Send students to a chosen page when registration succeeds

The Student Registration block's "After email confirmation" panel becomes
"After registration": the page it selects is now where a newly registered
student continues to, and a new autoRedirect toggle sends them there
instead of showing the link.

Only the two finished states qualify (RegistrationPage::isRegistrationComplete):
an invited student who is now logged in, and a self-signup back from the
emailed confirmation link. A validation error, an expired confirmation
link, and the intermediate "check your email" step all stay on the page so
their message is read.

The invited-student success previously had no link at all; it gains a
"Continue to your account" one. That path deliberately has no
WordPress-login-screen fallback — pointing someone already signed in at the
login screen helps nobody — so continueUrl() distinguishes "no page chosen"
from "page chosen", and the redirect does nothing until one is picked.

Closes #115

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

src/Auth/RegistrationPage.php

@@ -66,9 +66,20 @@ class RegistrationPage {
 
 		if ( is_user_logged_in() ) {
 			if ( self::RESULT_INVITE === $registered ) {
+				// An invited student is done the moment they land here logged in,
+				// so this is where their "continue" link belongs. The sign-in-page
+				// fallback is deliberately not used: pointing someone who is
+				// already signed in at the login screen helps nobody.
+				$continue = $this->continueUrl( $this->successPageId( $atts ) );
+				$link     = null === $continue
+					? ''
+					: '<p><a href="' . esc_url( $continue ) . '">'
+						. esc_html__( 'Continue to your account', 'unsupervised-schedular' )
+						. '</a></p>';
+
 				return '<div class="us-register-form"><p class="us-success">'
 					. esc_html__( 'Your account has been created and you are now logged in.', 'unsupervised-schedular' )
-					. '</p></div>';
+					. '</p>' . $link . '</div>';
 			}
 
 			return '<p>' . esc_html__( 'You already have an account and are logged in.', 'unsupervised-schedular' ) . '</p>';
@@ -98,7 +109,7 @@ class RegistrationPage {
 		$confirmResult = sanitize_key( Val::string( wp_unslash( $_GET['us_confirmed'] ?? '' ) ) );
 
 		// Where the post-confirmation prompt sends students to sign in.
-		$loginUrl = $this->loginUrl( Val::int( $atts['loginPageId'] ?? $atts['login_page_id'] ?? 0 ) );
+		$loginUrl = $this->loginUrl( $this->successPageId( $atts ) );
 
 		$policyForms       = $this->signupPolicies();
 		$accountQuestions  = $this->questions->findByScope( Question::SCOPE_ACCOUNT, activeOnly: true );
@@ -319,21 +330,68 @@ class RegistrationPage {
 		return $autoApprove ? self::RESULT_CONFIRM_GROUP : self::RESULT_CONFIRM;
 	}
 
+	/**
+	 * The page id chosen for the post-registration destination, from either the
+	 * block (`loginPageId`) or shortcode (`login_page_id`) attribute.
+	 *
+	 * @param array<int|string, mixed> $atts
+	 */
+	private function successPageId( array $atts ): int {
+		return Val::int( $atts['loginPageId'] ?? $atts['login_page_id'] ?? 0 );
+	}
+
 	/**
 	 * URL the post-confirmation sign-in link points to: the chosen login page
 	 * when one is configured (and still exists), otherwise the WordPress login
 	 * screen.
 	 */
 	private function loginUrl( int $loginPageId ): string {
-		if ( $loginPageId > 0 ) {
-			$url = get_permalink( $loginPageId );
+		return $this->continueUrl( $loginPageId ) ?? wp_login_url();
+	}
 
-			if ( is_string( $url ) ) {
-				return $url;
-			}
+	/**
+	 * The chosen post-registration page's URL, or null when none is configured
+	 * (or it has since been deleted). Unlike {@see loginUrl()} this has no
+	 * WordPress-login-screen fallback, so callers that need a page the student
+	 * was actually sent to — the invited-student link and the block's
+	 * auto-redirect — can tell "not configured" from "configured".
+	 */
+	public function continueUrl( int $pageId ): ?string {
+		if ( $pageId <= 0 ) {
+			return null;
 		}
 
