Module system improvements: Container modules

app/Module/ModuleContainerInterface.php

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * webtrees: online genealogy
+ * Copyright (C) 2023 webtrees development team
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace Fisharebest\Webtrees\Module;
+
+use Illuminate\Support\Collection;
+
+/**
+ * Interface ModuleCustomInterface - Classes and libraries for module system
+ */
+interface ModuleContainerInterface extends ModuleCustomInterface
+{
+    /**
+     * The list of modules contained within this module.
+     *
+     * @return Collection<ModuleCustomInterface>
+     */
+    public function containedModules(): Collection;
+}

app/Module/ModuleContainerTrait.php

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * webtrees: online genealogy
+ * Copyright (C) 2023 webtrees development team
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace Fisharebest\Webtrees\Module;
+
+use Illuminate\Support\Collection;
+
+/**
+ * Trait ModuleContainerTrait - default implementation of ModuleCustomInterface
+ */
+trait ModuleContainerTrait
+{    
+    /**
+     * The list of modules contained within this module.
+     *
+     * @return Collection<ModuleCustomInterface>
+     */
+    public function containedModules(): Collection
+    {
+        return new Collection();
+    }
+}

app/Services/ModuleService.php

@@ -187,6 +187,7 @@
 use Fisharebest\Webtrees\Module\ModuleAnalyticsInterface;
 use Fisharebest\Webtrees\Module\ModuleBlockInterface;
 use Fisharebest\Webtrees\Module\ModuleChartInterface;
+use Fisharebest\Webtrees\Module\ModuleContainerInterface;
 use Fisharebest\Webtrees\Module\ModuleCustomInterface;
 use Fisharebest\Webtrees\Module\ModuleDataFixInterface;
 use Fisharebest\Webtrees\Module\ModuleFooterInterface;
@@ -703,16 +704,30 @@ private function customModules(): Collection
 
                 return strlen($module_name) <= 30;
             })
-            ->map(static function (string $filename): ?ModuleCustomInterface {
+            ->flatMap(static function (string $filename): Collection {
                 $module = self::load($filename);
 
                 if ($module instanceof ModuleCustomInterface) {
-                    $module->setName('_' . basename(dirname($filename)) . '_');
-
-                    return $module;
+                    $moduleName = '_' . basename(dirname($filename)) . '_';
+                    $module->setName($moduleName);
+
+                    if ($module instanceof ModuleContainerInterface) {
+                        $collection = $module->containedModules()
+                            //force numeric keys
+                            ->values();
+
+                        $collection->each(function (ModuleCustomInterface $submodule, int $key) use ($moduleName) {
+                           $submodule->setName($moduleName . $key);
+                        });
+
+                        $collection->prepend($module);
+                        return $collection;
+                    }
+
+                    return new Collection([$module]);
                 }
 
-                return null;
+                return new Collection();
             })
             ->filter()
             ->mapWithKeys(static function (ModuleCustomInterface $module): array {