<?php
/**
 * Occurrence index: keeps the date table in sync with event posts.
 *
 * @package BeariusCalendar
 */

defined( 'ABSPATH' ) || exit;

/**
 * Index maintenance.
 */
class BCal_Index {

	/**
	 * Events waiting for sync at the end of the request.
	 *
	 * @var array
	 */
	private static $queue = array();

	/**
	 * True while syncing, so our own writes do not re-queue.
	 *
	 * @var bool
	 */
	private static $syncing = false;

	/**
	 * True while an import runs: changes are synced by the importer in batches.
	 *
	 * @var bool
	 */
	private static $paused = false;

	/**
	 * Stops queueing syncs (imports sync their events themselves).
	 */
	public static function pause() {
		self::$paused = true;
	}

	/**
	 * Resumes queueing syncs.
	 */
	public static function resume() {
		self::$paused = false;
	}

	/**
	 * Hooks.
	 */
	public static function init() {
		add_action( 'save_post_' . BCAL_PT, array( __CLASS__, 'queue' ), 20 );
		add_action( 'transition_post_status', array( __CLASS__, 'on_transition' ), 10, 3 );
		add_action( 'deleted_post', array( __CLASS__, 'delete_event' ) );
		add_action( 'set_object_terms', array( __CLASS__, 'on_terms' ), 10, 4 );
		add_action( 'added_post_meta', array( __CLASS__, 'on_meta' ), 10, 3 );
		add_action( 'updated_post_meta', array( __CLASS__, 'on_meta' ), 10, 3 );
		add_action( 'deleted_post_meta', array( __CLASS__, 'on_meta' ), 10, 3 );
		add_action( 'shutdown', array( __CLASS__, 'flush' ) );
		add_action( 'bcal_daily', array( __CLASS__, 'daily' ) );
		add_action( 'bcal_resync_step', array( __CLASS__, 'resync_step' ) );
	}

	/**
	 * Queues an event for sync.
	 *
	 * @param int $post_id Post ID.
	 */
	public static function queue( $post_id ) {
		if ( self::$syncing || self::$paused || wp_is_post_revision( $post_id ) ) {
			return;
		}
		self::$queue[ (int) $post_id ] = true;
	}

	/**
	 * Status changes (publish, trash, draft).
	 *
	 * @param string  $new_status New status.
	 * @param string  $old_status Old status.
	 * @param WP_Post $post       Post.
	 */
	public static function on_transition( $new_status, $old_status, $post ) {
		if ( $post instanceof WP_Post && BCAL_PT === $post->post_type ) {
			self::queue( $post->ID );
		}
	}

	/**
	 * Term changes.
	 *
	 * @param int    $object_id Object ID.
	 * @param array  $terms     Terms.
	 * @param array  $tt_ids    Term taxonomy IDs.
	 * @param string $taxonomy  Taxonomy.
	 */
	public static function on_terms( $object_id, $terms, $tt_ids, $taxonomy ) {
		if ( in_array( $taxonomy, array( 'bcal_city', 'bcal_venue', 'bcal_category', 'bcal_organizer' ), true ) && BCAL_PT === get_post_type( $object_id ) ) {
			self::queue( $object_id );
		}
	}

	/**
	 * Meta changes on our keys.
	 *
	 * @param mixed  $meta_id   Meta ID(s).
	 * @param int    $object_id Post ID.
	 * @param string $meta_key  Meta key.
	 */
	public static function on_meta( $meta_id, $object_id, $meta_key ) {
		if ( 0 === strpos( (string) $meta_key, '_bcal_' ) && BCAL_PT === get_post_type( $object_id ) ) {
			self::queue( $object_id );
		}
	}

	/**
	 * Syncs queued events.
	 */
	public static function flush() {
		// Handlers of bcal_event_synced may change meta and queue events again.
		$rounds = 0;
		while ( self::$queue && $rounds++ < 5 ) {
			$ids         = array_keys( self::$queue );
			self::$queue = array();
			foreach ( $ids as $id ) {
				self::sync_event( $id );
			}
		}
	}

	/**
	 * Rebuilds the rows of one event.
	 *
	 * @param int $post_id Event ID.
	 * @return int Number of rows written.
	 */
	public static function sync_event( $post_id ) {
		global $wpdb;

		$post_id = (int) $post_id;
		unset( self::$queue[ $post_id ] );
		self::$syncing = true;

		$table = BCal_Install::table();
		$wpdb->delete( $table, array( 'event_id' => $post_id ), array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery

		$post    = get_post( $post_id );
		$written = 0;

		if ( $post && BCAL_PT === $post->post_type && 'publish' === $post->post_status ) {
			$event = bcal_get_event( $post_id, true );

			if ( $event['start'] ) {
				$months  = max( 1, (int) bcal_opt( 'window_months' ) );
				$horizon = ( new DateTimeImmutable( 'now', wp_timezone() ) )->modify( '+' . $months . ' months' )->format( 'Y-m-d H:i:s' );
				$items   = bcal_expand_occurrences(
					$event['start'],
					$event['end_effective'],
					$event['rrule'],
					$event['exdates'],
					$horizon,
					500,
					bcal_is_recurring( $event ) ? bcal_now() : '',
					array(
						'rdates' => $event['rdates'],
						'exrule' => $event['exrule'],
					)
				);

				$city  = bcal_first_term( $post_id, 'bcal_city' );
				$venue = bcal_first_term( $post_id, 'bcal_venue' );
				$score = get_post_meta( $post_id, '_bcal_score', true );

				$base = array(
					'city_id'  => $city ? (int) $city->term_id : 0,
					'venue_id' => $venue ? (int) $venue->term_id : 0,
					'featured' => $event['featured'] ? 1 : 0,
					'pick'     => get_post_meta( $post_id, '_bcal_pick', true ) ? 1 : 0,
					'hidden'   => get_post_meta( $post_id, '_bcal_hidden', true ) ? 1 : 0,
					'score'    => ( '' === $score || null === $score ) ? null : (int) $score,
					'status'   => substr( $event['status'], 0, 20 ),
				);

				foreach ( $items as $item ) {
					list( $start, $end ) = $item;
					if ( '' === $end || $event['all_day'] ) {
						// Without an explicit end the event stays listed until the end of its day.
						$end = substr( '' !== $end ? $end : $start, 0, 10 ) . ' 23:59:59';
					}

					$row = array_merge(
						$base,
						array(
							'event_id'   => $post_id,
							'start_dt'   => $start,
							'end_dt'     => $end,
							'start_date' => substr( $start, 0, 10 ),
							'all_day'    => $event['all_day'] ? 1 : 0,
						)
					);

					if ( null === $row['score'] ) {
						unset( $row['score'] );
					}

					$formats = array();
					foreach ( array_keys( $row ) as $column ) {
						$formats[] = in_array( $column, array( 'status', 'start_dt', 'end_dt', 'start_date' ), true ) ? '%s' : '%d';
					}

					$wpdb->insert( $table, $row, $formats ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery
					++$written;
				}
			}
		}

		self::$syncing = false;
		self::touch();

		do_action( 'bcal_event_synced', $post_id, $written );

		return $written;
	}

	/**
	 * Removes all rows of an event.
	 *
	 * @param int $post_id Post ID.
	 */
	public static function delete_event( $post_id ) {
		global $wpdb;
		$wpdb->delete( BCal_Install::table(), array( 'event_id' => (int) $post_id ), array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery
		self::touch();
	}

	/**
	 * Updates a flag column on all rows of an event without a full resync.
	 * Used by the ranking and moderation features.
	 *
	 * @param int      $post_id Event ID.
	 * @param string   $column  hidden|pick|featured|score.
	 * @param int|null $value   Value.
	 */
	public static function set_flag( $post_id, $column, $value ) {
		global $wpdb;

		if ( ! in_array( $column, array( 'hidden', 'pick', 'featured', 'score' ), true ) ) {
			return;
		}

		$table = BCal_Install::table();
		if ( null === $value ) {
			$wpdb->query( $wpdb->prepare( 'UPDATE %i SET %i = NULL WHERE event_id = %d', $table, $column, $post_id ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery
		} else {
			$wpdb->query( $wpdb->prepare( 'UPDATE %i SET %i = %d WHERE event_id = %d', $table, $column, (int) $value, $post_id ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery
		}
		self::touch();
	}

	/**
	 * Invalidates cached queries.
	 */
	public static function touch() {
		wp_cache_set( 'last_changed', microtime(), 'bcal' );
	}

	/**
	 * Rebuilds a batch of events. Offset 0 clears the table first.
	 *
	 * @param int $offset Offset.
	 * @param int $limit  Batch size.
	 * @return array { done, total, next }
	 */
	public static function rebuild_batch( $offset, $limit = 200 ) {
		global $wpdb;

		if ( 0 === (int) $offset ) {
			$wpdb->query( $wpdb->prepare( 'TRUNCATE TABLE %i', BCal_Install::table() ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery
		}

