/*
Copyright 2024 New Vector Ltd.
Copyright 2022 The Matrix.org Foundation C.I.C.

SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
Please see LICENSE files in the repository root for full details.
*/

import { logger } from "matrix-js-sdk/src/logger";
import {
    ClientEvent,
    ClientEventHandlerMap,
    EventType,
    MatrixClient,
    MatrixEvent,
    MatrixEventEvent,
    MsgType,
    RelationType,
    TypedEventEmitter,
} from "matrix-js-sdk/src/matrix";
import { AudioContent, EncryptedFile } from "matrix-js-sdk/src/types";

import {
    ChunkRecordedPayload,
    createVoiceBroadcastRecorder,
    getMaxBroadcastLength,
    VoiceBroadcastInfoEventContent,
    VoiceBroadcastInfoEventType,
    VoiceBroadcastInfoState,
    VoiceBroadcastRecorder,
    VoiceBroadcastRecorderEvent,
} from "..";
import { uploadFile } from "../../ContentMessages";
import { createVoiceMessageContent } from "../../utils/createVoiceMessageContent";
import { IDestroyable } from "../../utils/IDestroyable";
import dis from "../../dispatcher/dispatcher";
import { ActionPayload } from "../../dispatcher/payloads";
import { VoiceBroadcastChunkEvents } from "../utils/VoiceBroadcastChunkEvents";
import { RelationsHelper, RelationsHelperEvent } from "../../events/RelationsHelper";
import { createReconnectedListener } from "../../utils/connection";
import { localNotificationsAreSilenced } from "../../utils/notifications";
import { BackgroundAudio } from "../../audio/BackgroundAudio";

export enum VoiceBroadcastRecordingEvent {
    StateChanged = "liveness_changed",
    TimeLeftChanged = "time_left_changed",
}

export type VoiceBroadcastRecordingState = VoiceBroadcastInfoState | "connection_error";

interface EventMap {
    [VoiceBroadcastRecordingEvent.StateChanged]: (state: VoiceBroadcastRecordingState) => void;
    [VoiceBroadcastRecordingEvent.TimeLeftChanged]: (timeLeft: number) => void;
}

export class VoiceBroadcastRecording
    extends TypedEventEmitter<VoiceBroadcastRecordingEvent, EventMap>
    implements IDestroyable
{
    private state: VoiceBroadcastRecordingState;
    private recorder: VoiceBroadcastRecorder | null = null;
    private dispatcherRef: string;
    private chunkEvents = new VoiceBroadcastChunkEvents();
    private chunkRelationHelper: RelationsHelper;
    private maxLength: number;
    private timeLeft: number;
    private toRetry: Array<() => Promise<void>> = [];
    private reconnectedListener: ClientEventHandlerMap[ClientEvent.Sync];
    private roomId: string;
    private infoEventId: string;
    private backgroundAudio = new BackgroundAudio();

    /**
     * Broadcast chunks have a sequence number to bring them in the correct order and to know if a message is missing.
     * This variable holds the last sequence number.
     * Starts with 0 because there is no chunk at the beginning of a broadcast.
     * Will be incremented when a chunk message is created.
     */
    private sequence = 0;

    public constructor(
        public readonly infoEvent: MatrixEvent,
        private client: MatrixClient,
        initialState?: VoiceBroadcastInfoState,
    ) {
        super();
        this.maxLength = getMaxBroadcastLength();
        this.timeLeft = this.maxLength;
        this.infoEventId = this.determineEventIdFromInfoEvent();
        this.roomId = this.determineRoomIdFromInfoEvent();

        if (initialState) {
            this.state = initialState;
        } else {
            this.state = this.determineInitialStateFromInfoEvent();
        }

        // TODO Michael W: listen for state updates

        this.infoEvent.on(MatrixEventEvent.BeforeRedaction, this.onBeforeRedaction);
        this.dispatcherRef = dis.register(this.onAction);
        this.chunkRelationHelper = this.initialiseChunkEventRelation();
        this.reconnectedListener = createReconnectedListener(this.onReconnect);
        this.client.on(ClientEvent.Sync, this.reconnectedListener);
    }

    private initialiseChunkEventRelation(): RelationsHelper {
        const relationsHelper = new RelationsHelper(
            this.infoEvent,
            RelationType.Reference,
            EventType.RoomMessage,
            this.client,
        );
        relationsHelper.on(RelationsHelperEvent.Add, this.onChunkEvent);

        relationsHelper.emitFetchCurrent().catch((err) => {
            logger.warn("error fetching server side relation for voice broadcast chunks", err);
            // fall back to local events
            relationsHelper.emitCurrent();
        });

        return relationsHelper;
    }

    private onChunkEvent = (event: MatrixEvent): void => {
        if (
            (!event.getId() && !event.getTxnId()) ||
            event.getContent()?.msgtype !== MsgType.Audio // don't add non-audio event
        ) {
            return;
        }

