fx_cast/ext/src/senders/mediaCast.ts

"use strict";

import options from "../lib/options";
import cast, { ensureInit } from "../shim/export";

import { Message, Receiver } from "../types";


function getLocalAddress () {
    const pc = new RTCPeerConnection();
    pc.createDataChannel(null);
    pc.createOffer().then(pc.setLocalDescription.bind(pc));

    return new Promise((resolve, reject) => {
        pc.addEventListener("icecandidate", ev => {
            if (ev.candidate) {
                resolve(ev.candidate.candidate.split(" ")[4]);
            }
        });
        pc.addEventListener("error", () => {
            reject();
        });
    });
}

function startMediaServer (filePath: string, port: number) {
    return new Promise((resolve, reject) => {
        backgroundPort.postMessage({
            subject: "bridge:/mediaServer/start"
          , data: {
                filePath: decodeURI(filePath)
              , port
            }
        });

        backgroundPort.addEventListener("message", function onMessage (ev) {
            const message = ev.data as Message;

            if (message.subject.startsWith("mediaCast:/mediaServer/")) {
                backgroundPort.removeEventListener("message", onMessage);
            }

            switch (message.subject) {
                case "mediaCast:/mediaServer/started": {
                    resolve();
                    break;
                }
                case "mediaCast:/mediaServer/error": {
                    reject();
                    break;
                }
            }
        });

        backgroundPort.start();
    });
}


let backgroundPort: MessagePort;

let currentSession: cast.Session;
let currentMedia: cast.media.Media;

let mediaElement: HTMLMediaElement;


function getSession (opts: InitOptions): Promise<cast.Session> {
    return new Promise(async (resolve, reject) => {
        /**
         * If a receiver is available, call requestSession. If a
         * specific receiver was specified, bypass receiver selector
         * and create session directly.
         */
        function receiverListener (availability: string) {
            if (availability === cast.ReceiverAvailability.AVAILABLE) {
                if (opts.receiver) {
                    cast._requestSession(
                            opts.receiver
                          , onRequestSessionSuccess
                          , onRequestSessionError);
                } else {
                    cast.requestSession(
                            onRequestSessionSuccess
                          , onRequestSessionError);
                }
            }
        }

        function onRequestSessionSuccess (session: cast.Session) {
            resolve(session);
        }
        function onRequestSessionError (err: cast.Error) {
            reject(err.description);
        }


        const sessionRequest = new cast.SessionRequest(
                cast.media.DEFAULT_MEDIA_RECEIVER_APP_ID);

        const apiConfig = new cast.ApiConfig(
                sessionRequest
              , null               // sessionListener
              , receiverListener); // receiverListener


        cast.initialize(apiConfig);
    });
}

function getMedia (opts: InitOptions): Promise<cast.media.Media> {
    return new Promise(async resolve => {
        let mediaUrlObject = new URL(opts.mediaUrl);
        const mediaTitle = mediaUrlObject.pathname;

        /**
         * If the media is a local file, start an HTTP media server
         * and change the media URL to point to it.
         */
        if (opts.mediaUrl.startsWith("file://")) {
            const host = await getLocalAddress();
            const port = await options.get("localMediaServerPort");

            try {
                // Wait until media server is listening
                await startMediaServer(mediaUrlObject.pathname, port);
            } catch (err) {
                console.error("Failed to start media server");
                return;
            }

            mediaUrlObject = new URL(`http://${host}:${port}/`);
        }


        const activeTrackIds: number[] = [];
        const mediaInfo = new cast.media.MediaInfo(mediaUrlObject.href, null);

        mediaInfo.metadata = new cast.media.GenericMediaMetadata();
        mediaInfo.metadata.metadataType = cast.media.MetadataType.GENERIC;
        mediaInfo.metadata.title = mediaTitle;
        mediaInfo.tracks = [];


        if (mediaElement) {
            if (mediaElement instanceof HTMLVideoElement) {
                if (mediaElement.poster) {
                    mediaInfo.metadata.images = [
                        new cast.Image(mediaElement.poster)
                    ];
                }
            }

            if (mediaElement.textTracks.length) {
                const tracks = Array.from(mediaElement.textTracks);
                const trackElements = mediaElement.querySelectorAll("track");

                tracks.forEach((track, index) => {
                    const trackElement = trackElements[index];

                    /**
                     * Create media.Track object with the index as the track ID
                     * and type as TrackType.TEXT.
                     */
                    const castTrack = new cast.media.Track(
                            index, cast.media.TrackType.TEXT);

                    // Copy TextTrack properties
                    castTrack.name = track.label;
                    castTrack.language = track.language;
                    castTrack.trackContentId = trackElement.src;
                    castTrack.trackContentType = "text/vtt";

                    switch (track.kind) {
                        case "subtitles":
                            castTrack.subtype =
                                    cast.media.TextTrackType.SUBTITLES;
                            break;
                        case "captions":
                            castTrack.subtype =
                                    cast.media.TextTrackType.CAPTIONS;
                            break;
                        case "descriptions":
                            castTrack.subtype =
                                    cast.media.TextTrackType.DESCRIPTIONS;
                            break;
                        case "chapters":
                            castTrack.subtype =
                                    cast.media.TextTrackType.CHAPTERS;
                            break;
                        case "metadata":
                            castTrack.subtype =
                                    cast.media.TextTrackType.METADATA;
                            break;

