Add Gutenberg dynamic-block wrappers for the front-end shortcodes

Wrap the four shortcodes (us_booking, us_student_login,
us_student_register, us_group_classes) in dynamic blocks so pages can be
previewed and styled in the block editor. Front-end rendering delegates
to the same page objects the shortcodes use; in the editor's
block-renderer REST preview a static, script-free BlockPreview is
rendered instead (no live REST calls, redirects, or Stripe.js). The
editor script (vanilla JS, no build step) registers each block with
wp.serverSideRender previews and shortcode transforms; frontend.css is
attached as the block style so previews pick up theme styling.

Resolves #44

Co-Authored-By: Claude Fable 5 <[email protected]>

src/BlockRegistrar.php

@@ -0,0 +1,126 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular;
+
+use Unsupervised\Schedular\Auth\LoginPage;
+use Unsupervised\Schedular\Auth\RegistrationPage;
+use Unsupervised\Schedular\Booking\BookingPage;
+use Unsupervised\Schedular\GroupClass\GroupClassPage;
+
+/**
+ * Registers Gutenberg dynamic-block wrappers for the front-end shortcodes so
+ * the pages can be previewed and styled inside the block editor.
+ *
+ * On the front end each block delegates to the same page object its shortcode
+ * uses, so output is identical either way. Inside the editor (the
+ * block-renderer REST preview used by wp.serverSideRender) a static preview
+ * from BlockPreview is rendered instead — same markup and CSS classes, no
+ * live REST calls, redirects, or Stripe.js.
+ */
+class BlockRegistrar {
+
+	public const SCRIPT_HANDLE = 'us-scheduler-blocks';
+	public const STYLE_HANDLE  = 'us-scheduler';
+
+	public function __construct(
+		private BookingPage $bookingPage,
+		private LoginPage $loginPage,
+		private RegistrationPage $registrationPage,
+		private GroupClassPage $groupClassPage,
+	) {}
+
+	public function register(): void {
+		add_action( 'init', [ $this, 'registerBlocks' ] );
+	}
+
+	public function registerBlocks(): void {
+		// The editor script registers the client side of each block (title,
+		// icon, shortcode transform) and previews it via wp.serverSideRender.
+		wp_register_script(
+			self::SCRIPT_HANDLE,
+			USC_PLUGIN_URL . 'assets/js/blocks.js',
+			[ 'wp-blocks', 'wp-element', 'wp-block-editor', 'wp-server-side-render', 'wp-i18n' ],
+			USC_VERSION,
+			true
+		);
+
+		// The front-end stylesheet doubles as the block style so editor
+		// previews look like the published page. ShortcodeRegistrar registers
+		// the same handle on the front end, hence the guard.
+		if ( ! wp_style_is( self::STYLE_HANDLE, 'registered' ) ) {
+			wp_register_style( self::STYLE_HANDLE, USC_PLUGIN_URL . 'assets/css/frontend.css', [], USC_VERSION );
+		}
+
+		foreach ( $this->blocks() as $name => $renderCallback ) {
+			register_block_type(
+				$name,
+				[
+					'api_version'     => '3',
+					'editor_script'   => self::SCRIPT_HANDLE,
+					'style'           => self::STYLE_HANDLE,
+					'render_callback' => $renderCallback,
+				]
+			);
+		}
+	}
+
+	/**
+	 * Block names mapped to their render callbacks.
+	 *
+	 * @return array<string, callable(array<string, mixed>): string>
+	 */
+	private function blocks(): array {
+		return [
+			'us-scheduler/booking'          => [ $this, 'renderBooking' ],
+			'us-scheduler/student-login'    => [ $this, 'renderLogin' ],
+			'us-scheduler/student-register' => [ $this, 'renderRegistration' ],
+			'us-scheduler/group-classes'    => [ $this, 'renderGroupClasses' ],
+		];
+	}
+
+	/**
+	 * Renders the booking block.
+	 *
+	 * @param array<string, mixed> $attributes Block attributes (unused — the blocks have none yet).
+	 */
+	public function renderBooking( array $attributes = [] ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+		return $this->isEditorPreview() ? BlockPreview::booking() : $this->bookingPage->render( [] );
+	}
+
+	/**
+	 * Renders the student-login block.
+	 *
+	 * @param array<string, mixed> $attributes Block attributes (unused — the blocks have none yet).
+	 */
+	public function renderLogin( array $attributes = [] ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+		return $this->isEditorPreview() ? BlockPreview::login() : $this->loginPage->render( [] );
+	}
+
+	/**
+	 * Renders the student-registration block.
+	 *
+	 * @param array<string, mixed> $attributes Block attributes (unused — the blocks have none yet).
+	 */
+	public function renderRegistration( array $attributes = [] ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+		return $this->isEditorPreview() ? BlockPreview::registration() : $this->registrationPage->render( [] );
+	}
+
+	/**
+	 * Renders the group-classes block.
+	 *
+	 * @param array<string, mixed> $attributes Block attributes (unused — the blocks have none yet).
+	 */
+	public function renderGroupClasses( array $attributes = [] ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+		return $this->isEditorPreview() ? BlockPreview::groupClasses() : $this->groupClassPage->render( [] );
+	}
+
+	/**
+	 * Whether this render is the editor's block-renderer REST preview rather
+	 * than a real front-end page render. Front-end template rendering never
+	 * happens inside a REST request, so REST_REQUEST is a reliable signal.
+	 */
+	protected function isEditorPreview(): bool {
+		return defined( 'REST_REQUEST' ) && (bool) constant( 'REST_REQUEST' );
+	}
+}