8 files changed, 1015 insertions, 234 deletions
diff --git a/phpBB/phpbb/captcha/plugins/captcha_abstract.php b/phpBB/phpbb/captcha/plugins/captcha_abstract.php
index 799947a84e..b29f144f97 100644
--- a/phpBB/phpbb/captcha/plugins/captcha_abstract.php
+++ b/phpBB/phpbb/captcha/plugins/captcha_abstract.php
@@ -195,7 +195,7 @@ abstract class captcha_abstract
 	{
 		global $config, $db, $user;
 
-		if (empty($user->lang))
+		if (!$user->is_setup())
 		{
 			$user->setup();
 		}
diff --git a/phpBB/phpbb/language/exception/invalid_plural_rule_exception.php b/phpBB/phpbb/language/exception/invalid_plural_rule_exception.php
new file mode 100644
index 0000000000..94e3466208
--- /dev/null
+++ b/phpBB/phpbb/language/exception/invalid_plural_rule_exception.php
@@ -0,0 +1,22 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language\exception;
+
+/**
+ * Thrown when nonexistent plural rule is specified
+ */
+class invalid_plural_rule_exception extends language_exception
+{
+
+}
diff --git a/phpBB/phpbb/language/exception/language_exception.php b/phpBB/phpbb/language/exception/language_exception.php
new file mode 100644
index 0000000000..b1258414aa
--- /dev/null
+++ b/phpBB/phpbb/language/exception/language_exception.php
@@ -0,0 +1,22 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language\exception;
+
+/**
+ * Base exception class for language exceptions
+ */
+class language_exception extends \phpbb\exception\runtime_exception
+{
+
+}
diff --git a/phpBB/phpbb/language/exception/language_file_not_found.php b/phpBB/phpbb/language/exception/language_file_not_found.php
new file mode 100644
index 0000000000..89364267eb
--- /dev/null
+++ b/phpBB/phpbb/language/exception/language_file_not_found.php
@@ -0,0 +1,22 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language\exception;
+
+/**
+ * This exception is thrown when the language file is not found
+ */
+class language_file_not_found extends language_exception
+{
+
+}
diff --git a/phpBB/phpbb/language/language.php b/phpBB/phpbb/language/language.php
new file mode 100644
index 0000000000..9c9a3b8df1
--- /dev/null
+++ b/phpBB/phpbb/language/language.php
@@ -0,0 +1,562 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language;
+
+use phpbb\language\exception\invalid_plural_rule_exception;
+
+/**
+ * Wrapper class for loading translations
+ */
+class language
+{
+	/**
+	 * Global fallback language
+	 *
+	 * ISO code of the language to fallback to when the specified language entries
+	 * cannot be found.
+	 *
+	 * @var string
+	 */
+	const FALLBACK_LANGUAGE = 'en';
+
+	/**
+	 * @var array	List of common language files
+	 */
+	protected $common_language_files;
+
+	/**
+	 * @var bool
+	 */
+	protected $common_language_files_loaded;
+
+	/**
+	 * @var string	ISO code of the default board language
+	 */
+	protected $default_language;
+
+	/**
+	 * @var string	ISO code of the User's language
+	 */
+	protected $user_language;
+
+	/**
+	 * @var array	Language fallback array (the order is important)
+	 */
+	protected $language_fallback;
+
+	/**
+	 * @var array	Array of language variables
+	 */
+	protected $lang;
+
+	/**
+	 * @var array	Loaded language sets
+	 */
+	protected $loaded_language_sets;
+
+	/**
+	 * @var \phpbb\language\language_file_loader Language file loader
+	 */
+	protected $loader;
+
+	/**
+	 * Constructor
+	 *
+	 * @param \phpbb\language\language_file_loader	$loader	Language file loader
+	 */
+	public function __construct(language_file_loader $loader)
+	{
+		$this->loader = $loader;
+
+		// Set up default information
+		$this->user_language		= false;
+		$this->default_language		= false;
+		$this->lang					= array(
+			// For BC with user::help array
+			'__help' => array(),
+		);
+		$this->loaded_language_sets	= array(
+			'core'	=> array(),
+			'ext'	=> array(),
+		);
+
+		// Common language files
+		$this->common_language_files = array(
+			'common',
+		);
+		$this->common_language_files_loaded = false;
+
+		$this->language_fallback = array(self::FALLBACK_LANGUAGE);
+	}
+
+	/**
+	 * Function to set user's language to display.
+	 *
+	 * @param string	$user_lang_iso	ISO code of the User's language
+	 */
+	public function set_user_language($user_lang_iso)
+	{
+		$this->user_language = $user_lang_iso;
+
+		$this->set_fallback_array();
+	}
+
+	/**
+	 * Function to set the board's default language to display.
+	 *
+	 * @param string	$default_lang_iso	ISO code of the board's default language
+	 */
+	public function set_default_language($default_lang_iso)
+	{
+		$this->default_language = $default_lang_iso;
+
+		$this->set_fallback_array();
+	}
+
+	/**
+	 * Returns language array
+	 *
+	 * Note: This function is needed for the BC purposes, until \phpbb\user::lang[] is
+	 *       not removed.
+	 *
+	 * @return array	Array of loaded language strings
+	 */
+	public function get_lang_array()
+	{
+		// Load common language files if they not loaded yet
+		if (!$this->common_language_files_loaded)
+		{
+			$this->load_common_language_files();
+		}
+
+		return $this->lang;
+	}
+
+	/**
+	 * Add Language Items
+	 *
+	 * Note: $use_help is assigned where needed (only use them to force inclusion).
