matrix.to/src/utils/cypher-wrapper.ts

/*
Copyright 2020 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the 'License');
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an 'AS IS' BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import {
    Client,
    Room,
    RoomAlias,
    User,
    getRoomIdFromAlias,
    searchPublicRooms,
    getUserDetails,
    convertMXCtoMediaQuery,
} from "matrix-cypher";
import { LinkKind, Permalink } from "../parser/types";

/* This is a collection of methods for providing fallback metadata
 * for cypher queries
 */

/*
 * Returns an instance of User with fallback information instead
 * of fetched metadata
 */
export const fallbackUser = (userId: string): User => ({
    displayname: userId,
});

/*
 * Returns an instance of Room with fallback information instead
 * of fecthed metadata
 */
export const fallbackRoom = ({
    identifier,
    roomId,
    roomAlias,
}: {
    identifier: string;
    roomId?: string;
    roomAlias?: string;
}): Room => {
    const roomId_ = roomId ? roomId : identifier;
    const roomAlias_ = roomAlias ? roomAlias : identifier;
    return {
        aliases: [roomAlias_],
        topic: "Unable to find room details.",
        canonical_alias: roomAlias_,
        name: roomAlias_,
        num_joined_members: 0,
        room_id: roomId_,
        guest_can_join: true,
        avatar_url: "",
        world_readable: false,
    };
};

/*
 * Tries to fetch room details from an alias. If it fails it uses
 * a `fallbackRoom`
 */
export async function getRoomFromAlias(
    client: Client,
    roomAlias: string
): Promise<Room> {
    let resolvedRoomAlias: RoomAlias;
    try {
        resolvedRoomAlias = await getRoomIdFromAlias(client, roomAlias);
    } catch {
        return fallbackRoom({ identifier: roomAlias });
    }

    try {
        return await searchPublicRooms(client, resolvedRoomAlias.room_id);
    } catch {
        return fallbackRoom({
            identifier: roomAlias,
            roomId: resolvedRoomAlias.room_id,
            roomAlias: roomAlias,
        });
    }
}

/*
 * Tries to fetch room details from a roomId. If it fails it uses
 * a `fallbackRoom`
 */
export async function getRoomFromId(
    client: Client,
    roomId: string
): Promise<Room> {
    try {
        return await searchPublicRooms(client, roomId);
    } catch {
        return fallbackRoom({ identifier: roomId });
    }
}

/*
 * Tries to fetch user details. If it fails it uses a `fallbackUser`
 */
export async function getUser(client: Client, userId: string): Promise<User> {
    try {
        return await getUserDetails(client, userId);
    } catch {
        return fallbackUser(userId);
    }
}

/*
 * Tries to fetch room details from a permalink. If it fails it uses
 * a `fallbackRoom`
 */
export async function getRoomFromPermalink(
    client: Client,
    link: Permalink
): Promise<Room> {
    switch (link.roomKind) {
        case LinkKind.Alias:
            return getRoomFromAlias(client, link.roomLink);
        case LinkKind.RoomId:
            return getRoomFromId(client, link.roomLink);
    }
}

/*
 * tries to convert an mxc to a media query. If it fails it
 * uses the empty string
 */
export function getMediaQueryFromMCX(mxc?: string): string {
    if (!mxc) {
        return "";
    }
    try {
        return convertMXCtoMediaQuery(
            // TODO: replace with correct client
            "https://matrix.org",
            mxc
        );
    } catch {
        return "";
    }
}