                        // Default to subtitles
                        default:
                            castTrack.subtype =
                                    cast.media.TextTrackType.SUBTITLES;
                    }

                    // Add track to mediaInfo
                    mediaInfo.tracks.push(castTrack);

                    // If enabled, mark as active track for load request
                    if (track.mode === "showing" || trackElement.default) {
                        activeTrackIds.push(index);
                    }
                });
            }
        }

        const loadRequest = new cast.media.LoadRequest(mediaInfo);
        loadRequest.autoplay = false;
        loadRequest.activeTrackIds = activeTrackIds;

        currentSession.loadMedia(loadRequest
              , (media) => resolve(media)
              , null);
    });
}


let ignoreMediaEvents = false;

async function registerMediaElementListeners () {
    if (await options.get("mediaSyncElement")) {

        function checkIgnore (ev: Event) {
            if (ignoreMediaEvents) {
                ignoreMediaEvents = false;
                ev.stopImmediatePropagation();
            }
        }

        mediaElement.addEventListener("play", checkIgnore, true);
        mediaElement.addEventListener("pause", checkIgnore, true);
        mediaElement.addEventListener("suspend", checkIgnore, true);
        mediaElement.addEventListener("seeking", checkIgnore, true);
        mediaElement.addEventListener("ratechange", checkIgnore, true);
        mediaElement.addEventListener("volumechange", checkIgnore, true);


        mediaElement.addEventListener("play", () => {
            currentMedia.play(null, null, null);
        });

        mediaElement.addEventListener("pause", () => {
            currentMedia.pause(null, null, null);
        });

        mediaElement.addEventListener("suspend", () => {
            // currentMedia.stop(null, null, null);
        });

        mediaElement.addEventListener("seeked", () => {
            const seekRequest = new cast.media.SeekRequest();
            seekRequest.currentTime = mediaElement.currentTime;

            currentMedia.seek(seekRequest, null, null);
        });

        mediaElement.addEventListener("ratechange", () => {
            currentMedia._sendMediaMessage({
                type: "SET_PLAYBACK_RATE"
              , playbackRate: mediaElement.playbackRate
            });
        });

        mediaElement.addEventListener("volumechange", () => {
            const newVolume = new cast.Volume(
                    currentMedia.volume.level
                  , currentMedia.volume.muted);

            const volumeRequest = new cast.media.VolumeRequest(newVolume);

            currentMedia.setVolume(volumeRequest);
        });


        currentMedia.addUpdateListener(isAlive => {
            if (!isAlive) {
                return;
            }

            const localPlayerState = mediaElement.paused
                ? cast.media.PlayerState.PAUSED
                : cast.media.PlayerState.PLAYING;

            if (localPlayerState !== currentMedia.playerState) {
                ignoreMediaEvents = true;

                switch (currentMedia.playerState) {
                    case cast.media.PlayerState.PLAYING: {
                        mediaElement.play();
                        break;
                    }
                    case cast.media.PlayerState.PAUSED: {
                        mediaElement.pause();
                        break;
                    }
                }
            }


            const localRepeatMode = mediaElement.loop
                ? cast.media.RepeatMode.SINGLE
                : cast.media.RepeatMode.OFF;

            if (localRepeatMode !== currentMedia.repeatMode) {
                ignoreMediaEvents = true;

                switch (currentMedia.repeatMode) {
                    case cast.media.RepeatMode.SINGLE: {
                        mediaElement.loop = true;
                        break;
                    }
                    case cast.media.RepeatMode.OFF: {
                        mediaElement.loop = false;
                        break;
                    }
                }
            }


            if (currentMedia.currentTime !== mediaElement.currentTime) {
                ignoreMediaEvents = true;
                mediaElement.currentTime = currentMedia.currentTime;
            }
        });
    }
}


interface InitOptions {
    mediaUrl: string;
    receiver: Receiver;
    targetElementId?: number;
}

export async function init (opts: InitOptions) {
    backgroundPort = await ensureInit();

    const isLocalMedia = opts.mediaUrl.startsWith("file://");
    const isLocalMediaEnabled = await options.get("localMediaEnabled");

    if (isLocalMedia && !isLocalMediaEnabled) {
        cast.logMessage("Local media casting not enabled");
        return;
    }

    if (opts.targetElementId) {
        mediaElement = browser.menus.getTargetElement(
                opts.targetElementId) as HTMLMediaElement;
    }

    currentSession = await getSession(opts);
    currentMedia = await getMedia(opts);

    if (opts.targetElementId) {
        registerMediaElementListeners();

        window.addEventListener("beforeunload", async () => {
            backgroundPort.postMessage({
                subject: "bridge:/mediaServer/stop"
            });

            if (await options.get("mediaStopOnUnload")) {
                currentSession.stop(null, null);
            }
        });
    }
}

/**
 * If loaded as a content script, the init values are
 * provided on the window object.
 */
if (window.location.protocol !== "moz-extension:") {
    const _window = (window as any);

    init({
        mediaUrl: _window.mediaUrl
      , receiver: _window.receiver
      , targetElementId: _window.targetElementId
    });
}