<?php
/**
 * The Strangecode Codebase - a general application development framework for PHP
 * For details visit the project site: <http://trac.strangecode.com/codebase/>
 * Copyright 2001-2012 Strangecode, LLC
 *
 * This file is part of The Strangecode Codebase.
 *
 * The Strangecode Codebase 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 3 of the License, or (at your option)
 * any later version.
 *
 * The Strangecode Codebase 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
 * The Strangecode Codebase. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * Prefs.inc.php
 *
 * Prefs provides an API for saving arbitrary values in a user's session, in cookies, and in the database.
 * Prefs can be stored into a database with the optional save() and load() methods.
 *
 * @author  Quinn Comendant <quinn@strangecode.com>
 * @version 3.0
 * @todo This class could really benefit from being refactored using the factory pattern, with backend storage mechanisms.
 *
 * Example of use (database storagetype):
---------------------------------------------------------------------
// Load preferences for the user's session.
require_once 'codebase/lib/Prefs.inc.php';
$prefs = new Prefs('my-namespace');
$prefs->setParam(array(
    'storagetype' => ($auth->isLoggedIn() ? 'database' : 'session'),
    'user_id' => $auth->get('user_id'),
));
$prefs->setDefaults(array(
    'search_num_results' => 25,
    'datalog_num_entries' => 25,
));
$prefs->load();

// Update preferences. Make sure to validate this input first!
$prefs->set('search_num_results', getFormData('search_num_results'));
$prefs->set('datalog_num_entries', getFormData('datalog_num_entries'));
$prefs->save();
---------------------------------------------------------------------
 */
class Prefs
{

    // Namespace of this instance of Prefs.
    protected $_ns;

    // Configuration parameters for this object.
    protected $_params = array(

        // Store preferences in one of the available storage mechanisms: session, cookie, database
        // This default should remain set to 'session' for legacy support.
        'storagetype' => 'session',

        // This parameter is only used for legacy support, superseded by the 'storagetype' setting.
        // Enable database storage. If this is false, all prefs will live only as long as the session.
        'persistent' => null,

        // ----------------------------------------------------------
        // Cookie-type settings.

        // Lifespan of the cookie. If set to an integer, interpreted as a timestamp (0 for 'when user closes browser'), otherwise as a strtotime-compatible value ('tomorrow', etc).
        'cookie_expire' => '+10 years',

        // The path on the server in which the cookie will be available on.
        'cookie_path' => '/',

        // The domain that the cookie is available to.
        'cookie_domain' => null,

        // ----------------------------------------------------------
        // Database-type settings.

        // The current user_id for which to load/save database-backed preferences.
        'user_id' => null,

        // How long before we force a reload of the persistent prefs data?
        'load_timeout' => 60,

        // Name of database table to store prefs.
        'db_table' => 'pref_tbl',

        // Automatically create table and verify columns. Better set to false after site launch.
        // This value is overwritten by the $app->getParam('db_create_tables') setting if it is available.
        'create_table' => true,

        // Original namespace set during __construct().
        // 'namespace' => '',
    );

    /**
     * Prefs constructor.
     */
    public function __construct($namespace='', array $params=null)
    {
        $app =& App::getInstance();

        $this->_ns = $namespace;

        // Save the original namespace for the DB pref_namespace column. $this->_ns, used in the SESSION variable, will change based on the user_id.
        $this->setParam(array('namespace' => $namespace));

        // Get create tables config from global context.
        if (!is_null($app->getParam('db_create_tables'))) {
            $this->setParam(array('create_table' => $app->getParam('db_create_tables')));
        }

        // Optional initial params.
        $this->setParam($params);

        if (isset($params['save_on_shutdown']) && $params['save_on_shutdown']) {
            // Run Prefs->save() upon script completion if we're using the database storagetype.
            // This only works if:
            // - 'storagetype' is provided as a parameter to the constructor rather than via setParam() later.
            // - $app->stop() is not called at the end of the script (which would close the PDO connection before the shutdown function runs).
            if ('database' == $this->getParam('storagetype')) {
                register_shutdown_function(array($this, 'save'));
            }
        }
    }

