feat(DeclarativeSettings): Allow to implement value getter and setter directly in Form

Instead of implementing the form class, a setter event listener and a getter event listener,
this allows to simply write a basic class that provides `getSchema`, `setValue` and `getValue` functions.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

5 files changed, 79 insertions, 13 deletions

diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 1219c0f5aa4..545c33f2572 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -698,6 +698,7 @@ return array(
     'OCP\\Settings\\Events\\DeclarativeSettingsSetValueEvent' => $baseDir . '/lib/public/Settings/Events/DeclarativeSettingsSetValueEvent.php',
     'OCP\\Settings\\IDeclarativeManager' => $baseDir . '/lib/public/Settings/IDeclarativeManager.php',
     'OCP\\Settings\\IDeclarativeSettingsForm' => $baseDir . '/lib/public/Settings/IDeclarativeSettingsForm.php',
+    'OCP\\Settings\\IDeclarativeSettingsFormWithHandlers' => $baseDir . '/lib/public/Settings/IDeclarativeSettingsFormWithHandlers.php',
     'OCP\\Settings\\IDelegatedSettings' => $baseDir . '/lib/public/Settings/IDelegatedSettings.php',
     'OCP\\Settings\\IIconSection' => $baseDir . '/lib/public/Settings/IIconSection.php',
     'OCP\\Settings\\IManager' => $baseDir . '/lib/public/Settings/IManager.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 0e93ee8addd..fcb2a0cd8c9 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -731,6 +731,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OCP\\Settings\\Events\\DeclarativeSettingsSetValueEvent' => __DIR__ . '/../../..' . '/lib/public/Settings/Events/DeclarativeSettingsSetValueEvent.php',
         'OCP\\Settings\\IDeclarativeManager' => __DIR__ . '/../../..' . '/lib/public/Settings/IDeclarativeManager.php',
         'OCP\\Settings\\IDeclarativeSettingsForm' => __DIR__ . '/../../..' . '/lib/public/Settings/IDeclarativeSettingsForm.php',
+        'OCP\\Settings\\IDeclarativeSettingsFormWithHandlers' => __DIR__ . '/../../..' . '/lib/public/Settings/IDeclarativeSettingsFormWithHandlers.php',
         'OCP\\Settings\\IDelegatedSettings' => __DIR__ . '/../../..' . '/lib/public/Settings/IDelegatedSettings.php',
         'OCP\\Settings\\IIconSection' => __DIR__ . '/../../..' . '/lib/public/Settings/IIconSection.php',
         'OCP\\Settings\\IManager' => __DIR__ . '/../../..' . '/lib/public/Settings/IManager.php',
diff --git a/lib/private/Settings/DeclarativeManager.php b/lib/private/Settings/DeclarativeManager.php
index 5c2b868f417..ee253b86449 100644
--- a/lib/private/Settings/DeclarativeManager.php
+++ b/lib/private/Settings/DeclarativeManager.php
@@ -22,6 +22,7 @@ use OCP\Settings\Events\DeclarativeSettingsRegisterFormEvent;
 use OCP\Settings\Events\DeclarativeSettingsSetValueEvent;
 use OCP\Settings\IDeclarativeManager;
 use OCP\Settings\IDeclarativeSettingsForm;
+use OCP\Settings\IDeclarativeSettingsFormWithHandlers;
 use Psr\Log\LoggerInterface;
 
 /**
@@ -32,6 +33,15 @@ use Psr\Log\LoggerInterface;
  * @psalm-import-type DeclarativeSettingsFormSchemaWithoutValues from IDeclarativeSettingsForm
  */
 class DeclarativeManager implements IDeclarativeManager {
+
+	/** @var array<string, list<IDeclarativeSettingsForm>> */
+	private array $declarativeForms = [];
+
+	/**
+	 * @var array<string, list<DeclarativeSettingsFormSchemaWithoutValues>>
+	 */
+	private array $appSchemas = [];
+
 	public function __construct(
 		private IEventDispatcher $eventDispatcher,
 		private IGroupManager    $groupManager,
@@ -43,11 +53,6 @@ class DeclarativeManager implements IDeclarativeManager {
 	}
 
 	/**
-	 * @var array<string, list<DeclarativeSettingsFormSchemaWithoutValues>>
-	 */
-	private array $appSchemas = [];
-
-	/**
 	 * @inheritdoc
 	 */
 	public function registerSchema(string $app, array $schema): void {
@@ -77,11 +82,15 @@ class DeclarativeManager implements IDeclarativeManager {
 	 * @inheritdoc
 	 */
 	public function loadSchemas(): void {
-		$declarativeSettings = $this->coordinator->getRegistrationContext()->getDeclarativeSettings();
-		foreach ($declarativeSettings as $declarativeSetting) {
-			/** @var IDeclarativeSettingsForm $declarativeSettingObject */
-			$declarativeSettingObject = Server::get($declarativeSetting->getService());
-			$this->registerSchema($declarativeSetting->getAppId(), $declarativeSettingObject->getSchema());
+		if (empty($this->declarativeForms)) {
+			$declarativeSettings = $this->coordinator->getRegistrationContext()->getDeclarativeSettings();
+			foreach ($declarativeSettings as $declarativeSetting) {
+				$app = $declarativeSetting->getAppId();
+				/** @var IDeclarativeSettingsForm $declarativeForm */
+				$declarativeForm = Server::get($declarativeSetting->getService());
+				$this->registerSchema($app, $declarativeForm->getSchema());
+				$this->declarativeForms[$app][] = $declarativeForm;
+			}
 		}
 
