<?php
/**
 * Friends REST
 *
 * This contains the functions for REST.
 *
 * @package Friends
 */

namespace Friends;

/**
 * This is the class for the REST part of the Friends Plugin.
 *
 * @since 0.6
 *
 * @package Friends
 * @author Alex Kirk
 */
class REST {
	const PREFIX = 'friends/v1';
	/**
	 * Contains a reference to the Friends class.
	 *
	 * @var Friends
	 */
	private $friends;

	/**
	 * Constructor
	 *
	 * @param Friends $friends A reference to the Friends object.
	 */
	public function __construct( Friends $friends ) {
		$this->friends = $friends;
		$this->register_hooks();
	}

	/**
	 * Register the WordPress hooks
	 */
	private function register_hooks() {
		add_action( 'rest_api_init', array( $this, 'add_rest_routes' ) );
		add_action( 'wp_trash_post', array( $this, 'notify_remote_friend_post_deleted' ) );
		add_action( 'before_delete_post', array( $this, 'notify_remote_friend_post_deleted' ) );
		add_action( 'set_user_role', array( $this, 'notify_remote_friend_request_accepted' ), 20, 3 );
	}

	/**
	 * Add the REST API to send and receive friend requests
	 */
	public function add_rest_routes() {
		register_rest_route(
			self::PREFIX,
			'friend-request',
			array(
				'methods'             => 'POST',
				'callback'            => array( $this, 'rest_friend_request' ),
				'permission_callback' => '__return_true',
			)
		);
		register_rest_route(
			self::PREFIX,
			'accept-friend-request',
			array(
				'methods'             => 'POST',
				'callback'            => array( $this, 'rest_accept_friend_request' ),
				'permission_callback' => '__return_true',
			)
		);
		register_rest_route(
			self::PREFIX,
			'post-deleted',
			array(
				'methods'             => 'POST',
				'callback'            => array( $this, 'rest_friend_post_deleted' ),
				'permission_callback' => '__return_true',
			)
		);
		register_rest_route(
			self::PREFIX,
			'embed',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'rest_embed_friend_post' ),
				'permission_callback' => '__return_true',
			)
		);
	}

	/**
	 * Receive a notification via REST that a friend request was accepted
	 *
	 * @param  \WP_REST_Request $request The incoming request.
	 * @return array The array to be returned via the REST API.
	 */
	public function rest_accept_friend_request( \WP_REST_Request $request ) {
		$request_id     = $request->get_param( 'request' );
		$friend_user_id = get_option( 'friends_request_' . sha1( $request_id ) );
		$friend_user    = false;
		if ( $friend_user_id ) {
			$friend_user = new User( $friend_user_id );
		}

		if ( ! $request_id || ! $friend_user || is_wp_error( $friend_user ) || ! $friend_user->user_url ) {
			return new \WP_Error(
				'friends_invalid_parameters',
				'Not all necessary parameters were provided.',
				array(
					'status' => 403,
				)
			);
		}

		$future_in_token = get_user_option( 'friends_future_in_token_' . sha1( $request_id ), $friend_user_id );
		$proof            = $request->get_param( 'proof' );
		if ( ! $proof || sha1( $future_in_token . $request_id ) !== $proof ) {
			return new \WP_Error(
				'friends_invalid_proof',
				'An invalid proof was provided.',
				array(
					'status' => 403,
				)
			);
		}

		$friend_user_login = User::get_user_login_for_url( $friend_user->user_url );
		if ( ! $friend_user->has_cap( 'pending_friend_request' ) ) {
			return new \WP_Error(
				'friends_offer_no_longer_valid',
				'The friendship offer is no longer valid.',
				array(
					'status' => 403,
				)
			);
		}

		$future_out_token = $request->get_param( 'key' );
		if ( ! is_string( $future_out_token ) || empty( $future_out_token ) ) {
			return new \WP_Error(
				'friends_invalid_key',
				'The key must be a non-empty string.',
				array(
					'status' => 403,
				)
			);
		}
		$friend_user->make_friend( $future_out_token, $future_in_token );

		$friend_user->update_user_icon_url( $request->get_param( 'icon_url' ) );
		if ( $request->get_param( 'name' ) ) {
			wp_update_user(
				array(
					'ID'           => $friend_user->ID,
					'nickname'     => $request->get_param( 'name' ),
					'first_name'   => $request->get_param( 'name' ),
					'display_name' => $request->get_param( 'name' ),
				)
			);
		}

		delete_user_option( $friend_user_id, 'friends_future_in_token_' . sha1( $request_id ) );

		do_action( 'notify_accepted_friend_request', $friend_user );
		return array(
			'signature' => sha1( $future_out_token . $future_in_token ),
		);
	}

