package io.livekit.android.room

import com.google.protobuf.util.JsonFormat
import io.livekit.android.ConnectOptions
import io.livekit.android.Version
import io.livekit.android.dagger.InjectionNames
import io.livekit.android.room.track.Track
import io.livekit.android.util.CloseableCoroutineScope
import io.livekit.android.util.Either
import io.livekit.android.util.LKLog
import io.livekit.android.util.safe
import kotlinx.coroutines.*
import kotlinx.coroutines.flow.MutableSharedFlow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.collectLatest
import kotlinx.serialization.decodeFromString
import kotlinx.serialization.encodeToString
import kotlinx.serialization.json.Json
import livekit.LivekitModels
import livekit.LivekitRtc
import okhttp3.*
import okio.ByteString
import okio.ByteString.Companion.toByteString
import org.webrtc.IceCandidate
import org.webrtc.PeerConnection
import org.webrtc.SessionDescription
import javax.inject.Inject
import javax.inject.Named
import kotlin.coroutines.Continuation
import kotlin.coroutines.suspendCoroutine

/**
 * SignalClient to LiveKit WS servers
 * @suppress
 */
class SignalClient
@Inject
constructor(
    private val websocketFactory: WebSocket.Factory,
    private val fromJsonProtobuf: JsonFormat.Parser,
    private val toJsonProtobuf: JsonFormat.Printer,
    private val json: Json,
    private val okHttpClient: OkHttpClient,
    @Named(InjectionNames.SIGNAL_JSON_ENABLED)
    private val useJson: Boolean,
    @Named(InjectionNames.DISPATCHER_IO)
    ioDispatcher: CoroutineDispatcher,
) : WebSocketListener() {
    var isConnected = false
        private set
    private var currentWs: WebSocket? = null
    private var isReconnecting: Boolean = false
    var listener: Listener? = null
    private var lastUrl: String? = null

    private var joinContinuation: CancellableContinuation<Either<LivekitRtc.JoinResponse, Unit>>? = null
    private val coroutineScope = CloseableCoroutineScope(SupervisorJob() + ioDispatcher)

    private val responseFlow = MutableSharedFlow<LivekitRtc.SignalResponse>(Int.MAX_VALUE)
    suspend fun join(
        url: String,
        token: String,
        options: ConnectOptions?,
    ) : LivekitRtc.JoinResponse {
        val joinResponse = connect(url,token, options)
        return (joinResponse as Either.Left).value
    }

    suspend fun reconnect(url: String, token: String){
        connect(
            url,
            token,
            ConnectOptions()
                .apply { reconnect = true }
        )
    }

    suspend fun connect(
        url: String,
        token: String,
        options: ConnectOptions?
    ) : Either<LivekitRtc.JoinResponse, Unit> {
        var wsUrlString = "$url/rtc" +
                "?protocol=$PROTOCOL_VERSION" +
                "&access_token=$token" +
                "&sdk=$SDK_TYPE" +
                "&version=${Version.CLIENT_VERSION}"
        isReconnecting = false
        if (options != null) {
            wsUrlString += "&auto_subscribe="
            wsUrlString += if (options.autoSubscribe) {
                "1"
            } else {
                "0"
            }
            if (options.reconnect) {
                wsUrlString += "&reconnect=1"
                isReconnecting = true
            }
        }

        LKLog.i { "connecting to $wsUrlString" }

        isConnected = false
        currentWs?.cancel()
        currentWs = null

        joinContinuation?.cancel()
        joinContinuation = null

        lastUrl = wsUrlString

        val request = Request.Builder()
            .url(wsUrlString)
            .build()
        currentWs = websocketFactory.newWebSocket(request, this)

        return suspendCancellableCoroutine {
            // Wait for join response through WebSocketListener
            joinContinuation = it
        }
    }

    @ExperimentalCoroutinesApi
    fun onReady(){
        coroutineScope.launch {
            responseFlow.collect {
                responseFlow.resetReplayCache()
                handleSignalResponseImpl(it)
            }
        }
    }
    //--------------------------------- WebSocket Listener --------------------------------------//
    override fun onOpen(webSocket: WebSocket, response: Response) {
        if (isReconnecting) {
            isReconnecting = false
            isConnected = true
            joinContinuation?.resumeWith(Result.success(Either.Right(Unit)))
        }
    }

    override fun onMessage(webSocket: WebSocket, text: String) {
        LKLog.v { text }
        val signalResponseBuilder = LivekitRtc.SignalResponse.newBuilder()
        fromJsonProtobuf.merge(text, signalResponseBuilder)
        val response = signalResponseBuilder.build()

        handleSignalResponse(response)
    }

    override fun onMessage(webSocket: WebSocket, bytes: ByteString) {
        val byteArray = bytes.toByteArray()
        val signalResponseBuilder = LivekitRtc.SignalResponse.newBuilder()
            .mergeFrom(byteArray)
        val response = signalResponseBuilder.build()

        handleSignalResponse(response)
    }

    override fun onClosed(webSocket: WebSocket, code: Int, reason: String) {
        LKLog.v { "websocket closed" }

