<?php
/**
 * Events REST endpoints.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Rest;

use SpaceBay\Events\EventFormatter;
use SpaceBay\Events\Events;
use SpaceBay\Members\MemberDirectory;
use SpaceBay\Spaces\SpaceAccess;
use SpaceBay\Spaces\SpaceRepository;
use WP_Error;
use WP_REST_Request;
use WP_REST_Server;

defined( 'ABSPATH' ) || exit;

/**
 * Lists, creates, changes and answers events.
 */
final class EventsController extends Controller {

	/**
	 * Registers the routes.
	 *
	 * @return void
	 */
	public function register_routes() {
		$fields = array(
			'title'         => array( 'type' => 'string' ),
			'description'   => array( 'type' => 'string' ),
			'starts_at'     => array( 'type' => 'string' ),
			'ends_at'       => array( 'type' => 'string' ),
			'location_type' => array(
				'type' => 'string',
				'enum' => array( 'online', 'in_person' ),
			),
			'location'      => array( 'type' => 'string' ),
			'online_url'    => array( 'type' => 'string' ),
		);

		/**
		 * Filters the fields an event form may send, as REST argument
		 * definitions. SpaceBay Pro adds "capacity".
		 *
		 * @since 1.0.0
		 *
		 * @param array $fields Argument definitions keyed by field.
		 */
		$fields = apply_filters( 'spacebay_event_fields', $fields );

		register_rest_route(
			$this->namespace,
			'/events',
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_items' ),
					'permission_callback' => array( $this, 'permission_events' ),
					'args'                => array_merge(
						$this->paging_args( 100 ),
						array(
							'space_id' => array(
								'type'    => 'integer',
								'default' => 0,
							),
							'when'     => array(
								'type'    => 'string',
								'enum'    => array( 'upcoming', 'past', 'range' ),
								'default' => 'upcoming',
							),
							'from'     => array( 'type' => 'string' ),
							'to'       => array( 'type' => 'string' ),
							'rsvp'     => array(
								'type'    => 'string',
								'enum'    => array( '', 'going' ),
								'default' => '',
							),
						)
					),
				),
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'create_item' ),
					'permission_callback' => array( $this, 'permission_create' ),
					'args'                => array_merge(
						$fields,
						array(
							'space_id' => array(
								'type'     => 'integer',
								'required' => true,
							),
							'notify'   => array(
								'type'    => 'boolean',
								'default' => true,
							),
						)
					),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/events/(?P<id>\d+)',
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_item' ),
					'permission_callback' => array( $this, 'permission_events' ),
				),
				array(
					'methods'             => WP_REST_Server::EDITABLE,
					'callback'            => array( $this, 'update_item' ),
					'permission_callback' => array( $this, 'permission_create' ),
					'args'                => $fields,
				),
				array(
					'methods'             => WP_REST_Server::DELETABLE,
					'callback'            => array( $this, 'delete_item' ),
					'permission_callback' => array( $this, 'permission_create' ),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/events/(?P<id>\d+)/cancel',
			array(
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'cancel_item' ),
					'permission_callback' => array( $this, 'permission_create' ),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/events/(?P<id>\d+)/rsvp',
			array(
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'rsvp' ),
					'permission_callback' => array( $this, 'permission_create' ),
					'args'                => array(
						'answer' => array(
							'type'     => 'string',
							'enum'     => array( 'going', 'maybe', 'not_going', '' ),
							'required' => true,
						),
					),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/events/(?P<id>\d+)/attendees',
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'attendees' ),
					'permission_callback' => array( $this, 'permission_events' ),
					'args'                => array_merge(
						$this->paging_args( 100 ),
						array(
							'answer' => array(
								'type'    => 'string',
								'enum'    => array( 'going', 'maybe' ),
								'default' => 'going',
							),
						)
					),
				),
			)
		);
	}