	/**
	 * Receive a friend request via REST
	 *
	 * @param  \WP_REST_Request $request The incoming request.
	 * @return array The array to be returned via the REST API.
	 */
	public function rest_friend_request( \WP_REST_Request $request ) {
		$version = $request->get_param( 'version' );
		if ( 2 !== intval( $version ) ) {
			return new \WP_Error(
				'friends_unsupported_protocol_version',
				'Incompatible Friends protocol version.',
				array(
					'status' => 403,
				)
			);
		}

		$codeword = $request->get_param( 'codeword' );
		if ( get_option( 'friends_require_codeword' ) && get_option( 'friends_codeword', 'friends' ) !== $codeword ) {
			return new \WP_Error(
				'friends_invalid_codeword',
				get_option( 'friends_wrong_codeword_message', 'An invalid codeword was provided.' ),
				array(
					'status' => 403,
				)
			);
		}

		$url = trim( $request->get_param( 'url' ) );
		if ( ! is_string( $url ) || ! Friends::check_url( $url ) || 0 === strcasecmp( home_url(), $url ) ) {
			return new \WP_Error(
				'friends_invalid_site',
				'An invalid site was provided.',
				array(
					'status' => 403,
				)
			);
		}

		$future_out_token = $request->get_param( 'key' );
		if ( ! is_string( $future_out_token ) || empty( $future_out_token ) ) {
			return new \WP_Error(
				'friends_invalid_key',
				'The key must be a non-empty string.',
				array(
					'status' => 403,
				)
			);
		}
		$user_login = User::get_user_login_for_url( $url );
		$friend_user = User::create( $user_login, 'friend_request', $url, $request->get_param( 'name' ), $request->get_param( 'icon_url' ) );
		if ( $friend_user->has_cap( 'friend' ) ) {
			if ( get_user_option( 'friends_out_token', $friend_user->ID ) && ! get_user_option( 'friends_out_token', $friend_user->ID ) ) {
				// TODO: trigger an accept friend request right away?
			}
			$friend_user->set_role( 'friend_request' );
		}
		$friend_user->update_user_icon_url( $request->get_param( 'icon_url' ) );
		$friend_user->update_user_option( 'friends_future_out_token', $request->get_param( 'key' ) );
		$message = $request->get_param( 'message' );
		if ( is_string( $message ) ) {
			$friend_user->update_user_option( 'friends_request_message', mb_substr( $message, 0, 2000 ) );
		}

		$request_id = wp_generate_password( 128, false );
		$friend_user->update_user_option( 'friends_request_id', $request_id );

		return array(
			'request' => $request_id,
		);
	}

	/**
	 * Notify friends of a deleted post
	 *
	 * @param  int $post_id The post id of the post that is deleted.
	 */
	public function notify_remote_friend_post_deleted( $post_id ) {
		$post = \WP_Post::get_instance( $post_id );
		if ( 'post' !== $post->post_type ) {
			return;
		}

		$friends = User_Query::all_friends();
		$friends = $friends->get_results();

		foreach ( $friends as $friend_user ) {
			$friend_rest_url = $friend_user->get_rest_url();

			$response = wp_safe_remote_post(
				$friend_rest_url . '/post-deleted',
				array(
					'body'        => array(
						'post_id' => $post_id,
						'auth'    => $friend_user->get_friend_auth(),
					),
					'timeout'     => 20,
					'redirection' => 5,
				)
			);
		}
	}

	/**
	 * Receive a REST message that a post was deleted.
	 *
	 * @param  \WP_REST_Request $request The incoming request.
	 * @return array The array to be returned via the REST API.
	 */
	public function rest_friend_post_deleted( $request ) {
		$tokens = explode( '-', $request->get_param( 'auth' ) );
		$user_id = $this->friends->access_control->verify_token( $tokens[0], isset( $tokens[1] ) ? $tokens[1] : null, isset( $tokens[2] ) ? $tokens[2] : null );
		if ( ! $user_id ) {
			return new \WP_Error(
				'friends_request_failed',
				__( 'Could not respond to the request.', 'friends' ),
				array(
					'status' => 403,
				)
			);
		}
		$friend_user     = new User( $user_id );
		$remote_post_id  = $request->get_param( 'post_id' );
		$remote_post_ids = $friend_user->get_remote_post_ids();

		if ( ! isset( $remote_post_ids[ $remote_post_id ] ) ) {
			return array(
				'deleted' => false,
			);
		}

		$post_id = $remote_post_ids[ $remote_post_id ];
		$post    = \WP_Post::get_instance( $post_id );
		if ( Friends::CPT === $post->post_type ) {
			wp_delete_post( $post_id );
		}