    /**
     * Setup the database table for this class.
     *
     * @access  public
     * @author  Quinn Comendant <quinn@strangecode.com>
     * @since   04 Jun 2006 16:41:42
     */
    public function initDB($recreate_db=false)
    {
        $app =& App::getInstance();
        $pdo =& \Strangecode\Codebase\PDO::getInstance();

        static $_db_tested = false;

        if ($recreate_db || !$_db_tested && $this->getParam('create_table')) {
            if ($recreate_db) {
                $pdo->query(sprintf("DROP TABLE IF EXISTS `%s`", $pdo->sanitizeIdentifier($this->getParam('db_table'))));
                $app->logMsg(sprintf('Dropping and recreating table %s.', $this->getParam('db_table')), LOG_INFO, __FILE__, __LINE__);
            }
            $stmt = $pdo->query(sprintf("
                CREATE TABLE IF NOT EXISTS `%s` (
                    `user_id` VARCHAR(32) NOT NULL DEFAULT '',
                    `pref_namespace` VARCHAR(32) NOT NULL DEFAULT '',
                    `pref_key` VARCHAR(64) NOT NULL DEFAULT '',
                    `pref_value` TEXT,
                    PRIMARY KEY (`user_id`, `pref_namespace`, `pref_key`)
                )
            ", $pdo->sanitizeIdentifier($this->getParam('db_table'))));

            if (!$pdo->columnExists($this->getParam('db_table'), array(
                'user_id',
                'pref_namespace',
                'pref_key',
                'pref_value',
            ), false, false)) {
                $app->logMsg(sprintf('Database table %s has invalid columns. Please update this table manually.', $this->getParam('db_table')), LOG_ALERT, __FILE__, __LINE__);
                trigger_error(sprintf('Database table %s has invalid columns. Please update this table manually.', $this->getParam('db_table')), E_USER_ERROR);
            }
        }
        $_db_tested = true;
    }

    /**
     * Set the params of this object.
     *
     * @param  array $params   Array of param keys and values to set.
     */
    public function setParam(array $params=null)
    {
        $app =& App::getInstance();

        // CLI scripts can't use prefs stored in HTTP-based protocols.
        if ($app->isCLI()
        && isset($params['storagetype'])
        && in_array($params['storagetype'], array('cookie', 'session'))) {
            $app->logMsg(sprintf('Storage type %s not available for CLI', $params['storagetype']), LOG_DEBUG, __FILE__, __LINE__);
        }

        // Convert the legacy param 'persistent' to 'storagetype=database'.
        // Old sites would set 'persistent' to true (use database) or false (use sessions).
        // If it is true, we set storagetype=database here.
        // If false, we rely on the default, sessions (which is assigned in the params).
        if (isset($params['persistent']) && $params['persistent'] && !isset($params['storagetype'])) {
            $params['storagetype'] = 'database';
        }

        // Append the user_id to the namespace to keep separate collections for different users.
        if (isset($params['user_id']) && $params['user_id']) {
            // $this->getParam('namespace') should always be available since it is set in __construct().
            $this->_ns = sprintf('%s-%s', $this->getParam('namespace'), $params['user_id']);
        }

        // Check max DB string lengths.
        if ((isset($params['storagetype']) && $params['storagetype'] == 'database') || $this->getParam('storagetype') == 'database') {
            if (isset($params['user_id']) && mb_strlen($params['user_id']) > 32) {
                $app->logMsg(sprintf('Prefs user_id param longer than 32 characters: %s', $params['user_id']), LOG_ERR, __FILE__, __LINE__);
            }
            if (isset($params['namespace']) && mb_strlen($params['namespace']) > 32) {
                $app->logMsg(sprintf('Prefs namespace longer than 32 characters: %s', $this->_ns), LOG_ERR, __FILE__, __LINE__);
            }
            if (isset($params['pref_key']) && mb_strlen($params['pref_key']) > 64) {
                $app->logMsg(sprintf('Prefs pref_key param longer than 64 characters: %s', $params['pref_key']), LOG_ERR, __FILE__, __LINE__);
            }
        }

        if (isset($params) && is_array($params)) {
            // Merge new parameters with old overriding only those passed.
            $this->_params = array_merge($this->_params, $params);
        }
    }

