<?php
/**
 * Events in spaces, with RSVPs.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Events;

use SpaceBay\Content\Renderer;
use SpaceBay\Core\Settings;
use SpaceBay\Database\Tables;
use SpaceBay\Feed\PostAccess;
use SpaceBay\Gamification\Gamification;
use SpaceBay\Gamification\Points;
use SpaceBay\Moderation\WordFilter;
use SpaceBay\Notifications\Notifications;
use SpaceBay\Spaces\SpaceAccess;
use SpaceBay\Spaces\SpaceRepository;
use SpaceBay\Support\RateLimit;
use SpaceBay\Support\Time;
use SpaceBay\Support\Url;
use WP_Error;

defined( 'ABSPATH' ) || exit;

/**
 * Creates, reads and changes events and RSVPs.
 */
final class Events {

	/**
	 * Cron hook that tells members about a new, changed or cancelled event.
	 *
	 * @var string
	 */
	const NOTIFY_HOOK = 'spacebay_event_notify';

	/**
	 * Answers a member can give.
	 *
	 * @var string[]
	 */
	const ANSWERS = array( 'going', 'maybe', 'not_going' );

	/**
	 * Longest description, in characters.
	 *
	 * @var int
	 */
	const MAX_DESCRIPTION = 5000;

	/**
	 * Columns read from the events table.
	 *
	 * @var string
	 */
	const COLUMNS = 'id, space_id, user_id, title, description, description_rendered, location_type, location, online_url, capacity, status, going_count, maybe_count, reminder_sent, starts_at, ends_at, created_at, updated_at';

	/**
	 * Hooks cron jobs and cleanup.
	 *
	 * @return void
	 */
	public static function init() {
		add_action( self::NOTIFY_HOOK, array( __CLASS__, 'notify' ), 10, 3 );
		add_action( 'spacebay_space_deleted', array( __CLASS__, 'on_space_deleted' ) );
		add_action( 'deleted_user', array( __CLASS__, 'delete_user_data' ), 20 );
		add_action( 'remove_user_from_blog', array( __CLASS__, 'delete_user_data' ), 20 );
	}

	/**
	 * Whether events are switched on.
	 *
	 * @return bool
	 */
	public static function enabled() {
		return (bool) Settings::get( 'events_enabled', true );
	}

	/**
	 * Whether a member may add events to a space.
	 *
	 * @param array $space   Space row.
	 * @param int   $user_id Member.
	 * @return bool
	 */
	public static function can_create( array $space, $user_id ) {
		if ( ! self::enabled() || ! $user_id || 'published' !== $space['status'] ) {
			return false;
		}

		if ( SpaceAccess::can_moderate( $space, $user_id ) ) {
			return true;
		}

		return 'members' === Settings::get( 'events_who', 'admins' ) && PostAccess::can_post( $space, $user_id );
	}

	/**
	 * Whether a member may change or delete an event.
	 *
	 * @param array $event   Event row.
	 * @param array $space   Space row.
	 * @param int   $user_id Member.
	 * @return bool
	 */
	public static function can_edit( array $event, array $space, $user_id ) {
		return $user_id > 0 && PostAccess::can_change( $space, $event['user_id'], $user_id );
	}

	/**
	 * Whether a member may answer an event.
	 *
	 * @param array $event   Event row.
	 * @param array $space   Space row.
	 * @param int   $user_id Member.
	 * @return bool
	 */
	public static function can_rsvp( array $event, array $space, $user_id ) {
		return 'published' === $event['status']
			&& strtotime( $event['ends_at'] . ' UTC' ) > time()
			&& PostAccess::can_comment( $space, $user_id );
	}

	/**
	 * Finds an event.
	 *
	 * @param int $id Event 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 -- Custom table, fresh read.
			$wpdb->prepare( 'SELECT ' . self::COLUMNS . ' FROM %i WHERE id = %d', Tables::name( 'events' ), absint( $id ) ), // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- COLUMNS is a class constant.
			ARRAY_A
		);

		return $row ? self::normalize( $row ) : null;
	}

	/**
	 * Lists events the viewer may read.
	 *
	 * @param array $args      space_id, from, to (UTC datetimes), when (upcoming|past|range), rsvp (going), page, per_page.
	 * @param int   $viewer_id Viewer.
	 * @return array{items: array[], total: int}
	 */
	public static function query( array $args, $viewer_id ) {
		global $wpdb;

