$instance;
  }

  /**
   * Loads the configured driver and validates it.
   *
   * @param   array|string  custom configuration or config group name
   * @return  void
   */
  public function __construct($config="default") {
    if (is_string($config)) {
      $name = $config;

      // Test the config group name
      if (($config = Kohana::config("identity.".$config)) === NULL) {
        throw new Exception("@todo NO USER LIBRARY CONFIGURATION FOR: $name");
      }

      if (is_array($config)) {
        // Append the default configuration options
        $config += Kohana::config("identity.default");
      } else {
        // Load the default group
        $config = Kohana::config("identity.default");
      }

      // Cache the config in the object
      $this->config = $config;

      // Set driver name
      $driver = "Identity_".ucfirst($this->config["driver"])."_Driver";

      // Load the driver
      if ( ! Kohana::auto_load($driver)) {
        throw new Kohana_Exception("core.driver_not_found", $this->config["driver"],
                                   get_class($this));
      }

      // Initialize the driver
      $this->driver = new $driver($this->config["params"]);

      // Validate the driver
      if ( !($this->driver instanceof Identity_Driver)) {
        throw new Kohana_Exception("core.driver_implements", $this->config["driver"],
                                   get_class($this), "Identity_Driver");
      }

      Kohana::log("debug", "Identity Library initialized");
    }
  }

  /**
   * Determine if if the current driver supports updates.
   *
   * @return boolean true if the driver supports updates; false if read only
   */
  static function is_writable() {
    return !empty(self::instance()->config["allow_updates"]);
  }

  /**
   * @see Identity_Driver::guest.
   */
  static function guest() {
    return self::instance()->driver->guest();
  }

  /**
   * @see Identity_Driver::create_user.
   */
  static function create_user($name, $full_name, $password) {
    return self::instance()->driver->create_user($name, $full_name, $password);
  }

  /**
   * @see Identity_Driver::is_correct_password.
   */
  static function is_correct_password($user, $password) {
    return self::instance()->driver->is_correct_password($user, $password);
  }

  /**
   * @see Identity_Driver::hash_password.
   */
  static function hash_password($password) {
    return self::instance()->driver->hash_password($password);
  }

  /**
   * Look up a user by id.
   * @param integer      $id the user id
   * @return User_Definition  the user object, or null if the id was invalid.
   */
  static function lookup_user($id) {
    return self::instance()->driver->lookup_user_by_field("id", $id);
  }

  /**
   * Look up a user by name.
   * @param integer      $name the user name
   * @return User_Definition  the user object, or null if the name was invalid.
   */
  static function lookup_user_by_name($name) {
    return self::instance()->driver->lookup_user_by_field("name", $name);
  }

  /**
   * Look up a user by hash.
   * @param string       $name the user name
   * @return User_Definition  the user object, or null if the name was invalid.
   */
  static function lookup_user_by_hash($hash) {
    return self::instance()->driver->lookup_user_by_field("hash", $hash);
  }

  /**
   * @see Identity_Driver::create_group.
   */
  static function create_group($name) {
    return self::instance()->driver->create_group($name);
  }

  /**
   * @see Identity_Driver::everybody.
   */
  static function everybody() {
    return self::instance()->driver->everybody();
  }

  /**
   * @see Identity_Driver::registered_users.
   */
  static function registered_users() {
    return self::instance()->driver->everybody();
  }

  /**
   * Look up a group by name.
   * @param integer      $id the group name
   * @return Group_Definition  the group object, or null if the name was invalid.
   */
  static function lookup_group_by_name($name) {
    return self::instance()->driver->lookup_group_by_field("name", $name);
  }

  /**
   * @see Identity_Driver::get_user_list.
   */
  static function get_user_list($ids) {
    return self::instance()->driver->get_user_list($ids);
  }

  static function get_login_form($url) {
    $form = new Forge($url, "", "post", array("id" => "g-login-form"));
    $form->set_attr('class', "g-narrow");
    $group = $form->group("login")->label(t("Login"));
    $group->input("name")->label(t("Username"))->id("g-username")->class(null);
    $group->password("password")->label(t("Password"))->id("g-password")->class(null);
    $group->inputs["name"]->error_messages("invalid_login", t("Invalid name or password"));
    $group->submit("")->value(t("Login"));
    return $form;
  }

  /**
   * Return the active user.  If there's no active user, return the guest user.
   *
   * @return User_Model
   */
  static function active() {
    // @todo (maybe) cache this object so we're not always doing session lookups.
    $user = Session::instance()->get("user", null);
    if (!isset($user)) {
      // Don't do this as a fallback in the Session::get() call because it can trigger unnecessary
      // work.
      $user = self::guest();
    }
    return $user;
  }

  /**
   * Change the active user.
   *
   * @return User_Model
   */
  static function set_active($user) {
    $session = Session::instance();
    $session->set("user", $user);
    $session->delete("group_ids");
    self::load_user();
  }

  /**
   * Return the array of group ids this user belongs to
   *
   * @return array
   */
  static function group_ids_for_active_user() {
    return Session::instance()->get("group_ids", array(1));
  }

  /**
   * Make sure that we have a session and group_ids cached in the session.  This is one
   * of the first calls to reference the user so call the Identity::instance to load the
   * driver classes.
   */
  static function load_user() {
    $session = Session::instance();
    if (!($user = $session->get("user"))) {
      $session->set("user", $user = self::guest());
    }

    // The installer cannot set a user into the session, so it just sets an id which we should
    // upconvert into a user.
    // @todo set the user name into the session instead of 2 and then use it to get the user object
    if ($user === 2) {
      $user = self::lookup_user_by_name("admin");
      self::login($user);
      $session->set("user", $user);
    }

    if (!$session->get("group_ids")) {
      $ids = array();
      foreach ($user->groups as $group) {
        $ids[] = $group->id;
      }
      $session->set("group_ids", $ids);
    }
  }

  /**
   * Log in as a given user.
   * @param object $user the user object.
   */
  static function login($user) {
    // @todo make this an interface call
    $user->login_count += 1;
    $user->last_login = time();
    $user->save();

    self::set_active($user);
    module::event("user_login", $user);
  }

  /**
   * Log out the active user and destroy the session.
   * @param object $user the user object.
   */
  static function logout() {
    $user = self::active();
    if (!$user->guest) {
      try {
        Session::instance()->destroy();
      } catch (Exception $e) {
        Kohana::log("error", $e);
      }
      module::event("user_logout", $user);
    }
  }
} // End Identity