Fix browser language detection (& tests)

src/Core/L10n/L10n.php

@@ -53,12 +53,12 @@ class L10n
 	 */
 	private $logger;
 
-	public function __construct(Configuration $config, Database $dba, LoggerInterface $logger)
+	public function __construct(Configuration $config, Database $dba, LoggerInterface $logger, array $server, array $get)
 	{
 		$this->dba    = $dba;
 		$this->logger = $logger;
 
-		$this->loadTranslationTable(L10n::detectLanguage($config->get('system', 'language', 'en')));
+		$this->loadTranslationTable(L10n::detectLanguage($server, $get, $config->get('system', 'language', 'en')));
 	}
 
 	/**
@@ -158,6 +158,11 @@ class L10n
 	{
 		$lang = Strings::sanitizeFilePathItem($lang);
 
+		// Don't override the language setting with empty languages
+		if (empty($lang)) {
+			return;
+		}
+
 		$a          = new \stdClass();
 		$a->strings = [];
 
@@ -166,12 +171,12 @@ class L10n
 		while ($p = $this->dba->fetch($addons)) {
 			$name = Strings::sanitizeFilePathItem($p['name']);
 			if (file_exists("addon/$name/lang/$lang/strings.php")) {
-				include "addon/$name/lang/$lang/strings.php";
+				include __DIR__ . "/../../../addon/$name/lang/$lang/strings.php";
 			}
 		}
 
-		if (file_exists("view/lang/$lang/strings.php")) {
+		if (file_exists(__DIR__ . "/../../../view/lang/$lang/strings.php")) {
-			include "view/lang/$lang/strings.php";
+			include __DIR__ . "/../../../view/lang/$lang/strings.php";
 		}
 
 		$this->lang    = $lang;
@@ -184,49 +189,78 @@ class L10n
 	 * @brief Returns the preferred language from the HTTP_ACCEPT_LANGUAGE header
 	 *
 	 * @param string $sysLang The default fallback language
+	 * @param array  $server  The $_SERVER array
+	 * @param array  $get     The $_GET array
 	 *
 	 * @return string The two-letter language code
 	 */
-	public static function detectLanguage(string $sysLang = 'en')
+	public static function detectLanguage(array $server, array $get, string $sysLang = 'en')
 	{
-		$lang_list = [];
+		$lang_variable = $server['HTTP_ACCEPT_LANGUAGE'] ?? null;
 
-		if (!empty($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
+		$acceptedLanguages = preg_split('/,\s*/', $lang_variable);
-			// break up string into pieces (languages and q factors)
-			preg_match_all('/([a-z]{1,8}(-[a-z]{1,8})?)\s*(;\s*q\s*=\s*(1|0\.[0-9]+))?/i', $_SERVER['HTTP_ACCEPT_LANGUAGE'], $lang_parse);
 
-			if (count($lang_parse[1])) {
+		if (empty($acceptedLanguages)) {
-				// go through the list of prefered languages and add a generic language
+			$acceptedLanguages = [];
-				// for sub-linguas (e.g. de-ch will add de) if not already in array
-				for ($i = 0; $i < count($lang_parse[1]); $i++) {
-					$lang_list[] = strtolower($lang_parse[1][$i]);
-					if (strlen($lang_parse[1][$i]) > 3) {
-						$dashpos = strpos($lang_parse[1][$i], '-');
-						if (!in_array(substr($lang_parse[1][$i], 0, $dashpos), $lang_list)) {
-							$lang_list[] = strtolower(substr($lang_parse[1][$i], 0, $dashpos));
-						}
-					}
-				}
-			}
 		}
 
-		if (isset($_GET['lang'])) {
+		// Add get as absolute quality accepted language (except this language isn't valid)
-			$lang_list = [$_GET['lang']];
+		if (!empty($get['lang'])) {
+			$acceptedLanguages[] = $get['lang'];
 		}
 