		$spaces = PostAccess::readable_space_ids( $viewer_id );

		if ( ! empty( $args['space_id'] ) ) {
			$spaces = in_array( (int) $args['space_id'], $spaces, true ) ? array( (int) $args['space_id'] ) : array();
		}

		if ( ! $spaces ) {
			return array(
				'items' => array(),
				'total' => 0,
			);
		}

		$per_page = max( 1, min( 100, absint( $args['per_page'] ?? 20 ) ) );
		$offset   = ( max( 1, absint( $args['page'] ?? 1 ) ) - 1 ) * $per_page;
		$when     = $args['when'] ?? 'upcoming';
		$now      = Time::now();
		$from     = 'range' === $when ? (string) $args['from'] : ( 'upcoming' === $when ? $now : '1970-01-01 00:00:00' );
		$to       = 'range' === $when ? (string) $args['to'] : ( 'upcoming' === $when ? '9999-12-31 00:00:00' : $now );
		$going    = 'going' === ( $args['rsvp'] ?? '' ) ? absint( $viewer_id ) : 0;
		$past     = 'past' === $when ? 1 : 0;
		$live     = 'upcoming' === $when ? 1 : 0;

		if ( $past ) {
			$from = '1970-01-01 00:00:00';
			$to   = $now;
		}

		$placeholders = implode( ',', array_fill( 0, count( $spaces ), '%d' ) );
		$params       = array_merge(
			array( Tables::name( 'events' ), Tables::name( 'event_rsvps' ), $going, $going, $from, $past, $to, $past, $to, $live ),
			$spaces
		);

		// Upcoming lists show published events that have not ended; past lists show ended ones (newest
		// first); ranges show events that overlap the range.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Placeholders are built from %d only.
		$rows  = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT e.id, e.space_id, e.user_id, e.title, e.description, e.description_rendered, e.location_type, e.location, e.online_url, e.capacity, e.status, e.going_count, e.maybe_count, e.reminder_sent, e.starts_at, e.ends_at, e.created_at, e.updated_at FROM %i e LEFT JOIN %i r ON r.event_id = e.id AND r.user_id = %d AND r.status = 'going' WHERE ( %d = 0 OR r.id IS NOT NULL ) AND e.ends_at >= %s AND ( ( %d = 1 AND e.ends_at < %s ) OR ( %d = 0 AND e.starts_at <= %s ) ) AND ( %d = 0 OR e.status = 'published' ) AND e.space_id IN ($placeholders) ORDER BY CASE WHEN %d = 1 THEN e.starts_at END DESC, e.starts_at ASC, e.id ASC LIMIT %d OFFSET %d",
				array_merge( $params, array( $past, $per_page, $offset ) )
			),
			ARRAY_A
		);
		$total = (int) $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(e.id) FROM %i e LEFT JOIN %i r ON r.event_id = e.id AND r.user_id = %d AND r.status = 'going' WHERE ( %d = 0 OR r.id IS NOT NULL ) AND e.ends_at >= %s AND ( ( %d = 1 AND e.ends_at < %s ) OR ( %d = 0 AND e.starts_at <= %s ) ) AND ( %d = 0 OR e.status = 'published' ) AND e.space_id IN ($placeholders)",
				$params
			)
		);
		// phpcs:enable

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

	/**
	 * Creates an event.
	 *
	 * @param array $space   Space row.
	 * @param array $input   Raw values.
	 * @param int   $user_id Organizer.
	 * @return array|WP_Error Event row.
	 */
	public static function create( array $space, array $input, $user_id ) {
		global $wpdb;

		$clean = self::clean( $input, null );

		if ( is_wp_error( $clean ) ) {
			return $clean;
		}

		if ( strtotime( $clean['starts_at'] . ' UTC' ) < time() - HOUR_IN_SECONDS ) {
			return self::field_error( 'spacebay_event_past', __( 'Choose a start time in the future.', 'spacebay' ), 'starts_at' );
		}

