<?php
namespace Core;

use \Exception;

class Environment
{
    protected static $requiredVariables = array(
        'applicationName',
        'managedMode',
        'opcache',

        'BASE_URL_HOST',
        'BASE_URL_PATH',
        'BASE_URL_SCHEME',

        'DB_main_HOST',
        'DB_main_LOGIN',
        'DB_main_NAME',
        'DB_main_PASSWORD',
        'DB_main_PREFIX',

        'SETTINGS_admin_name',
        'SETTINGS_admin_password',
        'SETTINGS_admin_email',
        'SETTINGS_title',
        'SETTINGS_locale',

        'WEB___DIR'
    );

    /**
     * An array of legacy keys to map them to the correct keys
     *
     * @see self::$requiredVariables
     * @var array
     */
    protected static $legacyVariablesMapping = array(
        // safemode legeacy fields
        'SETTINGS_admin_name' => 'admin_name',
        'SETTINGS_admin_password' => 'admin_password',
        'SETTINGS_admin_email' => 'admin_email',
        'SETTINGS_title' => 'title',
        'SETTINGS_locale' => 'locale',

        'DB_TABLE_PREFIX' => 'DB_main_PREFIX',
        'DB_main_PREFIX'  => 'DB_TABLE_PREFIX'
        // add other mappings below
    );

    /**
     * @param $varname
     * @return null|string
     */
    public function get($varname)
    {
        $value = $this->getFromEnvironment($varname);
        return $value;
    }

    /**
     * @param $key
     * @return array|false|string
     */
    protected function getEnvFunctionCall($param)
    {
        return getenv($param);
    }

    /**
     * @param $varname
     * @return null|string
     */
    protected function getFromEnvironment($varname)
    {
        $value = $this->getEnvFunctionCall($varname);

        if ($value !== false) {
            return $value;
        }

        // check legacy keys
        if (array_key_exists($varname, self::$legacyVariablesMapping)) {
            $value = $this->getEnvFunctionCall(self::$legacyVariablesMapping[$varname]);

            if ($value !== false) {
                return $value;
            }
        }

        return null;
    }

    public function systemCheck()
    {
        foreach (self::$requiredVariables as $variable) {
            if (null === $this->get($variable)) {
                throw new Exception("Undefined variable: $variable");
            }
        }
    }

    public function isLinux()
    {
        $pwd = getcwd();
        if (preg_match("/:/", $pwd)) {
            return false;
        }

        return true;
    }
}