    /**
     * Return the value of a parameter, if it exists.
     *
     * @access public
     * @param string $param        Which parameter to return.
     * @return mixed               Configured parameter value.
     */
    public function getParam($param)
    {
        $app =& App::getInstance();

        if (array_key_exists($param, $this->_params)) {
            return $this->_params[$param];
        } else {
            $app->logMsg(sprintf('Parameter is not set: %s', $param), LOG_DEBUG, __FILE__, __LINE__);
            return null;
        }
    }

    /*
    * Setup the SESSION storage array. This method is called at the beginning of each method that accesses $_SESSION['_prefs'].
    *
    * @access   public
    * @param
    * @return
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    02 Oct 2018 15:35:09
    */
    private function _init()
    {
        if ('cookie' != $this->getParam('storagetype') && !isset($_SESSION['_prefs'][$this->_ns])) {
            $this->clear();
        }
    }

    /**
     * Sets the default values for preferences. If a preference is not explicitly
     * set, the value set here will be used. Can be called multiple times to merge additional
     * defaults together. This is mostly only useful for the database storagetype, when you have
     * values you want to use as default, and those are not stored to the database (so the defaults
     * can be changed later and apply to all users who haven't make s specific setting).
     * For the cookie storagetype, using setDefaults just sets cookies but only if a cookie with
     * the same name is not already set.
     *
     * @param  array $defaults  Array of key-value pairs
     */
    public function setDefaults($defaults)
    {
        $app =& App::getInstance();

        $this->_init();

        if (isset($defaults) && is_array($defaults)) {
            switch ($this->getParam('storagetype')) {
            case 'session':
            case 'database':
                $_SESSION['_prefs'][$this->_ns]['defaults'] = array_merge($_SESSION['_prefs'][$this->_ns]['defaults'], $defaults);
                break;

            case 'cookie':
                foreach ($defaults as $key => $val) {
                    if (!$this->exists($key)) {
                        $this->set($key, $val);
                    }
                }
                unset($key, $val);
                break;
            }
        } else {
            $app->logMsg(sprintf('Wrong data-type passed to Prefs->setDefaults().', null), LOG_NOTICE, __FILE__, __LINE__);
        }
    }

    /**
     * Store a key-value pair.
     * When using the database storagetype, if the value is different than what is set by setDefaults the value will be scheduled to be saved in the database.
     *
     * @param  string $key          The name of the preference to modify.
     * @param  string $val          The new value for this preference.
     */
    public function set($key, $val)
    {
        $app =& App::getInstance();

        if (!is_scalar($key)) {
            $app->logMsg(sprintf('Key is not a string-compatible type (%s)', getDump($key)), LOG_NOTICE, __FILE__, __LINE__);
            return false;
        }
        $key = (string)$key;
        if ('' === trim($key)) {
            $app->logMsg(sprintf('Key is empty (val=%s)', $val), LOG_NOTICE, __FILE__, __LINE__);
            return false;
        }
        if (!is_scalar($val) && !is_array($val) && !is_object($val)) {
            $app->logMsg(sprintf('Value is not a compatible data type (%s=%s)', $key, getDump($val)), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }

        $this->_init();

        switch ($this->getParam('storagetype')) {
        // Both session and database prefs are saved in the session (for database, only temporarily until they are saved).
        case 'session':
        case 'database':
            // Set a saved preference if...
            // - there isn't a default.
            // - or the new value is different than the default
            // - or there is a previously existing saved key.
            if (!(isset($_SESSION['_prefs'][$this->_ns]['defaults']) && array_key_exists($key, $_SESSION['_prefs'][$this->_ns]['defaults']))
            || $_SESSION['_prefs'][$this->_ns]['defaults'][$key] != $val
            || $this->exists($key)) {
                $_SESSION['_prefs'][$this->_ns]['saved'][$key] = $val;
                $app->logMsg(sprintf('Setting session/database preference %s => %s', $key, getDump($val, true)), LOG_DEBUG, __FILE__, __LINE__);
            } else {
                $app->logMsg(sprintf('Not setting session/database preference %s => %s', $key, getDump($val, true)), LOG_DEBUG, __FILE__, __LINE__);
            }
            break;

