<?php
/**
 * In-app notifications.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Notifications;

use SpaceBay\Content\Media;
use SpaceBay\Core\Settings;
use SpaceBay\Database\Tables;
use SpaceBay\Feed\Comments;
use SpaceBay\Feed\Posts;
use SpaceBay\Frontend\Portal;
use SpaceBay\Members\Profiles;
use SpaceBay\Moderation\Moderation;
use SpaceBay\Spaces\Membership;
use SpaceBay\Spaces\SpaceAccess;
use SpaceBay\Spaces\SpaceRepository;
use SpaceBay\Support\Time;

defined( 'ABSPATH' ) || exit;

/**
 * Creates notifications from community events and reads them back.
 */
final class Notifications {

	/**
	 * Cron hook that sends one notification email. Only for emails that were
	 * scheduled by earlier test builds; newer ones wait in the queue below.
	 *
	 * @var string
	 */
	const EMAIL_HOOK = 'spacebay_send_notification_email';

	/**
	 * Cron hook that sends the notification emails that are waiting.
	 *
	 * One background job sends them all. Scheduling a job per email made an
	 * announcement to a large space write thousands of jobs to the cron list.
	 *
	 * @var string
	 */
	const QUEUE_HOOK = 'spacebay_notification_emails';

	/**
	 * Seconds one background run may spend on sending emails.
	 *
	 * @var int
	 */
	const QUEUE_SECONDS = 20;

	/**
	 * Hooks community events.
	 *
	 * @return void
	 */
	public static function init() {
		add_action( 'spacebay_post_created', array( __CLASS__, 'on_post_created' ), 10, 2 );
		add_action( 'spacebay_comment_created', array( __CLASS__, 'on_comment_created' ), 10, 3 );
		add_action( 'spacebay_reaction_added', array( __CLASS__, 'on_reaction' ), 10, 4 );
		add_action( 'spacebay_space_member_invited', array( __CLASS__, 'on_invited' ), 10, 4 );
		add_action( 'spacebay_membership_changed', array( __CLASS__, 'on_membership_changed' ), 10, 5 );
		add_action( 'spacebay_content_held', array( __CLASS__, 'on_review_needed' ) );
		add_action( 'spacebay_content_reported', array( __CLASS__, 'on_review_needed' ) );
		add_action( 'spacebay_member_pending', array( __CLASS__, 'on_member_pending' ) );
		add_action( 'spacebay_content_approved', array( __CLASS__, 'on_content_approved' ), 10, 4 );
		add_action( 'spacebay_content_removed', array( __CLASS__, 'on_content_removed' ), 10, 4 );
		add_action( 'spacebay_member_status_changed', array( __CLASS__, 'on_member_status_changed' ), 10, 4 );
		add_action( 'spacebay_post_deleted', array( __CLASS__, 'on_post_deleted' ) );
		add_action( 'deleted_user', array( __CLASS__, 'on_user_deleted' ) );
		add_action( Media::CLEANUP_HOOK, array( __CLASS__, 'cleanup' ) );
		add_action( self::EMAIL_HOOK, array( Mailer::class, 'send' ) );
		add_action( self::QUEUE_HOOK, array( __CLASS__, 'send_waiting_emails' ) );
	}

	/**
	 * Makes sure the background job for waiting emails is planned.
	 *
	 * @return void
	 */
	private static function plan_emails() {
		if ( ! wp_next_scheduled( self::QUEUE_HOOK ) ) {
			wp_schedule_single_event( time(), self::QUEUE_HOOK );
		}
	}

	/**
	 * Sends the notification emails that are waiting, oldest first, for a
	 * limited time; the rest goes out with the next background run.
	 *
	 * @return int Number of emails handed to the mailer.
	 */
	public static function send_waiting_emails() {
		global $wpdb;

		$table   = Tables::name( 'notifications' );
		$until   = microtime( true ) + self::QUEUE_SECONDS;
		$handled = 0;

		// Planned first: if this run is cut short (a slow mail server, a time limit, an error in
		// another plugin), the emails that are left still have a job.
		wp_schedule_single_event( time() + 2 * MINUTE_IN_SECONDS, self::QUEUE_HOOK );

