/*
Copyright 2015, 2016 OpenMarket Ltd
Copyright 2017, 2018 New Vector Ltd
Copyright 2019, 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.
*/

/*
 * Manages a list of all the currently active calls.
 *
 * This handler dispatches when voip calls are added/updated/removed from this list:
 * {
 *   action: 'call_state'
 *   room_id: <room ID of the call>
 * }
 *
 * To know the state of the call, this handler exposes a getter to
 * obtain the call for a room:
 *   var call = CallHandler.getCall(roomId)
 *   var state = call.call_state; // ringing|ringback|connected|ended|busy|stop_ringback|stop_ringing
 *
 * This handler listens for and handles the following actions:
 * {
 *   action: 'place_call',
 *   type: 'voice|video',
 *   room_id: <room that the place call button was pressed in>
 * }
 *
 * {
 *   action: 'incoming_call'
 *   call: MatrixCall
 * }
 *
 * {
 *   action: 'hangup'
 *   room_id: <room that the hangup button was pressed in>
 * }
 *
 * {
 *   action: 'answer'
 *   room_id: <room that the answer button was pressed in>
 * }
 */

import React from 'react';

import {MatrixClientPeg} from './MatrixClientPeg';
import PlatformPeg from './PlatformPeg';
import Modal from './Modal';
import { _t } from './languageHandler';
import { createNewMatrixCall } from 'matrix-js-sdk/src/webrtc/call';
import dis from './dispatcher/dispatcher';
import WidgetUtils from './utils/WidgetUtils';
import WidgetEchoStore from './stores/WidgetEchoStore';
import SettingsStore from './settings/SettingsStore';
import {Jitsi} from "./widgets/Jitsi";
import {WidgetType} from "./widgets/WidgetType";
import {SettingLevel} from "./settings/SettingLevel";
import { ActionPayload } from "./dispatcher/payloads";
import {base32} from "rfc4648";

import QuestionDialog from "./components/views/dialogs/QuestionDialog";
import ErrorDialog from "./components/views/dialogs/ErrorDialog";
import WidgetStore from "./stores/WidgetStore";
import { WidgetMessagingStore } from "./stores/widgets/WidgetMessagingStore";
import { ElementWidgetActions } from "./stores/widgets/ElementWidgetActions";
import { MatrixCall, CallErrorCode, CallState, CallEvent, CallParty, CallType } from "matrix-js-sdk/src/webrtc/call";
import Analytics from './Analytics';
import CountlyAnalytics from "./CountlyAnalytics";
import {UIFeature} from "./settings/UIFeature";
import { CallError } from "matrix-js-sdk/src/webrtc/call";
import { logger } from 'matrix-js-sdk/src/logger';
import DesktopCapturerSourcePicker from "./components/views/elements/DesktopCapturerSourcePicker"
import { Action } from './dispatcher/actions';
import VoipUserMapper from './VoipUserMapper';
import { addManagedHybridWidget, isManagedHybridWidgetEnabled } from './widgets/ManagedHybrid';
import { randomUppercaseString, randomLowercaseString } from "matrix-js-sdk/src/randomstring";

export const PROTOCOL_PSTN = 'm.protocol.pstn';
export const PROTOCOL_PSTN_PREFIXED = 'im.vector.protocol.pstn';
export const PROTOCOL_SIP_NATIVE = 'im.vector.protocol.sip_native';
export const PROTOCOL_SIP_VIRTUAL = 'im.vector.protocol.sip_virtual';

const CHECK_PROTOCOLS_ATTEMPTS = 3;
// Event type for room account data and room creation content used to mark rooms as virtual rooms
// (and store the ID of their native room)
export const VIRTUAL_ROOM_EVENT_TYPE = 'im.vector.is_virtual_room';

enum AudioID {
    Ring = 'ringAudio',
    Ringback = 'ringbackAudio',
    CallEnd = 'callendAudio',
    Busy = 'busyAudio',
}

interface ThirdpartyLookupResponseFields {
    /* eslint-disable camelcase */

    // im.vector.sip_native
    virtual_mxid?: string;
    is_virtual?: boolean;

    // im.vector.sip_virtual
    native_mxid?: string;
    is_native?: boolean;

    // common
    lookup_success?: boolean;