        case 'cookie':
            $name = $this->_getCookieName($key);
            $val = json_encode($val);
            $app->setCookie($name, $val, $this->getParam('cookie_expire'), $this->getParam('cookie_path'), $this->getParam('cookie_domain'));
            $_COOKIE[$name] = $val;
            $app->logMsg(sprintf('Setting cookie preference %s => %s', $key, $val), LOG_DEBUG, __FILE__, __LINE__);
            break;
        }

    }

    /**
     * Returns the value of the requested preference. Saved values take precedence, but if none is set
     * a default value is returned, or if not that, null.
     *
     * @param string $key       The name of the preference to retrieve (or null to retrieve all keys).
     * @return string           The value of the preference.
     */
    public function get($key=null)
    {
        $app =& App::getInstance();

        $this->_init();

        switch ($this->getParam('storagetype')) {
        case 'session':
        case 'database':
            if (is_null($key) && isset($_SESSION['_prefs'][$this->_ns]['saved'])) {
                return $_SESSION['_prefs'][$this->_ns]['saved'];
            }
            if ($this->exists($key)) {
                $app->logMsg(sprintf('Found %s in saved', $key), LOG_DEBUG, __FILE__, __LINE__);
                return $_SESSION['_prefs'][$this->_ns]['saved'][$key];
            }
            if (isset($_SESSION['_prefs'][$this->_ns]['defaults']) && array_key_exists($key, $_SESSION['_prefs'][$this->_ns]['defaults'])) {
                $app->logMsg(sprintf('Found %s in defaults', $key), LOG_DEBUG, __FILE__, __LINE__);
                return $_SESSION['_prefs'][$this->_ns]['defaults'][$key];
            }
            $app->logMsg(sprintf('Key not found in prefs cache: %s', $key), LOG_DEBUG, __FILE__, __LINE__);
            return null;

        case 'cookie':
            if (is_null($key)) {
                $app->logMsg(sprintf('Unable to get(null) when using cookie storagetype.', null), LOG_WARNING, __FILE__, __LINE__);
                return null;
            }
            $name = $this->_getCookieName($key);
            if ($this->exists($key) && '' != $_COOKIE[$name]) {
                $val = json_decode($_COOKIE[$name], true);
                $app->logMsg(sprintf('Found %s in cookie: %s', $key, getDump($val)), LOG_DEBUG, __FILE__, __LINE__);
                return $val;
            }
            $app->logMsg(sprintf('Did not find %s in cookie', $key), LOG_DEBUG, __FILE__, __LINE__);
            return null;
        }
    }

    /**
     * To see if a preference has been set.
     *
     * @param string $key       The name of the preference to check.
     * @return boolean          True if the preference isset and not empty false otherwise.
     */
    public function exists($key)
    {
        $this->_init();

        switch ($this->getParam('storagetype')) {
        case 'session':
        case 'database':
            // isset() does not return TRUE for array keys that correspond to a NULL value, while array_key_exists() does.
            return (isset($_SESSION['_prefs'][$this->_ns]['saved']) && array_key_exists($key, $_SESSION['_prefs'][$this->_ns]['saved']));

        case 'cookie':
            $name = $this->_getCookieName($key);
            return (isset($_COOKIE) && array_key_exists($name, $_COOKIE));
        }

    }

    /**
     * Delete an existing preference value. This will also remove the value from the database, once save() is called.
     *
     * @param string $key       The name of the preference to delete.
     */
    public function delete($key)
    {
        $app =& App::getInstance();

        $this->_init();

        switch ($this->getParam('storagetype')) {
        case 'session':
        case 'database':
            unset($_SESSION['_prefs'][$this->_ns]['saved'][$key]);
            break;

        case 'cookie':
            if ($this->exists($key)) {
                // Just set the existing value to an empty string, which expires in the past.
                $name = $this->_getCookieName($key);
                $app->setCookie($name, '', time() - 86400);
                // Also unset the received cookie value, so it is unavailable.
                unset($_COOKIE[$name]);
            }
            break;
        }