		// Counted after the form is valid, so typing mistakes do not use up attempts.
		$limited = RateLimit::hit( 'event', $user_id, 10, HOUR_IN_SECONDS );

		if ( is_wp_error( $limited ) ) {
			return $limited;
		}

		$now = Time::now();
		$wpdb->insert( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- Custom table.
			Tables::name( 'events' ),
			array_merge(
				$clean,
				array(
					'space_id'   => (int) $space['id'],
					'user_id'    => absint( $user_id ),
					'status'     => 'published',
					'created_at' => $now,
					'updated_at' => $now,
				)
			)
		);

		$event = self::find( (int) $wpdb->insert_id );

		if ( ! $event ) {
			return new WP_Error( 'spacebay_event_failed', __( 'The event could not be saved. Please try again.', 'spacebay' ), array( 'status' => 500 ) );
		}

		// The organizer is going.
		self::answer( $event, $user_id, 'going', true );
		$event = self::find( $event['id'] );

		// Only space moderators may announce an event to every member of the space.
		if ( ! empty( $input['notify'] ) && SpaceAccess::can_moderate( $space, $user_id ) ) {
			wp_schedule_single_event( time(), self::NOTIFY_HOOK, array( (int) $event['id'], 'event_new', absint( $user_id ) ) );
		}

		/**
		 * Fires after an event is created.
		 *
		 * @since 1.0.0
		 *
		 * @param array $event Event row.
		 * @param array $space Space row.
		 */
		do_action( 'spacebay_event_created', $event, $space );

		return $event;
	}

	/**
	 * Changes an event. Members who answered hear about a new time or place.
	 *
	 * @param array $event   Event row.
	 * @param array $input   Raw values.
	 * @param int   $user_id Member who changes it.
	 * @return array|WP_Error
	 */
	public static function update( array $event, array $input, $user_id ) {
		global $wpdb;

		$clean = self::clean( $input, $event );

		if ( is_wp_error( $clean ) ) {
			return $clean;
		}

		$moved = $clean['starts_at'] !== $event['starts_at'] || $clean['location'] !== $event['location'] || $clean['online_url'] !== $event['online_url'] || $clean['location_type'] !== $event['location_type'];

		if ( $clean['starts_at'] !== $event['starts_at'] ) {
			$clean['reminder_sent'] = 0;
		}

		$clean['updated_at'] = Time::now();
		$wpdb->update( Tables::name( 'events' ), $clean, array( 'id' => (int) $event['id'] ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.

		if ( $moved && 'published' === $event['status'] ) {
			wp_schedule_single_event( time(), self::NOTIFY_HOOK, array( (int) $event['id'], 'event_updated', absint( $user_id ) ) );
		}

		$updated = self::find( $event['id'] );

		/**
		 * Fires after an event is changed.
		 *
		 * @since 1.0.0
		 *
		 * @param array $updated Event row after the change.
		 * @param array $event   Event row before the change.
		 */
		do_action( 'spacebay_event_updated', $updated, $event );

		return $updated;
	}

	/**
	 * Cancels an event and tells members who said they would come.
	 *
	 * @param array $event   Event row.
	 * @param int   $user_id Member who cancels it.
	 * @return array|null Null when the event was deleted meanwhile.
	 */
	public static function cancel( array $event, $user_id ) {
		global $wpdb;

		if ( 'cancelled' !== $event['status'] ) {
			$wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
				Tables::name( 'events' ),
				array(
					'status'     => 'cancelled',
					'updated_at' => Time::now(),
				),
				array( 'id' => (int) $event['id'] )
			);

			Points::remove_ref( 'event:' . (int) $event['id'] );

			if ( strtotime( $event['ends_at'] . ' UTC' ) > time() ) {
				wp_schedule_single_event( time(), self::NOTIFY_HOOK, array( (int) $event['id'], 'event_cancelled', absint( $user_id ) ) );
			}
		}

		return self::find( $event['id'] );
	}

	/**
	 * Deletes an event with its answers.
	 *
	 * @param array $event Event row.
	 * @return void
	 */
	public static function delete( array $event ) {
		global $wpdb;