	/**
	 * Anyone who may open the community, while events are on.
	 *
	 * @return true|WP_Error
	 */
	public function permission_events() {
		if ( ! Events::enabled() ) {
			return $this->events_off();
		}

		return $this->permission_community();
	}

	/**
	 * Logged-in, active members, while events are on.
	 *
	 * @return true|WP_Error
	 */
	public function permission_create() {
		if ( ! Events::enabled() ) {
			return $this->events_off();
		}

		return $this->permission_logged_in();
	}

	/**
	 * Lists events.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function get_items( $request ) {
		$viewer = get_current_user_id();
		$args   = array(
			'space_id' => (int) $request['space_id'],
			'when'     => $request['when'],
			'rsvp'     => $viewer ? $request['rsvp'] : '',
			'page'     => $request['page'],
			'per_page' => $request['per_page'],
		);

		if ( 'range' === $request['when'] ) {
			$from = strtotime( (string) $request['from'] );
			$to   = strtotime( (string) $request['to'] );

			if ( ! $from || ! $to || $to < $from || $to - $from > 62 * DAY_IN_SECONDS ) {
				return new WP_Error( 'spacebay_event_range', __( 'Choose a range of up to two months.', 'spacebay' ), array( 'status' => 400 ) );
			}

			$args['from'] = gmdate( 'Y-m-d H:i:s', $from );
			$args['to']   = gmdate( 'Y-m-d H:i:s', $to );
		}

		$result = Events::query( $args, $viewer );

		return $this->paged_response( EventFormatter::many( $result['items'], $viewer ), $result['total'], $request['per_page'] );
	}

	/**
	 * Returns one event.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function get_item( $request ) {
		$found = $this->readable( (int) $request['id'] );

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

		return rest_ensure_response( $this->full( $found['event'], $found['space'] ) );
	}

	/**
	 * Creates an event.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function create_item( $request ) {
		$space = $this->visible_space( (int) $request['space_id'] );

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

		if ( ! Events::can_create( $space, get_current_user_id() ) ) {
			return new WP_Error( 'spacebay_event_forbidden', __( 'Only space admins and moderators can add events to this space.', 'spacebay' ), array( 'status' => 403 ) );
		}

		$event = Events::create( $space, $this->input( $request ), get_current_user_id() );

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

		$response = rest_ensure_response( $this->full( $event, $space ) );
		$response->set_status( 201 );

		return $response;
	}

	/**
	 * Changes an event.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function update_item( $request ) {
		$found = $this->editable( (int) $request['id'] );

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

		$event = Events::update( $found['event'], $this->input( $request ), get_current_user_id() );

		return is_wp_error( $event ) ? $event : rest_ensure_response( $this->full( $event, $found['space'] ) );
	}

	/**
	 * Cancels an event.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function cancel_item( $request ) {
		$found = $this->editable( (int) $request['id'] );

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

		$event = Events::cancel( $found['event'], get_current_user_id() );

		return $event ? rest_ensure_response( $this->full( $event, $found['space'] ) ) : $this->gone();
	}

	/**
	 * Deletes an event.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function delete_item( $request ) {
		$found = $this->editable( (int) $request['id'] );

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

		Events::delete( $found['event'] );

		return rest_ensure_response( array( 'deleted' => true ) );
	}

	/**
	 * Saves the viewer's answer.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function rsvp( $request ) {
		$found = $this->readable( (int) $request['id'] );

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

		$user_id = get_current_user_id();

		if ( ! Events::can_rsvp( $found['event'], $found['space'], $user_id ) ) {
			$message = 'published' !== $found['event']['status'] || strtotime( $found['event']['ends_at'] . ' UTC' ) <= time()
				? __( 'This event has ended or was cancelled.', 'spacebay' )
				: __( 'Join the space to answer this event.', 'spacebay' );

			return new WP_Error( 'spacebay_rsvp_forbidden', $message, array( 'status' => 403 ) );
		}

		$saved = Events::answer( $found['event'], $user_id, (string) $request['answer'] );