        this.chunkEvents.addEvent(event);
    };

    private determineEventIdFromInfoEvent(): string {
        const infoEventId = this.infoEvent.getId();

        if (!infoEventId) {
            throw new Error("Cannot create broadcast for info event without Id.");
        }

        return infoEventId;
    }

    private determineRoomIdFromInfoEvent(): string {
        const roomId = this.infoEvent.getRoomId();

        if (!roomId) {
            throw new Error(`Cannot create broadcast for unknown room (info event ${this.infoEventId})`);
        }

        return roomId;
    }

    /**
     * Determines the initial broadcast state.
     * Checks all related events. If one has the "stopped" state → stopped, else started.
     */
    private determineInitialStateFromInfoEvent(): VoiceBroadcastRecordingState {
        const room = this.client.getRoom(this.roomId);
        const relations = room
            ?.getUnfilteredTimelineSet()
            ?.relations?.getChildEventsForEvent(this.infoEventId, RelationType.Reference, VoiceBroadcastInfoEventType);
        const relatedEvents = relations?.getRelations();
        return !relatedEvents?.find((event: MatrixEvent) => {
            return event.getContent()?.state === VoiceBroadcastInfoState.Stopped;
        })
            ? VoiceBroadcastInfoState.Started
            : VoiceBroadcastInfoState.Stopped;
    }

    public getTimeLeft(): number {
        return this.timeLeft;
    }

    /**
     * Retries failed actions on reconnect.
     */
    private onReconnect = async (): Promise<void> => {
        // Do nothing if not in connection_error state.
        if (this.state !== "connection_error") return;

        // Copy the array, so that it is possible to remove elements from it while iterating over the original.
        const toRetryCopy = [...this.toRetry];

        for (const retryFn of this.toRetry) {
            try {
                await retryFn();
                // Successfully retried. Remove from array copy.
                toRetryCopy.splice(toRetryCopy.indexOf(retryFn), 1);
            } catch {
                // The current retry callback failed. Stop the loop.
                break;
            }
        }

        this.toRetry = toRetryCopy;

        if (this.toRetry.length === 0) {
            // Everything has been successfully retried. Recover from error state to paused.
            await this.pause();
        }
    };

    private async setTimeLeft(timeLeft: number): Promise<void> {
        if (timeLeft <= 0) {
            // time is up - stop the recording
            return await this.stop();
        }

        // do never increase time left; no action if equals
        if (timeLeft >= this.timeLeft) return;

        this.timeLeft = timeLeft;
        this.emit(VoiceBroadcastRecordingEvent.TimeLeftChanged, timeLeft);
    }

    public async start(): Promise<void> {
        return this.getRecorder().start();
    }

    public async stop(): Promise<void> {
        if (this.state === VoiceBroadcastInfoState.Stopped) return;

        this.setState(VoiceBroadcastInfoState.Stopped);
        await this.stopRecorder();
        await this.sendInfoStateEvent(VoiceBroadcastInfoState.Stopped);
    }

    public async pause(): Promise<void> {
        // stopped or already paused recordings cannot be paused
        if (
            (
                [VoiceBroadcastInfoState.Stopped, VoiceBroadcastInfoState.Paused] as VoiceBroadcastRecordingState[]
            ).includes(this.state)
        )
            return;

        this.setState(VoiceBroadcastInfoState.Paused);
        await this.stopRecorder();
        await this.sendInfoStateEvent(VoiceBroadcastInfoState.Paused);
    }

    public async resume(): Promise<void> {
        if (this.state !== VoiceBroadcastInfoState.Paused) return;

        this.setState(VoiceBroadcastInfoState.Resumed);
        await this.getRecorder().start();
        await this.sendInfoStateEvent(VoiceBroadcastInfoState.Resumed);
    }

    public toggle = async (): Promise<void> => {
        if (this.getState() === VoiceBroadcastInfoState.Paused) return this.resume();

        if (
            (
                [VoiceBroadcastInfoState.Started, VoiceBroadcastInfoState.Resumed] as VoiceBroadcastRecordingState[]
            ).includes(this.getState())
        ) {
            return this.pause();
        }
    };

    public getState(): VoiceBroadcastRecordingState {
        return this.state;
    }

    private getRecorder(): VoiceBroadcastRecorder {
        if (!this.recorder) {
            this.recorder = createVoiceBroadcastRecorder();
            this.recorder.on(VoiceBroadcastRecorderEvent.ChunkRecorded, this.onChunkRecorded);
            this.recorder.on(VoiceBroadcastRecorderEvent.CurrentChunkLengthUpdated, this.onCurrentChunkLengthUpdated);
        }

        return this.recorder;
    }

    public async destroy(): Promise<void> {
        if (this.recorder) {
            this.recorder.stop();
            this.recorder.destroy();
        }

        this.infoEvent.off(MatrixEventEvent.BeforeRedaction, this.onBeforeRedaction);
        this.removeAllListeners();
        dis.unregister(this.dispatcherRef);
        this.chunkEvents = new VoiceBroadcastChunkEvents();
        this.chunkRelationHelper.destroy();
        this.client.off(ClientEvent.Sync, this.reconnectedListener);
    }

    private onBeforeRedaction = (): void => {
        if (this.getState() !== VoiceBroadcastInfoState.Stopped) {
            this.setState(VoiceBroadcastInfoState.Stopped);
            // destroy cleans up everything
            this.destroy();
        }
    };

    private onAction = (payload: ActionPayload): void => {
        if (payload.action !== "call_state") return;