		$total = (int) $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM {$wpdb->posts} WHERE post_type = %s AND post_status = 'publish'", BCAL_PT ) ); // phpcs:ignore WordPress.DB
		$ids   = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM {$wpdb->posts} WHERE post_type = %s AND post_status = 'publish' ORDER BY ID ASC LIMIT %d OFFSET %d", BCAL_PT, $limit, $offset ) ); // phpcs:ignore WordPress.DB

		foreach ( $ids as $id ) {
			self::sync_event( (int) $id );
		}

		$next = (int) $offset + count( $ids );

		return array(
			'done'  => $next >= $total || ! $ids,
			'total' => $total,
			'next'  => $next,
		);
	}

	/**
	 * Re-syncs, in the background, every event that has no end of its own.
	 * Used when the default duration changes: their end moves with it.
	 */
	public static function schedule_resync() {
		update_option(
			'bcal_resync',
			array(
				'last_id' => 0,
				'done'    => 0,
				'total'   => self::count_without_end(),
			),
			false
		);
		wp_clear_scheduled_hook( 'bcal_resync_step' );
		wp_schedule_single_event( time() + 5, 'bcal_resync_step' );
	}

	/**
	 * Published events without a saved end.
	 *
	 * @return int
	 */
	private static function count_without_end() {
		global $wpdb;
		return (int) $wpdb->get_var( // phpcs:ignore WordPress.DB
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->posts} p WHERE p.post_type = %s AND p.post_status = 'publish' AND NOT EXISTS ( SELECT 1 FROM {$wpdb->postmeta} m WHERE m.post_id = p.ID AND m.meta_key = '_bcal_end' AND m.meta_value <> '' )",
				BCAL_PT
			)
		);
	}

	/**
	 * One background batch (cron).
	 */
	public static function resync_step() {
		global $wpdb;

		$state = get_option( 'bcal_resync' );
		if ( ! is_array( $state ) ) {
			return;
		}

		$ids = $wpdb->get_col( // phpcs:ignore WordPress.DB
			$wpdb->prepare(
				"SELECT p.ID FROM {$wpdb->posts} p WHERE p.post_type = %s AND p.post_status = 'publish' AND p.ID > %d AND NOT EXISTS ( SELECT 1 FROM {$wpdb->postmeta} m WHERE m.post_id = p.ID AND m.meta_key = '_bcal_end' AND m.meta_value <> '' ) ORDER BY p.ID ASC LIMIT 300",
				BCAL_PT,
				(int) $state['last_id']
			)
		);

		if ( ! $ids ) {
			delete_option( 'bcal_resync' );
			return;
		}

		foreach ( $ids as $id ) {
			self::sync_event( (int) $id );
		}

		$state['last_id'] = (int) end( $ids );
		$state['done']    = (int) $state['done'] + count( $ids );
		update_option( 'bcal_resync', $state, false );
		wp_schedule_single_event( time() + 10, 'bcal_resync_step' );
	}

	/**
	 * Background re-sync progress, or null when idle.
	 *
	 * @return array|null { done, total }
	 */
	public static function resync_status() {
		$state = get_option( 'bcal_resync' );
		return is_array( $state ) ? array(
			'done'  => (int) $state['done'],
			'total' => max( (int) $state['total'], (int) $state['done'] ),
		) : null;
	}

	/**
	 * Daily job: extend recurring events past the rolling horizon.
	 */
	public static function daily() {
		global $wpdb;
		$ids = $wpdb->get_col( $wpdb->prepare( "SELECT DISTINCT post_id FROM {$wpdb->postmeta} WHERE meta_key IN ( %s, %s ) AND meta_value <> ''", '_bcal_rrule', '_bcal_rdates' ) ); // phpcs:ignore WordPress.DB
		foreach ( $ids as $id ) {
			self::sync_event( (int) $id );
		}
	}

	/**
	 * Index statistics for the tools screen.
	 *
	 * @return array
	 */
	public static function stats() {
		global $wpdb;
		$table = BCal_Install::table();
		return array(
			'rows'     => (int) $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(*) FROM %i', $table ) ), // phpcs:ignore WordPress.DB.DirectDatabaseQuery
			'events'   => (int) $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(DISTINCT event_id) FROM %i', $table ) ), // phpcs:ignore WordPress.DB.DirectDatabaseQuery
			'upcoming' => (int) $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(*) FROM %i WHERE end_dt >= %s', $table, bcal_now() ) ), // phpcs:ignore WordPress.DB.DirectDatabaseQuery
		);
	}
}