<?php
/*
 * @package AJAX_Chat
 * @author Sebastian Tschan
 * @copyright (c) Sebastian Tschan
 * @license GNU Affero General Public License
 * @link https://blueimp.net/ajax/
 */

class AJAXChatLanguage {

    private $_regExpAcceptLangCode;
    private $_availableLangCodes;
    private $_defaultLangCode;
    private $_strictMode;
    private $_langCode;

    function __construct($availableLangCodes, $defaultLangCode, $langCode=null, $strictMode=false) {
        $this->_regExpAcceptLangCode = '/^([a-z]{1,8}(?:-[a-z]{1,8})*)(?:;\s*q=(0(?:\.[0-9]{1,3})?|1(?:\.0{1,3})?))?$/i';
        $this->_availableLangCodes = $availableLangCodes;
        $this->_defaultLangCode = $defaultLangCode;
        if($langCode && in_array($langCode, $availableLangCodes)) {
            $this->_langCode = $langCode;
        }
        $this->_strictMode = $strictMode;
    }

    // Method to detect the language code from the HTTP_ACCEPT_LANGUAGE header:
    function detectLangCode() {
        // If HTTP_ACCEPT_LANGUAGE is empty use defaultLangCode:
        if(empty($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
            $this->_langCode = $this->_defaultLangCode;
            return;
        }

        // Split up the HTTP_ACCEPT_LANGUAGE header:
        $acceptedLanguages = preg_split('/,\s*/', $_SERVER['HTTP_ACCEPT_LANGUAGE']);

        $currentLangCode = $this->_defaultLangCode;
        $currentLangQuality = 0.0;

        foreach($acceptedLanguages as $acceptedLanguage) {
            // Parse the language string:
            $match = preg_match($this->_regExpAcceptLangCode, $acceptedLanguage, $matches);
            // Check if the syntax is valid:
            if(!$match) {
                continue;
            }

            // Get and split the language code:
            $langCodeParts = explode ('-', $matches[1]);

            // Get the language quality given as float value:
            if(isset($matches[2])) {
                $langQuality = (float)$matches[2];
            } else {
                // Missing language quality value is maximum quality:
                $langQuality = 1.0;
            }

            //  Go through it until the language code is empty:
            while(count($langCodeParts)) {
                // Join the current langCodeParts:
                $langCode = strtolower(join('-', $langCodeParts));
                // Check if the langCode is in the available list:
                if(in_array($langCode, $this->_availableLangCodes)) {
                    // Check the quality setting:
                    if ($langQuality > $currentLangQuality) {
                        $currentLangCode = $langCode;
                        $currentLangQuality = $langQuality;
                        break;
                    }
                }
                // If strict mode is set, don't minimalize the language code:
                if($this->_strictMode) {
                    break;
                }
                // else chop off the right part:
                array_pop($langCodeParts);
            }
        }

        $this->_langCode = $currentLangCode;
    }

    function getLangCode() {
        if(!$this->_langCode) {
            $this->detectLangCode();
        }
        return $this->_langCode;
    }

    function setLangCode($langCode) {
        $this->_langCode = $langCode;
    }

    function getLangCodes() {
        return $this->_availableLangCodes;
    }

}