MDL-68227 core_h5p: localize H5P editor strings

H5P editor has a folder with all supported languages in JS files.
A mechanish has been added to let users to translate them using AMOS.
That's how the translations are managed (the order how they are processed):

- If there a JS file for a language, it's loaded.
- If a string has been translated in Moodle (they are placed in
h5plib_vXXX), it will override strings loaded from the JS file.

h5p/classes/editor.php

@@ -378,15 +378,10 @@ private function add_assets_to_page(): void {
         $PAGE->requires->js(autoloader::get_h5p_editor_library_url('scripts/h5peditor-editor.js' . $cachebuster), true);
         $PAGE->requires->js(autoloader::get_h5p_editor_library_url('scripts/h5peditor-init.js' . $cachebuster), true);
 
-        // Add translations.
+        // Load editor translations.
         $language = framework::get_language();
-        $languagescript = "language/{$language}.js";
-
-        if (!file_exists("{$CFG->dirroot}" . autoloader::get_h5p_editor_library_base($languagescript))) {
-            $languagescript = 'language/en.js';
-        }
-        $PAGE->requires->js(autoloader::get_h5p_editor_library_url($languagescript . $cachebuster),
-            true);
+        $editorstrings = $this->get_editor_translations($language);
+        $PAGE->requires->data_for_js('H5PEditor.language.core', $editorstrings, false);
 
         // Add JavaScript settings.
         $root = $CFG->wwwroot;
@@ -423,6 +418,47 @@ private function add_assets_to_page(): void {
         $PAGE->requires->data_for_js('H5PIntegration', $settings, true);
     }
 
+    /**
+     * Get editor translations for the defined language.
+     * Check if the editor strings have been translated in Moodle.
+     * If the strings exist, they will override the existing ones in the JS file.
+     *
+     * @param string $language The language for the translations to be returned.
+     * @return array The editor string translations.
+     */
+    private function get_editor_translations(string $language): array {
+        global $CFG;
+
+        // Add translations.
+        $languagescript = "language/{$language}.js";
+
+        if (!file_exists("{$CFG->dirroot}" . autoloader::get_h5p_editor_library_base($languagescript))) {
+            $languagescript = 'language/en.js';
+        }
+
+        // Check if the editor strings have been translated in Moodle.
+        // If the strings exist, they will override the existing ones in the JS file.
+
+        // Get existing strings from current JS language file.
+        $langcontent = file_get_contents("{$CFG->dirroot}" . autoloader::get_h5p_editor_library_base($languagescript));
+
+        // Get only the content between { } (for instance, ; at the end of the file has to be removed).
+        $langcontent = substr($langcontent, 0, strpos($langcontent, '}', -0) + 1);
+        $langcontent = substr($langcontent, strpos($langcontent, '{'));
+
+        // Parse the JS language content and get a PHP array.
+        $editorstrings = helper::parse_js_array($langcontent);
+        foreach ($editorstrings as $key => $value) {
+            $stringkey = 'editor:'.strtolower(trim($key));
+            $value = autoloader::get_h5p_string($stringkey, $language);
+            if (!empty($value)) {
+                $editorstrings[$key] = $value;
+            }
+        }
+
+        return $editorstrings;
+    }
+
     /**
      * Preprocess the data sent through the form to the H5P JS Editor Library.
      *

h5p/classes/helper.php

@@ -82,7 +82,6 @@ public static function save_h5p(factory $factory, \stored_file $file, \stdClass
         return false;
     }
 
-
     /**
      * Get the error messages stored in our H5P framework.
      *
@@ -410,4 +409,24 @@ public static function get_cache_librarykey(string $library): string {
         // Remove whitespaces and replace '.' to '_'.
         return str_replace('.', '_', str_replace(' ', '', $library));
     }
+
+    /**
+     * Parse a JS array to a PHP array.
+     *
+     * @param  string $jscontent The JS array to parse to PHP array.
+     * @return array The JS array converted to PHP array.
+     */
+    public static function parse_js_array(string $jscontent): array {
+        $jsarray = preg_split('/,\n\s+/', substr($jscontent, 0, -1));
+        $jsarray = preg_replace('~{?\\n~', '', $jsarray);
+
+        $strings = [];
+        foreach ($jsarray as $key => $value) {
+            $splitted = explode(":", $value, 2);
+            $value = preg_replace("/^['|\"](.*)['|\"]$/", "$1", trim($splitted[1], ' ,'));
+            $strings[ trim($splitted[0]) ] = str_replace("\'", "'", $value);
+        }
+
+        return $strings;
+    }
 }

h5p/classes/local/library/autoloader.php

@@ -149,6 +149,17 @@ public static function get_h5p_editor_library_base(?string $filepath = null): st
         return component_class_callback(self::get_handler_classname(), 'get_h5p_editor_library_base', [$filepath]);
     }
 
+    /**
+     * Returns a localized string, if it exists in the h5plib plugin and the value it's different from the English version.
+     *
+     * @param string $identifier The key identifier for the localized string
+     * @param string $language Language to get the localized string.
+     * @return string|null The localized string or null if it doesn't exist in this H5P library plugin.
+     */
+    public static function get_h5p_string(string $identifier, string $language): ?string {
+        return component_class_callback(self::get_handler_classname(), 'get_h5p_string', [$identifier, $language]);
+    }
+
     /**
      * Register the H5P autoloader.
      */

h5p/classes/local/library/handler.php

@@ -123,6 +123,31 @@ public static function get_h5p_editor_library_url(?string $filepath = null, ?arr
         return new \moodle_url(static::get_h5p_editor_library_base($filepath), $params);
     }
 
+    /**
+     * Returns a localized string, if it exists in the h5plib plugin and the value it's different from the English version.
+     *
+     * @param string $identifier The key identifier for the localized string
+     * @param string $language Language to get the localized string.
+     * @return string|null The localized string or null if it doesn't exist in this H5P library plugin.
+     */
+    public static function get_h5p_string(string $identifier, string $language): ?string {
+        $value = null;
+        $h5pversion = static::get_h5p_version();
+        $component = 'h5plib_v' . $h5pversion;
+        if (get_string_manager()->string_exists($identifier, $component)) {
+            $defaultmoodlelang = 'en';
+            // In Moodle, all the English strings always will exist because they have to be declared in order to let users
+            // to translate them. That's why, this method will only replace existing key if the value is different from
+            // the English version and the current language is not English.
+            $string = new \lang_string($identifier, $component);
+            if ($language === $defaultmoodlelang || $string->out($language) !== $string->out($defaultmoodlelang)) {
+                $value = $string->out($language);
+            }
+        }
+
+        return $value;
+    }
+
     /**
      * Return the list of classes with their location within the joubel directory.
      *

h5p/h5plib/v124/joubel/editor/readme_moodle.txt

@@ -8,6 +8,13 @@ Import procedure:
 - Copy all the files from the folder repository in this directory.
 - In the method ns.LibrarySelector.prototype.appendTo (scripts/h5peditor-library-selector.js),
   comment the line "this.$selector.appendTo($element);" to avoid the display of the Hub Selector.
+- Review strings in joubel/editor/language/en.js and compare them with
+existing ones in lang/en/h5plib_vXXX.php: add the new ones and remove the
+unexisting ones. Remember to use the AMOS script commands, such CPY, to copy
+all the existing strings from the previous version. As you'll see, all the
+strings in en.js have been converted following these rules:
+  * Prefix  "editor:" has been added.
+  * Keys have been lowercased.
 
 Removed:
  * composer.json