    /* eslint-enable camelcase */
}

interface ThirdpartyLookupResponse {
    userid: string,
    protocol: string,
    fields: ThirdpartyLookupResponseFields,
}

// Unlike 'CallType' in js-sdk, this one includes screen sharing
// (because a screen sharing call is only a screen sharing call to the caller,
// to the callee it's just a video call, at least as far as the current impl
// is concerned).
export enum PlaceCallType {
    Voice = 'voice',
    Video = 'video',
    ScreenSharing = 'screensharing',
}

function getRemoteAudioElement(): HTMLAudioElement {
    // this needs to be somewhere at the top of the DOM which
    // always exists to avoid audio interruptions.
    // Might as well just use DOM.
    const remoteAudioElement = document.getElementById("remoteAudio") as HTMLAudioElement;
    if (!remoteAudioElement) {
        console.error(
            "Failed to find remoteAudio element - cannot play audio!" +
            "You need to add an <audio/> to the DOM.",
        );
        return null;
    }
    return remoteAudioElement;
}

export default class CallHandler {
    private calls = new Map<string, MatrixCall>(); // roomId -> call
    private audioPromises = new Map<AudioID, Promise<void>>();
    private dispatcherRef: string = null;
    private supportsPstnProtocol = null;
    private pstnSupportPrefixed = null; // True if the server only support the prefixed pstn protocol
    private supportsSipNativeVirtual = null; // im.vector.protocol.sip_virtual and im.vector.protocol.sip_native
    private pstnSupportCheckTimer: NodeJS.Timeout; // number actually because we're in the browser
    // For rooms we've been invited to, true if they're from virtual user, false if we've checked and they aren't.
    private invitedRoomsAreVirtual = new Map<string, boolean>();
    private invitedRoomCheckInProgress = false;

    static sharedInstance() {
        if (!window.mxCallHandler) {
            window.mxCallHandler = new CallHandler()
        }

        return window.mxCallHandler;
    }

    /*
     * Gets the user-facing room associated with a call (call.roomId may be the call "virtual room"
     * if a voip_mxid_translate_pattern is set in the config)
     */
    public static roomIdForCall(call: MatrixCall): string {
        if (!call) return null;
        return VoipUserMapper.sharedInstance().nativeRoomForVirtualRoom(call.roomId) || call.roomId;
    }

    start() {
        this.dispatcherRef = dis.register(this.onAction);
        // add empty handlers for media actions, otherwise the media keys
        // end up causing the audio elements with our ring/ringback etc
        // audio clips in to play.
        if (navigator.mediaSession) {
            navigator.mediaSession.setActionHandler('play', function() {});
            navigator.mediaSession.setActionHandler('pause', function() {});
            navigator.mediaSession.setActionHandler('seekbackward', function() {});
            navigator.mediaSession.setActionHandler('seekforward', function() {});
            navigator.mediaSession.setActionHandler('previoustrack', function() {});
            navigator.mediaSession.setActionHandler('nexttrack', function() {});
        }

        if (SettingsStore.getValue(UIFeature.Voip)) {
            MatrixClientPeg.get().on('Call.incoming', this.onCallIncoming);
        }

        this.checkProtocols(CHECK_PROTOCOLS_ATTEMPTS);
    }

    stop() {
        const cli = MatrixClientPeg.get();
        if (cli) {
            cli.removeListener('Call.incoming', this.onCallIncoming);
        }
        if (this.dispatcherRef !== null) {
            dis.unregister(this.dispatcherRef);
            this.dispatcherRef = null;
        }
    }

    private async checkProtocols(maxTries) {
        try {
            const protocols = await MatrixClientPeg.get().getThirdpartyProtocols();

            if (protocols[PROTOCOL_PSTN] !== undefined) {
                this.supportsPstnProtocol = Boolean(protocols[PROTOCOL_PSTN]);
                if (this.supportsPstnProtocol) this.pstnSupportPrefixed = false;
            } else if (protocols[PROTOCOL_PSTN_PREFIXED] !== undefined) {
                this.supportsPstnProtocol = Boolean(protocols[PROTOCOL_PSTN_PREFIXED]);
                if (this.supportsPstnProtocol) this.pstnSupportPrefixed = true;
            } else {
                this.supportsPstnProtocol = null;
            }

            dis.dispatch({action: Action.PstnSupportUpdated});

