<?php
namespace Bsr\Utils\Configuration;

class Configuration {

    /**
     * @var Bsr\Config\Configuration
     */
    private static $instance = null;

    /**
     * @var
     */
    private static $customConfigFilePath;

    /**
     * ! WARNING !
     *
     * Those are default values, if you need to change them for a particular host,
     * please just create a file named 'configuration.local.php' in the same directory
     * and redefine the values there !
     *
     * This file must contain an array named $configuration containing the keys you
     * want to redefine. Then, those values will be used to replace those in the
     * array defined just below.
     *
     * @var array configuration values
     */
    private $values = array();

    /**
     * 
     */
    private function __construct() 
    {
        if (!isset($this->values['session'])) {
            $this->values['session'] = array();
        }

        if (!isset($this->values['session']['save_path'])) {
            $this->values['session']['save_path'] = session_save_path();
        }

        if (file_exists(self::getConfigFilePath())) {
            $this->loadConfigFromFile();
        }
    }
    
    /**
     * The path to the file including file name
     * @param string $filePath
     * @return void
     */
    public static function setConfigFilePath($filePath, $clearPrevious = false)
    {
        if (!file_exists($filePath)) {
            throw new \RuntimeException("The file path $filePath, does not exist");
        }
        self::$customConfigFilePath = $filePath;
        $instance = self::getInstance();
        if ($clearPrevious) {
            $instance->clear();
        }
        self::getInstance()->loadConfigFromFile();
    }

    /**
     *
     * @return String
     */
    public static function getConfigFilePath()
    {
        if (null === self::$customConfigFilePath) {
            $envfile = getenv('APPLICATION_ENV') === 'development' ? 'local' : 'global';
            self::$customConfigFilePath = realpath(dirname(__FILE__) . "/../../../../../../config/configuration.$envfile.php");
        }
        return self::$customConfigFilePath;
    }

    /**
     * @return array
     * @throws \RuntimeException
     */
    public function getConfigFromFile()
    {
        if (!file_exists(self::getConfigFilePath())) {
            throw new \RuntimeException("The file : {self::getConfigFilePath()} does not exist");
        }
        return include self::getConfigFilePath();
    }

    /**
     *
     * @return void
     * @throws \RuntimeException
     */
    private function loadConfigFromFile()
    {
        $this->setCustomConfig($this->getConfigFromFile());
    }

    /**
     * @param array $config
     * @return void
     */
    public function setCustomConfig(array $config)
    {
        $this->values = array_replace_recursive($this->values, $config);
    }

    /**
     * @return array
     */
    public function getConfig()
    {
        return $this->values;
    }

    /**
     * Checks whether the nested key exists
     *
     * @param array $data
     * @param array $keys 
     * @return boolean 
     */
    public static function existsKeys(array $data, array $keys)
    {
        foreach ($keys as $k) {
            if (!isset($data[$k])) {
                return false;
            }
            $data = $data[$k];
        }
        return true;
    }

    /**
     * @param array $data
     * @param array $keys 
     * @param any $default
     * @return boolean 
     */
    public static function fetchRecursive(array $data, array $keys, $default = null)
    {
        foreach ($keys as $k) {
            if (!is_array($data)) {
                throw new \Exception("Try to access non-array as array, key '$key''");
            }
            if (!isset($data[$k])) {
                return $default;
            }
            $data = $data[$k];
        }
        return $data;
    }

    /**
     * Return array of keys if dot notation string is passed
     * @param string|array $keys
     */
    public static function parseKeys($keys)
    {
        if (is_string($keys)) {
            $keys = explode('.', $keys);
        } else if (!is_array($keys)) {
            throw new \RuntimeException('Unsupported $keys paramater type');
        }
        return $keys;
    }

    /**
     * Allow clearing previously loaded config
     */
    public function clear()
    {
        $this->values = array();
    }

    /**
     * @return string
     * @throws \Exception
     */
    public function value($keys, $default)
    {
        return self::fetchRecursive($this->values, self::parseKeys($keys), $default);
    }

    /**
     * @return boolean
     */
    public static function has($keys)
    {
        return self::existsKeys(self::get(), self::parseKeys($keys));
    }

    /**
     * @param $name
     * @param mixed $default the default value for your configuration option
     * @return mixed return the configuration value if the key is find, the default otherwise
     */
    public static function get($name = null, $default = null)
    {
        if (null === $name) {
            return self::getInstance()->getConfig();
        }
        return self::getInstance()->value($name, $default);
    }

    /**
     * @return Bsr\Config\Configuration
     */
    public static function getInstance()
    {
        if(is_null(self::$instance)) {
            self::$instance = new Configuration();
        }
        return self::$instance;
    }
}