		// Emails that waited longer than a day are no longer news, for example after the plugin was switched off for a while.
		$wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Background job on an indexed flag.
			$wpdb->prepare( 'UPDATE %i SET email_pending = 0 WHERE email_pending = 1 AND created_at < %s', $table, gmdate( 'Y-m-d H:i:s', time() - DAY_IN_SECONDS ) )
		);

		do {
			$ids = array_map(
				'intval',
				(array) $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Background job on an indexed flag.
					$wpdb->prepare( 'SELECT id FROM %i WHERE email_pending = 1 ORDER BY id ASC LIMIT 50', $table )
				)
			);

			foreach ( $ids as $id ) {
				// Claimed first and only by one run: an email is never sent twice, also when two
				// runs overlap or a run is cut short.
				$claimed = $wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
					$wpdb->prepare( 'UPDATE %i SET email_pending = 0 WHERE id = %d AND email_pending = 1', $table, $id )
				);

				if ( 1 !== (int) $claimed ) {
					continue;
				}

				try {
					Mailer::send( $id );
				} catch ( \Throwable $error ) {
					// One email that cannot be built or sent must not hold up the others.
					unset( $error );
				}

				++$handled;

				if ( microtime( true ) >= $until ) {
					break;
				}
			}
		} while ( $ids && microtime( true ) < $until );

		// A clean finish: drop the safety job, then plan a new one only when emails are left.
		wp_unschedule_hook( self::QUEUE_HOOK );

		$left = (int) $wpdb->get_var( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Background job on an indexed flag.
			$wpdb->prepare( 'SELECT id FROM %i WHERE email_pending = 1 LIMIT 1', $table )
		);

		if ( $left ) {
			self::plan_emails();
		}

		return $handled;
	}

	/**
	 * Notifies members mentioned in a new post.
	 *
	 * @param array $post     Post row.
	 * @param int[] $mentions Mentioned user IDs.
	 * @return void
	 */
	public static function on_post_created( $post, $mentions ) {
		foreach ( (array) $mentions as $user_id ) {
			self::add( (int) $user_id, $post['user_id'], 'mention_post', 'post', $post['id'], self::post_data( $post ), 'posts/' . $post['id'] );
		}
	}

	/**
	 * Notifies the post author, the parent comment author and mentioned members.
	 *
	 * @param array $comment  Comment row.
	 * @param array $post     Post row.
	 * @param int[] $mentions Mentioned user IDs.
	 * @return void
	 */
	public static function on_comment_created( $comment, $post, $mentions ) {
		$data     = self::post_data( $post, $comment['message'] );
		$route    = 'posts/' . $post['id'];
		$notified = array( (int) $comment['user_id'] );

		if ( $comment['parent_id'] ) {
			$parent = Comments::find( $comment['parent_id'] );

			if ( $parent && ! in_array( $parent['user_id'], $notified, true ) ) {
				self::add( $parent['user_id'], $comment['user_id'], 'reply_comment', 'post', $post['id'], $data, $route );
				$notified[] = $parent['user_id'];
			}
		}

		if ( ! in_array( (int) $post['user_id'], $notified, true ) ) {
			self::add( $post['user_id'], $comment['user_id'], 'comment_post', 'post', $post['id'], $data, $route );
			$notified[] = (int) $post['user_id'];
		}

		foreach ( (array) $mentions as $user_id ) {
			if ( ! in_array( (int) $user_id, $notified, true ) ) {
				self::add( (int) $user_id, $comment['user_id'], 'mention_comment', 'post', $post['id'], $data, $route );
			}
		}
	}

