/*
 * Copyright (c) 2025 Meshtastic LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package com.geeksville.mesh.service

import com.geeksville.mesh.MeshProtos
import com.geeksville.mesh.MeshProtos.MeshPacket
import com.geeksville.mesh.MeshProtos.ToRadio
import com.geeksville.mesh.concurrent.handledLaunch
import com.geeksville.mesh.fromRadio
import com.geeksville.mesh.repository.radio.RadioInterfaceService
import dagger.Lazy
import java8.util.concurrent.CompletableFuture
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.delay
import kotlinx.coroutines.withTimeoutOrNull
import org.meshtastic.core.data.repository.MeshLogRepository
import org.meshtastic.core.data.repository.PacketRepository
import org.meshtastic.core.database.entity.MeshLog
import org.meshtastic.core.model.DataPacket
import org.meshtastic.core.model.MessageStatus
import org.meshtastic.core.model.util.toOneLineString
import org.meshtastic.core.model.util.toPIIString
import org.meshtastic.core.service.ConnectionState
import timber.log.Timber
import java.util.UUID
import java.util.concurrent.ConcurrentLinkedQueue
import java.util.concurrent.TimeUnit
import java.util.concurrent.TimeoutException
import javax.inject.Inject
import javax.inject.Singleton

@Singleton
class PacketHandler
@Inject
constructor(
    private val packetRepository: Lazy<PacketRepository>,
    private val serviceBroadcasts: MeshServiceBroadcasts,
    private val radioInterfaceService: RadioInterfaceService,
    private val meshLogRepository: Lazy<MeshLogRepository>,
    private val connectionStateHolder: MeshServiceConnectionStateHolder,
) {

    private var queueJob: Job? = null
    private val scope = CoroutineScope(Dispatchers.IO)

    private val queuedPackets = ConcurrentLinkedQueue<MeshPacket>()
    private val queueResponse = mutableMapOf<Int, CompletableFuture<Boolean>>()

    /**
     * Send a command/packet to our radio. But cope with the possibility that we might start up before we are fully
     * bound to the RadioInterfaceService
     */
    fun sendToRadio(p: ToRadio.Builder) {
        val built = p.build()
        Timber.d("Sending to radio ${built.toPIIString()}")
        val b = built.toByteArray()

        radioInterfaceService.sendToRadio(b)
        changeStatus(p.packet.id, MessageStatus.ENROUTE)

        if (p.packet.hasDecoded()) {
            val packetToSave =
                MeshLog(
                    uuid = UUID.randomUUID().toString(),
                    message_type = "Packet",
                    received_date = System.currentTimeMillis(),
                    raw_message = p.packet.toString(),
                    fromNum = p.packet.from,
                    portNum = p.packet.decoded.portnumValue,
                    fromRadio = fromRadio { packet = p.packet },
                )
            insertMeshLog(packetToSave)
        }
    }

    /**
     * Send a mesh packet to the radio, if the radio is not currently connected this function will throw
     * NotConnectedException
     */
    fun sendToRadio(packet: MeshPacket) {
        queuedPackets.add(packet)
        startPacketQueue()
    }

    fun stopPacketQueue() {
        if (queueJob?.isActive == true) {
            Timber.i("Stopping packet queueJob")
            queueJob?.cancel()
            queueJob = null
            queuedPackets.clear()
            queueResponse.entries.lastOrNull { !it.value.isDone }?.value?.complete(false)
            queueResponse.clear()
        }
    }

    fun handleQueueStatus(queueStatus: MeshProtos.QueueStatus) {
        Timber.d("queueStatus ${queueStatus.toOneLineString()}")
        val (success, isFull, requestId) = with(queueStatus) { Triple(res == 0, free == 0, meshPacketId) }
        if (success && isFull) return // Queue is full, wait for free != 0
        if (requestId != 0) {
            queueResponse.remove(requestId)?.complete(success)
        } else {
            queueResponse.entries.lastOrNull { !it.value.isDone }?.value?.complete(success)
        }
    }

    fun removeResponse(dataRequestId: Int, complete: Boolean) {
        queueResponse.remove(dataRequestId)?.complete(complete)
    }

    @Suppress("TooGenericExceptionCaught", "SwallowedException")
    private fun startPacketQueue() {
        if (queueJob?.isActive == true) return
        queueJob =
            scope.handledLaunch {
                Timber.d("packet queueJob started")
                while (connectionStateHolder.getState() == ConnectionState.CONNECTED) {
                    // take the first packet from the queue head
                    val packet = queuedPackets.poll() ?: break
                    try {
                        // send packet to the radio and wait for response
                        val response = sendPacket(packet)
                        Timber.d("queueJob packet id=${packet.id.toUInt()} waiting")
                        val success = response.get(2, TimeUnit.MINUTES)
                        Timber.d("queueJob packet id=${packet.id.toUInt()} success $success")
                    } catch (e: TimeoutException) {
                        Timber.d("queueJob packet id=${packet.id.toUInt()} timeout")
                    } catch (e: Exception) {
                        Timber.d("queueJob packet id=${packet.id.toUInt()} failed")
                    }
                }
            }
    }

    /** Change the status on a DataPacket and update watchers */
    private fun changeStatus(packetId: Int, m: MessageStatus) = scope.handledLaunch {
        if (packetId != 0) {
            getDataPacketById(packetId)?.let { p ->
                if (p.status == m) return@handledLaunch
                packetRepository.get().updateMessageStatus(p, m)
                serviceBroadcasts.broadcastMessageStatus(packetId, m)
            }
        }
    }

    @Suppress("MagicNumber")
    private suspend fun getDataPacketById(packetId: Int): DataPacket? = withTimeoutOrNull(1000) {
        var dataPacket: DataPacket? = null
        while (dataPacket == null) {
            dataPacket = packetRepository.get().getPacketById(packetId)?.data
            if (dataPacket == null) delay(100)
        }
        dataPacket
    }

    @Suppress("TooGenericExceptionCaught")
    private fun sendPacket(packet: MeshPacket): CompletableFuture<Boolean> {
        // send the packet to the radio and return a CompletableFuture that will be completed with
        // the result
        val future = CompletableFuture<Boolean>()
        queueResponse[packet.id] = future
        try {
            if (connectionStateHolder.getState() != ConnectionState.CONNECTED) throw RadioNotConnectedException()
            sendToRadio(ToRadio.newBuilder().apply { this.packet = packet })
        } catch (ex: Exception) {
            Timber.e("sendToRadio error:", ex)
            future.complete(false)
        }
        return future
    }

    private fun insertMeshLog(packetToSave: MeshLog) {
        scope.handledLaunch {
            // Do not log, because might contain PII
            // info("insert: ${packetToSave.message_type} =
            // ${packetToSave.raw_message.toOneLineString()}")
            meshLogRepository.get().insert(packetToSave)
        }
    }
}