/*
 * 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.model

import android.app.Application
import android.net.Uri
import android.os.RemoteException
import androidx.annotation.StringRes
import androidx.lifecycle.SavedStateHandle
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import androidx.navigation.toRoute
import com.geeksville.mesh.AdminProtos
import com.geeksville.mesh.ChannelProtos
import com.geeksville.mesh.ClientOnlyProtos.DeviceProfile
import com.geeksville.mesh.ConfigProtos
import com.geeksville.mesh.IMeshService
import com.geeksville.mesh.MeshProtos
import com.geeksville.mesh.ModuleConfigProtos
import com.geeksville.mesh.Portnums
import com.geeksville.mesh.Position
import com.geeksville.mesh.R
import com.geeksville.mesh.android.Logging
import com.geeksville.mesh.config
import com.geeksville.mesh.database.entity.MyNodeEntity
import com.geeksville.mesh.deviceProfile
import com.geeksville.mesh.moduleConfig
import com.geeksville.mesh.repository.datastore.RadioConfigRepository
import com.geeksville.mesh.service.MeshService.ConnectionState
import com.geeksville.mesh.ui.AdminRoute
import com.geeksville.mesh.ui.ConfigRoute
import com.geeksville.mesh.ui.ModuleRoute
import com.geeksville.mesh.ui.ResponseState
import com.geeksville.mesh.ui.Route
import com.geeksville.mesh.util.UiText
import com.google.protobuf.MessageLite
import dagger.hilt.android.lifecycle.HiltViewModel
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.flow.firstOrNull
import kotlinx.coroutines.flow.launchIn
import kotlinx.coroutines.flow.mapLatest
import kotlinx.coroutines.flow.onEach
import kotlinx.coroutines.flow.update
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import java.io.FileOutputStream
import javax.inject.Inject

/**
 * Data class that represents the current RadioConfig state.
 */
data class RadioConfigState(
    val isLocal: Boolean = false,
    val connected: Boolean = false,
    val route: String = "",
    val metadata: MeshProtos.DeviceMetadata? = null,
    val userConfig: MeshProtos.User = MeshProtos.User.getDefaultInstance(),
    val channelList: List<ChannelProtos.ChannelSettings> = emptyList(),
    val radioConfig: ConfigProtos.Config = config {},
    val moduleConfig: ModuleConfigProtos.ModuleConfig = moduleConfig {},
    val ringtone: String = "",
    val cannedMessageMessages: String = "",
    val responseState: ResponseState<Boolean> = ResponseState.Empty,
)

@HiltViewModel
class RadioConfigViewModel @Inject constructor(
    savedStateHandle: SavedStateHandle,
    private val app: Application,
    private val radioConfigRepository: RadioConfigRepository,
) : ViewModel(), Logging {
    private val meshService: IMeshService? get() = radioConfigRepository.meshService

    private val destNum = savedStateHandle.toRoute<Route.RadioConfig>().destNum
    private val _destNode = MutableStateFlow<Node?>(null)
    val destNode: StateFlow<Node?> get() = _destNode

    private val requestIds = MutableStateFlow(hashSetOf<Int>())
    private val _radioConfigState = MutableStateFlow(RadioConfigState())
    val radioConfigState: StateFlow<RadioConfigState> = _radioConfigState

    private val _currentDeviceProfile = MutableStateFlow(deviceProfile {})
    val currentDeviceProfile get() = _currentDeviceProfile.value

    init {
        @OptIn(ExperimentalCoroutinesApi::class)
        radioConfigRepository.nodeDBbyNum
            .mapLatest { nodes -> nodes[destNum] ?: nodes.values.firstOrNull() }
            .distinctUntilChanged()
            .onEach {
                _destNode.value = it
                _radioConfigState.update { state -> state.copy(metadata = it?.metadata) }
            }
            .launchIn(viewModelScope)

        radioConfigRepository.deviceProfileFlow.onEach {
            _currentDeviceProfile.value = it
        }.launchIn(viewModelScope)

        radioConfigRepository.meshPacketFlow.onEach(::processPacketResponse)
            .launchIn(viewModelScope)

        combine(radioConfigRepository.connectionState, radioConfigState) { connState, configState ->
            _radioConfigState.update { it.copy(connected = connState == ConnectionState.CONNECTED) }
            if (connState.isDisconnected() && configState.responseState.isWaiting()) {
                sendError(R.string.disconnected)
            }
        }.launchIn(viewModelScope)

        radioConfigRepository.myNodeInfo.onEach { ni ->
            _radioConfigState.update { it.copy(isLocal = destNum == null || destNum == ni?.myNodeNum) }
        }.launchIn(viewModelScope)