    }

    /**
     * Resets all existing values under this namespace. This should be executed with the same consideration as $auth->clear(), such as when logging out.
     * Set $save true to persist the clear action to the storage (i.e., erase all stored prefs for this user).
     */
    public function clear($scope='all', $save=false)
    {
        $app =& App::getInstance();

        switch ($scope) {
        case 'all' :
            switch ($this->getParam('storagetype')) {
            case 'session':
            case 'database':
                $_SESSION['_prefs'][$this->_ns] = array(
                    'loaded' => false,
                    'load_datetime' => '1970-01-01',
                    'defaults' => array(),
                    'saved' => array(),
                );
                break;
            case 'cookie':
                foreach ($_COOKIE as $key => $value) {
                    // All cookie keys with our internal prefix. Use only the last part as the key.
                    if (preg_match('/^' . preg_quote(sprintf('_prefs-%s-', $this->_ns)) . '(.+)$/i', $key, $match)) {
                        $this->delete($match[1]);
                    }
                }
                break;
            }
            break;

        case 'defaults' :
            $_SESSION['_prefs'][$this->_ns]['defaults'] = array();
            break;

        case 'saved' :
            $_SESSION['_prefs'][$this->_ns]['saved'] = array();
            break;
        }

        if ($save) {
            $this->save(true);
            $app->logMsg(sprintf('Deleted all %s %s prefs for user_id %s', $this->getParam('storagetype'), $this->_ns, $this->getParam('user_id')), LOG_INFO, __FILE__, __LINE__);
        } else {
            $app->logMsg(sprintf('Cleared %s %s prefs', $scope, $this->_ns), LOG_DEBUG, __FILE__, __LINE__);
        }
    }

    /*
    * Retrieves all prefs from the database and stores them in the $_SESSION.
    *
    * @access   public
    * @param    bool    $force  Set to always load from database, regardless if _isLoaded() or not.
    * @return   bool    True if loading succeeded.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    04 Jun 2006 16:56:53
    */
    public function load($force=false)
    {
        $app =& App::getInstance();
        $pdo =& \Strangecode\Codebase\PDO::getInstance();

        // Skip this method if not using the db.
        if ('database' != $this->getParam('storagetype')) {
            $app->logMsg('Prefs->load() does nothing unless using a database storagetype.', LOG_DEBUG, __FILE__, __LINE__);
            return true;
        }

        $this->initDB();

        $this->_init();

        // Prefs already loaded for this session.
        if (!$force && $this->_isLoaded()) {
            return true;
        }

        // User_id must not be empty.
        if ('' === $this->getParam('user_id')) {
            $app->logMsg(sprintf('Cannot load prefs because user_id not set.', null), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }

        // Clear existing cache.
        $this->clear('saved');

        // Retrieve all prefs for this user and namespace.
        $stmt = $pdo->prepare(sprintf("SELECT `pref_key`, `pref_value` FROM `%s` WHERE `user_id` = ? AND `pref_namespace` = ? LIMIT 100000", $pdo->sanitizeIdentifier($this->getParam('db_table'))));
        $stmt->execute([$this->getParam('user_id'), $this->getParam('namespace')]);
        while (list($key, $val) = $stmt->fetch(\PDO::FETCH_NUM)) {
            $_SESSION['_prefs'][$this->_ns]['saved'][$key] = unserialize($val);
        }

        $app->logMsg(sprintf('Loaded %s prefs from database.', sizeof($_SESSION['_prefs'][$this->_ns]['saved'])), LOG_DEBUG, __FILE__, __LINE__);