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

		$event = Events::find( $found['event']['id'] );

		return $event ? rest_ensure_response( $this->full( $event, $found['space'] ) ) : $this->gone();
	}

	/**
	 * Error for an event that was deleted while the request ran.
	 *
	 * @return WP_Error
	 */
	private function gone() {
		return new WP_Error( 'spacebay_event_not_found', __( 'This event no longer exists.', 'spacebay' ), array( 'status' => 404 ) );
	}

	/**
	 * Lists members who answered going or maybe.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return \WP_REST_Response|WP_Error
	 */
	public function attendees( $request ) {
		$found = $this->readable( (int) $request['id'] );

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

		$result = Events::attendees( $found['event']['id'], $request['answer'], $request['page'], $request['per_page'] );

		return $this->paged_response( $this->members( $result['ids'] ), $result['total'], $request['per_page'] );
	}

	/**
	 * An event with its first attendees.
	 *
	 * @param array $event Event row.
	 * @param array $space Space row.
	 * @return array
	 */
	private function full( array $event, array $space ) {
		$viewer = get_current_user_id();
		$data   = EventFormatter::one( $event, $space, $viewer, Events::answer_of( $event['id'], $viewer ) );
		$going  = Events::attendees( $event['id'], 'going', 1, 12 );

		$data['attendees'] = $this->members( $going['ids'] );

		return $data;
	}

	/**
	 * Formats members, leaving out hidden profiles for other viewers.
	 *
	 * @param int[] $ids Member IDs.
	 * @return array[]
	 */
	private function members( array $ids ) {
		$hidden = \SpaceBay\Members\Profiles::hidden_ids();
		$viewer = get_current_user_id();
		$users  = array();

		cache_users( $ids );

		foreach ( $ids as $id ) {
			$user = get_userdata( $id );

			if ( $user && ( ! in_array( $id, $hidden, true ) || $id === $viewer ) ) {
				$users[] = $user;
			}
		}

		return MemberDirectory::format_many( $users );
	}

	/**
	 * Finds an event the viewer may read.
	 *
	 * @param int $id Event ID.
	 * @return array|WP_Error Event and space.
	 */
	private function readable( $id ) {
		$event = Events::find( $id );
		$space = $event ? SpaceRepository::find( $event['space_id'] ) : null;

		if ( ! $event || ! $space || ! SpaceAccess::can_read( $space, get_current_user_id() ) ) {
			return new WP_Error( 'spacebay_event_not_found', __( 'Event not found.', 'spacebay' ), array( 'status' => 404 ) );
		}

		return array(
			'event' => $event,
			'space' => $space,
		);
	}

	/**
	 * Finds an event the viewer may change.
	 *
	 * @param int $id Event ID.
	 * @return array|WP_Error Event and space.
	 */
	private function editable( $id ) {
		$found = $this->readable( $id );

		if ( ! is_wp_error( $found ) && ! Events::can_edit( $found['event'], $found['space'], get_current_user_id() ) ) {
			return $this->forbidden();
		}

		return $found;
	}

	/**
	 * Event fields sent with a request.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return array
	 */
	private function input( $request ) {
		$input = array();

		$keys = array( 'title', 'description', 'starts_at', 'ends_at', 'location_type', 'location', 'online_url', 'notify' );

		/** This filter is documented in includes/Rest/EventsController.php */
		$keys = array_merge( $keys, array_keys( (array) apply_filters( 'spacebay_event_fields', array() ) ) );

		foreach ( array_unique( $keys ) as $key ) {
			if ( null !== $request[ $key ] ) {
				$input[ $key ] = $request[ $key ];
			}
		}

		return $input;
	}

	/**
	 * Error used while events are switched off.
	 *
	 * @return WP_Error
	 */
	private function events_off() {
		return new WP_Error( 'spacebay_events_off', __( 'Events are switched off in this community.', 'spacebay' ), array( 'status' => 404 ) );
	}
}