            if (protocols[PROTOCOL_SIP_NATIVE] !== undefined && protocols[PROTOCOL_SIP_VIRTUAL] !== undefined) {
                this.supportsSipNativeVirtual = Boolean(
                    protocols[PROTOCOL_SIP_NATIVE] && protocols[PROTOCOL_SIP_VIRTUAL],
                );
            }

            dis.dispatch({action: Action.VirtualRoomSupportUpdated});
        } catch (e) {
            if (maxTries === 1) {
                console.log("Failed to check for protocol support and no retries remain: assuming no support", e);
            } else {
                console.log("Failed to check for protocol support: will retry", e);
                this.pstnSupportCheckTimer = setTimeout(() => {
                    this.checkProtocols(maxTries - 1);
                }, 10000);
            }
        }
    }

    public getSupportsPstnProtocol() {
        return this.supportsPstnProtocol;
    }

    public getSupportsVirtualRooms() {
        return this.supportsPstnProtocol;
    }

    public pstnLookup(phoneNumber: string): Promise<ThirdpartyLookupResponse[]> {
        return MatrixClientPeg.get().getThirdpartyUser(
            this.pstnSupportPrefixed ? PROTOCOL_PSTN_PREFIXED : PROTOCOL_PSTN, {
                'm.id.phone': phoneNumber,
            },
        );
    }

    public sipVirtualLookup(nativeMxid: string): Promise<ThirdpartyLookupResponse[]> {
        return MatrixClientPeg.get().getThirdpartyUser(
            PROTOCOL_SIP_VIRTUAL, {
                'native_mxid': nativeMxid,
            },
        );
    }

    public sipNativeLookup(virtualMxid: string): Promise<ThirdpartyLookupResponse[]> {
        return MatrixClientPeg.get().getThirdpartyUser(
            PROTOCOL_SIP_NATIVE, {
                'virtual_mxid': virtualMxid,
            },
        );
    }

    private onCallIncoming = (call) => {
        // we dispatch this synchronously to make sure that the event
        // handlers on the call are set up immediately (so that if
        // we get an immediate hangup, we don't get a stuck call)
        dis.dispatch({
            action: 'incoming_call',
            call: call,
        }, true);
    }

    getCallForRoom(roomId: string): MatrixCall {
        return this.calls.get(roomId) || null;
    }

    getAnyActiveCall() {
        for (const call of this.calls.values()) {
            if (call.state !== CallState.Ended) {
                return call;
            }
        }
        return null;
    }

    getAllActiveCalls() {
        const activeCalls = [];

        for (const call of this.calls.values()) {
            if (call.state !== CallState.Ended && call.state !== CallState.Ringing) {
                activeCalls.push(call);
            }
        }
        return activeCalls;
    }

    getAllActiveCallsNotInRoom(notInThisRoomId) {
        const callsNotInThatRoom = [];

        for (const [roomId, call] of this.calls.entries()) {
            if (roomId !== notInThisRoomId && call.state !== CallState.Ended) {
                callsNotInThatRoom.push(call);
            }
        }
        return callsNotInThatRoom;
    }

    play(audioId: AudioID) {
        // TODO: Attach an invisible element for this instead
        // which listens?
        const audio = document.getElementById(audioId) as HTMLMediaElement;
        if (audio) {
            const playAudio = async () => {
                try {
                    // This still causes the chrome debugger to break on promise rejection if
                    // the promise is rejected, even though we're catching the exception.
                    await audio.play();
                } catch (e) {
                    // This is usually because the user hasn't interacted with the document,
                    // or chrome doesn't think so and is denying the request. Not sure what
                    // we can really do here...
                    // https://github.com/vector-im/element-web/issues/7657
                    console.log("Unable to play audio clip", e);
                }
            };
            if (this.audioPromises.has(audioId)) {
                this.audioPromises.set(audioId, this.audioPromises.get(audioId).then(() => {
                    audio.load();
                    return playAudio();
                }));
            } else {
                this.audioPromises.set(audioId, playAudio());
            }
        }
    }

    pause(audioId: AudioID) {
        // TODO: Attach an invisible element for this instead
        // which listens?
        const audio = document.getElementById(audioId) as HTMLMediaElement;
        if (audio) {
            if (this.audioPromises.has(audioId)) {
                this.audioPromises.set(audioId, this.audioPromises.get(audioId).then(() => audio.pause()));
            } else {
                // pause doesn't return a promise, so just do it
                audio.pause();
            }
        }
    }