 		$this->eventDispatcher->dispatchTyped(new DeclarativeSettingsRegisterFormEvent($this));
@@ -224,6 +233,10 @@ class DeclarativeManager implements IDeclarativeManager {
 		$storageType = $this->getStorageType($app, $fieldId);
 		switch ($storageType) {
 			case DeclarativeSettingsTypes::STORAGE_TYPE_EXTERNAL:
+				$form = $this->getForm($app, $formId);
+				if ($form !== null && $form instanceof IDeclarativeSettingsFormWithHandlers) {
+					return $form->getValue($fieldId, $user);
+				}
 				$event = new DeclarativeSettingsGetValueEvent($user, $app, $formId, $fieldId);
 				$this->eventDispatcher->dispatchTyped($event);
 				return $event->getValue();
@@ -244,6 +257,12 @@ class DeclarativeManager implements IDeclarativeManager {
 		$storageType = $this->getStorageType($app, $fieldId);
 		switch ($storageType) {
 			case DeclarativeSettingsTypes::STORAGE_TYPE_EXTERNAL:
+				$form = $this->getForm($app, $formId);
+				if ($form !== null && $form instanceof IDeclarativeSettingsFormWithHandlers) {
+					$form->setValue($fieldId, $value, $user);
+					break;
+				}
+				// fall back to event handling
 				$this->eventDispatcher->dispatchTyped(new DeclarativeSettingsSetValueEvent($user, $app, $formId, $fieldId, $value));
 				break;
 			case DeclarativeSettingsTypes::STORAGE_TYPE_INTERNAL:
@@ -254,6 +273,20 @@ class DeclarativeManager implements IDeclarativeManager {
 		}
 	}
 
+	/**
+	 * If a declarative setting was registered as a form and not just a schema
+	 * then this will yield the registering form.
+	 */
+	private function getForm(string $app, string $formId): ?IDeclarativeSettingsForm {
+		$allForms = $this->declarativeForms[$app] ?? [];
+		foreach ($allForms as $form) {
+			if ($form->getSchema()['id'] === $formId) {
+				return $form;
+			}
+		}
+		return null;
+	}
+
 	private function getInternalValue(IUser $user, string $app, string $formId, string $fieldId): mixed {
 		$sectionType = $this->getSectionType($app, $fieldId);
 		$defaultValue = $this->getDefaultValue($app, $formId, $fieldId);
diff --git a/lib/public/Settings/DeclarativeSettingsTypes.php b/lib/public/Settings/DeclarativeSettingsTypes.php
index 82444af9b82..7edf0cbdd6e 100644
--- a/lib/public/Settings/DeclarativeSettingsTypes.php
+++ b/lib/public/Settings/DeclarativeSettingsTypes.php
@@ -32,8 +32,9 @@ final class DeclarativeSettingsTypes {
 	/**
 	 * IDeclarativeSettingsForm storage_type which is determines where and how the config value is stored
 	 *
-	 *
-	 * For `external` storage_type the app implementing \OCP\Settings\SetDeclarativeSettingsValueEvent and \OCP\Settings\GetDeclarativeSettingsValueEvent events is responsible for storing and retrieving the config value.
+	 * For `external` storage_type the app needs to either implement event listeners for \OCP\Settings\SetDeclarativeSettingsValueEvent
+	 * and \OCP\Settings\GetDeclarativeSettingsValueEvent or the IDeclarativeSettingsForm also needs to implement
+	 * IDeclarativeSettingsFormWithHandlers for storing and retrieving the config value.
 	 *
 	 * @since 29.0.0
 	 */
@@ -43,7 +44,6 @@ final class DeclarativeSettingsTypes {
 	 * IDeclarativeSettingsForm storage_type which is determines where and how the config value is stored
 	 *
 	 * For `internal` storage_type the config value is stored in default `appconfig` and `preferences` tables.
-	 * For `external` storage_type the app implementing \OCP\Settings\SetDeclarativeSettingsValueEvent and \OCP\Settings\GetDeclarativeSettingsValueEvent events is responsible for storing and retrieving the config value.
 	 *
 	 * @since 29.0.0
 	 */
diff --git a/lib/public/Settings/IDeclarativeSettingsFormWithHandlers.php b/lib/public/Settings/IDeclarativeSettingsFormWithHandlers.php
new file mode 100644
index 00000000000..180df73d995
--- /dev/null
+++ b/lib/public/Settings/IDeclarativeSettingsFormWithHandlers.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Settings;
+
+use OCP\IUser;
+
+/**
+ * @since 31.0.0
+ */
+interface IDeclarativeSettingsFormWithHandlers extends IDeclarativeSettingsForm {
+
+	/**
+	 * This function is called to get the current value of a specific forms field.
+	 * @since 31.0.0
+	 */
+	public function getValue(string $fieldId, IUser $user): mixed;
+
+	/**
+	 * This function is called when a user updated a form field to persist the setting.
+	 * @since 31.0.0
+	 */
+	public function setValue(string $fieldId, mixed $value, IUser $user): void;
+
+}