-		// check if we have translations for the preferred languages and pick the 1st that has
+		// return the sys language in case there's nothing to do
-		foreach ($lang_list as $lang) {
+		if (empty($acceptedLanguages)) {
-			if ($lang === 'en' || (file_exists("view/lang/$lang") && is_dir("view/lang/$lang"))) {
+			return $sysLang;
-				$preferred = $lang;
+		}
+
+		// Set the syslang as default fallback
+		$current_lang = $sysLang;
+		// start with quality zero (every guessed language is more acceptable ..)
+		$current_q = 0;
+
+		foreach ($acceptedLanguages as $acceptedLanguage) {
+			$res = preg_match(
+				'/^([a-z]{1,8}(?:-[a-z]{1,8})*)(?:;\s*q=(0(?:\.[0-9]{1,3})?|1(?:\.0{1,3})?))?$/i',
+				$acceptedLanguage,
+				$matches
+			);
+
+			// Invalid language? -> skip
+			if (!$res) {
+				continue;
+			}
+
+			// split language codes based on it's "-"
+			$lang_code = explode('-', $matches[1]);
+
+			// determine the quality of the guess
+			if (isset($matches[2])) {
+				$lang_quality = (float)$matches[2];
+			} else {
+				// fallback so without a quality parameter, it's probably the best
+				$lang_quality = 1;
+			}
+
+			// loop through each part of the code-parts
+			while (count($lang_code)) {
+				// try to mix them so we can get double-code parts too
+				$match_lang = strtolower(join('-', $lang_code));
+				if (file_exists(__DIR__ . "/../../../view/lang/$match_lang") &&
+				    is_dir(__DIR__ . "/../../../view/lang/$match_lang")) {
+					if ($lang_quality > $current_q) {
+						$current_lang = $match_lang;
+						$current_q    = $lang_quality;
 						break;
 					}
 				}
-		if (isset($preferred)) {
+
-			return $preferred;
+				// remove the most right code-part
+				array_pop($lang_code);
+			}
 		}
 
-		// in case none matches, get the system wide configured language, or fall back to English
+		return $current_lang;
-		return $sysLang;
 	}
 
 	/**

static/dependencies.config.php

@@ -4,6 +4,7 @@ use Dice\Dice;
 use Friendica\App;
 use Friendica\Core\Cache;
 use Friendica\Core\Config;
+use Friendica\Core\L10n\L10n;
 use Friendica\Core\Lock\ILock;
 use Friendica\Database\Database;
 use Friendica\Factory;
@@ -173,4 +174,9 @@ return [
 			['addRoutes', [include __DIR__ . '/routes.config.php'], Dice::CHAIN_CALL],
 		],
 	],
+	L10n::class => [
+		'constructParams' => [
+			$_SERVER, $_GET
+		],
+	],
 ];

tests/src/Core/L10n/L10nTest.php

@@ -0,0 +1,95 @@
+<?php
+
+namespace src\Core\L10n;
+
+use Friendica\Core\L10n\L10n;
+use Friendica\Test\MockedTest;
+
+class L10nTest extends MockedTest
+{
+	public function dataDetectLanguage()
+	{
+		return [
+			'empty'   => [
+				'server'  => [],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'en',
+			],
+			'withGet' => [
+				'server'  => [],
+				'get'     => ['lang' => 'de'],
+				'default' => 'en',
+				'assert'  => 'de',
+			],
+			'withPipe' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'en-gb'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'en-gb',
+			],
+			'withoutPipe' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'fr',
+			],
+			'withQuality1' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr;q=0.5,de'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'de',
+			],
+			'withQuality2' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr;q=0.5,de;q=0.2'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'fr',
+			],
+			'withLangOverride' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr;q=0.5,de;q=0.2'],
+				'get'     => ['lang' => 'it'],
+				'default' => 'en',
+				'assert'  => 'it',
+			],
+			'withQualityAndPipe' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr;q=0.5,de;q=0.2,nb-no;q=0.7'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'nb-no',
+			],
+			'withQualityAndInvalid' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'fr;q=0.5,bla;q=0.2,nb-no;q=0.7'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'nb-no',
+			],
+			'withQualityAndInvalid2' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'blu;q=0.9,bla;q=0.2,nb-no;q=0.7'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'nb-no',
+			],
+			'withQualityAndInvalidAndAbsolute' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'blu;q=0.9,de,nb-no;q=0.7'],
+				'get'     => [],
+				'default' => 'en',
+				'assert'  => 'de',
+			],
+			'withInvalidGet' => [
+				'server'  => ['HTTP_ACCEPT_LANGUAGE' => 'blu;q=0.9,nb-no;q=0.7'],
+				'get'     => ['lang' => 'blu'],
+				'default' => 'en',
+				'assert'  => 'nb-no',
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider dataDetectLanguage
+	 */
+	public function testDetectLanguage(array $server, array $get, string $default, string $assert)
+	{
+		$this->assertEquals($assert, L10n::detectLanguage($server, $get, $default));
+	}
+}