        // Data loaded only once per session.
        $_SESSION['_prefs'][$this->_ns]['loaded'] = true;
        $_SESSION['_prefs'][$this->_ns]['load_datetime'] = date('Y-m-d H:i:s');

        return true;
    }

    /*
    * Returns true if the prefs had been loaded from the database into the $_SESSION recently.
    * This function is simply a check so the database isn't access every page load.
    *
    * @access   private
    * @return   bool    True if prefs are loaded.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    04 Jun 2006 17:12:44
    */
    protected function _isLoaded()
    {
        if ('database' != $this->getParam('storagetype')) {
            $app->logMsg('Prefs->_isLoaded() does nothing unless using a database storagetype.', LOG_DEBUG, __FILE__, __LINE__);
            return true;
        }

        $this->_init();

        if (isset($_SESSION['_prefs'][$this->_ns]['load_datetime'])
        && strtotime($_SESSION['_prefs'][$this->_ns]['load_datetime']) > time() - $this->getParam('load_timeout')
        && isset($_SESSION['_prefs'][$this->_ns]['loaded'])
        && true === $_SESSION['_prefs'][$this->_ns]['loaded']) {
            return true;
        } else {
            return false;
        }
    }

    /*
    * Saves all prefs stored in the $_SESSION into the database.
    *
    * @access   public
    * @return   bool    True if prefs exist and were saved.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    04 Jun 2006 17:19:56
    */
    public function save($allow_empty=false)
    {
        $app =& App::getInstance();
        $pdo =& \Strangecode\Codebase\PDO::getInstance();

        // Skip this method if not using the db.
        if ('database' != $this->getParam('storagetype')) {
            $app->logMsg('Prefs->save() does nothing unless using a database storagetype.', LOG_DEBUG, __FILE__, __LINE__);
            return true;
        }

        // User_id must not be empty.
        if ('' === $this->getParam('user_id')) {
            $app->logMsg(sprintf('Cannot save prefs because user_id not set.', null), LOG_DEBUG, __FILE__, __LINE__);
            return false;
        }

        $this->initDB();

        $this->_init();

        if (isset($_SESSION['_prefs'][$this->_ns]['saved']) && is_array($_SESSION['_prefs'][$this->_ns]['saved']) && ($allow_empty || !empty($_SESSION['_prefs'][$this->_ns]['saved']))) {
            // Delete old prefs from database.
            $stmt = $pdo->prepare(sprintf("DELETE FROM `%s` WHERE `user_id` = ? AND `pref_namespace` = ?", $pdo->sanitizeIdentifier($this->getParam('db_table'))));
            $stmt->execute([$this->getParam('user_id'), $this->getParam('namespace')]);

            // Insert new prefs.
            $insert_values = array();
            foreach ($_SESSION['_prefs'][$this->_ns]['saved'] as $key => $val) {
                $insert_values[] = sprintf("(%s, %s, %s, %s)",
                    $pdo->quote($this->getParam('user_id')),
                    $pdo->quote($this->getParam('namespace')),
                    $pdo->quote($key),
                    $pdo->quote(serialize($val))
                );
            }
            if (!empty($insert_values)) {
                $stmt = $pdo->query(sprintf("
                    INSERT INTO `%s`
                    (`user_id`, `pref_namespace`, `pref_key`, `pref_value`)
                    VALUES
                    %s
                ", $pdo->sanitizeIdentifier($this->getParam('db_table')), join(', ', $insert_values)));
                $app->logMsg(sprintf('Saved %s prefs to database for user_id %s.', sizeof($insert_values), $this->getParam('user_id')), LOG_DEBUG, __FILE__, __LINE__);
            }

            return true;
        }

        return false;
    }

    /*
    *
    *
    * @access   public
    * @param
    * @return
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    02 May 2014 18:17:04
    */
    protected function _getCookieName($key)
    {
        $app =& App::getInstance();

        if (mb_strpos($key, sprintf('_prefs-%s', $this->_ns)) === 0) {
            $app->logMsg(sprintf('Invalid key name (%s). Leave off "_prefs-%s-" and it should work.', $key, $this->_ns), LOG_NOTICE, __FILE__, __LINE__);
        }
        // Use standardized class data names: _ + classname + namespace + variablekey
        // (namespace = namespace + user_id)
        return sprintf('_prefs-%s-%s', $this->_ns, $key);
    }
}