Building a Multilingual PHP Website

<?xml version="1.0" encoding="UTF-8"?>
<language name="en">

 <page name="errors">
  <phase name="empty">Please fill in all the fields</phase>
  <phase name="email_not_found">E-mail not found in database</phase>
  <phase name="login_error">Login error</phase>
  <phase name="email_not_valid">E-mail not valid</phase>
  <phase name="password6">Password must be at least 6 characters</phase>
  <phase name="pass_no_match">Passwords do not match</phase>
  <phase name="template_not_found">Template not found</phase>
 </page>
</language>

<?php
public function load_phrases($lang_id) {
  $xml = new DomDocument('1.0');

  //path to language directory
  $lang_path=(LANG_PATH.$lang_id.'.xml');
  $xml->load($lang_path);

  //phrases are inside page tags, first we must get these
  $page = $xml->getElementsByTagName('page');
  $page_num=$page->length;

  for($i = 0; $i < $page_num; $i++) {
    $page=$xml->getElementsByTagName('page')->item($i);
     
     //get phase tags and store them into array
     foreach($page->getElementsByTagName('phase') as $phase) {
      $phase_name = $phase->getAttribute('name');
      $phrases[$phase_name] = $phase->firstChild->nodeValue;
      $phrases[$phase_name] = str_replace('n','<br/>',$phrases[$phase_name]);
     }
 
  }

 $this->phrases=$phrases;
 }
?>

<?php
public function lang_id() {
  //determine page language
   $lang_id= isset($_COOKIE['lang']) ? $_COOKIE['lang'] : 'en';

  //set the language cookie and update cookie expiration date
    if(!isset($_COOKIE['lang'])) {
      $expiration_date=time()+3600*24*365;
      setcookie('lang',$lang_id,$expiration_date,'/');
    }

 return $lang_id;
 }

 public function change_lang($lang_id) {
     setcookie('lang',$lang_id,$expiration_date,'/');  
 }
?>

<?php
public function __construct() {
  $this->load_phrases($this->lang_id());
 }
?>

CREATE TABLE IF NOT EXISTS `lang` (
  `lang_id` varchar(2) COLLATE utf8_unicode_ci NOT NULL,
  `lang_name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`lang_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE IF NOT EXISTS `phrases` (
  `phrase_id` int(10) NOT NULL AUTO_INCREMENT,
  `lang_id` varchar(2) COLLATE utf8_unicode_ci NOT NULL,
  `phrase_type` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  `phrase_name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  `phrase_text` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`phrase_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

<?php
public function load_phrases($lang_id,$page_name) {
  $this->db->q("SELECT * FROM phrases WHERE lang_id='$lang_id' AND (phrase_type='global' OR phrase_type='$page_name')");
  while($f=$this->db->f_row()) {
   $phrases[$f['phrase_name'] = $f['phrase_text'];
  }
  
  return $phrases;
 }
?>

<?php
echo $lang->phrases[' email_not_valid ']; // prints out E-mail not valid; email_not_valid is the value of phrase_name database field
?>

<?php
public function __construct($lang_id,$page_name) {
  $this->db = new db; // load database class
  $this->phrases = $this->load_phrases($lang_id,$page_name);
 }
?>

public function get_current_filename() {
   $current_file = $_SERVER["SCRIPT_NAME"];
   $parts = Explode('/', $current_file);
   $current_file = $parts[count($parts) - 1];
   $current_file = substr($current_file,0,strlen($current_file)-4);
   return $current_file;
 }

RewriteRule ^([a-zA-Z]{2})/(.*)$ /$2?lang_id=$1 [L,QSA]

<?php
//fetch lang ID
$lang_id = !input::check_varchar($_GET['lang_id'],2,false) ? 'en' : $_GET['lang_id'];
DEFINE('LANG_ID',$lang_id);

//fetch phrases, global and for this page
$page_name = !input::check_varchar($_GET['page_name'],20,false) ? globals::get_current_filename() : $_GET['page_name'];
$lang = new lang($lang_id,$page_name);
?>