    private matchesCallForThisRoom(call: MatrixCall) {
        // We don't allow placing more than one call per room, but that doesn't mean there
        // can't be more than one, eg. in a glare situation. This checks that the given call
        // is the call we consider 'the' call for its room.
        const mappedRoomId = CallHandler.roomIdForCall(call);

        const callForThisRoom = this.getCallForRoom(mappedRoomId);
        return callForThisRoom && call.callId === callForThisRoom.callId;
    }

    private setCallListeners(call: MatrixCall) {
        const mappedRoomId = CallHandler.roomIdForCall(call);

        call.on(CallEvent.Error, (err: CallError) => {
            if (!this.matchesCallForThisRoom(call)) return;

            Analytics.trackEvent('voip', 'callError', 'error', err.toString());
            console.error("Call error:", err);

            if (err.code === CallErrorCode.NoUserMedia) {
                this.showMediaCaptureError(call);
                return;
            }

            if (
                MatrixClientPeg.get().getTurnServers().length === 0 &&
                SettingsStore.getValue("fallbackICEServerAllowed") === null
            ) {
                this.showICEFallbackPrompt();
                return;
            }

            Modal.createTrackedDialog('Call Failed', '', ErrorDialog, {
                title: _t('Call Failed'),
                description: err.message,
            });
        });
        call.on(CallEvent.Hangup, () => {
            if (!this.matchesCallForThisRoom(call)) return;

            Analytics.trackEvent('voip', 'callHangup');

            this.removeCallForRoom(mappedRoomId);
        });
        call.on(CallEvent.State, (newState: CallState, oldState: CallState) => {
            if (!this.matchesCallForThisRoom(call)) return;

            this.setCallState(call, newState);

            switch (oldState) {
                case CallState.Ringing:
                    this.pause(AudioID.Ring);
                    break;
                case CallState.InviteSent:
                    this.pause(AudioID.Ringback);
                    break;
            }

            switch (newState) {
                case CallState.Ringing:
                    this.play(AudioID.Ring);
                    break;
                case CallState.InviteSent:
                    this.play(AudioID.Ringback);
                    break;
                case CallState.Ended:
                {
                    Analytics.trackEvent('voip', 'callEnded', 'hangupReason', call.hangupReason);
                    this.removeCallForRoom(mappedRoomId);
                    if (oldState === CallState.InviteSent && (
                        call.hangupParty === CallParty.Remote ||
                        (call.hangupParty === CallParty.Local && call.hangupReason === CallErrorCode.InviteTimeout)
                    )) {
                        this.play(AudioID.Busy);
                        let title;
                        let description;
                        if (call.hangupReason === CallErrorCode.UserHangup) {
                            title = _t("Call Declined");
                            description = _t("The other party declined the call.");
                        } else if (call.hangupReason === CallErrorCode.InviteTimeout) {
                            title = _t("Call Failed");
                            // XXX: full stop appended as some relic here, but these
                            // strings need proper input from design anyway, so let's
                            // not change this string until we have a proper one.
                            description = _t('The remote side failed to pick up') + '.';
                        } else {
                            title = _t("Call Failed");
                            description = _t("The call could not be established");
                        }

                        Modal.createTrackedDialog('Call Handler', 'Call Failed', ErrorDialog, {
                            title, description,
                        });
                    } else if (
                        call.hangupReason === CallErrorCode.AnsweredElsewhere && oldState === CallState.Connecting
                    ) {
                        Modal.createTrackedDialog('Call Handler', 'Call Failed', ErrorDialog, {
                            title: _t("Answered Elsewhere"),
                            description: _t("The call was answered on another device."),
                        });
                    } else if (oldState !== CallState.Fledgling && oldState !== CallState.Ringing) {
                        // don't play the end-call sound for calls that never got off the ground
                        this.play(AudioID.CallEnd);
                    }

                    this.logCallStats(call, mappedRoomId);
                    break;
                }
            }
        });
        call.on(CallEvent.Replaced, (newCall: MatrixCall) => {
            if (!this.matchesCallForThisRoom(call)) return;

