<?php
/**
 * Feed and post endpoints.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Rest;

use SpaceBay\Content\Reactions;
use SpaceBay\Content\Terms;
use SpaceBay\Feed\Formatter;
use SpaceBay\Feed\PostAccess;
use SpaceBay\Feed\Posts;
use SpaceBay\Spaces\SpaceAccess;
use SpaceBay\Spaces\SpaceRepository;
use SpaceBay\Support\RateLimit;
use SpaceBay\Support\Slug;
use WP_Error;
use WP_REST_Request;
use WP_REST_Response;
use WP_REST_Server;

defined( 'ABSPATH' ) || exit;

/**
 * Reads the feed and creates, edits, deletes, pins, likes and saves posts.
 */
final class PostsController extends Controller {

	/**
	 * Registers the routes.
	 *
	 * @return void
	 */
	public function register_routes() {
		$id_arg = array(
			'id' => array(
				'type'     => 'integer',
				'required' => true,
			),
		);

		register_rest_route(
			$this->namespace,
			'/feed',
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_items' ),
					'permission_callback' => array( $this, 'permission_community' ),
					'args'                => array_merge(
						$this->paging_args( 50 ),
						array(
							'space_id'    => array(
								'type'    => 'integer',
								'default' => 0,
							),
							'user_id'     => array(
								'type'    => 'integer',
								'default' => 0,
							),
							'topic'       => array(
								'type'              => 'string',
								'default'           => '',
								'sanitize_callback' => array( $this, 'sanitize_slug' ),
							),
							'hashtag'     => array(
								'type'              => 'string',
								'default'           => '',
								'sanitize_callback' => array( Terms::class, 'hashtag_slug' ),
							),
							'bookmarked'  => array(
								'type'    => 'boolean',
								'default' => false,
							),
							'orderby'     => array(
								'type'    => 'string',
								'enum'    => array( 'latest', 'activity' ),
								'default' => 'latest',
							),
							// False skips counting every post: X-WP-Total then only says whether more pages follow.
							'count_total' => array(
								'type'    => 'boolean',
								'default' => true,
							),
						)
					),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/posts',
			array(
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'create_item' ),
					'permission_callback' => array( $this, 'permission_logged_in' ),
					'args'                => $this->content_args( true ),
				),
			)
		);

		register_rest_route(
			$this->namespace,
			'/posts/(?P<id>\d+)',
			array(
				'args' => $id_arg,
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_item' ),
					'permission_callback' => array( $this, 'permission_community' ),
				),
				array(
					'methods'             => WP_REST_Server::EDITABLE,
					'callback'            => array( $this, 'update_item' ),
					'permission_callback' => array( $this, 'permission_logged_in' ),
					'args'                => $this->content_args( false ),
				),
				array(
					'methods'             => WP_REST_Server::DELETABLE,
					'callback'            => array( $this, 'delete_item' ),
					'permission_callback' => array( $this, 'permission_logged_in' ),
				),
			)
		);

		foreach ( array( 'pin', 'like', 'bookmark' ) as $action ) {
			register_rest_route(
				$this->namespace,
				'/posts/(?P<id>\d+)/' . $action,
				array(
					'args' => $id_arg,
					array(
						'methods'             => WP_REST_Server::CREATABLE,
						'callback'            => array( $this, 'toggle_' . $action ),
						'permission_callback' => array( $this, 'permission_logged_in' ),
						'args'                => array(
							'on' => array(
								'type'     => 'boolean',
								'required' => true,
							),
						),
					),
				)
			);
		}
	}

	/**
	 * Sanitizes a slug argument. A wrapper is needed because the REST API
	 * passes the request as the second argument, which sanitize_title()
	 * would treat as a fallback title.
	 *
	 * @param mixed $value Raw value.
	 * @return string
	 */
	public function sanitize_slug( $value ) {
		return Slug::make( rawurldecode( (string) $value ) );
	}

	/**
	 * Lists posts.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function get_items( $request ) {
		$viewer_id = get_current_user_id();
		$args      = array(
			'space_id' => (int) $request['space_id'],
			'user_id'  => (int) $request['user_id'],
			'search'   => $request['search'],
			'orderby'  => $request['orderby'],
			'page'     => $request['page'],
			'per_page' => $request['per_page'],
			'count'    => (bool) $request['count_total'],
		);

		if ( $args['space_id'] ) {
			$space = $this->visible_space( $args['space_id'] );

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

		if ( '' !== $request['topic'] ) {
			$topic = Terms::topic_by_slug( $request['topic'] );

			if ( ! $topic ) {
				return $this->paged_response( array(), 0, $args['per_page'] );
			}

			$args['topic_id'] = $topic['id'];
		}

		if ( '' !== $request['hashtag'] ) {
			$args['hashtag'] = $request['hashtag'];
		}

		if ( $request['bookmarked'] ) {
			if ( ! $viewer_id ) {
				return $this->permission_logged_in();
			}