	/**
	 * Notifies authors when their post or comment is liked.
	 *
	 * @param string $object_type "post" or "comment".
	 * @param int    $object_id   Object ID.
	 * @param int    $user_id     Member who reacted.
	 * @param string $type        "like" or "bookmark".
	 * @return void
	 */
	public static function on_reaction( $object_type, $object_id, $user_id, $type ) {
		if ( 'like' !== $type ) {
			return;
		}

		if ( 'post' === $object_type ) {
			$post = Posts::find( $object_id );

			if ( $post ) {
				self::add( $post['user_id'], $user_id, 'like_post', 'post', $post['id'], self::post_data( $post ), 'posts/' . $post['id'] );
			}

			return;
		}

		$comment = Comments::find( $object_id );
		$post    = $comment ? Posts::find( $comment['post_id'] ) : null;

		if ( $comment && $post ) {
			self::add( $comment['user_id'], $user_id, 'like_comment', 'post', $post['id'], self::post_data( $post, $comment['message'] ), 'posts/' . $post['id'] );
		}
	}

	/**
	 * Notifies a member who was invited to a space.
	 *
	 * @param int    $space_id Space ID.
	 * @param int    $user_id  Invited member.
	 * @param int    $actor_id Member who invited.
	 * @param string $mode     "invite" or "add".
	 * @return void
	 */
	public static function on_invited( $space_id, $user_id, $actor_id, $mode ) {
		$space = SpaceRepository::find( $space_id );

		if ( $space && 'invite' === $mode ) {
			self::add( $user_id, $actor_id, 'space_invite', 'space', $space['id'], self::space_data( $space ), 'spaces/' . $space['slug'] );
		}
	}

	/**
	 * Notifies space admins about join requests, and members when approved.
	 *
	 * @param int        $space_id Space ID.
	 * @param int        $user_id  Member.
	 * @param string     $role     New role.
	 * @param string     $status   New status.
	 * @param array|null $existing Previous membership.
	 * @return void
	 */
	public static function on_membership_changed( $space_id, $user_id, $role, $status, $existing ) {
		unset( $role );

		$space = SpaceRepository::find( $space_id );

		if ( ! $space ) {
			return;
		}

		$data = self::space_data( $space );

		if ( 'pending' === $status && ( ! $existing || 'pending' !== $existing['status'] ) ) {
			foreach ( self::space_admin_ids( $space_id ) as $admin_id ) {
				self::add( $admin_id, $user_id, 'space_request', 'space', $space['id'], $data, 'spaces/' . $space['slug'] );
			}
		}

		if ( 'active' === $status && $existing && 'pending' === $existing['status'] ) {
			self::add( $user_id, get_current_user_id(), 'space_approved', 'space', $space['id'], $data, 'spaces/' . $space['slug'] );
		}
	}

	/**
	 * Tells moderators that something waits for review. Moderators get one
	 * unread notice at a time, however many items arrive.
	 *
	 * @return void
	 */
	public static function on_review_needed() {
		foreach ( Moderation::moderator_ids() as $moderator_id ) {
			self::add( $moderator_id, 0, 'review_needed', 'moderation', 0, array(), 'moderation' );
		}
	}

	/**
	 * Tells moderators that a new member waits for approval.
	 *
	 * @param int $user_id New member.
	 * @return void
	 */
	public static function on_member_pending( $user_id ) {
		foreach ( Moderation::moderator_ids() as $moderator_id ) {
			self::add( $moderator_id, $user_id, 'member_pending', 'moderation', 0, array(), 'moderation/members' );
		}
	}

	/**
	 * Tells authors that their post or comment was approved.
	 *
	 * @param string $type         "post" or "comment".
	 * @param array  $row          Content row.
	 * @param int    $moderator_id Moderator.
	 * @param bool   $is_new       Whether the content is published for the first time.
	 * @return void
	 */
	public static function on_content_approved( $type, $row, $moderator_id, $is_new ) {
		$post = 'post' === $type ? $row : Posts::find( $row['post_id'] );

		if ( $post && $is_new ) {
			self::add( $row['user_id'], $moderator_id, $type . '_approved', 'post', $post['id'], self::post_data( $post, $row['message'] ), 'posts/' . $post['id'] );
		}
	}

	/**
	 * Tells authors that a moderator removed their post or comment.
	 *
	 * @param string $type         "post" or "comment".
	 * @param array  $row          Content row.
	 * @param array  $space        Space row.
	 * @param int    $moderator_id Moderator.
	 * @return void
	 */
	public static function on_content_removed( $type, $row, $space, $moderator_id ) {
		$data            = self::space_data( $space );
		$data['excerpt'] = wp_trim_words( wp_strip_all_tags( (string) $row['message'] ), 20, '…' );

		self::add( $row['user_id'], $moderator_id, $type . '_removed', 'space', $space['id'], $data, 'spaces/' . $space['slug'] );
	}