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

	public function rest_embed_friend_post( $request ) {
		if ( empty( $_GET['url'] ) ) {
			return false;
		}
		$post_id = $this->friends->feed->url_to_postid( $_GET['url'] );
		if ( empty( $post_id ) ) {
			return false;
		}

		if ( ! in_array( get_post_type( $post_id ), apply_filters( 'friends_frontend_post_types', array() ) ) ) {
			return false;
		}

		enqueue_embed_scripts();
		$post = get_post( $post_id );
		$args = compact( 'post' );
		setup_postdata( $post );

		header( 'Content-type: text/html' );
		Friends::template_loader()->get_template_part( 'embed/header-embed', null, $args );
		Friends::template_loader()->get_template_part( 'embed/embed-content', null, $args );
		exit;
	}

	/**
	 * Discover the REST URL for a friend site
	 *
	 * @param  array $feeds The URL of the site.
	 * @return string|\WP_Error The REST URL or an error.
	 */
	public function get_friends_rest_url( $feeds ) {
		foreach ( $feeds as $feed_url => $feed ) {
			if ( isset( $feed['parser'] ) && 'friends' === $feed['parser'] ) {
				return $feed_url;
			}
		}

		return false;
	}

	/**
	 * Discover the REST URL for a friend site
	 *
	 * @param  string $url The URL of the site.
	 * @return string|\WP_Error The REST URL or an error.
	 */
	public function discover_rest_url( $url ) {
		if ( ! is_string( $url ) || ! Friends::check_url( $url ) ) {
			return new \WP_Error( 'invalid-url-given', 'An invalid URL was given.' );
		}

		$response = wp_safe_remote_get(
			$url,
			array(
				'timeout'     => 20,
				'redirection' => 5,
			)
		);

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

		if ( 200 === wp_remote_retrieve_response_code( $response ) ) {
			$dom = new \DOMDocument();
			set_error_handler( '__return_null' );
			$dom->loadHTML( wp_remote_retrieve_body( $response ) );
			restore_error_handler();

			$xpath = new \DOMXpath( $dom );
			foreach ( $xpath->query( '//link[@rel and @href]' ) as $link ) {
				if ( 'friends-base-url' === $link->getAttribute( 'rel' ) ) {
					$rest_url = $link->getAttribute( 'href' );
					if ( is_string( $rest_url ) && Friends::check_url( $rest_url ) ) {
						return $rest_url;
					}
				}
			}
		}

		return null;
	}

	/**
	 * Notify the friend's site via REST about the accepted friend request.
	 *
	 * Accepting a friend request is simply setting the role to "friend".
	 *
	 * @param  int    $user_id   The user id.
	 * @param  string $new_role  The new role.
	 * @param  string $old_roles The old roles.
	 */
	public function notify_remote_friend_request_accepted( $user_id, $new_role, $old_roles ) {
		if ( 'friend' !== $new_role && 'acquaintance' !== $new_role ) {
			return;
		}

		$request_token = get_user_option( 'friends_request_id', $user_id );
		if ( ! $request_token ) {
			// We were accepted, so no need to notify the other.
			return;
		}

		$friend_user = new User( $user_id );

		$friend_rest_url  = $friend_user->get_rest_url();
		$request_id       = $friend_user->get_user_option( 'friends_request_id' );
		$future_out_token = $friend_user->get_user_option( 'friends_future_out_token' );
		$future_in_token  = wp_generate_password( 128, false );

		$current_user = wp_get_current_user();
		$response     = wp_safe_remote_post(
			$friend_rest_url . '/accept-friend-request',
			array(
				'body'        => array(
					'request'  => $request_id,
					'proof'    => sha1( $future_out_token . $request_id ),
					'key'      => $future_in_token,
					'name'     => $current_user->display_name,
					'icon_url' => get_avatar_url( $current_user->ID ),
				),
				'timeout'     => 20,
				'redirection' => 5,
			)
		);

		if ( 200 !== wp_remote_retrieve_response_code( $response ) ) {
			// TODO find a way to message the user.
			return;
		}

		$json = json_decode( wp_remote_retrieve_body( $response ) );
		if ( ! isset( $json->signature ) || sha1( $future_in_token . $future_out_token ) !== $json->signature ) {
			$friend_user->set_role( 'friend_request' );
			// TODO find a way to message the user.
			return;
		}

		$friend_user->make_friend( $future_out_token, $future_in_token );
		$friend_user->delete_user_option( 'friends_request_id' );
		$friend_user->delete_user_option( 'friends_future_out_token' );

		/*
		TODO
		if ( isset( $json->user_icon_url ) ) {
		$this->friends->access_control->update_user_icon_url( $friend_user->ID, $json->user_icon_url );
		}
		When their friend request is no longer valid
		$friend_user->set_role( 'pending_friend_request' );
		if ( isset( $json->friend_request_pending ) ) {
		}
		}
		*/
	}
}