<?php
namespace BSR\Lib;

class Configuration {
    private static $instance = null;

    /**
     * ! 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 $custom_config_filename = 'configuration.local.php';

    private function __construct() {
        // by default, set the session save path to the default value;
        $this->values['session']['save_path'] = session_save_path();

        if(!file_exists($this->custom_config_filename)) {
            throw new \RuntimeException('No configuration.local.php file was found. Create it with the proper config.');
        }
         
        $configuration  = include_once realpath(dirname(__FILE__) . '/../config/') . $this->custom_config_filename;

        if(!is_array($configuration)) {
            throw new \RuntimeException("You custom configuration in '{$this->custom_config_filename}' must be in a variable named '\$configuration' and be an array.");
        }

        $this->values = array_replace_recursive($this->values, $configuration);
    }

    private function dotNotationAccess($data, $key, $default=null)
    {
        $keys = explode('.', $key);
        foreach ($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;
    }

    private function value($name, $default) {
        return $this->dotNotationAccess($this->values, $name, $default);
    }

    /**
     * @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, $default = null) {
        if(is_null(self::$instance)) {
            self::$instance = new Configuration();
        }

        return self::$instance->value($name, $default);
    }
}