+	 *
+	 * Examples:
+	 * <code>
+	 * $component = array('posting');
+	 * $component = array('posting', 'viewtopic')
+	 * $component = 'posting'
+	 * </code>
+	 *
+	 * @param string|array	$component		The name of the language component to load
+	 * @param string|null	$extension_name	Name of the extension to load component from, or null for core file
+	 */
+	public function add_lang($component, $extension_name = null)
+	{
+		// Load common language files if they not loaded yet
+		// This needs to be here to correctly merge language arrays
+		if (!$this->common_language_files_loaded)
+		{
+			$this->load_common_language_files();
+		}
+
+		if (!is_array($component))
+		{
+			if (!is_null($extension_name))
+			{
+				$this->load_extension($extension_name, $component);
+			}
+			else
+			{
+				$this->load_core_file($component);
+			}
+		}
+		else
+		{
+			foreach ($component as $lang_file)
+			{
+				$this->add_lang($lang_file, $extension_name);
+			}
+		}
+	}
+
+	/**
+	 * Advanced language substitution
+	 *
+	 * Function to mimic sprintf() with the possibility of using phpBB's language system to substitute nullar/singular/plural forms.
+	 * Params are the language key and the parameters to be substituted.
+	 * This function/functionality is inspired by SHS` and Ashe.
+	 *
+	 * Example call: <samp>$user->lang('NUM_POSTS_IN_QUEUE', 1);</samp>
+	 *
+	 * If the first parameter is an array, the elements are used as keys and subkeys to get the language entry:
+	 * Example: <samp>$user->lang(array('datetime', 'AGO'), 1)</samp> uses $user->lang['datetime']['AGO'] as language entry.
+	 *
+	 * @return string	Return localized string or the language key if the translation is not available
+	 */
+	public function lang()
+	{
+		// Load common language files if they not loaded yet
+		if (!$this->common_language_files_loaded)
+		{
+			$this->load_common_language_files();
+		}
+
+		$args = func_get_args();
+		$key = $args[0];
+
+		if (is_array($key))
+		{
+			$lang = &$this->lang[array_shift($key)];
+
+			foreach ($key as $_key)
+			{
+				$lang = &$lang[$_key];
+			}
+		}
+		else
+		{
+			$lang = &$this->lang[$key];
+		}
+
+		// Return if language string does not exist
+		if (!isset($lang) || (!is_string($lang) && !is_array($lang)))
+		{
+			return $key;
+		}
+
+		// If the language entry is a string, we simply mimic sprintf() behaviour
+		if (is_string($lang))
+		{
+			if (sizeof($args) == 1)
+			{
+				return $lang;
+			}
+
+			// Replace key with language entry and simply pass along...
+			$args[0] = $lang;
+			return call_user_func_array('sprintf', $args);
+		}
+		else if (sizeof($lang) == 0)
+		{
+			// If the language entry is an empty array, we just return the language key
+			return $args[0];
+		}
+
+		// It is an array... now handle different nullar/singular/plural forms
+		$key_found = false;
+
+		// We now get the first number passed and will select the key based upon this number
+		for ($i = 1, $num_args = sizeof($args); $i < $num_args; $i++)
+		{
+			if (is_int($args[$i]) || is_float($args[$i]))
+			{
+				if ($args[$i] == 0 && isset($lang[0]))
+				{
+					// We allow each translation using plural forms to specify a version for the case of 0 things,
+					// so that "0 users" may be displayed as "No users".
+					$key_found = 0;
+					break;
+				}
+				else
+				{
+					$use_plural_form = $this->get_plural_form($args[$i]);
+					if (isset($lang[$use_plural_form]))
+					{
+						// The key we should use exists, so we use it.
+						$key_found = $use_plural_form;
+					}
+					else
+					{
+						// If the key we need to use does not exist, we fall back to the previous one.
+						$numbers = array_keys($lang);
+
+						foreach ($numbers as $num)
+						{
+							if ($num > $use_plural_form)
+							{
+								break;
+							}
+
+							$key_found = $num;
+						}
+					}
+					break;
+				}
+			}
+		}
+
+		// Ok, let's check if the key was found, else use the last entry (because it is mostly the plural form)
+		if ($key_found === false)
+		{
+			$numbers = array_keys($lang);
+			$key_found = end($numbers);
+		}
+
+		// Use the language string we determined and pass it to sprintf()
+		$args[0] = $lang[$key_found];
+		return call_user_func_array('sprintf', $args);
+	}
+
+	/**
+	 * Loads common language files
+	 */
+	protected function load_common_language_files()
+	{
+		if (!$this->common_language_files_loaded)
+		{
+			foreach ($this->common_language_files as $lang_file)
+			{
+				$this->load_core_file($lang_file);
+			}
+
+			$this->common_language_files_loaded = true;
+		}
+	}
+
+	/**
+	 * Determine which plural form we should use.
+	 *
+	 * For some languages this is not as simple as for English.
+	 *
+	 * @param int|float		$number		The number we want to get the plural case for. Float numbers are floored.
+	 * @param int|bool		$force_rule	False to use the plural rule of the language package
+	 *									or an integer to force a certain plural rule
+	 *
+	 * @return int	The plural-case we need to use for the number plural-rule combination
+	 *
+	 * @throws \phpbb\language\exception\invalid_plural_rule_exception	When $force_rule has an invalid value
