<?php

/**
 * Session handler for storing sessions to database
 *
 * @see /wire/core/SessionHandler.php
 *
 * ProcessWire 2.x 
 * Copyright (C) 2012 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://www.processwire.com
 *
 */

class SessionHandlerDB extends WireSessionHandler implements Module, ConfigurableModule {

	public static function getModuleInfo() {
		return array(
			'title' => 'Session Handler Database', 
			'version' => 2, 
			'summary' => "Installing this module makes ProcessWire store sessions in the database rather than the file system. Note that this module will log you out after install or uninstall.",
			'installs' => array('ProcessSessionDB')
			);
	}

	/**
	 * Table created by this module
	 *
	 */
	const dbTableName = 'sessions';

	/**
	 * Quick reference to database
	 *
	 */
	protected $database; 

	/**
	 * Construct
	 *
	 */
	public function __construct() {
		parent::__construct();
		$this->database = wire('database');
		$this->set('useIP', 0); // track IP address?
		$this->set('useUA', 0); // track query string?
	}

	/**
	 * Read and return data for session indicated by $id
	 *
	 * @param string $id Session ID
	 * @return string Serialized data or blank string if none
	 *
	 */
	public function read($id) {
		
		$table = self::dbTableName; 
		$database = $this->database;
		$data = '';
		
		$query = $database->prepare("SELECT GET_LOCK(:id, 10)"); 
		$query->execute(array(":id" => $id)); 
		$query = $database->prepare("SELECT data FROM `$table` WHERE id=:id");
		$query->execute(array(":id" => $id)); 
		if($query->rowCount()) {
			$data = $query->fetchColumn();
			if(empty($data)) $data = '';
		}
		$query->closeCursor();
			
		return $data; 
	}

	/**
	 * Write the given $data for the given session ID
	 *
	 * @param string $id Session ID
	 * @param string Serialized data to write
	 * @return bool
	 *
	 */
	public function write($id, $data) {
		$table = self::dbTableName;
		$database = $this->database;
		$user = $this->wire('user');
		$page = $this->wire('page');
		$id = $database->escapeStr($id);
		$user_id = $user && $user->id ? (int) $user->id : 0; 
		$pages_id = $page && $page->id ? (int) $page->id : 0;
		$data = $database->escapeStr($data);
		$ua = ($this->useUA && isset($_SERVER['HTTP_USER_AGENT'])) ? $database->escapeStr(substr($_SERVER['HTTP_USER_AGENT'], 0, 255)) : '';
		$ip = $this->useIP ? ((int) wire('session')->getIP(true)) : '';
		
		$s = "user_id=$user_id, pages_id=$pages_id, data='$data'"; 
		if($ip) $s .= ", ip=$ip";
		if($ua) $s .= ", ua='$ua'";
		$sql = 	"INSERT INTO $table SET id='$id', $s ";
		$sql .= "ON DUPLICATE KEY UPDATE $s, ts=NOW()";
		
		$query = $database->prepare($sql); 
		$result = $query->execute() ? true : false;
		$database->exec("SELECT RELEASE_LOCK('$id')");
		
		return $result; 
	}

	/**
	 * Destroy the session indicated by the given session ID
	 *
	 * @param string $id Session ID
	 * @return bool True on success, false on failure 
	 *
	 */
	public function destroy($id) {
		$table = self::dbTableName;
		$database = $this->database;
		$query = $database->prepare("DELETE FROM `$table` WHERE id=:id"); 
		$query->execute(array(":id" => $id)); 
		setcookie(session_name(), '', time()-3600);
		return true; 
	}

	/**
	 * Garbage collection: remove stale sessions
	 *
	 * @param int $seconds Max lifetime of a session
	 * @return bool True on success, false on failure
	 *
	 */
	public function gc($seconds) {
		$table = self::dbTableName; 
		$seconds = (int) $seconds; 
		$sql = "DELETE FROM `$table` WHERE ts < DATE_SUB(NOW(), INTERVAL $seconds SECOND)";
		return $this->database->exec($sql);
	}

	/**
	 * Install sessions table
	 *
	 */
	public function ___install() {
		
		$table = self::dbTableName;

		$sql = 	"CREATE TABLE `$table` (" . 
				"id CHAR(32) NOT NULL, " . 
				"user_id INT UNSIGNED NOT NULL, " . 
				"pages_id INT UNSIGNED NOT NULL, " . 
				"data TEXT NOT NULL, " . 
				"ts TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, " . 
				"ip INT UNSIGNED NOT NULL DEFAULT 0, " . 
				"ua VARCHAR(255) NOT NULL DEFAULT '', " . 
				"PRIMARY KEY (id), " . 
				"INDEX (pages_id), " . 
				"INDEX (user_id), " . 
				"INDEX (ts) " . 
				") ENGINE=InnoDB DEFAULT CHARSET=utf8";

		$this->database->query($sql); 
	}

	/**
	 * Drop sessions table
	 *
	 */
	public function ___uninstall() {
		$this->database->query("DROP TABLE " . self::dbTableName); 
	}

	/**
	 * Session configuration options
	 *
	 */
	public static function getModuleConfigInputfields(array $data) {

		$form = new InputfieldWrapper();

		// check if their DB table is the latest version
		$query = wire('database')->query("SHOW COLUMNS FROM " . self::dbTableName . " WHERE field='ip'"); 
		if(!$query->rowCount()) {
			wire('modules')->error("DB format changed - You must uninstall this module and re-install before configuring."); 
			return $form;
		}

		$description = __('Checking this box will enable the data to be displayed in your admin sessions list.', __FILE__);

		$f = wire('modules')->get('InputfieldCheckbox'); 
		$f->attr('name', 'useIP'); 
		$f->attr('value', 1);
		$f->attr('checked', empty($data['useIP']) ? '' : 'checked'); 
		$f->label = __('Track IP addresses in session data?', __FILE__); 
		$f->description = $description;
		$form->add($f);

		$f = wire('modules')->get('InputfieldCheckbox'); 
		$f->attr('name', 'useUA'); 
		$f->attr('value', 1);
		$f->attr('checked', empty($data['useUA']) ? '' : 'checked'); 
		$f->label = __('Track user agent in session data?', __FILE__); 
		$f->notes = __('The user agent typically contains information about the browser being used.', __FILE__);
		$f->description = $description;
		$form->add($f);

		return $form;
	}

	/**
	 * Provides direct reference access to set values in the $data array
	 *
	 * For some reason PHP 5.4+ requires this, as it apparently doesn't see WireData
	 *
	 */
	public function __set($key, $value) {
		$this->set($key, $value);
	}


	/**
	 * Provides direct reference access to variables in the $data array
	 *
	 * For some reason PHP 5.4+ requires this, as it apparently doesn't see WireData
	 *
	 * Otherwise the same as get()
	 *
	 * @param string $key
	 *
	 */
	public function __get($key) {
		return $this->get($key);
	}


}