		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom tables.
		$wpdb->delete( Tables::name( 'event_rsvps' ), array( 'event_id' => (int) $event['id'] ) );
		$wpdb->delete( Tables::name( 'events' ), array( 'id' => (int) $event['id'] ) );
		$wpdb->delete(
			Tables::name( 'notifications' ),
			array(
				'object_type' => 'event',
				'object_id'   => (int) $event['id'],
			)
		);
		// phpcs:enable

		Points::remove_ref( 'event:' . (int) $event['id'] );

		/**
		 * Fires after an event is deleted.
		 *
		 * @since 1.0.0
		 *
		 * @param array $event Deleted event row.
		 */
		do_action( 'spacebay_event_deleted', $event );
	}

	/**
	 * Saves a member's answer.
	 *
	 * @param array  $event   Event row.
	 * @param int    $user_id Member.
	 * @param string $answer  "going", "maybe", "not_going" or "" to remove it.
	 * @param bool   $force   Skip checks such as a place limit (the organizer).
	 * @return true|WP_Error
	 */
	public static function answer( array $event, $user_id, $answer, $force = false ) {
		global $wpdb;

		$user_id = absint( $user_id );
		$table   = Tables::name( 'event_rsvps' );
		$current = self::answer_of( $event['id'], $user_id );

		if ( '' !== $answer && ! in_array( $answer, self::ANSWERS, true ) ) {
			return new WP_Error( 'spacebay_rsvp_invalid', __( 'Choose going, maybe or can’t go.', 'spacebay' ), array( 'status' => 400 ) );
		}

		/**
		 * Filters whether an answer may be saved, for example to enforce a place
		 * limit (SpaceBay Pro). Return a WP_Error to refuse it.
		 *
		 * @since 1.0.0
		 *
		 * @param true|WP_Error $allowed Whether the answer may be saved.
		 * @param array         $event   Event row.
		 * @param int           $user_id Member.
		 * @param string        $answer  New answer.
		 * @param string        $current Current answer.
		 * @param bool          $force   Whether the organizer answers (no limits).
		 */
		$allowed = apply_filters( 'spacebay_event_answer_check', true, $event, $user_id, $answer, (string) $current, (bool) $force );

		if ( is_wp_error( $allowed ) ) {
			return $allowed;
		}

		if ( '' === $answer ) {
			$wpdb->delete( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
				$table,
				array(
					'event_id' => (int) $event['id'],
					'user_id'  => $user_id,
				)
			);
		} elseif ( $current ) {
			$wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
				$table,
				array(
					'status'     => $answer,
					'updated_at' => Time::now(),
				),
				array(
					'event_id' => (int) $event['id'],
					'user_id'  => $user_id,
				)
			);
		} else {
			$wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table; the unique key keeps one answer per member.
				$wpdb->prepare(
					'INSERT IGNORE INTO %i (event_id, user_id, status, created_at, updated_at) VALUES (%d, %d, %s, %s, %s)',
					$table,
					(int) $event['id'],
					$user_id,
					$answer,
					Time::now(),
					Time::now()
				)
			);
		}

		self::recount( $event['id'] );

		if ( 'going' === $answer ) {
			Gamification::earn( $user_id, 'event', 'event:' . (int) $event['id'], 'event', (int) $event['id'] );
		} elseif ( 'going' === $current ) {
			Points::remove( $user_id, 'event:' . (int) $event['id'] );
		}

		/**
		 * Fires after a member answers an event.
		 *
		 * @since 1.0.0
		 *
		 * @param array  $event   Event row.
		 * @param int    $user_id Member.
		 * @param string $answer  New answer, empty when removed.
		 * @param string $current Previous answer.
		 */
		do_action( 'spacebay_event_rsvp', $event, $user_id, $answer, (string) $current );

		return true;
	}

	/**
	 * A member's answer.
	 *
	 * @param int $event_id Event ID.
	 * @param int $user_id  Member.
	 * @return string Empty when the member did not answer.
	 */
	public static function answer_of( $event_id, $user_id ) {
		global $wpdb;

		if ( ! $user_id ) {
			return '';
		}

		return (string) $wpdb->get_var( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Fresh read.
			$wpdb->prepare( 'SELECT status FROM %i WHERE event_id = %d AND user_id = %d', Tables::name( 'event_rsvps' ), absint( $event_id ), absint( $user_id ) )
		);
	}