+	 */
+	public function get_plural_form($number, $force_rule = false)
+	{
+		$number			= (int) $number;
+		$plural_rule	= ($force_rule !== false) ? $force_rule : ((isset($this->lang['PLURAL_RULE'])) ? $this->lang['PLURAL_RULE'] : 1);
+
+		if ($plural_rule > 15 || $plural_rule < 0)
+		{
+			throw new invalid_plural_rule_exception('INVALID_PLURAL_RULE', array(
+				'plural_rule' => $plural_rule,
+			));
+		}
+
+		/**
+		 * The following plural rules are based on a list published by the Mozilla Developer Network
+		 * https://developer.mozilla.org/en/Localization_and_Plurals
+		 */
+		switch ($plural_rule)
+		{
+			case 0:
+				/**
+				 * Families: Asian (Chinese, Japanese, Korean, Vietnamese), Persian, Turkic/Altaic (Turkish), Thai, Lao
+				 * 1 - everything: 0, 1, 2, ...
+				 */
+				return 1;
+
+			case 1:
+				/**
+				 * Families: Germanic (Danish, Dutch, English, Faroese, Frisian, German, Norwegian, Swedish), Finno-Ugric (Estonian, Finnish, Hungarian), Language isolate (Basque), Latin/Greek (Greek), Semitic (Hebrew), Romanic (Italian, Portuguese, Spanish, Catalan)
+				 * 1 - 1
+				 * 2 - everything else: 0, 2, 3, ...
+				 */
+				return ($number === 1) ? 1 : 2;
+
+			case 2:
+				/**
+				 * Families: Romanic (French, Brazilian Portuguese)
+				 * 1 - 0, 1
+				 * 2 - everything else: 2, 3, ...
+				 */
+				return (($number === 0) || ($number === 1)) ? 1 : 2;
+
+			case 3:
+				/**
+				 * Families: Baltic (Latvian)
+				 * 1 - 0
+				 * 2 - ends in 1, not 11: 1, 21, ... 101, 121, ...
+				 * 3 - everything else: 2, 3, ... 10, 11, 12, ... 20, 22, ...
+				 */
+				return ($number === 0) ? 1 : ((($number % 10 === 1) && ($number % 100 != 11)) ? 2 : 3);
+
+			case 4:
+				/**
+				 * Families: Celtic (Scottish Gaelic)
+				 * 1 - is 1 or 11: 1, 11
+				 * 2 - is 2 or 12: 2, 12
+				 * 3 - others between 3 and 19: 3, 4, ... 10, 13, ... 18, 19
+				 * 4 - everything else: 0, 20, 21, ...
+				 */
+				return ($number === 1 || $number === 11) ? 1 : (($number === 2 || $number === 12) ? 2 : (($number >= 3 && $number <= 19) ? 3 : 4));
+
+			case 5:
+				/**
+				 * Families: Romanic (Romanian)
+				 * 1 - 1
+				 * 2 - is 0 or ends in 01-19: 0, 2, 3, ... 19, 101, 102, ... 119, 201, ...
+				 * 3 - everything else: 20, 21, ...
+				 */
+				return ($number === 1) ? 1 : ((($number === 0) || (($number % 100 > 0) && ($number % 100 < 20))) ? 2 : 3);
+
+			case 6:
+				/**
+				 * Families: Baltic (Lithuanian)
+				 * 1 - ends in 1, not 11: 1, 21, 31, ... 101, 121, ...
+				 * 2 - ends in 0 or ends in 10-20: 0, 10, 11, 12, ... 19, 20, 30, 40, ...
+				 * 3 - everything else: 2, 3, ... 8, 9, 22, 23, ... 29, 32, 33, ...
+				 */
+				return (($number % 10 === 1) && ($number % 100 != 11)) ? 1 : ((($number % 10 < 2) || (($number % 100 >= 10) && ($number % 100 < 20))) ? 2 : 3);
+
+			case 7:
+				/**
+				 * Families: Slavic (Croatian, Serbian, Russian, Ukrainian)
+				 * 1 - ends in 1, not 11: 1, 21, 31, ... 101, 121, ...
+				 * 2 - ends in 2-4, not 12-14: 2, 3, 4, 22, 23, 24, 32, ...
+				 * 3 - everything else: 0, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 26, ...
+				 */
+				return (($number % 10 === 1) && ($number % 100 != 11)) ? 1 : ((($number % 10 >= 2) && ($number % 10 <= 4) && (($number % 100 < 10) || ($number % 100 >= 20))) ? 2 : 3);
+
+			case 8:
+				/**
+				 * Families: Slavic (Slovak, Czech)
+				 * 1 - 1
+				 * 2 - 2, 3, 4
+				 * 3 - everything else: 0, 5, 6, 7, ...
+				 */
+				return ($number === 1) ? 1 : ((($number >= 2) && ($number <= 4)) ? 2 : 3);
+
+			case 9:
+				/**
+				 * Families: Slavic (Polish)
+				 * 1 - 1
+				 * 2 - ends in 2-4, not 12-14: 2, 3, 4, 22, 23, 24, 32, ... 104, 122, ...
+				 * 3 - everything else: 0, 5, 6, ... 11, 12, 13, 14, 15, ... 20, 21, 25, ...
+				 */
+				return ($number === 1) ? 1 : ((($number % 10 >= 2) && ($number % 10 <= 4) && (($number % 100 < 12) || ($number % 100 > 14))) ? 2 : 3);
+
+			case 10:
+				/**
+				 * Families: Slavic (Slovenian, Sorbian)
+				 * 1 - ends in 01: 1, 101, 201, ...
+				 * 2 - ends in 02: 2, 102, 202, ...
+				 * 3 - ends in 03-04: 3, 4, 103, 104, 203, 204, ...
+				 * 4 - everything else: 0, 5, 6, 7, 8, 9, 10, 11, ...
+				 */
+				return ($number % 100 === 1) ? 1 : (($number % 100 === 2) ? 2 : ((($number % 100 === 3) || ($number % 100 === 4)) ? 3 : 4));
+
+			case 11:
+				/**
+				 * Families: Celtic (Irish Gaeilge)
+				 * 1 - 1
+				 * 2 - 2
+				 * 3 - is 3-6: 3, 4, 5, 6
+				 * 4 - is 7-10: 7, 8, 9, 10
+				 * 5 - everything else: 0, 11, 12, ...
+				 */
+				return ($number === 1) ? 1 : (($number === 2) ? 2 : (($number >= 3 && $number <= 6) ? 3 : (($number >= 7 && $number <= 10) ? 4 : 5)));
+
+			case 12:
+				/**
+				 * Families: Semitic (Arabic)
+				 * 1 - 1
+				 * 2 - 2
+				 * 3 - ends in 03-10: 3, 4, ... 10, 103, 104, ... 110, 203, 204, ...
+				 * 4 - ends in 11-99: 11, ... 99, 111, 112, ...
+				 * 5 - everything else: 100, 101, 102, 200, 201, 202, ...
+				 * 6 - 0
+				 */
+				return ($number === 1) ? 1 : (($number === 2) ? 2 : ((($number % 100 >= 3) && ($number % 100 <= 10)) ? 3 : ((($number % 100 >= 11) && ($number % 100 <= 99)) ? 4 : (($number != 0) ? 5 : 6))));
