<?php
/**
 * ownCloud
 *
 * @author Frank Karlitschek
 * @author Jakob Sack
 * @copyright 2012 Frank Karlitschek frank@owncloud.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/*
 *
 * The following SQL statement is just a help for developers and will not be
 * executed!
 *
 * CREATE TABLE  `appconfig` (
 * `appid` VARCHAR( 255 ) NOT NULL ,
 * `configkey` VARCHAR( 255 ) NOT NULL ,
 * `configvalue` VARCHAR( 255 ) NOT NULL
 * )
 *
 */

/**
 * This class provides an easy way for apps to store config values in the
 * database.
 */
class OC_Appconfig {

	private static $cache = array();

	/**
	 * @brief Get all apps using the config
	 * @return array with app ids
	 *
	 * This function returns a list of all apps that have at least one
	 * entry in the appconfig table.
	 */
	public static function getApps() {
		// No magic in here!
		$query = OC_DB::prepare('SELECT DISTINCT `appid` FROM `*PREFIX*appconfig`');
		$result = $query->execute();

		$apps = array();
		while ($row = $result->fetchRow()) {
			$apps[] = $row["appid"];
		}

		return $apps;
	}

	/**
	 * @brief Get the available keys for an app
	 * @param string $app the app we are looking for
	 * @return array with key names
	 *
	 * This function gets all keys of an app. Please note that the values are
	 * not returned.
	 */
	public static function getKeys($app) {
		// No magic in here as well
		$query = OC_DB::prepare('SELECT `configkey` FROM `*PREFIX*appconfig` WHERE `appid` = ?');
		$result = $query->execute(array($app));

		$keys = array();
		while ($row = $result->fetchRow()) {
			$keys[] = $row["configkey"];
		}

		return $keys;
	}

	private static function getAppValues($app) {
		if (!isset(self::$cache[$app])) {
			self::$cache[$app] = array();
		}
		$query = OC_DB::prepare('SELECT `configvalue`, `configkey` FROM `*PREFIX*appconfig`'
			. ' WHERE `appid` = ?');
		$result = $query->execute(array($app));
		while ($row = $result->fetchRow()) {
			self::$cache[$app][$row['configkey']] = $row['configvalue'];
		}
		return self::$cache[$app];
	}

	/**
	 * @brief Gets the config value
	 * @param string $app app
	 * @param string $key key
	 * @param string $default = null, default value if the key does not exist
	 * @return string the value or $default
	 *
	 * This function gets a value from the appconfig table. If the key does
	 * not exist the default value will be returned
	 */
	public static function getValue($app, $key, $default = null) {
		if (!isset(self::$cache[$app])) {
			self::$cache[$app] = array();
		}
		if (isset(self::$cache[$app][$key])) {
			return self::$cache[$app][$key];
		}
		$values = self::getAppValues($app);
		if (isset($values[$key])) {
			return $values[$key];
		} else {
			self::$cache[$app][$key] = $default;
			return $default;
		}
	}

	/**
	 * @brief check if a key is set in the appconfig
	 * @param string $app
	 * @param string $key
	 * @return bool
	 */
	public static function hasKey($app, $key) {
		if (isset(self::$cache[$app]) and isset(self::$cache[$app][$key])) {
			return true;
		}
		$exists = self::getKeys($app);
		return in_array($key, $exists);
	}

	/**
	 * @brief sets a value in the appconfig
	 * @param string $app app
	 * @param string $key key
	 * @param string $value value
	 * @return bool
	 *
	 * Sets a value. If the key did not exist before it will be created.
	 */
	public static function setValue($app, $key, $value) {
		// Does the key exist? yes: update. No: insert
		if (!self::hasKey($app, $key)) {
			$query = OC_DB::prepare('INSERT INTO `*PREFIX*appconfig` ( `appid`, `configkey`, `configvalue` )'
				. ' VALUES( ?, ?, ? )');
			$query->execute(array($app, $key, $value));
		} else {
			$query = OC_DB::prepare('UPDATE `*PREFIX*appconfig` SET `configvalue` = ?'
				. ' WHERE `appid` = ? AND `configkey` = ?');
			$query->execute(array($value, $app, $key));
		}
		// TODO where should this be documented?
		\OC_Hook::emit('OC_Appconfig', 'post_set_value', array(
			'app' => $app,
			'key' => $key,
			'value' => $value
		));
		if (!isset(self::$cache[$app])) {
			self::$cache[$app] = array();
		}
		self::$cache[$app][$key] = $value;
	}

	/**
	 * @brief Deletes a key
	 * @param string $app app
	 * @param string $key key
	 * @return bool
	 *
	 * Deletes a key.
	 */
	public static function deleteKey($app, $key) {
		// Boring!
		$query = OC_DB::prepare('DELETE FROM `*PREFIX*appconfig` WHERE `appid` = ? AND `configkey` = ?');
		$query->execute(array($app, $key));
		if (isset(self::$cache[$app]) and isset(self::$cache[$app][$key])) {
			unset(self::$cache[$app][$key]);
		}

		return true;
	}

	/**
	 * @brief Remove app from appconfig
	 * @param string $app app
	 * @return bool
	 *
	 * Removes all keys in appconfig belonging to the app.
	 */
	public static function deleteApp($app) {
		// Nothing special
		$query = OC_DB::prepare('DELETE FROM `*PREFIX*appconfig` WHERE `appid` = ?');
		$query->execute(array($app));
		self::$cache[$app] = array();

		return true;
	}

	/**
	 * get multiply values, either the app or key can be used as wildcard by setting it to false
	 *
	 * @param app
	 * @param key
	 * @return array
	 */
	public static function getValues($app, $key) {
		if ($app !== false and $key !== false) {
			return false;
		}
		$fields = '`configvalue`';
		$where = 'WHERE';
		$params = array();
		if ($app !== false) {
			$fields .= ', `configkey`';
			$where .= ' `appid` = ?';
			$params[] = $app;
			$key = 'configkey';
		} else {
			$fields .= ', `appid`';
			$where .= ' `configkey` = ?';
			$params[] = $key;
			$key = 'appid';
		}
		$queryString = 'SELECT ' . $fields . ' FROM `*PREFIX*appconfig` ' . $where;
		$query = OC_DB::prepare($queryString);
		$result = $query->execute($params);
		$values = array();
		while ($row = $result->fetchRow()) {
			$values[$row[$key]] = $row['configvalue'];
		}
		return $values;
	}
}