	/**
	 * Answers of a member for several events.
	 *
	 * @param int[] $event_ids Event IDs.
	 * @param int   $user_id   Member.
	 * @return array<int, string>
	 */
	public static function answers_of( array $event_ids, $user_id ) {
		global $wpdb;

		$event_ids = array_values( array_filter( array_map( 'absint', $event_ids ) ) );

		if ( ! $event_ids || ! $user_id ) {
			return array();
		}

		$placeholders = implode( ',', array_fill( 0, count( $event_ids ), '%d' ) );
		$rows         = $wpdb->get_results( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- One query per list.
			$wpdb->prepare( // phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber -- The IN() list has one %d per ID.
				"SELECT event_id, status FROM %i WHERE user_id = %d AND event_id IN ($placeholders)", // phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Placeholders are built from %d only.
				array_merge( array( Tables::name( 'event_rsvps' ), absint( $user_id ) ), $event_ids )
			),
			ARRAY_A
		);

		return wp_list_pluck( (array) $rows, 'status', 'event_id' );
	}

	/**
	 * Members who answered, newest answers last.
	 *
	 * @param int    $event_id Event ID.
	 * @param string $answer   "going" or "maybe".
	 * @param int    $page     Page.
	 * @param int    $per_page Per page.
	 * @return array{ids: int[], total: int}
	 */
	public static function attendees( $event_id, $answer, $page = 1, $per_page = 50 ) {
		global $wpdb;

		$table    = Tables::name( 'event_rsvps' );
		$per_page = max( 1, min( 100, absint( $per_page ) ) );
		$offset   = ( max( 1, absint( $page ) ) - 1 ) * $per_page;

		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table, paged.
		$ids   = $wpdb->get_col( $wpdb->prepare( 'SELECT user_id FROM %i WHERE event_id = %d AND status = %s ORDER BY created_at ASC, id ASC LIMIT %d OFFSET %d', $table, absint( $event_id ), $answer, $per_page, $offset ) );
		$total = (int) $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(id) FROM %i WHERE event_id = %d AND status = %s', $table, absint( $event_id ), $answer ) );
		// phpcs:enable

		return array(
			'ids'   => array_map( 'intval', (array) $ids ),
			'total' => $total,
		);
	}

	/**
	 * Notifies members about an event. Runs in the background.
	 *
	 * New events go to every active member of the space; changes, cancellations
	 * and reminders go to members who answered going or maybe.
	 *
	 * @param int    $event_id Event ID.
	 * @param string $action   "event_new", "event_updated", "event_cancelled" or "event_reminder".
	 * @param int    $actor_id Member who caused it.
	 * @return void
	 */
	public static function notify( $event_id, $action, $actor_id ) {
		global $wpdb;

		$event = self::find( $event_id );
		$space = $event ? SpaceRepository::find( $event['space_id'] ) : null;

		if ( ! $event || ! $space ) {
			return;
		}

		// Only the cancellation itself goes out for a cancelled event.
		if ( 'cancelled' === $event['status'] && 'event_cancelled' !== $action ) {
			return;
		}

		if ( 'event_new' === $action ) {
			$ids = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Background job.
				$wpdb->prepare( "SELECT user_id FROM %i WHERE space_id = %d AND status = 'active'", Tables::name( 'space_members' ), (int) $space['id'] )
			);
		} else {
			$ids = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Background job.
				$wpdb->prepare( "SELECT user_id FROM %i WHERE event_id = %d AND status IN ('going', 'maybe')", Tables::name( 'event_rsvps' ), (int) $event['id'] )
			);
		}

		$data = array(
			'title'       => $event['title'],
			'space_title' => $space['title'],
			'starts_at'   => Time::iso( $event['starts_at'] ),
			'excerpt'     => self::when_text( $event ),
		);

		foreach ( array_map( 'intval', (array) $ids ) as $user_id ) {
			if ( $user_id !== (int) $actor_id && SpaceAccess::can_read( $space, $user_id ) ) {
				Notifications::add( $user_id, (int) $actor_id, $action, 'event', (int) $event['id'], $data, 'events/' . (int) $event['id'] );
			}
		}
	}