+
+			case 13:
+				/**
+				 * Families: Semitic (Maltese)
+				 * 1 - 1
+				 * 2 - is 0 or ends in 01-10: 0, 2, 3, ... 9, 10, 101, 102, ...
+				 * 3 - ends in 11-19: 11, 12, ... 18, 19, 111, 112, ...
+				 * 4 - everything else: 20, 21, ...
+				 */
+				return ($number === 1) ? 1 : ((($number === 0) || (($number % 100 > 1) && ($number % 100 < 11))) ? 2 : ((($number % 100 > 10) && ($number % 100 < 20)) ? 3 : 4));
+
+			case 14:
+				/**
+				 * Families: Slavic (Macedonian)
+				 * 1 - ends in 1: 1, 11, 21, ...
+				 * 2 - ends in 2: 2, 12, 22, ...
+				 * 3 - everything else: 0, 3, 4, ... 10, 13, 14, ... 20, 23, ...
+				 */
+				return ($number % 10 === 1) ? 1 : (($number % 10 === 2) ? 2 : 3);
+
+			case 15:
+				/**
+				 * Families: Icelandic
+				 * 1 - ends in 1, not 11: 1, 21, 31, ... 101, 121, 131, ...
+				 * 2 - everything else: 0, 2, 3, ... 10, 11, 12, ... 20, 22, ...
+				 */
+				return (($number % 10 === 1) && ($number % 100 != 11)) ? 1 : 2;
+		}
+	}
+
+	/**
+	 * Returns language fallback data
+	 *
+	 * @return array
+	 */
+	protected function set_fallback_array()
+	{
+		$fallback_array = array();
+
+		if ($this->user_language !== false)
+		{
+			$fallback_array[] = $this->user_language;
+		}
+
+		if ($this->default_language !== false)
+		{
+			$fallback_array[] = $this->default_language;
+		}
+
+		$fallback_array[] = self::FALLBACK_LANGUAGE;
+
+		$this->language_fallback = $fallback_array;
+	}
+
+	/**
+	 * Load core language file
+	 *
+	 * @param string	$component	Name of the component to load
+	 */
+	protected function load_core_file($component)
+	{
+		// Check if the component is already loaded
+		if (isset($this->loaded_language_sets['core'][$component]))
+		{
+			return;
+		}
+
+		$this->loader->load($component, $this->language_fallback, $this->lang);
+		$this->loaded_language_sets['core'][$component] = true;
+	}
+
+	/**
+	 * Load extension language file
+	 *
+	 * @param string	$extension_name	Name of the extension to load language from
+	 * @param string	$component		Name of the component to load
+	 */
+	protected function load_extension($extension_name, $component)
+	{
+		// Check if the component is already loaded
+		if (isset($this->loaded_language_sets['ext'][$extension_name][$component]))
+		{
+			return;
+		}
+
+		$this->loader->load_extension($extension_name, $component, $this->language_fallback, $this->lang);
+		$this->loaded_language_sets['ext'][$extension_name][$component] = true;
+	}
+}
diff --git a/phpBB/phpbb/language/language_file_helper.php b/phpBB/phpbb/language/language_file_helper.php
new file mode 100644
index 0000000000..18d7b62e21
--- /dev/null
+++ b/phpBB/phpbb/language/language_file_helper.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language;
+
+use Symfony\Component\Finder\Finder;
+
+/**
+ * Helper class for language file related functions
+ */
+class language_file_helper
+{
+	/**
+	 * @var string	Path to phpBB's root
+	 */
+	protected $phpbb_root_path;
+
+	/**
+	 * Constructor
+	 *
+	 * @param string	$phpbb_root_path	Path to phpBB's root
+	 */
+	public function __construct($phpbb_root_path)
+	{
+		$this->phpbb_root_path = $phpbb_root_path;
+	}
+
+	/**
+	 * Returns available languages
+	 *
+	 * @return array
+	 */
+	public function get_available_languages()
+	{
+		// Find available language packages
+		$finder = new Finder();
+		$finder->files()
+			->name('iso.txt')
+			->depth('== 1')
+			->in($this->phpbb_root_path . 'language');
+
+		$available_languages = array();
+		foreach ($finder as $file)
+		{
+			$path = $file->getRelativePath();
+			$info = explode("\n", $file->getContents());
+
+			$available_languages[] = array(
+				// Get the name of the directory containing iso.txt
+				'iso' => $path,
+
+				// Recover data from file
+				'name' => trim($info[0]),
+				'local_name' => trim($info[1]),
+				'author' => trim($info[2])
+			);
+		}
+
+		return $available_languages;
+	}
+}
diff --git a/phpBB/phpbb/language/language_file_loader.php b/phpBB/phpbb/language/language_file_loader.php
new file mode 100644
index 0000000000..510a29279a
--- /dev/null
+++ b/phpBB/phpbb/language/language_file_loader.php
@@ -0,0 +1,212 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\language;
+
+use \phpbb\language\exception\language_file_not_found;
+
+/**
+ * Language file loader
+ */
+class language_file_loader
+{
+	/**
+	 * @var string	Path to phpBB's root
+	 */
+	protected $phpbb_root_path;
+
+	/**
+	 * @var string	Extension of PHP files
+	 */
+	protected $php_ext;
+
+	/**
+	 * @var \phpbb\extension\manager	Extension manager
+	 */
+	protected $extension_manager;
+
+	/**
+	 * Constructor
+	 *
+	 * @param string	$phpbb_root_path	Path to phpBB's root
+	 * @param string	$php_ext			Extension of PHP files
+	 */
+	public function __construct($phpbb_root_path, $php_ext)
+	{
+		$this->phpbb_root_path	= $phpbb_root_path;
+		$this->php_ext			= $php_ext;
+
+		$this->extension_manager = null;
+	}
+
+	/**
+	 * Extension manager setter
+	 *
+	 * @param \phpbb\extension\manager	$extension_manager	Extension manager
+	 */
