/*
Copyright 2023 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.
*/

export type TrackId = string;

export class MediaTrackHandler {
    public constructor(private readonly pc: RTCPeerConnection) {}

    public getLocalTracks(kind: "audio" | "video"): MediaStreamTrack[] {
        const isNotNullAndKind = (track: MediaStreamTrack | null): boolean => {
            return track !== null && track.kind === kind;
        };
        return this.pc
            .getTransceivers()
            .filter((t) => t.currentDirection === "sendonly" || t.currentDirection === "sendrecv")
            .filter((t) => t.sender !== null)
            .map((t) => t.sender)
            .map((s) => s.track)
            .filter(isNotNullAndKind) as MediaStreamTrack[];
    }

    public getTackById(trackId: string): MediaStreamTrack | undefined {
        return this.pc
            .getTransceivers()
            .map((t) => {
                if (t?.sender.track !== null && t.sender.track.id === trackId) {
                    return t.sender.track;
                }
                if (t?.receiver.track !== null && t.receiver.track.id === trackId) {
                    return t.receiver.track;
                }
                return undefined;
            })
            .find((t) => t !== undefined);
    }

    public getLocalTrackIdByMid(mid: string): string | undefined {
        const transceiver = this.pc.getTransceivers().find((t) => t.mid === mid);
        return transceiver?.sender?.track?.id;
    }

    public getRemoteTrackIdByMid(mid: string): string | undefined {
        const transceiver = this.pc.getTransceivers().find((t) => t.mid === mid);
        return transceiver?.receiver?.track?.id;
    }

    public getActiveSimulcastStreams(): number {
        //@TODO implement this right.. Check how many layer configured
        return 3;
    }

    public getTransceiverByTrackId(trackId: TrackId): RTCRtpTransceiver | undefined {
        return this.pc.getTransceivers().find((t) => {
            return t.receiver.track.id === trackId || (t.sender.track !== null && t.sender.track.id === trackId);
        });
    }
}