            console.log(`Call ID ${call.callId} is being replaced by call ID ${newCall.callId}`);

            if (call.state === CallState.Ringing) {
                this.pause(AudioID.Ring);
            } else if (call.state === CallState.InviteSent) {
                this.pause(AudioID.Ringback);
            }

            this.calls.set(mappedRoomId, newCall);
            this.setCallListeners(newCall);
            this.setCallState(newCall, newCall.state);
        });
    }

    private async logCallStats(call: MatrixCall, mappedRoomId: string) {
        const stats = await call.getCurrentCallStats();
        logger.debug(
            `Call completed. Call ID: ${call.callId}, virtual room ID: ${call.roomId}, ` +
            `user-facing room ID: ${mappedRoomId}, direction: ${call.direction}, ` +
            `our Party ID: ${call.ourPartyId}, hangup party: ${call.hangupParty}, ` +
            `hangup reason: ${call.hangupReason}`,
        );
        if (!stats) {
            logger.debug(
                "Call statistics are undefined. The call has " +
                "probably failed before a peerConn was established",
            );
            return;
        }
        logger.debug("Local candidates:");
        for (const cand of stats.filter(item => item.type === 'local-candidate')) {
            const address = cand.address || cand.ip; // firefox uses 'address', chrome uses 'ip'
            logger.debug(
                `${cand.id} - type: ${cand.candidateType}, address: ${address}, port: ${cand.port}, ` +
                `protocol: ${cand.protocol}, relay protocol: ${cand.relayProtocol}, network type: ${cand.networkType}`,
            );
        }
        logger.debug("Remote candidates:");
        for (const cand of stats.filter(item => item.type === 'remote-candidate')) {
            const address = cand.address || cand.ip; // firefox uses 'address', chrome uses 'ip'
            logger.debug(
                `${cand.id} - type: ${cand.candidateType}, address: ${address}, port: ${cand.port}, ` +
                `protocol: ${cand.protocol}`,
            );
        }
        logger.debug("Candidate pairs:");
        for (const pair of stats.filter(item => item.type === 'candidate-pair')) {
            logger.debug(
                `${pair.localCandidateId} / ${pair.remoteCandidateId} - state: ${pair.state}, ` +
                `nominated: ${pair.nominated}, ` +
                `requests sent ${pair.requestsSent}, requests received  ${pair.requestsReceived},  ` +
                `responses received: ${pair.responsesReceived}, responses sent: ${pair.responsesSent}, ` +
                `bytes received: ${pair.bytesReceived}, bytes sent: ${pair.bytesSent}, `,
            );
        }
    }

    private setCallAudioElement(call: MatrixCall) {
        const audioElement = getRemoteAudioElement();
        if (audioElement) call.setRemoteAudioElement(audioElement);
    }

    private setCallState(call: MatrixCall, status: CallState) {
        const mappedRoomId = CallHandler.roomIdForCall(call);

        console.log(
            `Call state in ${mappedRoomId} changed to ${status}`,
        );

        dis.dispatch({
            action: 'call_state',
            room_id: mappedRoomId,
            state: status,
        });
    }

    private removeCallForRoom(roomId: string) {
        this.calls.delete(roomId);
    }

    private showICEFallbackPrompt() {
        const cli = MatrixClientPeg.get();
        const code = sub => <code>{sub}</code>;
        Modal.createTrackedDialog('No TURN servers', '', QuestionDialog, {
            title: _t("Call failed due to misconfigured server"),
            description: <div>
                <p>{_t(
                    "Please ask the administrator of your homeserver " +
                    "(<code>%(homeserverDomain)s</code>) to configure a TURN server in " +
                    "order for calls to work reliably.",
                    { homeserverDomain: cli.getDomain() }, { code },
                )}</p>
                <p>{_t(
                    "Alternatively, you can try to use the public server at " +
                    "<code>turn.matrix.org</code>, but this will not be as reliable, and " +
                    "it will share your IP address with that server. You can also manage " +
                    "this in Settings.",
                    null, { code },
                )}</p>
            </div>,
            button: _t('Try using turn.matrix.org'),
            cancelButton: _t('OK'),
            onFinished: (allow) => {
                SettingsStore.setValue("fallbackICEServerAllowed", null, SettingLevel.DEVICE, allow);
                cli.setFallbackICEServerAllowed(allow);
            },
        }, null, true);
    }