+	public function set_extension_manager(\phpbb\extension\manager $extension_manager)
+	{
+		$this->extension_manager = $extension_manager;
+	}
+
+	/**
+	 * Loads language array for the given component
+	 *
+	 * @param string		$component	Name of the language component
+	 * @param string|array	$locale		ISO code of the language to load, or array of ISO codes if you want to
+	 * 									specify additional language fallback steps
+	 * @param array			$lang		Array reference containing language strings
+	 */
+	public function load($component, $locale, &$lang)
+	{
+		$locale = (array) $locale;
+
+		// Determine path to language directory
+		$path = $this->phpbb_root_path . 'language/';
+
+		$this->load_file($path, $component, $locale, $lang);
+	}
+
+	/**
+	 * Loads language array for the given extension component
+	 *
+	 * @param string		$extension	Name of the extension
+	 * @param string		$component	Name of the language component
+	 * @param string|array	$locale		ISO code of the language to load, or array of ISO codes if you want to
+	 * 									specify additional language fallback steps
+	 * @param array			$lang		Array reference containing language strings
+	 */
+	public function load_extension($extension, $component, $locale, &$lang)
+	{
+		// Check if extension manager was loaded
+		if ($this->extension_manager === null)
+		{
+			// If not, let's return
+			return;
+		}
+
+		$locale = (array) $locale;
+
+		// Determine path to language directory
+		$path = $this->extension_manager->get_extension_path($extension, true) . 'language/';
+
+		$this->load_file($path, $component, $locale, $lang);
+	}
+
+	/**
+	 * Prepares language file loading
+	 *
+	 * @param string	$path		Path to search for file in
+	 * @param string	$component	Name of the language component
+	 * @param array		$locale		Array containing language fallback options
+	 * @param array		$lang		Array reference of language strings
+	 */
+	protected function load_file($path, $component, $locale, &$lang)
+	{
+		// This is BC stuff and not the best idea as it makes language fallback
+		// implementation quite hard like below.
+		if (strpos($this->phpbb_root_path . $component, $path) === 0)
+		{
+			// Filter out the path
+			$path_diff = str_replace($path, '', dirname($this->phpbb_root_path . $component));
+			$language_file = basename($component, '.' . $this->php_ext);
+			$component = '';
+
+			// This step is needed to resolve language/en/subdir style $component
+			// $path already points to the language base directory so we need to eliminate
+			// the first directory from the path (that should be the language directory)
+			$path_diff_parts = explode('/', $path_diff);
+
+			if (sizeof($path_diff_parts) > 1)
+			{
+				array_shift($path_diff_parts);
+				$component = implode('/', $path_diff_parts) . '/';
+			}
+
+			$component .= $language_file;
+		}
+
+		// Determine filename
+		$filename = $component . '.' . $this->php_ext;
+
+		// Determine path to file
+		$file_path = $this->get_language_file_path($path, $filename, $locale);
+
+		// Load language array
+		$this->load_language_file($file_path, $lang);
+	}
+
+	/**
+	 * This function implements language fallback logic
+	 *
+	 * @param string	$path		Path to language directory
+	 * @param string	$filename	Filename to load language strings from
+	 *
+	 * @return string	Relative path to language file
+	 *
+	 * @throws \phpbb\language\exception\language_file_not_exists	When the path to the file cannot be resolved
+	 */
+	protected function get_language_file_path($path, $filename, $locales)
+	{
+		// Language fallback logic
+		foreach ($locales as $locale)
+		{
+			$language_file_path = $path . $locale . '/' . $filename;
+
+			// If we are in install, try to use the updated version, when available
+			if (defined('IN_INSTALL'))
+			{
+				$install_language_path = str_replace('language/', 'install/update/new/language/', $language_file_path);
+				if (file_exists($install_language_path))
+				{
+					return $install_language_path;
+				}
+			}
+
+			if (file_exists($language_file_path))
+			{
+				return $language_file_path;
+			}
+		}
+
+		// The language file is not exist
+		throw new language_file_not_found('Language file ' . $language_file_path . ' couldn\'t be opened.');
+	}
+
+	/**
+	 * Loads language file
+	 *
+	 * @param string	$path	Path to language file to load
+	 * @param array		$lang	Reference of the array of language strings
+	 */
+	protected function load_language_file($path, &$lang)
+	{
+		// BC code for language files with help
+		$help = array();
+
+		// Do not suppress error if in DEBUG mode
+		if (defined('DEBUG'))
+		{
+			include $path;
+		}
+		else
+		{
+			@include $path;
+		}
+
+		if (!empty($help))
+		{
+			$lang['__help'] = array_merge($lang['__help'], $help);
+		}
+	}
+}
diff --git a/phpBB/phpbb/user.php b/phpBB/phpbb/user.php
index 882e9cef26..c33070d6f4 100644
--- a/phpBB/phpbb/user.php
+++ b/phpBB/phpbb/user.php
@@ -21,8 +21,11 @@ namespace phpbb;
 */
 class user extends \phpbb\session
 {
-	var $lang = array();
-	var $help = array();
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
 	var $style = array();
 	var $date_format;
 