        // pause on any call action
        this.pause();
    };

    private setState(state: VoiceBroadcastRecordingState): void {
        this.state = state;
        this.emit(VoiceBroadcastRecordingEvent.StateChanged, this.state);
    }

    private onCurrentChunkLengthUpdated = (currentChunkLength: number): void => {
        this.setTimeLeft(this.maxLength - this.chunkEvents.getLengthSeconds() - currentChunkLength);
    };

    private onChunkRecorded = async (chunk: ChunkRecordedPayload): Promise<void> => {
        const uploadAndSendFn = async (): Promise<void> => {
            const { url, file } = await this.uploadFile(chunk);
            await this.sendVoiceMessage(chunk, url, file);
        };

        await this.callWithRetry(uploadAndSendFn);
    };

    /**
     * This function is called on connection errors.
     * It sets the connection error state and stops the recorder.
     */
    private async onConnectionError(): Promise<void> {
        this.playConnectionErrorAudioNotification().catch(() => {
            // Error logged in playConnectionErrorAudioNotification().
        });
        await this.stopRecorder(false);
        this.setState("connection_error");
    }

    private async playConnectionErrorAudioNotification(): Promise<void> {
        if (localNotificationsAreSilenced(this.client)) {
            return;
        }

        await this.backgroundAudio.pickFormatAndPlay("./media/error", ["mp3", "ogg"]);
    }

    private async uploadFile(chunk: ChunkRecordedPayload): ReturnType<typeof uploadFile> {
        return uploadFile(
            this.client,
            this.roomId,
            new Blob([chunk.buffer], {
                type: this.getRecorder().contentType,
            }),
        );
    }

    private async sendVoiceMessage(chunk: ChunkRecordedPayload, url?: string, file?: EncryptedFile): Promise<void> {
        /**
         * Increment the last sequence number and use it for this message.
         * Done outside of the sendMessageFn to get a scoped value.
         * Also see {@link VoiceBroadcastRecording.sequence}.
         */
        const sequence = ++this.sequence;

        const sendMessageFn = async (): Promise<void> => {
            const content = createVoiceMessageContent(
                url,
                this.getRecorder().contentType,
                Math.round(chunk.length * 1000),
                chunk.buffer.length,
                file,
            );
            content["m.relates_to"] = {
                rel_type: RelationType.Reference,
                event_id: this.infoEventId,
            };
            (<AudioContent>content)["io.element.voice_broadcast_chunk"] = {
                sequence,
            };

            await this.client.sendMessage(this.roomId, content);
        };

        await this.callWithRetry(sendMessageFn);
    }

    /**
     * Sends an info state event with given state.
     * On error stores a resend function and setState(state) in {@link toRetry} and
     * sets the broadcast state to connection_error.
     */
    private async sendInfoStateEvent(state: VoiceBroadcastInfoState): Promise<void> {
        const sendEventFn = async (): Promise<void> => {
            await this.client.sendStateEvent(
                this.roomId,
                VoiceBroadcastInfoEventType,
                {
                    device_id: this.client.getDeviceId(),
                    state,
                    last_chunk_sequence: this.sequence,
                    ["m.relates_to"]: {
                        rel_type: RelationType.Reference,
                        event_id: this.infoEventId,
                    },
                } as VoiceBroadcastInfoEventContent,
                this.client.getSafeUserId(),
            );
        };

        await this.callWithRetry(sendEventFn);
    }

    /**
     * Calls the function.
     * On failure adds it to the retry list and triggers connection error.
     * {@link toRetry}
     * {@link onConnectionError}
     */
    private async callWithRetry(retryAbleFn: () => Promise<void>): Promise<void> {
        try {
            await retryAbleFn();
        } catch {
            this.toRetry.push(retryAbleFn);
            this.onConnectionError();
        }
    }

    private async stopRecorder(emit = true): Promise<void> {
        if (!this.recorder) {
            return;
        }

        try {
            const lastChunk = await this.recorder.stop();
            if (lastChunk && emit) {
                await this.onChunkRecorded(lastChunk);
            }
        } catch (err) {
            logger.warn("error stopping voice broadcast recorder", err);
        }
    }
}