-		return wp_login_url();
+		$url = get_permalink( $pageId );
+
+		return is_string( $url ) ? $url : null;
+	}
+
+	/**
+	 * Whether this request is a *finished* registration — the states the
+	 * block's auto-redirect may act on:
+	 *
+	 * - an invited student who just signed up and is now logged in, and
+	 * - a self-signup returning from the emailed confirmation link, whether
+	 *   their account is ready (`ready`) or awaiting studio approval (`1`).
+	 *
+	 * Deliberately excluded: the intermediate "check your email" step (the
+	 * student would never see the instruction) and every failure — a validation
+	 * error or an expired confirmation link (`expired`) — so the message always
+	 * gets shown. The `us_confirmed` values are set by
+	 * {@see EmailConfirmationHandler::maybeConfirm()}.
+	 */
+	public function isRegistrationComplete(): bool {
+		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only display flag; the submit that set it was nonce-checked.
+		$registered = sanitize_key( Val::string( wp_unslash( $_GET['us_registered'] ?? '' ) ) );
+
+		if ( self::RESULT_INVITE === $registered ) {
+			return is_user_logged_in();
+		}
+
+		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only display flag set by EmailConfirmationHandler's redirect.
+		$confirmed = sanitize_key( Val::string( wp_unslash( $_GET['us_confirmed'] ?? '' ) ) );
+
+		return in_array( $confirmed, [ '1', 'ready' ], true );
 	}
 
 	/**

src/BlockRegistrar.php

@@ -109,6 +109,7 @@ class BlockRegistrar {
 						'type'    => 'number',
 						'default' => 0,
 					],
+					'autoRedirect'      => $redirectToggle,
 					'inviteOnlyMessage' => [
 						'type'    => 'string',
 						'default' => '',
@@ -170,10 +171,11 @@ class BlockRegistrar {
 	/**
 	 * Server-side auto-redirect for blocks that opt in via their autoRedirect
 	 * attribute: logged-out visitors on a page containing the booking block
-	 * are sent to its login page, and logged-in visitors on a page containing
-	 * the student-login block are sent to its booking page. Hooked on
-	 * `template_redirect` because block rendering happens after output has
-	 * started, too late to send a Location header.
+	 * are sent to its login page, logged-in visitors on a page containing the
+	 * student-login block are sent to its booking page, and a student who has
+	 * just finished registering is sent to the register block's chosen page.
+	 * Hooked on `template_redirect` because block rendering happens after
+	 * output has started, too late to send a Location header.
 	 */
 	public function maybeAutoRedirect(): void {
 		if ( is_admin() || ! is_singular() ) {
@@ -185,6 +187,10 @@ class BlockRegistrar {
 			return;
 		}
 
+		if ( $this->maybeRedirectAfterRegistration( $post ) ) {
+			return;
+		}
+
 		if ( is_user_logged_in() ) {
 			$attrs = $this->firstBlockAttrs( $post->post_content, 'us-scheduler/student-login' );
 			if ( null === $attrs || ! Val::bool( $attrs['autoRedirect'] ?? false ) ) {
@@ -217,6 +223,45 @@ class BlockRegistrar {
 		$this->redirect( $this->bookingPage->loginUrl( $loginPageId ) );
 	}
 
+	/**
+	 * Sends a student whose registration has just completed to the register
+	 * block's chosen page, when the block opts in. Only the finished states
+	 * qualify (see {@see RegistrationPage::isRegistrationComplete()}): a
+	 * failure or the "check your email" step stays put so its message is read.
+	 * Unlike the other blocks there is no login-screen fallback — with no page
+	 * chosen there is nowhere to send them, so the link is shown instead.
+	 *
+	 * Returns whether the redirect was issued (it only ever returns in tests;
+	 * {@see redirect()} exits in production).
+	 */
+	private function maybeRedirectAfterRegistration( \WP_Post $post ): bool {
+		// Checked before parsing the content because it is a couple of query
+		// args, whereas every front-end request would otherwise pay for a
+		// third block scan.
+		if ( ! $this->registrationPage->isRegistrationComplete() ) {
+			return false;
+		}
+
+		$attrs = $this->firstBlockAttrs( $post->post_content, 'us-scheduler/student-register' );
+		if ( null === $attrs || ! Val::bool( $attrs['autoRedirect'] ?? false ) ) {
+			return false;
+		}
+
+		$pageId = Val::int( $attrs['loginPageId'] ?? 0 );
+		if ( $pageId === $post->ID ) {
+			return false; // Redirecting the page to itself would loop.
+		}
+
+		$url = $this->registrationPage->continueUrl( $pageId );
+		if ( null === $url ) {
+			return false;
+		}
+
+		$this->redirect( $url );
+
+		return true;
+	}
+
 	/**
 	 * Attributes of the first occurrence of the named block in the content,
 	 * searching inner blocks so blocks nested inside groups or columns are