@@ -42,35 +45,63 @@ class user extends \phpbb\session
 	var $img_lang;
 	var $img_array = array();
 
+	/** @var bool */
+	protected $is_setup_flag;
+
 	// Able to add new options (up to id 31)
 	var $keyoptions = array('viewimg' => 0, 'viewflash' => 1, 'viewsmilies' => 2, 'viewsigs' => 3, 'viewavatars' => 4, 'viewcensors' => 5, 'attachsig' => 6, 'bbcode' => 8, 'smilies' => 9, 'sig_bbcode' => 15, 'sig_smilies' => 16, 'sig_links' => 17);
 
 	/**
 	* Constructor to set the lang path
+	*
 	* @param string $datetime_class Class name of datetime class
+	* @param \phpbb\language\language	$lang	phpBB's Language loader
 	*/
-	function __construct($datetime_class)
+	function __construct(\phpbb\language\language $lang, $datetime_class)
 	{
 		global $phpbb_root_path;
 
 		$this->lang_path = $phpbb_root_path . 'language/';
+		$this->language = $lang;
 		$this->datetime = $datetime_class;
+
+		$this->is_setup_flag = false;
 	}
 
 	/**
-	* Function to set custom language path (able to use directory outside of phpBB)
-	*
-	* @param string $lang_path New language path used.
-	* @access public
-	*/
-	function set_custom_lang_path($lang_path)
+	 * Returns whether user::setup was called
+	 *
+	 * @return bool
+	 */
+	public function is_setup()
 	{
-		$this->lang_path = $lang_path;
+		return $this->is_setup_flag;
+	}
 
-		if (substr($this->lang_path, -1) != '/')
+	/**
+	 * Magic getter for BC compatibility
+	 *
+	 * Implement array access for user::lang.
+	 *
+	 * @param string	$param_name	Name of the BC component the user want to access
+	 *
+	 * @return array	The appropriate array
+	 *
+	 * @deprecated 3.2.0-dev (To be removed: 4.0.0)
+	 */
+	public function __get($param_name)
+	{
+		if ($param_name === 'lang')
+		{
+			return $this->language->get_lang_array();
+		}
+		else if ($param_name === 'help')
 		{
-			$this->lang_path .= '/';
+			$help_array = $this->language->get_lang_array();
+			return $help_array['__help'];
 		}
+
+		return array();
 	}
 
 	/**
@@ -81,6 +112,8 @@ class user extends \phpbb\session
 		global $db, $request, $template, $config, $auth, $phpEx, $phpbb_root_path, $cache;
 		global $phpbb_dispatcher;
 
+		$this->language->set_default_language($config['default_lang']);
+
 		if ($this->data['user_id'] != ANONYMOUS)
 		{
 			$user_lang_name = (file_exists($this->lang_path . $this->data['user_lang'] . "/common.$phpEx")) ? $this->data['user_lang'] : basename($config['default_lang']);
@@ -98,6 +131,7 @@ class user extends \phpbb\session
 			{
 				$lang_override = $request->variable($config['cookie_name'] . '_lang', '', true, \phpbb\request\request_interface::COOKIE);
 			}
+
 			if ($lang_override)
 			{
 				$use_lang = basename($lang_override);
@@ -108,6 +142,7 @@ class user extends \phpbb\session
 			{
 				$user_lang_name = basename($config['default_lang']);
 			}
+
 			$user_date_format = $config['default_dateformat'];
 			$user_timezone = $config['board_timezone'];
 
@@ -187,6 +222,8 @@ class user extends \phpbb\session
 		$this->lang_name = $user_lang_name;
 		$this->date_format = $user_date_format;
 
+		$this->language->set_user_language($user_lang_name);
+
 		try
 		{
 			$this->timezone = new \DateTimeZone($user_timezone);
@@ -197,17 +234,6 @@ class user extends \phpbb\session
 			$this->timezone = new \DateTimeZone('UTC');
 		}
 
-		// We include common language file here to not load it every time a custom language file is included
-		$lang = &$this->lang;
-
-		// Do not suppress error if in DEBUG mode
-		$include_result = (defined('DEBUG')) ? (include $this->lang_path . $this->lang_name . "/common.$phpEx") : (@include $this->lang_path . $this->lang_name . "/common.$phpEx");
-
-		if ($include_result === false)
-		{
-			die('Language file ' . $this->lang_path . $this->lang_name . "/common.$phpEx" . " couldn't be opened.");
-		}
-
 		$this->add_lang($lang_set);
 		unset($lang_set);
 