	/**
	 * Welcomes members whose account was approved.
	 *
	 * @param int    $user_id      Member.
	 * @param string $status       New status.
	 * @param string $old          Previous status.
	 * @param int    $moderator_id Moderator.
	 * @return void
	 */
	public static function on_member_status_changed( $user_id, $status, $old, $moderator_id ) {
		if ( 'active' === $status && 'pending' === $old ) {
			self::add( $user_id, $moderator_id, 'member_approved', 'moderation', 0, array(), '' );
		}
	}

	/**
	 * Saves a notification and schedules its email.
	 *
	 * Nothing is saved when the member would notify themselves, cannot see
	 * the content, or already has the same unread notification.
	 *
	 * @param int    $user_id     Recipient.
	 * @param int    $actor_id    Member who caused it.
	 * @param string $action      Action key.
	 * @param string $object_type "post" or "space".
	 * @param int    $object_id   Object ID.
	 * @param array  $data        Text shown in the notification.
	 * @param string $route       Portal path to open.
	 * @return int Notification ID, or 0.
	 */
	public static function add( $user_id, $actor_id, $action, $object_type, $object_id, array $data, $route ) {
		global $wpdb;

		$user_id  = absint( $user_id );
		$actor_id = absint( $actor_id );

		if ( ! $user_id || $user_id === $actor_id || ! get_userdata( $user_id ) || SpaceAccess::is_restricted( $user_id ) ) {
			return 0;
		}

		if ( 'post' === $object_type && ! self::can_read_post( $object_id, $user_id ) ) {
			return 0;
		}

		if ( 'event' === $object_type ) {
			$event = \SpaceBay\Events\Events::find( $object_id );
			$space = $event ? \SpaceBay\Spaces\SpaceRepository::find( $event['space_id'] ) : null;

			if ( ! $space || ! SpaceAccess::can_read( $space, $user_id ) ) {
				return 0;
			}
		}

		/**
		 * Filters whether a notification is created.
		 *
		 * @since 1.0.0
		 *
		 * @param bool   $create   Whether to create it.
		 * @param int    $user_id  Recipient.
		 * @param string $action   Action key.
		 * @param int    $actor_id Member who caused it.
		 */
		if ( ! apply_filters( 'spacebay_create_notification', true, $user_id, $action, $actor_id ) ) {
			return 0;
		}

		$table     = Tables::name( 'notifications' );
		$duplicate = $wpdb->get_var( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Fresh check before writing.
			$wpdb->prepare(
				'SELECT id FROM %i WHERE user_id = %d AND actor_id = %d AND action = %s AND object_type = %s AND object_id = %d AND is_read = 0',
				$table,
				$user_id,
				$actor_id,
				$action,
				$object_type,
				absint( $object_id )
			)
		);

		if ( $duplicate ) {
			return 0;
		}

		// The email is not sent here: the row is marked and one background job sends what is waiting.
		$email = Settings::get( 'emails_enabled', true ) && Preferences::wants_email( $user_id, $action );

		$wpdb->insert( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
			$table,
			array(
				'user_id'       => $user_id,
				'actor_id'      => $actor_id,
				'action'        => sanitize_key( $action ),
				'object_type'   => $object_type,
				'object_id'     => absint( $object_id ),
				'content'       => wp_json_encode( $data ),
				'url'           => $route,
				'is_read'       => 0,
				'email_pending' => $email ? 1 : 0,
				'created_at'    => Time::now(),
			)
		);