    private showMediaCaptureError(call: MatrixCall) {
        let title;
        let description;

        if (call.type === CallType.Voice) {
            title = _t("Unable to access microphone");
            description = <div>
                {_t(
                    "Call failed because microphone could not be accessed. " +
                    "Check that a microphone is plugged in and set up correctly.",
                )}
            </div>;
        } else if (call.type === CallType.Video) {
            title = _t("Unable to access webcam / microphone");
            description = <div>
                {_t("Call failed because webcam or microphone could not be accessed. Check that:")}
                <ul>
                    <li>{_t("A microphone and webcam are plugged in and set up correctly")}</li>
                    <li>{_t("Permission is granted to use the webcam")}</li>
                    <li>{_t("No other application is using the webcam")}</li>
                </ul>
            </div>;
        }

        Modal.createTrackedDialog('Media capture failed', '', ErrorDialog, {
            title, description,
        }, null, true);
    }

    private async placeCall(
        roomId: string, type: PlaceCallType,
        localElement: HTMLVideoElement, remoteElement: HTMLVideoElement,
    ) {
        Analytics.trackEvent('voip', 'placeCall', 'type', type);
        CountlyAnalytics.instance.trackStartCall(roomId, type === PlaceCallType.Video, false);

        const mappedRoomId = (await VoipUserMapper.sharedInstance().getOrCreateVirtualRoomForRoom(roomId)) || roomId;
        logger.debug("Mapped real room " + roomId + " to room ID " + mappedRoomId);

        const timeUntilTurnCresExpire = MatrixClientPeg.get().getTurnServersExpiry() - Date.now();
        console.log("Current turn creds expire in " + timeUntilTurnCresExpire + " seconds");
        const call = createNewMatrixCall(MatrixClientPeg.get(), mappedRoomId);

        this.calls.set(roomId, call);

        this.setCallListeners(call);
        this.setCallAudioElement(call);

        this.setActiveCallRoomId(roomId);

        if (type === PlaceCallType.Voice) {
            call.placeVoiceCall();
        } else if (type === 'video') {
            call.placeVideoCall(
                remoteElement,
                localElement,
            );
        } else if (type === PlaceCallType.ScreenSharing) {
            const screenCapErrorString = PlatformPeg.get().screenCaptureErrorString();
            if (screenCapErrorString) {
                this.removeCallForRoom(roomId);
                console.log("Can't capture screen: " + screenCapErrorString);
                Modal.createTrackedDialog('Call Handler', 'Unable to capture screen', ErrorDialog, {
                    title: _t('Unable to capture screen'),
                    description: screenCapErrorString,
                });
                return;
            }

            call.placeScreenSharingCall(
                remoteElement,
                localElement,
                async () : Promise<DesktopCapturerSource> => {
                    const {finished} = Modal.createDialog(DesktopCapturerSourcePicker);
                    const [source] = await finished;
                    return source;
                });
        } else {
            console.error("Unknown conf call type: " + type);
        }
    }

    private onAction = (payload: ActionPayload) => {
        switch (payload.action) {
            case 'place_call':
                {
                    // We might be using managed hybrid widgets
                    if (isManagedHybridWidgetEnabled()) {
                        addManagedHybridWidget(payload.room_id);
                        return;
                    }

                    // if the runtime env doesn't do VoIP, whine.
                    if (!MatrixClientPeg.get().supportsVoip()) {
                        Modal.createTrackedDialog('Call Handler', 'VoIP is unsupported', ErrorDialog, {
                            title: _t('VoIP is unsupported'),
                            description: _t('You cannot place VoIP calls in this browser.'),
                        });
                        return;
                    }

                    // don't allow > 2 calls to be placed.
                    if (this.getAllActiveCalls().length > 1) {
                        Modal.createTrackedDialog('Call Handler', 'Existing Call', ErrorDialog, {
                            title: _t('Too Many Calls'),
                            description: _t("You've reached the maximum number of simultaneous calls."),
                        });
                        return;
                    }

                    const room = MatrixClientPeg.get().getRoom(payload.room_id);
                    if (!room) {
                        console.error(`Room ${payload.room_id} does not exist.`);
                        return;
                    }

                    if (this.getCallForRoom(room.roomId)) {
                        Modal.createTrackedDialog('Call Handler', 'Existing Call with user', ErrorDialog, {
                            title: _t('Already in call'),
                            description: _t("You're already in a call with this person."),
                        });
                        return;
                    }

                    const members = room.getJoinedMembers();
                    if (members.length <= 1) {
                        Modal.createTrackedDialog('Call Handler', 'Cannot place call with self', ErrorDialog, {
                            description: _t('You cannot place a call with yourself.'),
                        });
                        return;
                    } else if (members.length === 2) {
                        console.info(`Place ${payload.type} call in ${payload.room_id}`);