	/**
	 * Date and time of an event in the site's time zone, for emails.
	 *
	 * @param array $event Event row.
	 * @return string
	 */
	public static function when_text( array $event ) {
		$start = strtotime( $event['starts_at'] . ' UTC' );

		return wp_date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), $start ) . ' (' . wp_timezone_string() . ')';
	}

	/**
	 * Deletes the events of a deleted space.
	 *
	 * @param array $space Deleted space row.
	 * @return void
	 */
	public static function on_space_deleted( $space ) {
		global $wpdb;

		$ids = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cleanup.
			$wpdb->prepare( 'SELECT id FROM %i WHERE space_id = %d', Tables::name( 'events' ), (int) $space['id'] )
		);

		foreach ( (array) $ids as $id ) {
			$event = self::find( (int) $id );

			if ( $event ) {
				self::delete( $event );
			}
		}
	}

	/**
	 * Removes the answers and the events of a deleted member, like their posts.
	 *
	 * @param int $user_id Member.
	 * @return void
	 */
	public static function delete_user_data( $user_id ) {
		global $wpdb;

		$table  = Tables::name( 'event_rsvps' );
		$events = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cleanup.
			$wpdb->prepare( 'SELECT event_id FROM %i WHERE user_id = %d', $table, absint( $user_id ) )
		);

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

		foreach ( (array) $events as $event_id ) {
			self::recount( (int) $event_id );
		}

		$own = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cleanup.
			$wpdb->prepare( 'SELECT id FROM %i WHERE user_id = %d', Tables::name( 'events' ), absint( $user_id ) )
		);

		foreach ( (array) $own as $id ) {
			$event = self::find( (int) $id );

			if ( $event ) {
				self::delete( $event );
			}
		}
	}

	/**
	 * Stores the number of answers on the event row.
	 *
	 * @param int $event_id Event ID.
	 * @return void
	 */
	private static function recount( $event_id ) {
		global $wpdb;

		$table  = Tables::name( 'event_rsvps' );
		$counts = $wpdb->get_results( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Counter refresh after a write.
			$wpdb->prepare( 'SELECT status, COUNT(id) AS total FROM %i WHERE event_id = %d GROUP BY status', $table, absint( $event_id ) ),
			ARRAY_A
		);
		$map    = wp_list_pluck( (array) $counts, 'total', 'status' );

		$wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table.
			Tables::name( 'events' ),
			array(
				'going_count' => (int) ( $map['going'] ?? 0 ),
				'maybe_count' => (int) ( $map['maybe'] ?? 0 ),
			),
			array( 'id' => absint( $event_id ) )
		);
	}

	/**
	 * Validates event fields.
	 *
	 * @param array      $input Raw values.
	 * @param array|null $event Event being changed, or null for a new one.
	 * @return array|WP_Error Columns to save.
	 */
	private static function clean( array $input, $event ) {
		$title = trim( sanitize_text_field( (string) ( $input['title'] ?? ( $event['title'] ?? '' ) ) ) );

		if ( '' === $title ) {
			return self::field_error( 'spacebay_event_title', __( 'Give the event a name.', 'spacebay' ), 'title' );
		}

		if ( mb_strlen( $title ) > 120 ) {
			return self::field_error( 'spacebay_event_title', __( 'Keep the name under 120 characters.', 'spacebay' ), 'title' );
		}

		$text = array_key_exists( 'description', $input ) ? (string) $input['description'] : (string) ( $event['description'] ?? '' );

		if ( mb_strlen( $text ) > self::MAX_DESCRIPTION ) {
			return self::field_error( 'spacebay_event_description', __( 'The description is too long.', 'spacebay' ), 'description' );
		}

		$starts = self::datetime( $input['starts_at'] ?? null, $event['starts_at'] ?? '' );

		if ( '' === $starts ) {
			return self::field_error( 'spacebay_event_start', __( 'Choose when the event starts.', 'spacebay' ), 'starts_at' );
		}