        listener?.onClose(reason, code)
    }

    override fun onClosing(webSocket: WebSocket, code: Int, reason: String) {
        LKLog.v { "websocket closing" }
    }

    override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
        var reason: String? = null
        try {
            lastUrl?.let {
                val validationUrl = "http" + it.
                    substring(2).
                    replaceFirst("/rtc?", "/rtc/validate?")
                val request = Request.Builder().url(validationUrl).build()
                val resp = okHttpClient.newCall(request).execute()
                if (!resp.isSuccessful) {
                    reason = resp.body?.string()
                }
            }
        } catch (e: Throwable) {
            LKLog.e(e) { "failed to validate connection" }
        }

        if (reason != null) {
            LKLog.e(t) { "websocket failure: $reason" }
            listener?.onError(Exception(reason))
        } else {
            LKLog.e(t) { "websocket failure: $response" }
            listener?.onError(t as Exception)
        }
    }

    //------------------------------- End WebSocket Listener ------------------------------------//

    private fun fromProtoSessionDescription(sd: LivekitRtc.SessionDescription): SessionDescription {
        val rtcSdpType = when (sd.type) {
            SD_TYPE_ANSWER -> SessionDescription.Type.ANSWER
            SD_TYPE_OFFER -> SessionDescription.Type.OFFER
            SD_TYPE_PRANSWER -> SessionDescription.Type.PRANSWER
            else -> throw IllegalArgumentException("invalid RTC SdpType: ${sd.type}")
        }
        return SessionDescription(rtcSdpType, sd.sdp)
    }

    private fun toProtoSessionDescription(sdp: SessionDescription): LivekitRtc.SessionDescription {
        val sdBuilder = LivekitRtc.SessionDescription.newBuilder()
        sdBuilder.sdp = sdp.description
        sdBuilder.type = when (sdp.type) {
            SessionDescription.Type.ANSWER -> SD_TYPE_ANSWER
            SessionDescription.Type.OFFER -> SD_TYPE_OFFER
            SessionDescription.Type.PRANSWER -> SD_TYPE_PRANSWER
            else -> throw IllegalArgumentException("invalid RTC SdpType: ${sdp.type}")
        }

        return sdBuilder.build()
    }

    fun sendOffer(offer: SessionDescription) {
        val sd = toProtoSessionDescription(offer)
        val request = LivekitRtc.SignalRequest.newBuilder()
            .setOffer(sd)
            .build()

        sendRequest(request)
    }

    fun sendAnswer(answer: SessionDescription) {
        val sd = toProtoSessionDescription(answer)
        val request = LivekitRtc.SignalRequest.newBuilder()
            .setAnswer(sd)
            .build()

        sendRequest(request)
    }

    fun sendCandidate(candidate: IceCandidate, target: LivekitRtc.SignalTarget){
        val iceCandidateJSON = IceCandidateJSON(
            candidate = candidate.sdp,
            sdpMid = candidate.sdpMid,
            sdpMLineIndex = candidate.sdpMLineIndex
        )

        val trickleRequest = LivekitRtc.TrickleRequest.newBuilder()
            .setCandidateInit(json.encodeToString(iceCandidateJSON))
            .setTarget(target)
            .build()

        val request = LivekitRtc.SignalRequest.newBuilder()
            .setTrickle(trickleRequest)
            .build()

        sendRequest(request)
    }

    fun sendMuteTrack(trackSid: String, muted: Boolean) {
        val muteRequest = LivekitRtc.MuteTrackRequest.newBuilder()
            .setSid(trackSid)
            .setMuted(muted)
            .build()

        val request = LivekitRtc.SignalRequest.newBuilder()
            .setMute(muteRequest)
            .build()

        sendRequest(request)
    }

    /**
     * @param builder an optional builder to include other parameters related to the track
     */
    fun sendAddTrack(
        cid: String,
        name: String,
        type: LivekitModels.TrackType,
        builder: LivekitRtc.AddTrackRequest.Builder = LivekitRtc.AddTrackRequest.newBuilder()
    ) {
        val addTrackRequest = builder
            .setCid(cid)
            .setName(name)
            .setType(type)
        val request = LivekitRtc.SignalRequest.newBuilder()
            .setAddTrack(addTrackRequest)
            .build()

        sendRequest(request)
    }

    fun sendUpdateTrackSettings(sid: String, disabled: Boolean, videoQuality: LivekitRtc.VideoQuality) {
        val trackSettings = LivekitRtc.UpdateTrackSettings.newBuilder()
            .addTrackSids(sid)
            .setDisabled(disabled)
            .setQuality(videoQuality)

         val request = LivekitRtc.SignalRequest.newBuilder()
            .setTrackSetting(trackSettings)
            .build()

        sendRequest(request)
    }

    fun sendUpdateSubscription(sid: String, subscribe: Boolean) {
        val subscription = LivekitRtc.UpdateSubscription.newBuilder()
            .addTrackSids(sid)
            .setSubscribe(subscribe)

         val request = LivekitRtc.SignalRequest.newBuilder()
            .setSubscription(subscription)
            .build()