@@ -393,6 +419,8 @@ class user extends \phpbb\session
 			}
 		}
 
+		$this->is_setup_flag = true;
+
 		return;
 	}
 
@@ -406,103 +434,13 @@ class user extends \phpbb\session
 	*
 	* If the first parameter is an array, the elements are used as keys and subkeys to get the language entry:
 	* Example: <samp>$user->lang(array('datetime', 'AGO'), 1)</samp> uses $user->lang['datetime']['AGO'] as language entry.
+	*
+	* @deprecated 3.2.0-dev (To be removed 4.0.0)
 	*/
 	function lang()
 	{
 		$args = func_get_args();
-		$key = $args[0];
-
-		if (is_array($key))
-		{
-			$lang = &$this->lang[array_shift($key)];
-
-			foreach ($key as $_key)
-			{
-				$lang = &$lang[$_key];
-			}
-		}
-		else
-		{
-			$lang = &$this->lang[$key];
-		}
-
-		// Return if language string does not exist
-		if (!isset($lang) || (!is_string($lang) && !is_array($lang)))
-		{
-			return $key;
-		}
-
-		// If the language entry is a string, we simply mimic sprintf() behaviour
-		if (is_string($lang))
-		{
-			if (sizeof($args) == 1)
-			{
-				return $lang;
-			}
-
-			// Replace key with language entry and simply pass along...
-			$args[0] = $lang;
-			return call_user_func_array('sprintf', $args);
-		}
-		else if (sizeof($lang) == 0)
-		{
-			// If the language entry is an empty array, we just return the language key
-			return $args[0];
-		}
-
-		// It is an array... now handle different nullar/singular/plural forms
-		$key_found = false;
-
-		// We now get the first number passed and will select the key based upon this number
-		for ($i = 1, $num_args = sizeof($args); $i < $num_args; $i++)
-		{
-			if (is_int($args[$i]) || is_float($args[$i]))
-			{
-				if ($args[$i] == 0 && isset($lang[0]))
-				{
-					// We allow each translation using plural forms to specify a version for the case of 0 things,
-					// so that "0 users" may be displayed as "No users".
-					$key_found = 0;
-					break;
-				}
-				else
-				{
-					$use_plural_form = $this->get_plural_form($args[$i]);
-					if (isset($lang[$use_plural_form]))
-					{
-						// The key we should use exists, so we use it.
-						$key_found = $use_plural_form;
-					}
-					else
-					{
-						// If the key we need to use does not exist, we fall back to the previous one.
-						$numbers = array_keys($lang);
-
-						foreach ($numbers as $num)
-						{
-							if ($num > $use_plural_form)
-							{
-								break;
-							}
-
-							$key_found = $num;
-						}
-					}
-					break;
-				}
-			}
-		}
-
-		// Ok, let's check if the key was found, else use the last entry (because it is mostly the plural form)
-		if ($key_found === false)
-		{
-			$numbers = array_keys($lang);
-			$key_found = end($numbers);
-		}
-
-		// Use the language string we determined and pass it to sprintf()
-		$args[0] = $lang[$key_found];
-		return call_user_func_array('sprintf', $args);
+		return call_user_func_array(array($this->language, 'lang'), $args);
 	}
 
 	/**
@@ -512,24 +450,22 @@ class user extends \phpbb\session
 	* @param $number        int|float   The number we want to get the plural case for. Float numbers are floored.
 	* @param $force_rule    mixed   False to use the plural rule of the language package
 	*                               or an integer to force a certain plural rule
-	* @return   int     The plural-case we need to use for the number plural-rule combination
+	* @return int|bool     The plural-case we need to use for the number plural-rule combination, false if $force_rule
+	* 					   was invalid.
+	*
+	* @deprecated: 3.2.0-dev (To be removed: 3.3.0)
 	*/
 	function get_plural_form($number, $force_rule = false)
 	{
-		$number = (int) $number;
-
-		// Default to English system
-		$plural_rule = ($force_rule !== false) ? $force_rule : ((isset($this->lang['PLURAL_RULE'])) ? $this->lang['PLURAL_RULE'] : 1);
-
-		return phpbb_get_plural_form($plural_rule, $number);
+		return $this->language->get_plural_form($number, $force_rule);
 	}
 
 	/**
 	* Add Language Items - use_db and use_help are assigned where needed (only use them to force inclusion)
 	*
 	* @param mixed $lang_set specifies the language entries to include
-	* @param bool $use_db internal variable for recursion, do not use
-	* @param bool $use_help internal variable for recursion, do not use
+	* @param bool $use_db internal variable for recursion, do not use	@deprecated 3.2.0-dev (To be removed: 3.3.0)
+	* @param bool $use_help internal variable for recursion, do not use	@deprecated 3.2.0-dev (To be removed: 3.3.0)
 	* @param string $ext_name The extension to load language from, or empty for core files
 	*
 	* Examples:
@@ -540,11 +476,14 @@ class user extends \phpbb\session
 	* $lang_set = 'posting'
 	* $lang_set = array('help' => 'faq', 'db' => array('help:faq', 'posting'))
 	* </code>
+	*
+	* Note: $use_db and $use_help should be removed. The old function was kept for BC purposes,
+	* 		so the BC logic is handled here.
+	*
+	* @deprecated: 3.2.0-dev (To be removed: 3.3.0)
 	*/
 	function add_lang($lang_set, $use_db = false, $use_help = false, $ext_name = '')
 	{
-		global $phpEx;
-
 		if (is_array($lang_set))
 		{
 			foreach ($lang_set as $key => $lang_file)
@@ -555,6 +494,7 @@ class user extends \phpbb\session
 