			$args['bookmarked'] = true;
		}

		$result = Posts::query( $args, $viewer_id );

		return $this->paged_response( Formatter::posts( $result['items'], $viewer_id ), $result['total'], $args['per_page'] );
	}

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

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

		return rest_ensure_response( Formatter::post( $found['post'], get_current_user_id() ) );
	}

	/**
	 * Publishes a post.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function create_item( $request ) {
		$post = Posts::create( $this->content_input( $request ), get_current_user_id() );

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

		$response = rest_ensure_response( Formatter::post( $post, get_current_user_id() ) );
		$response->set_status( 201 );

		return $response;
	}

	/**
	 * Edits a post. Authors and space moderators only.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function update_item( $request ) {
		$found = $this->changeable_post( $request['id'] );

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

		$post = Posts::update( $found['post'], $this->content_input( $request ), get_current_user_id() );

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

		return rest_ensure_response( Formatter::post( $post, get_current_user_id() ) );
	}

	/**
	 * Deletes a post. Authors and space moderators only.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function delete_item( $request ) {
		$found = $this->changeable_post( $request['id'] );

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

		Posts::delete( array( $found['post']['id'] ) );

		return rest_ensure_response(
			array(
				'deleted' => true,
				'id'      => $found['post']['id'],
			)
		);
	}

	/**
	 * Pins or unpins a post. Space moderators only.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function toggle_pin( $request ) {
		$found = $this->readable_post( $request['id'] );

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

		if ( ! SpaceAccess::can_moderate( $found['space'], get_current_user_id() ) ) {
			return $this->forbidden();
		}

		return rest_ensure_response( Formatter::post( Posts::set_pinned( $found['post'], (bool) $request['on'] ), get_current_user_id() ) );
	}

	/**
	 * Likes or unlikes a post.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function toggle_like( $request ) {
		return $this->react( $request, 'like' );
	}

	/**
	 * Saves or unsaves a post.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function toggle_bookmark( $request ) {
		return $this->react( $request, 'bookmark' );
	}

	/**
	 * Applies a reaction.
	 *
	 * @param WP_REST_Request $request Request.
	 * @param string          $type    Reaction type.
	 * @return WP_REST_Response|WP_Error
	 */
	private function react( $request, $type ) {
		$limited = RateLimit::hit( 'react', get_current_user_id(), 60 );

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

		$found = $this->readable_post( $request['id'] );

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

		$user_id = get_current_user_id();

		if ( 'like' === $type && ! PostAccess::can_comment( $found['space'], $user_id ) ) {
			return new WP_Error( 'spacebay_cannot_react', __( 'Join this space to like posts.', 'spacebay' ), array( 'status' => 403 ) );
		}

		Reactions::set( 'post', $found['post']['id'], $user_id, $type, (bool) $request['on'] );
		Posts::forget( $found['post']['id'] );

		return rest_ensure_response( Formatter::post( Posts::find( $found['post']['id'] ), $user_id ) );
	}

	/**
	 * Returns a post and its space when the viewer may read it.
	 *
	 * @param int $id Post ID.
	 * @return array{post: array, space: array}|WP_Error
	 */
	protected function readable_post( $id ) {
		$post  = Posts::find( $id );
		$space = $post ? SpaceRepository::find( $post['space_id'] ) : null;

		if ( ! $post || ! $space || 'published' !== $post['status'] || ! SpaceAccess::can_read( $space, get_current_user_id() ) ) {
			return new WP_Error( 'spacebay_post_not_found', __( 'Post not found.', 'spacebay' ), array( 'status' => 404 ) );
		}

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

	/**
	 * Returns a post the viewer may edit or delete.
	 *
	 * @param int $id Post ID.
	 * @return array{post: array, space: array}|WP_Error
	 */
	private function changeable_post( $id ) {
		$found = $this->readable_post( $id );

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

		if ( ! PostAccess::can_change( $found['space'], $found['post']['user_id'], get_current_user_id() ) ) {
			return $this->forbidden();
		}

		return $found;
	}

	/**
	 * Picks content fields from the request.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return array
	 */
	private function content_input( $request ) {
		$input = array();

		foreach ( array( 'space_id', 'title', 'message', 'media_ids', 'topic_ids' ) as $field ) {
			if ( $request->has_param( $field ) ) {
				$input[ $field ] = $request->get_param( $field );
			}
		}

		return $input;
	}

	/**
	 * Argument schema for creating and editing posts.
	 *
	 * @param bool $is_new Whether a space is required.
	 * @return array
	 */
	private function content_args( $is_new ) {
		$args = array(
			'title'     => array( 'type' => 'string' ),
			'message'   => array( 'type' => 'string' ),
			'media_ids' => array(
				'type'     => 'array',
				'items'    => array( 'type' => 'integer' ),
				'maxItems' => 10,
			),
			'topic_ids' => array(
				'type'     => 'array',
				'items'    => array( 'type' => 'integer' ),
				'maxItems' => Terms::MAX_TOPICS,
			),
		);

		if ( $is_new ) {
			$args['space_id'] = array(
				'type'     => 'integer',
				'required' => true,
			);
		}

		return $args;
	}
}