Editor: Make Fediverse preview template filterable

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Add a filter to allow modifying the ActivityPub preview template
 * `@mentions` in the JSON representation of the reply
 
 ### Improved

includes/class-activitypub.php

@@ -102,10 +102,15 @@ public static function render_activitypub_template( $template ) {
 		} elseif ( is_comment() ) {
 			$activitypub_template = ACTIVITYPUB_PLUGIN_DIR . '/templates/comment-json.php';
 		} elseif ( \is_singular() && ! is_post_disabled( \get_the_ID() ) ) {
-			$preview = \get_query_var( 'preview' );
-			if ( $preview ) {
+			if ( \get_query_var( 'preview' ) ) {
 				\define( 'ACTIVITYPUB_PREVIEW', true );
-				$activitypub_template = ACTIVITYPUB_PLUGIN_DIR . '/templates/post-preview.php';
+
+				/**
+				 * Filter the template used for the ActivityPub preview.
+				 *
+				 * @param string $activitypub_template Absolute path to the template file.
+				 */
+				$activitypub_template = apply_filters( 'activitypub_preview_template', ACTIVITYPUB_PLUGIN_DIR . '/templates/post-preview.php' );
 			} else {
 				$activitypub_template = ACTIVITYPUB_PLUGIN_DIR . '/templates/post-json.php';
 			}

readme.txt

@@ -134,6 +134,7 @@ For reasons of data protection, it is not possible to see the followers of other
 
 = Unreleased =
 
+* Added: A filter to allow modifying the ActivityPub preview template
 * Added: `@mentions` in the JSON representation of the reply
 * Improved: HTML to e-mail text conversion
 

tests/includes/class-test-activitypub.php

@@ -26,4 +26,34 @@ public function test_post_type_support() {
 		$this->assertContains( 'post', \get_post_types_by_support( 'activitypub' ) );
 		$this->assertContains( 'page', \get_post_types_by_support( 'activitypub' ) );
 	}
+
+	/**
+	 * Test activitypub_preview_template filter.
+	 *
+	 * @covers ::render_activitypub_template
+	 */
+	public function test_preview_template_filter() {
+		// Create a test post.
+		$post_id = self::factory()->post->create();
+		$this->go_to( get_permalink( $post_id ) );
+
+		// Simulate ActivityPub request and preview mode.
+		$_SERVER['HTTP_ACCEPT'] = 'application/activity+json';
+		\set_query_var( 'preview', true );
+
+		// Add filter before testing.
+		\add_filter(
+			'activitypub_preview_template',
+			function () {
+				return '/custom/template.php';
+			}
+		);
+
+		// Test that the filter is applied.
+		$template = \Activitypub\Activitypub::render_activitypub_template( 'original.php' );
+		$this->assertEquals( '/custom/template.php', $template, 'Custom preview template should be used when filter is applied.' );
+
+		// Clean up.
+		unset( $_SERVER['HTTP_ACCEPT'] );
+	}
 }