                        this.placeCall(payload.room_id, payload.type, payload.local_element, payload.remote_element);
                    } else { // > 2
                        dis.dispatch({
                            action: "place_conference_call",
                            room_id: payload.room_id,
                            type: payload.type,
                            remote_element: payload.remote_element,
                            local_element: payload.local_element,
                        });
                    }
                }
                break;
            case 'place_conference_call':
                console.info("Place conference call in " + payload.room_id);
                Analytics.trackEvent('voip', 'placeConferenceCall');
                CountlyAnalytics.instance.trackStartCall(payload.room_id, payload.type === PlaceCallType.Video, true);
                this.startCallApp(payload.room_id, payload.type);
                break;
            case 'end_conference':
                console.info("Terminating conference call in " + payload.room_id);
                this.terminateCallApp(payload.room_id);
                break;
            case 'hangup_conference':
                console.info("Leaving conference call in "+ payload.room_id);
                this.hangupCallApp(payload.room_id);
                break;
            case 'incoming_call':
                {
                    // if the runtime env doesn't do VoIP, stop here.
                    if (!MatrixClientPeg.get().supportsVoip()) {
                        return;
                    }

                    const call = payload.call as MatrixCall;

                    const mappedRoomId = CallHandler.roomIdForCall(call);
                    if (this.getCallForRoom(mappedRoomId)) {
                        // ignore multiple incoming calls to the same room
                        return;
                    }

                    Analytics.trackEvent('voip', 'receiveCall', 'type', call.type);
                    this.calls.set(mappedRoomId, call)
                    this.setCallListeners(call);

                    // get ready to send encrypted events in the room, so if the user does answer
                    // the call, we'll be ready to send. NB. This is the protocol-level room ID not
                    // the mapped one: that's where we'll send the events.
                    const cli = MatrixClientPeg.get();
                    cli.prepareToEncrypt(cli.getRoom(call.roomId));
                }
                break;
            case 'hangup':
            case 'reject':
                if (!this.calls.get(payload.room_id)) {
                    return; // no call to hangup
                }
                if (payload.action === 'reject') {
                    this.calls.get(payload.room_id).reject();
                } else {
                    this.calls.get(payload.room_id).hangup(CallErrorCode.UserHangup, false);
                }
                // don't remove the call yet: let the hangup event handler do it (otherwise it will throw
                // the hangup event away)
                break;
            case 'answer': {
                if (!this.calls.has(payload.room_id)) {
                    return; // no call to answer
                }

                if (this.getAllActiveCalls().length > 1) {
                    Modal.createTrackedDialog('Call Handler', 'Existing Call', ErrorDialog, {
                        title: _t('Too Many Calls'),
                        description: _t("You've reached the maximum number of simultaneous calls."),
                    });
                    return;
                }

                const call = this.calls.get(payload.room_id);
                call.answer();
                this.setCallAudioElement(call);
                this.setActiveCallRoomId(payload.room_id);
                CountlyAnalytics.instance.trackJoinCall(payload.room_id, call.type === CallType.Video, false);
                dis.dispatch({
                    action: "view_room",
                    room_id: payload.room_id,
                });
                break;
            }
        }
    }

    setActiveCallRoomId(activeCallRoomId: string) {
        logger.info("Setting call in room " + activeCallRoomId + " active");

        for (const [roomId, call] of this.calls.entries()) {
            if (call.state === CallState.Ended) continue;

            if (roomId === activeCallRoomId) {
                call.setRemoteOnHold(false);
            } else {
                logger.info("Holding call in room " + roomId + " because another call is being set active");
                call.setRemoteOnHold(true);
            }
        }
    }

