Fix context/plural related issues in i18n

Because we were using the stock translator from Aura, we had painful
issues when:

* A plural message was used with `__()` an array would be returned which
  is never right.
* When an unknown context is used the `__x()` method fails.

Refs cakephp#8833
Refs cakephp#9985

src/I18n/Formatter/IcuFormatter.php

@@ -52,16 +52,6 @@ public function format($locale, $message, array $vars)
             return $this->_formatMessage($locale, $message, $vars);
         }
 
-        if (isset($vars['_context'], $message['_context'])) {
-            $message = $message['_context'][$vars['_context']];
-            unset($vars['_context']);
-        }
-
-        // Assume first context when no context key was passed
-        if (isset($message['_context'])) {
-            $message = current($message['_context']);
-        }
-
         if (!is_string($message)) {
             $count = isset($vars['_count']) ? $vars['_count'] : 0;
             unset($vars['_count'], $vars['_singular']);

src/I18n/I18n.php

@@ -16,10 +16,10 @@
 
 use Aura\Intl\FormatterLocator;
 use Aura\Intl\PackageLocator;
-use Aura\Intl\TranslatorFactory;
 use Cake\Cache\Cache;
 use Cake\I18n\Formatter\IcuFormatter;
 use Cake\I18n\Formatter\SprintfFormatter;
+use Cake\I18n\TranslatorFactory;
 use Locale;
 
 /**

src/I18n/Translator.php

@@ -0,0 +1,151 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ *
+ * This file contains sections from the Aura Project
+ * @license https://github.com/auraphp/Aura.Intl/blob/3.x/LICENSE
+ *
+ * The Aura Project for PHP.
+ *
+ * @package Aura.Intl
+ * @license http://opensource.org/licenses/bsd-license.php BSD
+ */
+namespace Cake\I18n;
+
+use Aura\Intl\TranslatorInterface;
+use Aura\Intl\FormatterInterface;
+
+/**
+ * Provides missing message behavior for CakePHP internal message formats.
+ *
+ * @internal
+ */
+class Translator implements TranslatorInterface
+{
+    /**
+     * A fallback translator.
+     *
+     * @var \Aura\Intl\TranslatorInterface
+     */
+    protected $fallback;
+
+    /**
+     * The formatter to use when translating messages.
+     *
+     * @var \Aura\Intl\FormatterInterface
+     */
+    protected $formatter;
+
+    /**
+     * The locale being used for translations.
+     *
+     * @var string
+     */
+    protected $locale;
+
+    /**
+     * The message keys and translations.
+     *
+     * @var array
+     */
+    protected $messages = [];
+
+    /**
+     * Constructor
+     *
+     * @param string $locale The locale being used.
+     * @param array $messages The message keys and translations.
+     * @param \Aura\Intl\FormatterInterface $formatter A message formatter.
+     * @param \Aura\Intl\TranslatorInterface $fallback A fallback translator.
+     */
+    public function __construct(
+        $locale,
+        array $messages,
+        FormatterInterface $formatter,
+        TranslatorInterface $fallback = null
+    ) {
+        $this->locale    = $locale;
+        $this->messages  = $messages;
+        $this->formatter = $formatter;
+        $this->fallback  = $fallback;
+    }
+
+    /**
+     * Gets the message translation by its key.
+     *
+     * @param string $key The message key.
+     * @return mixed The message translation string, or false if not found.
+     */
+    protected function getMessage($key)
+    {
+        if (isset($this->messages[$key])) {
+            return $this->messages[$key];
+        }
+
+        if ($this->fallback) {
+            // get the message from the fallback translator
+            $message = $this->fallback->getMessage($key);
+            // speed optimization: retain locally
+            $this->messages[$key] = $message;
+            // done!
+            return $message;
+        }
+
+        // no local message, no fallback
+        return false;
+    }
+
+    /**
+     * Translates the message formatting any placeholders
+     *
+     *
+     * @param string $key The message key.
+     * @param array $tokensValues Token values to interpolate into the
+     *   message.
+     * @return string The translated message with tokens replaced.
+     */
+    public function translate($key, array $tokensValues = [])
+    {
+        $message = $this->getMessage($key);
+
+        if (!$message) {
+            // Fallback to the message key
+            $message = $key;
+        }
+
+        // Check for missing/invalid context
+        if (isset($message['_context'])) {
+            $context = isset($tokensValues['_context']) ? $tokensValues['_context'] : null;
+            unset($tokensValues['_context']);
+
+            // No or missing context, fallback to the key/first message
+            if ($context === null) {
+                $message = current($message['_context']);
+            } elseif(!isset($message['_context'][$context])) {
+                $message = $key;
+            } elseif (!isset($message['_context'][$context])) {
+                $message = $key;
+            } else {
+                $message = $message['_context'][$context];
+            }
+        }
+
+        if (!$tokensValues) {
+            // Fallback for plurals that were using the singular key
+            if (is_array($message)) {
+                return array_values($message + [''])[0];
+            }
+            return $message;
+        }
+
+        return $this->formatter->format($this->locale, $message, $tokensValues);
+    }
+}