		$ends = self::datetime( $input['ends_at'] ?? null, $event['ends_at'] ?? '' );
		$ends = '' === $ends ? gmdate( 'Y-m-d H:i:s', strtotime( $starts . ' UTC' ) + HOUR_IN_SECONDS ) : $ends;
		$span = strtotime( $ends . ' UTC' ) - strtotime( $starts . ' UTC' );

		if ( $span <= 0 ) {
			return self::field_error( 'spacebay_event_end', __( 'The event must end after it starts.', 'spacebay' ), 'ends_at' );
		}

		if ( $span > 14 * DAY_IN_SECONDS ) {
			return self::field_error( 'spacebay_event_end', __( 'An event can last 14 days at most.', 'spacebay' ), 'ends_at' );
		}

		$type = sanitize_key( (string) ( $input['location_type'] ?? ( $event['location_type'] ?? 'online' ) ) );
		$type = in_array( $type, array( 'online', 'in_person' ), true ) ? $type : 'online';
		$url  = array_key_exists( 'online_url', $input ) ? trim( (string) $input['online_url'] ) : (string) ( $event['online_url'] ?? '' );
		$url  = '' === $url ? '' : Url::clean( $url );

		if ( array_key_exists( 'online_url', $input ) && '' !== trim( (string) $input['online_url'] ) && '' === $url ) {
			return self::field_error( 'spacebay_event_url', __( 'Enter a full link that starts with https://, for example https://meet.example.com/team.', 'spacebay' ), 'online_url' );
		}

		$place    = mb_substr( trim( sanitize_text_field( (string) ( $input['location'] ?? ( $event['location'] ?? '' ) ) ) ), 0, 200 );
		$rendered = Renderer::render( $text );
		$check    = $title . "\n" . $rendered['text'] . "\n" . $place;

		// Events cannot wait for review, so blocked words are refused or hidden like in private messages.
		if ( WordFilter::find( $check ) ) {
			if ( 'block' === Settings::get( 'blocked_words_action', 'review' ) || WordFilter::find( $title . "\n" . $place ) ) {
				return new WP_Error( 'spacebay_blocked_words', __( 'The event contains words that are not allowed here.', 'spacebay' ), array( 'status' => 400 ) );
			}

			$rendered = Renderer::render( WordFilter::mask( $rendered['text'] ) );
		}

		$clean = array(
			'title'                => $title,
			'description'          => $rendered['text'],
			'description_rendered' => $rendered['html'],
			'location_type'        => $type,
			'location'             => 'in_person' === $type ? $place : '',
			'online_url'           => 'online' === $type ? substr( $url, 0, 255 ) : '',
			'starts_at'            => $starts,
			'ends_at'              => $ends,
		);

		/**
		 * Filters the clean values of an event before it is saved. Add-ons add
		 * their own columns here, such as "capacity" (SpaceBay Pro).
		 *
		 * @since 1.0.0
		 *
		 * @param array      $clean Clean values.
		 * @param array      $input Raw values.
		 * @param array|null $event Event being changed, null for a new one.
		 */
		return apply_filters( 'spacebay_event_clean', $clean, $input, $event );
	}

	/**
	 * An error about one form field.
	 *
	 * @param string $code    Error code.
	 * @param string $message Message.
	 * @param string $field   Field name.
	 * @return WP_Error
	 */
	private static function field_error( $code, $message, $field ) {
		return new WP_Error(
			$code,
			$message,
			array(
				'status' => 400,
				'field'  => $field,
			)
		);
	}

	/**
	 * Turns an ISO 8601 time into a UTC MySQL datetime.
	 *
	 * @param mixed  $value    Raw value, or null to keep the fallback.
	 * @param string $fallback Current value.
	 * @return string Empty when not valid.
	 */
	private static function datetime( $value, $fallback ) {
		if ( null === $value || '' === $value ) {
			return null === $value ? (string) $fallback : '';
		}

		$time = strtotime( (string) $value );

		if ( false === $time || $time < strtotime( '2000-01-01' ) || $time > strtotime( '2100-01-01' ) ) {
			return '';
		}

		return gmdate( 'Y-m-d H:i:s', $time );
	}

	/**
	 * Casts a row.
	 *
	 * @param array $row Row.
	 * @return array
	 */
	public static function normalize( array $row ) {
		foreach ( array( 'id', 'space_id', 'user_id', 'capacity', 'going_count', 'maybe_count', 'reminder_sent' ) as $key ) {
			$row[ $key ] = (int) $row[ $key ];
		}

		return $row;
	}
}