		$id = (int) $wpdb->insert_id;

		if ( $id && $email ) {
			self::plan_emails();
		}

		/**
		 * Fires after a notification is created.
		 *
		 * @since 1.0.0
		 *
		 * @param int    $id      Notification ID.
		 * @param int    $user_id Recipient.
		 * @param string $action  Action key.
		 */
		do_action( 'spacebay_notification_created', $id, $user_id, $action );

		return $id;
	}

	/**
	 * Lists a member's notifications, newest first.
	 *
	 * @param int  $user_id     User ID.
	 * @param int  $page        Page, from 1.
	 * @param int  $per_page    Items per page.
	 * @param bool $unread_only Only unread ones.
	 * @return array{items: array[], total: int}
	 */
	public static function for_user( $user_id, $page = 1, $per_page = 20, $unread_only = false ) {
		global $wpdb;

		$table    = Tables::name( 'notifications' );
		$per_page = max( 1, min( 50, absint( $per_page ) ) );
		$offset   = ( max( 1, absint( $page ) ) - 1 ) * $per_page;
		$read_max = $unread_only ? 0 : 1;

		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Per-user list that changes often.
		$total = (int) $wpdb->get_var(
			$wpdb->prepare( 'SELECT COUNT(id) FROM %i WHERE user_id = %d AND is_read <= %d', $table, absint( $user_id ), $read_max )
		);
		$rows  = $wpdb->get_results(
			$wpdb->prepare(
				'SELECT id, user_id, actor_id, action, object_type, object_id, content, url, is_read, created_at FROM %i WHERE user_id = %d AND is_read <= %d ORDER BY created_at DESC, id DESC LIMIT %d OFFSET %d',
				$table,
				absint( $user_id ),
				$read_max,
				$per_page,
				$offset
			),
			ARRAY_A
		);
		// phpcs:enable

		// Load the people behind the page of notifications together, not one by one.
		$actor_ids = array_values( array_unique( array_filter( array_map( 'intval', wp_list_pluck( (array) $rows, 'actor_id' ) ) ) ) );

		if ( $actor_ids ) {
			cache_users( $actor_ids );
			Profiles::get_many( $actor_ids );
		}

		return array(
			'items' => array_map( array( __CLASS__, 'format' ), (array) $rows ),
			'total' => $total,
		);
	}

	/**
	 * Number of unread notifications.
	 *
	 * @param int $user_id User ID.
	 * @return int
	 */
	public static function unread_count( $user_id ) {
		global $wpdb;

		return (int) $wpdb->get_var( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Live counter.
			$wpdb->prepare( 'SELECT COUNT(id) FROM %i WHERE user_id = %d AND is_read = 0', Tables::name( 'notifications' ), absint( $user_id ) )
		);
	}

	/**
	 * Marks notifications as read.
	 *
	 * @param int        $user_id User ID.
	 * @param int[]|null $ids     IDs, or null for all.
	 * @return void
	 */
	public static function mark_read( $user_id, $ids = null ) {
		global $wpdb;

		$table = Tables::name( 'notifications' );

		if ( null === $ids ) {
			$wpdb->update( $table, array( 'is_read' => 1 ), array( 'user_id' => absint( $user_id ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
			return;
		}

		foreach ( array_slice( array_map( 'absint', $ids ), 0, 100 ) as $id ) {
			$wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
				$table,
				array( 'is_read' => 1 ),
				array(
					'id'      => $id,
					'user_id' => absint( $user_id ),
				)
			);
		}
	}

	/**
	 * Finds one notification row.
	 *
	 * @param int $id Notification ID.
	 * @return array|null
	 */
	public static function find( $id ) {
		global $wpdb;

		$row = $wpdb->get_row( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Single row by primary key.
			$wpdb->prepare( 'SELECT id, user_id, actor_id, action, object_type, object_id, content, url, is_read, created_at FROM %i WHERE id = %d', Tables::name( 'notifications' ), absint( $id ) ),
			ARRAY_A
		);

		return $row ? $row : null;
	}

	/**
	 * Formats a notification with text in the reader's language.
	 *
	 * @param array $row Row.
	 * @return array
	 */
	public static function format( array $row ) {
		$data  = json_decode( (string) $row['content'], true );
		$data  = is_array( $data ) ? $data : array();
		$actor = get_userdata( (int) $row['actor_id'] );
		$name  = $actor ? $actor->display_name : __( 'Someone', 'spacebay' );

