Register an user to attend or un-attend to an event

assets/css/translation-events.css

@@ -2,7 +2,7 @@
     width: 10%;
     vertical-align: top;
 }
-.translation-event-form #event-title, 
+.translation-event-form #event-title,
 .translation-event-form #event-description {
     width: 30%;
 }
@@ -40,10 +40,6 @@
     float: left;
     padding: 1em;
 }
-button#join-event {
-    width: 100%;
-    display: block;
-}
 .event-details-stats {
     clear: both;
     margin: 1em;

includes/class-wporg-gp-translation-events-route.php

@@ -6,7 +6,7 @@
  * @package wporg-gp-translation-events
  */
 class WPORG_GP_Translation_Events_Route extends GP_Route {
-
+	public const USER_META_KEY_ATTENDING = 'translation-events-attending';
 
 	/**
 	 * WPORG_GP_Translation_Events_Route constructor.
@@ -106,15 +106,19 @@ public function events_edit( $event_id ) {
 	 * @return void
 	 */
 	public function events_details( $event_slug ) {
+		$user = wp_get_current_user();
 		$event = get_page_by_path( $event_slug, OBJECT, 'event' );
 		if ( ! $event ) {
 			$this->die_with_404();
 		}
 
-		$event_title       = $event->post_title;
-		$event_description = $event->post_content;
-		$event_start       = get_post_meta( $event->ID, '_event_start', true ) ?? '';
-		$event_end         = get_post_meta( $event->ID, '_event_end', true ) ?? '';
+		$event_id = $event->ID;
+		$event_title         = $event->post_title;
+		$event_description   = $event->post_content;
+		$event_start         = get_post_meta( $event->ID, '_event_start', true ) ?? '';
+		$event_end           = get_post_meta( $event->ID, '_event_end', true ) ?? '';
+		$attending_event_ids = get_user_meta( $user->ID, self::USER_META_KEY_ATTENDING, true ) ?: array();
+		$user_is_attending   = isset( $attending_event_ids[ $event_id ] );
 
 		$stats_calculator = new WPORG_GP_Translation_Events_Stats_Calculator();
 		try {
@@ -127,6 +131,43 @@ public function events_details( $event_slug ) {
 		$this->tmpl( 'event', get_defined_vars() );
 	}
 
+	/**
+	 * Toggle whether the current user is attending an event.
+	 * If the user is not currently marked as attending, they will be marked as attending.
+	 * If the user is currently marked as attending, they will be marked as not attending.
+	 *
+	 * @param int $event_id
+	 */
+	public function events_attend( int $event_id ) {
+		$user = wp_get_current_user();
+		if ( ! $user ) {
+			$this->die_with_error( 'Only logged-in users can attend events', 403 );
+		}
+
+		$event = get_post( $event_id );
+		if ( ! $event ) {
+			$this->die_with_404();
+		}
+
+		$event_ids = get_user_meta( $user->ID, self::USER_META_KEY_ATTENDING, true ) ?? [];
+		if ( ! $event_ids ) {
+			$event_ids = [];
+		}
+
+		if ( ! isset( $event_ids[ $event_id ] ) ) {
+			// Not yet attending, mark as attending.
+			$event_ids[ $event_id ] = true;
+		} else {
+			// Currently attending, mark as not attending.
+			unset( $event_ids[ $event_id ] );
+		}
+
+		update_user_meta( $user->ID, self::USER_META_KEY_ATTENDING, $event_ids );
+
+		wp_safe_redirect( gp_url( "/events/$event->post_name" ) );
+		exit;
+	}
+
 	/**
 	 * Convert date time stored in UTC to a date time in a time zone.
 	 *

includes/class-wporg-gp-translation-events-translation-listener.php

@@ -151,9 +151,8 @@ function ( $event ) use ( $at ) {
 	private function select_events_user_is_registered_for( array $events, int $user_id ): array {
 		return array_filter(
 			$events,
-			function ( WPORG_GP_Translation_Events_Event $event ) {
-				// TODO.
-				return true;
+			function ( $event ) use ( $attending_event_ids ) {
+				return isset( $attending_event_ids[ $event->ID ] );
 			}
 		);
 	}

templates/event.php

@@ -29,7 +29,13 @@
 		</div>
 		<?php  if ( is_user_logged_in() ) : ?>
 		<div class="event-details-join">
-			<button class="button is-primary" id="join-event">Attend Event</button>
+			<form class="event-details-attend" method="post" action="<?php echo esc_url( gp_url( "/events/attend/$event_id" ) )?>">
+				<?php if ( ! $user_is_attending ): ?>
+					<input type="submit" class="button is-primary" value="Attend Event"/>
+				<?php else: ?>
+					<input type="submit" class="button is-secondary" value="You're attending"/>
+				<?php endif ?>
+			</form>
 		</div>
 		<?php endif; ?>
 	</div>

wporg-gp-translation-events.php

@@ -250,6 +250,7 @@ function() {
 		GP::$router->add( '/events?', array( 'WPORG_GP_Translation_Events_Route', 'events_list' ), 'get' );
 		GP::$router->add( '/events/new', array( 'WPORG_GP_Translation_Events_Route', 'events_create' ), 'get' );
 		GP::$router->add( '/events/edit/(\d+)', array( 'WPORG_GP_Translation_Events_Route', 'events_edit' ), 'get' );
+		GP::$router->add( '/events/attend/(\d+)', array( 'WPORG_GP_Translation_Events_Route', 'events_attend' ), 'post' );
 		GP::$router->add( '/events/([a-z0-9_-]+)', array( 'WPORG_GP_Translation_Events_Route', 'events_details' ), 'get' );
 
 		require_once __DIR__ . '/includes/class-wporg-gp-translation-events-event.php';