 				if ($key == 'db')
 				{
+					// This is never used
 					$this->add_lang($lang_file, true, $use_help, $ext_name);
 				}
 				else if ($key == 'help')
@@ -563,7 +503,7 @@ class user extends \phpbb\session
 				}
 				else if (!is_array($lang_file))
 				{
-					$this->set_lang($this->lang, $this->help, $lang_file, $use_db, $use_help, $ext_name);
+					$this->set_lang($lang_file, $use_help, $ext_name);
 				}
 				else
 				{
@@ -574,8 +514,37 @@ class user extends \phpbb\session
 		}
 		else if ($lang_set)
 		{
-			$this->set_lang($this->lang, $this->help, $lang_set, $use_db, $use_help, $ext_name);
+			$this->set_lang($lang_set, $use_help, $ext_name);
+		}
+	}
+
+	/**
+	 * BC function for loading language files
+	 *
+	 * @deprecated 3.2.0-dev (To be removed: 3.3.0)
+	 */
+	private function set_lang($lang_set, $use_help, $ext_name)
+	{
+		if (empty($ext_name))
+		{
+			$ext_name = null;
+		}
+
+		if ($use_help && strpos($lang_set, '/') !== false)
+		{
+			$component = dirname($lang_set) . '/help_' . basename($lang_set);
+
+			if ($component[0] === '/')
+			{
+				$component = substr($component, 1);
+			}
+		}
+		else
+		{
+			$component = (($use_help) ? 'help_' : '') . $lang_set;
 		}
+
+		$this->language->add_lang($component, $ext_name);
 	}
 
 	/**
@@ -585,6 +554,10 @@ class user extends \phpbb\session
 	* @param mixed $lang_set specifies the language entries to include
 	* @param bool $use_db internal variable for recursion, do not use
 	* @param bool $use_help internal variable for recursion, do not use
+	*
+	* Note: $use_db and $use_help should be removed. Kept for BC purposes.
+	*
+	* @deprecated: 3.2.0-dev (To be removed: 3.3.0)
 	*/
 	function add_lang_ext($ext_name, $lang_set, $use_db = false, $use_help = false)
 	{
@@ -597,109 +570,6 @@ class user extends \phpbb\session
 	}
 
 	/**
-	* Set language entry (called by add_lang)
-	* @access private
-	*/
-	function set_lang(&$lang, &$help, $lang_file, $use_db = false, $use_help = false, $ext_name = '')
-	{
-		global $phpbb_root_path, $phpEx;
-
-		// Make sure the language name is set (if the user setup did not happen it is not set)
-		if (!$this->lang_name)
-		{
-			global $config;
-			$this->lang_name = basename($config['default_lang']);
-		}
-
-		// $lang == $this->lang
-		// $help == $this->help
-		// - add appropriate variables here, name them as they are used within the language file...
-		if (!$use_db)
-		{
-			if ($use_help && strpos($lang_file, '/') !== false)
-			{
-				$filename = dirname($lang_file) . '/help_' . basename($lang_file);
-			}
-			else
-			{
-				$filename = (($use_help) ? 'help_' : '') . $lang_file;
-			}
-
-			if ($ext_name)
-			{
-				global $phpbb_extension_manager;
-				$ext_path = $phpbb_extension_manager->get_extension_path($ext_name, true);
-
-				$lang_path = $ext_path . 'language/';
-			}
-			else
-			{
-				$lang_path = $this->lang_path;
-			}
-
-			if (strpos($phpbb_root_path . $filename, $lang_path . $this->lang_name . '/') === 0)
-			{
-				$language_filename = $phpbb_root_path . $filename;
-			}
-			else
-			{
-				$language_filename = $lang_path . $this->lang_name . '/' . $filename . '.' . $phpEx;
-			}
-
-			// If we are in install, try to use the updated version, when available
-			$install_language_filename = str_replace('language/', 'install/update/new/language/', $language_filename);
-			if (defined('IN_INSTALL') && file_exists($install_language_filename))
-			{
-				$language_filename = $install_language_filename;
-			}
-
-			if (!file_exists($language_filename))
-			{
-				global $config;
-
-				if ($this->lang_name == 'en')
-				{
-					// The user's selected language is missing the file, the board default's language is missing the file, and the file doesn't exist in /en.
-					$language_filename = str_replace($lang_path . 'en', $lang_path . $this->data['user_lang'], $language_filename);
-					trigger_error('Language file ' . $language_filename . ' couldn\'t be opened.', E_USER_ERROR);
-				}
-				else if ($this->lang_name == basename($config['default_lang']))
-				{
-					// Fall back to the English Language
-					$reset_lang_name = $this->lang_name;
-					$this->lang_name = 'en';
-					$this->set_lang($lang, $help, $lang_file, $use_db, $use_help, $ext_name);
-					$this->lang_name = $reset_lang_name;
-				}
-				else if ($this->lang_name == $this->data['user_lang'])
-				{
-					// Fall back to the board default language
-					$reset_lang_name = $this->lang_name;
-					$this->lang_name = basename($config['default_lang']);
-					$this->set_lang($lang, $help, $lang_file, $use_db, $use_help, $ext_name);
-					$this->lang_name = $reset_lang_name;
-				}
-
-				return;
-			}
-
-			// Do not suppress error if in DEBUG mode
-			$include_result = (defined('DEBUG')) ? (include $language_filename) : (@include $language_filename);
-
-			if ($include_result === false)
-			{
-				trigger_error('Language file ' . $language_filename . ' couldn\'t be opened.', E_USER_ERROR);
-			}
-		}
-		else if ($use_db)
-		{
-			// Get Database Language Strings
-			// Put them into $lang if nothing is prefixed, put them into $help if help: is prefixed
-			// For example: help:faq, posting
-		}
-	}
-
-	/**
 	* Format user date
 	*
 	* @param int $gmepoch unix timestamp
@@ -808,7 +678,7 @@ class user extends \phpbb\session
 
 		if ($alt)
 		{
-			$alt = $this->lang($alt);
+			$alt = $this->language->lang($alt);
 			$title = ' title="' . $alt . '"';
 		}
 		return '<span class="imageset ' . $img . '"' . $title . '>' . $alt . '</span>';