		return array(
			'id'         => (int) $row['id'],
			'action'     => $row['action'],
			'text'       => self::text( $row['action'], $name, $data ),
			'excerpt'    => isset( $data['excerpt'] ) ? (string) $data['excerpt'] : '',
			'actor'      => array(
				'id'     => $actor ? (int) $actor->ID : 0,
				'name'   => $name,
				'avatar' => get_avatar_url( $actor ? $actor->ID : 0, array( 'size' => 64 ) ),
			),
			'route'      => (string) $row['url'],
			'url'        => Portal::link( (string) $row['url'] ),
			'is_read'    => (bool) $row['is_read'],
			'created_at' => Time::iso( $row['created_at'] ),
		);
	}

	/**
	 * Sentence describing a notification.
	 *
	 * @param string $action Action key.
	 * @param string $name   Actor name.
	 * @param array  $data   Stored data.
	 * @return string
	 */
	public static function text( $action, $name, array $data ) {
		$space = (string) ( $data['space_title'] ?? '' );

		switch ( $action ) {
			case 'mention_post':
				/* translators: 1: Member name, 2: Space name. */
				return sprintf( __( '%1$s mentioned you in a post in %2$s', 'spacebay' ), $name, $space );
			case 'mention_comment':
				/* translators: %s: Member name. */
				return sprintf( __( '%s mentioned you in a comment', 'spacebay' ), $name );
			case 'comment_post':
				/* translators: %s: Member name. */
				return sprintf( __( '%s commented on your post', 'spacebay' ), $name );
			case 'reply_comment':
				/* translators: %s: Member name. */
				return sprintf( __( '%s replied to your comment', 'spacebay' ), $name );
			case 'like_post':
				/* translators: %s: Member name. */
				return sprintf( __( '%s liked your post', 'spacebay' ), $name );
			case 'like_comment':
				/* translators: %s: Member name. */
				return sprintf( __( '%s liked your comment', 'spacebay' ), $name );
			case 'space_invite':
				/* translators: 1: Member name, 2: Space name. */
				return sprintf( __( '%1$s invited you to join %2$s', 'spacebay' ), $name, $space );
			case 'space_request':
				/* translators: 1: Member name, 2: Space name. */
				return sprintf( __( '%1$s asked to join %2$s', 'spacebay' ), $name, $space );
			case 'space_approved':
				/* translators: %s: Space name. */
				return sprintf( __( 'You are now a member of %s', 'spacebay' ), $space );
			case 'review_needed':
				return __( 'New posts, comments or reports are waiting for review', 'spacebay' );
			case 'member_pending':
				/* translators: %s: Member name. */
				return sprintf( __( '%s is waiting for approval to join', 'spacebay' ), $name );
			case 'post_approved':
				/* translators: %s: Space name. */
				return sprintf( __( 'Your post in %s was approved', 'spacebay' ), $space );
			case 'comment_approved':
				return __( 'Your comment was approved', 'spacebay' );
			case 'post_removed':
				/* translators: %s: Space name. */
				return sprintf( __( 'A moderator removed your post in %s', 'spacebay' ), $space );
			case 'comment_removed':
				/* translators: %s: Space name. */
				return sprintf( __( 'A moderator removed your comment in %s', 'spacebay' ), $space );
			case 'member_approved':
				return __( 'Welcome! Your account was approved. You can now join spaces and post.', 'spacebay' );
			case 'badge_earned':
				if ( ! empty( $data['given'] ) ) {
					/* translators: 1: Member name, 2: Badge name. */
					return sprintf( __( '%1$s gave you the “%2$s” badge', 'spacebay' ), $name, (string) ( $data['badge'] ?? '' ) );
				}