    /**
     * @returns true if we are currently in any call where we haven't put the remote party on hold
     */
    hasAnyUnheldCall() {
        for (const call of this.calls.values()) {
            if (call.state === CallState.Ended) continue;
            if (!call.isRemoteOnHold()) return true;
        }

        return false;
    }

    private async startCallApp(roomId: string, type: string) {
        dis.dispatch({
            action: 'appsDrawer',
            show: true,
        });

        // prevent double clicking the call button
        const room = MatrixClientPeg.get().getRoom(roomId);
        const currentJitsiWidgets = WidgetUtils.getRoomWidgetsOfType(room, WidgetType.JITSI);
        const hasJitsi = currentJitsiWidgets.length > 0
            || WidgetEchoStore.roomHasPendingWidgetsOfType(roomId, currentJitsiWidgets, WidgetType.JITSI);
        if (hasJitsi) {
            Modal.createTrackedDialog('Call already in progress', '', ErrorDialog, {
                title: _t('Call in Progress'),
                description: _t('A call is currently being placed!'),
            });
            return;
        }

        const jitsiDomain = Jitsi.getInstance().preferredDomain;
        const jitsiAuth = await Jitsi.getInstance().getJitsiAuth();
        let confId;
        if (jitsiAuth === 'openidtoken-jwt') {
            // Create conference ID from room ID
            // For compatibility with Jitsi, use base32 without padding.
            // More details here:
            // https://github.com/matrix-org/prosody-mod-auth-matrix-user-verification
            confId = base32.stringify(Buffer.from(roomId), { pad: false });
        } else {
            // Create a random conference ID
            const random = randomUppercaseString(1) + randomLowercaseString(23);
            confId = 'Jitsi' + random;
        }

        let widgetUrl = WidgetUtils.getLocalJitsiWrapperUrl({auth: jitsiAuth});

        // TODO: Remove URL hacks when the mobile clients eventually support v2 widgets
        const parsedUrl = new URL(widgetUrl);
        parsedUrl.search = ''; // set to empty string to make the URL class use searchParams instead
        parsedUrl.searchParams.set('confId', confId);
        widgetUrl = parsedUrl.toString();

        const widgetData = {
            conferenceId: confId,
            isAudioOnly: type === 'voice',
            domain: jitsiDomain,
            auth: jitsiAuth,
            roomName: room.name,
        };

        const widgetId = (
            'jitsi_' +
            MatrixClientPeg.get().credentials.userId +
            '_' +
            Date.now()
        );

        WidgetUtils.setRoomWidget(roomId, widgetId, WidgetType.JITSI, widgetUrl, 'Jitsi', widgetData).then(() => {
            console.log('Jitsi widget added');
        }).catch((e) => {
            if (e.errcode === 'M_FORBIDDEN') {
                Modal.createTrackedDialog('Call Failed', '', ErrorDialog, {
                    title: _t('Permission Required'),
                    description: _t("You do not have permission to start a conference call in this room"),
                });
            }
            console.error(e);
        });
    }

    private terminateCallApp(roomId: string) {
        Modal.createTrackedDialog('Confirm Jitsi Terminate', '', QuestionDialog, {
            hasCancelButton: true,
            title: _t("End conference"),
            description: _t("This will end the conference for everyone. Continue?"),
            button: _t("End conference"),
            onFinished: (proceed) => {
                if (!proceed) return;

                // We'll just obliterate them all. There should only ever be one, but might as well
                // be safe.
                const roomInfo = WidgetStore.instance.getRoom(roomId);
                const jitsiWidgets = roomInfo.widgets.filter(w => WidgetType.JITSI.matches(w.type));
                jitsiWidgets.forEach(w => {
                    // setting invalid content removes it
                    WidgetUtils.setRoomWidget(roomId, w.id);
                });
            },
        });
    }

    private hangupCallApp(roomId: string) {
        const roomInfo = WidgetStore.instance.getRoom(roomId);
        if (!roomInfo) return; // "should never happen" clauses go here

        const jitsiWidgets = roomInfo.widgets.filter(w => WidgetType.JITSI.matches(w.type));
        jitsiWidgets.forEach(w => {
            const messaging = WidgetMessagingStore.instance.getMessagingForId(w.id);
            if (!messaging) return; // more "should never happen" words

            messaging.transport.send(ElementWidgetActions.HangupCall, {});
        });
    }
}