<?php
/**
 * Outbox collection file.
 *
 * @package Activitypub
 */

namespace Activitypub\Collection;

use Activitypub\Dispatcher;
use Activitypub\Scheduler;
use Activitypub\Activity\Activity;
use Activitypub\Activity\Base_Object;

use function Activitypub\add_to_outbox;

/**
 * ActivityPub Outbox Collection
 *
 * @link https://www.w3.org/TR/activitypub/#outbox
 */
class Outbox {
	const POST_TYPE = 'ap_outbox';

	/**
	 * Add an Item to the outbox.
	 *
	 * @param Activity $activity   Full Activity object that will be added to the outbox.
	 * @param int      $user_id    The real or imaginary user ID of the actor that published the activity that will be added to the outbox.
	 * @param string   $visibility Optional. The visibility of the content. Default: `ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC`. See `constants.php` for possible values: `ACTIVITYPUB_CONTENT_VISIBILITY_*`.
	 *
	 * @return false|int|\WP_Error The added item or an error.
	 */
	public static function add( Activity $activity, $user_id, $visibility = ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC ) {
		$actor_type = Actors::get_type_by_id( $user_id );
		$object_id  = self::get_object_id( $activity );
		$title      = self::get_object_title( $activity->get_object() );

		if ( ! $activity->get_actor() ) {
			$activity->set_actor( Actors::get_by_id( $user_id )->get_id() );
		}

		$outbox_item = array(
			'post_type'    => self::POST_TYPE,
			'post_title'   => sprintf(
				/* translators: 1. Activity type, 2. Object Title or Excerpt */
				__( '[%1$s] %2$s', 'activitypub' ),
				$activity->get_type(),
				\wp_trim_words( $title, 5 )
			),
			'post_content' => wp_slash( $activity->to_json() ),
			// ensure that user ID is not below 0.
			'post_author'  => \max( $user_id, 0 ),
			'post_status'  => 'pending',
			'meta_input'   => array(
				'_activitypub_object_id'         => $object_id,
				'_activitypub_activity_type'     => $activity->get_type(),
				'_activitypub_activity_actor'    => $actor_type,
				'activitypub_content_visibility' => $visibility,
			),
		);

		$has_kses = false !== \has_filter( 'content_save_pre', 'wp_filter_post_kses' );
		if ( $has_kses ) {
			// Prevent KSES from corrupting JSON in post_content.
			\kses_remove_filters();
		}

		$id = \wp_insert_post( $outbox_item, true );

		// Update the activity ID if the post was inserted successfully.
		if ( $id && ! \is_wp_error( $id ) ) {
			$activity->set_id( \get_the_guid( $id ) );

			\wp_update_post(
				array(
					'ID'           => $id,
					'post_content' => \wp_slash( $activity->to_json() ),
				)
			);
		}

		if ( $has_kses ) {
			\kses_init_filters();
		}

		if ( \is_wp_error( $id ) ) {
			return $id;
		}

		if ( ! $id ) {
			return false;
		}

		self::invalidate_existing_items( $object_id, $activity->get_type(), $id );

		return $id;
	}

	/**
	 * Invalidate existing outbox items with the same activity type and object ID
	 * by setting their status to 'publish'.
	 *
	 * @param string $object_id     The ID of the activity object.
	 * @param string $activity_type The type of the activity.
	 * @param int    $current_id    The ID of the current outbox item to exclude.
	 *
	 * @return void
	 */
	private static function invalidate_existing_items( $object_id, $activity_type, $current_id ) {
		// Do not invalidate items for Announce activities.
		if ( 'Announce' === $activity_type ) {
			return;
		}

		$meta_query = array(
			array(
				'key'   => '_activitypub_object_id',
				'value' => $object_id,
			),
		);

		// For non-Delete activities, only invalidate items of the same type.
		if ( 'Delete' !== $activity_type ) {
			$meta_query[] = array(
				'key'   => '_activitypub_activity_type',
				'value' => $activity_type,
			);
		}

		$existing_items = get_posts(
			array(
				'post_type'   => self::POST_TYPE,
				'post_status' => 'pending',
				'exclude'     => array( $current_id ),
				// phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_query
				'meta_query'  => $meta_query,
				'fields'      => 'ids',
			)
		);

		foreach ( $existing_items as $existing_item_id ) {
			$event_args = array(
				Dispatcher::$callback,
				$existing_item_id,
				Dispatcher::$batch_size,
				\get_post_meta( $existing_item_id, '_activitypub_outbox_offset', true ) ?: 0, // phpcs:ignore
			);

			$timestamp = \wp_next_scheduled( 'activitypub_async_batch', $event_args );
			\wp_unschedule_event( $timestamp, 'activitypub_async_batch', $event_args );

			$timestamp = \wp_next_scheduled( 'activitypub_process_outbox', array( $existing_item_id ) );
			\wp_unschedule_event( $timestamp, 'activitypub_process_outbox', array( $existing_item_id ) );

			\wp_publish_post( $existing_item_id );
			\delete_post_meta( $existing_item_id, '_activitypub_outbox_offset' );
		}
	}

	/**
	 * Creates an Undo activity.
	 *
	 * @param int|\WP_Post $outbox_item The Outbox post or post ID.
	 *
	 * @return int|bool The ID of the outbox item or false on failure.
	 */
	public static function undo( $outbox_item ) {
		$outbox_item = get_post( $outbox_item );
		$activity    = self::get_activity( $outbox_item );