				/* translators: %s: Badge name. */
				return sprintf( __( 'You earned the “%s” badge', 'spacebay' ), (string) ( $data['badge'] ?? '' ) );
			case 'level_up':
				/* translators: %s: Level name, for example "Regular". */
				return sprintf( __( 'You reached a new level: %s', 'spacebay' ), (string) ( $data['level'] ?? '' ) );
			case 'event_new':
				/* translators: 1: Event name, 2: Space name. */
				return sprintf( __( 'New event in %2$s: %1$s', 'spacebay' ), (string) ( $data['title'] ?? '' ), $space );
			case 'event_updated':
				/* translators: %s: Event name. */
				return sprintf( __( 'The time or place of %s changed', 'spacebay' ), (string) ( $data['title'] ?? '' ) );
			case 'event_cancelled':
				/* translators: %s: Event name. */
				return sprintf( __( '%s was cancelled', 'spacebay' ), (string) ( $data['title'] ?? '' ) );
			case 'event_reminder':
				/* translators: %s: Event name. */
				return sprintf( __( 'Reminder: %s starts soon', 'spacebay' ), (string) ( $data['title'] ?? '' ) );
		}

		/**
		 * Filters the text of a custom notification action.
		 *
		 * @since 1.0.0
		 *
		 * @param string $text   Text.
		 * @param string $action Action key.
		 * @param string $name   Actor name.
		 * @param array  $data   Stored data.
		 */
		return (string) apply_filters( 'spacebay_notification_text', '', $action, $name, $data );
	}

	/**
	 * Removes notifications about a deleted post.
	 *
	 * @param array $post Deleted post row.
	 * @return void
	 */
	public static function on_post_deleted( $post ) {
		global $wpdb;

		$wpdb->delete( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
			Tables::name( 'notifications' ),
			array(
				'object_type' => 'post',
				'object_id'   => (int) $post['id'],
			)
		);
	}

	/**
	 * Removes notifications to and from a deleted user.
	 *
	 * @param int $user_id User ID.
	 * @return void
	 */
	public static function on_user_deleted( $user_id ) {
		global $wpdb;

		$table = Tables::name( 'notifications' );
		$wpdb->delete( $table, array( 'user_id' => absint( $user_id ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
		$wpdb->delete( $table, array( 'actor_id' => absint( $user_id ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
	}

	/**
	 * Deletes read notifications older than 90 days and all older than 180 days.
	 *
	 * @return void
	 */
	public static function cleanup() {
		global $wpdb;

		$wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Daily cron.
			$wpdb->prepare(
				'DELETE FROM %i WHERE ( is_read = 1 AND created_at < %s ) OR created_at < %s',
				Tables::name( 'notifications' ),
				gmdate( 'Y-m-d H:i:s', time() - 90 * DAY_IN_SECONDS ),
				gmdate( 'Y-m-d H:i:s', time() - 180 * DAY_IN_SECONDS )
			)
		);
	}

	/**
	 * Whether a member may read a post.
	 *
	 * @param int $post_id Post ID.
	 * @param int $user_id User ID.
	 * @return bool
	 */
	private static function can_read_post( $post_id, $user_id ) {
		$post  = Posts::find( $post_id );
		$space = $post ? SpaceRepository::find( $post['space_id'] ) : null;

		return $space && SpaceAccess::can_read( $space, $user_id );
	}

	/**
	 * Data stored for post notifications.
	 *
	 * @param array  $post Post row.
	 * @param string $text Text to quote; defaults to the post.
	 * @return array
	 */
	private static function post_data( array $post, $text = '' ) {
		$space = SpaceRepository::find( $post['space_id'] );
		$text  = '' !== $text ? $text : ( '' !== $post['title'] ? $post['title'] : $post['message'] );

		return array(
			'space_title' => $space ? $space['title'] : '',
			'excerpt'     => wp_trim_words( wp_strip_all_tags( $text ), 20, '…' ),
		);
	}

	/**
	 * Data stored for space notifications.
	 *
	 * @param array $space Space row.
	 * @return array
	 */
	private static function space_data( array $space ) {
		return array(
			'space_title' => $space['title'],
			'excerpt'     => '',
		);
	}

	/**
	 * Active admins of a space.
	 *
	 * @param int $space_id Space ID.
	 * @return int[]
	 */
	private static function space_admin_ids( $space_id ) {
		$result = Membership::list_members( $space_id, 'active', 1, 50 );
		$ids    = array();

		foreach ( $result['items'] as $row ) {
			if ( 'admin' === $row['role'] ) {
				$ids[] = (int) $row['user_id'];
			}
		}

		return $ids;
	}
}