src/I18n/TranslatorFactory.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         3.3.12
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\I18n;
+
+use Aura\Intl\TranslatorFactory as BaseTranslatorFactory;
+
+use Aura\Intl\TranslatorInterface;
+use Aura\Intl\FormatterInterface;
+
+/**
+ * Factory to create translators
+ *
+ * @internal
+ */
+class TranslatorFactory extends BaseTranslatorFactory
+{
+    /**
+     * The class to use for new instances.
+     *
+     * @var string
+     */
+    protected $class = 'Cake\I18n\Translator';
+}

tests/TestCase/I18n/Formatter/IcuFormatterTest.php

@@ -124,55 +124,6 @@ public function testBadMessageFormat()
         $formatter->format('en_US', '{crazy format', ['some', 'vars']);
     }
 
-    /**
-     * Tests that strings stored inside context namespaces can also be formatted
-     *
-     * @return void
-     */
-    public function testFormatWithContext()
-    {
-        $messages = [
-            'simple' => [
-                '_context' => [
-                    'context a' => 'Text "a" {0}',
-                    'context b' => 'Text "b" {0}'
-                ]
-            ],
-            'complex' => [
-                '_context' => [
-                    'context b' => [
-                        0 => 'Only one',
-                        1 => 'there are {0}'
-                    ]
-                ]
-            ]
-        ];
-
-        $formatter = new IcuFormatter();
-        $this->assertEquals(
-            'Text "a" is good',
-            $formatter->format('en', $messages['simple'], ['_context' => 'context a', 'is good'])
-        );
-        $this->assertEquals(
-            'Text "b" is good',
-            $formatter->format('en', $messages['simple'], ['_context' => 'context b', 'is good'])
-        );
-        $this->assertEquals(
-            'Text "a" is good',
-            $formatter->format('en', $messages['simple'], ['is good'])
-        );
-
-        $this->assertEquals(
-            'Only one',
-            $formatter->format('en', $messages['complex'], ['_context' => 'context b', '_count' => 1])
-        );
-
-        $this->assertEquals(
-            'there are 2',
-            $formatter->format('en', $messages['complex'], ['_context' => 'context b', '_count' => 2, 2])
-        );
-    }
-
     /**
      * Tests that it is possible to provide a singular fallback when passing a string message.
      * This is useful for getting quick feedback on the code during development instead of

tests/TestCase/I18n/I18nTest.php

@@ -68,7 +68,7 @@ public function tearDown()
     public function testDefaultTranslator()
     {
         $translator = I18n::translator();
-        $this->assertInstanceOf('Aura\Intl\Translator', $translator);
+        $this->assertInstanceOf('Aura\Intl\TranslatorInterface', $translator);
         $this->assertEquals('%d is 1 (po translated)', $translator->translate('%d = 1'));
     }
 
@@ -244,6 +244,17 @@ public function testBasicTranslateFunction()
         $this->assertEquals('1 is 1 (po translated)', __('%d = 1', 1));
     }
 
+    /**
+     * Tests the __() function on a plural key
+     *
+     * @return void
+     */
+    public function testBasicTranslateFunctionPluralData()
+    {
+        I18n::defaultFormatter('sprintf');
+        $this->assertEquals('%d is 1 (po translated)', __('%d = 0 or > 1'));
+    }
+
     /**
      * Tests the __n() function
      *
@@ -386,6 +397,30 @@ public function testBasicContextFunctionNoString()
         $this->assertEquals('', __x('character', 'letter'));
     }
 
+    /**
+     * Tests the __x() function with an invalid context
+     *
+     * @return void
+     */
+    public function testBasicContextFunctionInvalidContext()
+    {
+        I18n::translator('default', 'en_US', function () {
+            $package = new Package('default');
+            $package->setMessages([
+                'letter' => [
+                    '_context' => [
+                        'noun' => 'a paper letter',
+                    ]
+                ]
+            ]);
+
+            return $package;
+        });
+
+        $this->assertEquals('letter', __x('garbage', 'letter'));
+        $this->assertEquals('a paper letter', __('letter'));
+    }
+
     /**
      * Tests the __xn() function
      *