		$type = 'Undo';
		if ( 'Create' === $activity->get_type() ) {
			$type = 'Delete';
		} elseif ( 'Add' === $activity->get_type() ) {
			$type = 'Remove';
		}

		return add_to_outbox( $activity, $type, $outbox_item->post_author );
	}

	/**
	 * Reschedule an activity.
	 *
	 * @param int|\WP_Post $outbox_item The Outbox post or post ID.
	 *
	 * @return bool True if the activity was rescheduled, false otherwise.
	 */
	public static function reschedule( $outbox_item ) {
		$outbox_item = get_post( $outbox_item );

		$outbox_item->post_status = 'pending';
		$outbox_item->post_date   = current_time( 'mysql' );

		wp_update_post( $outbox_item );

		Scheduler::schedule_outbox_activity_for_federation( $outbox_item->ID );

		return true;
	}

	/**
	 * Get the Activity object from the Outbox item.
	 *
	 * @param int|\WP_Post $outbox_item The Outbox post or post ID.
	 * @return Activity|\WP_Error The Activity object or WP_Error.
	 */
	public static function get_activity( $outbox_item ) {
		$outbox_item = get_post( $outbox_item );
		$actor       = self::get_actor( $outbox_item );
		if ( is_wp_error( $actor ) ) {
			return $actor;
		}

		$activity_object = \json_decode( $outbox_item->post_content, true );
		$type            = \get_post_meta( $outbox_item->ID, '_activitypub_activity_type', true );

		if ( $activity_object['type'] === $type ) {
			$activity = Activity::init_from_array( $activity_object );
			if ( ! $activity->get_actor() ) {
				$activity->set_actor( $actor->get_id() );
			}
		} else {
			$activity = new Activity();
			$activity->set_type( $type );
			$activity->set_id( $outbox_item->guid );
			$activity->set_actor( $actor->get_id() );
			// Pre-fill the Activity with data (for example cc and to).
			$activity->set_object( $activity_object );
		}

		if ( 'Update' === $type ) {
			$activity->set_updated( gmdate( ACTIVITYPUB_DATE_TIME_RFC3339, strtotime( $outbox_item->post_modified ) ) );
		}

		/**
		 * Filters the Activity object before it is returned.
		 *
		 * @param Activity $activity    The Activity object.
		 * @param \WP_Post $outbox_item The outbox item post object.
		 */
		return apply_filters( 'activitypub_get_outbox_activity', $activity, $outbox_item );
	}

	/**
	 * Get the Actor object from the Outbox item.
	 *
	 * @param \WP_Post $outbox_item The Outbox post.
	 *
	 * @return \Activitypub\Model\User|\Activitypub\Model\Blog|\WP_Error The Actor object or WP_Error.
	 */
	public static function get_actor( $outbox_item ) {
		$actor_type = \get_post_meta( $outbox_item->ID, '_activitypub_activity_actor', true );

		switch ( $actor_type ) {
			case 'blog':
				$actor_id = Actors::BLOG_USER_ID;
				break;
			case 'application':
				$actor_id = Actors::APPLICATION_USER_ID;
				break;
			case 'user':
			default:
				$actor_id = $outbox_item->post_author;
				break;
		}

		return Actors::get_by_id( $actor_id );
	}

	/**
	 * Get the Activity object from the Outbox item.
	 *
	 * @param \WP_Post $outbox_item The Outbox post.
	 *
	 * @return Activity|\WP_Error The Activity object or WP_Error.
	 */
	public static function maybe_get_activity( $outbox_item ) {
		if ( ! $outbox_item instanceof \WP_Post ) {
			return new \WP_Error( 'invalid_outbox_item', 'Invalid Outbox item.' );
		}

		if ( 'ap_outbox' !== $outbox_item->post_type ) {
			return new \WP_Error( 'invalid_outbox_item', 'Invalid Outbox item.' );
		}

		// Check if Outbox Activity is public.
		$visibility = \get_post_meta( $outbox_item->ID, 'activitypub_content_visibility', true );

		if ( ! in_array( $visibility, array( ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC, ACTIVITYPUB_CONTENT_VISIBILITY_QUIET_PUBLIC ), true ) ) {
			return new \WP_Error( 'private_outbox_item', 'Not a public Outbox item.' );
		}

		$activity_types = \apply_filters( 'rest_activitypub_outbox_activity_types', array( 'Announce', 'Create', 'Like', 'Update' ) );
		$activity_type  = \get_post_meta( $outbox_item->ID, '_activitypub_activity_type', true );

		if ( ! in_array( $activity_type, $activity_types, true ) ) {
			return new \WP_Error( 'private_outbox_item', 'Not public Outbox item type.' );
		}

		return self::get_activity( $outbox_item );
	}

	/**
	 * Get the object ID of an activity.
	 *
	 * @param Activity|Base_Object|string $data The activity object.
	 *
	 * @return string The object ID.
	 */
	private static function get_object_id( $data ) {
		$object = $data->get_object();

		if ( is_object( $object ) ) {
			return self::get_object_id( $object );
		}

		if ( is_string( $object ) ) {
			return $object;
		}

		return $data->get_id() ?? $data->get_actor();
	}

	/**
	 * Get the title of an activity recursively.
	 *
	 * @param Base_Object $activity_object The activity object.
	 *
	 * @return string The title.
	 */
	private static function get_object_title( $activity_object ) {
		if ( ! $activity_object ) {
			return '';
		}

		if ( is_string( $activity_object ) ) {
			$post_id = url_to_postid( $activity_object );

			return $post_id ? get_the_title( $post_id ) : '';
		}

		$title = $activity_object->get_name() ?? $activity_object->get_content();

		if ( ! $title && $activity_object->get_object() instanceof Base_Object ) {
			$title = $activity_object->get_object()->get_name() ?? $activity_object->get_object()->get_content();
		}

		return $title;
	}
}