        sendRequest(request)
    }
    
    fun sendLeave() {
        val request = LivekitRtc.SignalRequest.newBuilder()
            .setLeave(LivekitRtc.LeaveRequest.newBuilder().build())
            .build()
        sendRequest(request)
    }

    private fun sendRequest(request: LivekitRtc.SignalRequest) {
        LKLog.v { "sending request: $request" }
        if (!isConnected || currentWs == null) {
            LKLog.w { "not connected, could not send request $request" }
            return
        }
        val sent: Boolean
        if (useJson) {
            val message = toJsonProtobuf.print(request)
            sent = currentWs?.send(message) ?: false
        } else {
            val message = request.toByteArray().toByteString()
            sent = currentWs?.send(message) ?: false
        }

        if (!sent) {
            LKLog.e { "error sending request: $request" }
        }
    }

    private fun handleSignalResponse(response: LivekitRtc.SignalResponse) {
        if (!isConnected) {
            // Only handle joins if not connected.
            if (response.hasJoin()) {
                isConnected = true
                joinContinuation?.resumeWith(Result.success(Either.Left(response.join)))
            } else {
                LKLog.e { "Received response while not connected. ${toJsonProtobuf.print(response)}" }
            }
            return
        }
        coroutineScope.launch {
            responseFlow.tryEmit(response)
        }
    }
    private fun handleSignalResponseImpl(response: LivekitRtc.SignalResponse) {
        LKLog.v { "response: $response" }
        when (response.messageCase) {
            LivekitRtc.SignalResponse.MessageCase.ANSWER -> {
                val sd = fromProtoSessionDescription(response.answer)
                listener?.onAnswer(sd)
            }
            LivekitRtc.SignalResponse.MessageCase.OFFER -> {
                val sd = fromProtoSessionDescription(response.offer)
                listener?.onOffer(sd)
            }
            LivekitRtc.SignalResponse.MessageCase.TRICKLE -> {
                val iceCandidateJson =
                    json.decodeFromString<IceCandidateJSON>(response.trickle.candidateInit)
                val iceCandidate = IceCandidate(
                    iceCandidateJson.sdpMid,
                    iceCandidateJson.sdpMLineIndex,
                    iceCandidateJson.candidate
                )
                listener?.onTrickle(iceCandidate, response.trickle.target)
            }
            LivekitRtc.SignalResponse.MessageCase.UPDATE -> {
                listener?.onParticipantUpdate(response.update.participantsList)
            }
            LivekitRtc.SignalResponse.MessageCase.TRACK_PUBLISHED -> {
                listener?.onLocalTrackPublished(response.trackPublished)
            }
            LivekitRtc.SignalResponse.MessageCase.SPEAKERS_CHANGED -> {
                listener?.onSpeakersChanged(response.speakersChanged.speakersList)
            }
            LivekitRtc.SignalResponse.MessageCase.JOIN -> {
                LKLog.d { "received unexpected extra join message?" }
            }
            LivekitRtc.SignalResponse.MessageCase.LEAVE -> {
                listener?.onLeave()
            }
            LivekitRtc.SignalResponse.MessageCase.MUTE -> {
                listener?.onRemoteMuteChanged(response.mute.sid, response.mute.muted)
            }
            LivekitRtc.SignalResponse.MessageCase.ROOM_UPDATE -> {
                //TODO
            }
            LivekitRtc.SignalResponse.MessageCase.MESSAGE_NOT_SET,
            null -> {
                LKLog.v { "empty messageCase!" }
            }
        }.safe()
    }

    fun close() {
        isConnected = false
        coroutineScope.close()
        currentWs?.close(1000, "Normal Closure")
    }

    interface Listener {
        fun onAnswer(sessionDescription: SessionDescription)
        fun onOffer(sessionDescription: SessionDescription)
        fun onTrickle(candidate: IceCandidate, target: LivekitRtc.SignalTarget)
        fun onLocalTrackPublished(response: LivekitRtc.TrackPublishedResponse)
        fun onParticipantUpdate(updates: List<LivekitModels.ParticipantInfo>)
        fun onSpeakersChanged(speakers: List<LivekitModels.SpeakerInfo>)
        fun onClose(reason: String, code: Int)
        fun onRemoteMuteChanged(trackSid: String, muted: Boolean)
        fun onLeave()
        fun onError(error: Exception)
    }

    companion object {
        const val SD_TYPE_ANSWER = "answer"
        const val SD_TYPE_OFFER = "offer"
        const val SD_TYPE_PRANSWER = "pranswer"
        const val PROTOCOL_VERSION = 4
        const val SDK_TYPE = "android"

        private fun iceServer(url: String) =
            PeerConnection.IceServer.builder(url).createIceServer()

        // more stun servers might slow it down, WebRTC recommends 3 max
        val DEFAULT_ICE_SERVERS = listOf(
            iceServer("stun:stun.l.google.com:19302"),
            iceServer("stun:stun1.l.google.com:19302"),
//            iceServer("stun:stun2.l.google.com:19302"),
//            iceServer("stun:stun3.l.google.com:19302"),
//            iceServer("stun:stun4.l.google.com:19302"),
        )
    }
}