        debug("RadioConfigViewModel created")
    }

    private val myNodeInfo: StateFlow<MyNodeEntity?> get() = radioConfigRepository.myNodeInfo
    val myNodeNum get() = myNodeInfo.value?.myNodeNum
    val maxChannels get() = myNodeInfo.value?.maxChannels ?: 8

    val hasPaFan: Boolean
        get() = destNode.value?.user?.hwModel in setOf(
            null,
            MeshProtos.HardwareModel.UNRECOGNIZED,
            MeshProtos.HardwareModel.UNSET,
            MeshProtos.HardwareModel.BETAFPV_2400_TX,
            MeshProtos.HardwareModel.RADIOMASTER_900_BANDIT_NANO,
            MeshProtos.HardwareModel.RADIOMASTER_900_BANDIT,
        )

    override fun onCleared() {
        super.onCleared()
        debug("RadioConfigViewModel cleared")
    }

    private fun request(
        destNum: Int,
        requestAction: suspend (IMeshService, Int, Int) -> Unit,
        errorMessage: String,
    ) = viewModelScope.launch {
        meshService?.let { service ->
            val packetId = service.packetId
            try {
                requestAction(service, packetId, destNum)
                requestIds.update { it.apply { add(packetId) } }
                _radioConfigState.update { state ->
                    if (state.responseState is ResponseState.Loading) {
                        val total = maxOf(requestIds.value.size, state.responseState.total)
                        state.copy(responseState = state.responseState.copy(total = total))
                    } else {
                        state.copy(
                            route = "", // setter (response is PortNum.ROUTING_APP)
                            responseState = ResponseState.Loading(),
                        )
                    }
                }
            } catch (ex: RemoteException) {
                errormsg("$errorMessage: ${ex.message}")
            }
        }
    }

    fun setOwner(user: MeshProtos.User) {
        setRemoteOwner(destNode.value?.num ?: return, user)
    }

    private fun setRemoteOwner(destNum: Int, user: MeshProtos.User) = request(
        destNum,
        { service, packetId, _ ->
            _radioConfigState.update { it.copy(userConfig = user) }
            service.setRemoteOwner(packetId, user.toByteArray())
        },
        "Request setOwner error",
    )

    private fun getOwner(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.getRemoteOwner(packetId, dest) },
        "Request getOwner error"
    )

    fun updateChannels(
        new: List<ChannelProtos.ChannelSettings>,
        old: List<ChannelProtos.ChannelSettings>,
    ) {
        val destNum = destNode.value?.num ?: return
        getChannelList(new, old).forEach { setRemoteChannel(destNum, it) }

        if (destNum == myNodeNum) viewModelScope.launch {
            radioConfigRepository.replaceAllSettings(new)
        }
        _radioConfigState.update { it.copy(channelList = new) }
    }

    private fun setChannels(channelUrl: String) = viewModelScope.launch {
        val new = Uri.parse(channelUrl).toChannelSet()
        val old = radioConfigRepository.channelSetFlow.firstOrNull() ?: return@launch
        updateChannels(new.settingsList, old.settingsList)
    }

    private fun setRemoteChannel(destNum: Int, channel: ChannelProtos.Channel) = request(
        destNum,
        { service, packetId, dest ->
            service.setRemoteChannel(packetId, dest, channel.toByteArray())
        },
        "Request setRemoteChannel error"
    )

    private fun getChannel(destNum: Int, index: Int) = request(
        destNum,
        { service, packetId, dest -> service.getRemoteChannel(packetId, dest, index) },
        "Request getChannel error"
    )

    fun setConfig(config: ConfigProtos.Config) {
        setRemoteConfig(destNode.value?.num ?: return, config)
    }

    private fun setRemoteConfig(destNum: Int, config: ConfigProtos.Config) = request(
        destNum,
        { service, packetId, dest ->
            _radioConfigState.update { it.copy(radioConfig = config) }
            service.setRemoteConfig(packetId, dest, config.toByteArray())
        },
        "Request setConfig error",
    )

    private fun getConfig(destNum: Int, configType: Int) = request(
        destNum,
        { service, packetId, dest -> service.getRemoteConfig(packetId, dest, configType) },
        "Request getConfig error",
    )

    fun setModuleConfig(config: ModuleConfigProtos.ModuleConfig) {
        setModuleConfig(destNode.value?.num ?: return, config)
    }

    private fun setModuleConfig(destNum: Int, config: ModuleConfigProtos.ModuleConfig) = request(
        destNum,
        { service, packetId, dest ->
            _radioConfigState.update { it.copy(moduleConfig = config) }
            service.setModuleConfig(packetId, dest, config.toByteArray())
        },
        "Request setConfig error",
    )

    private fun getModuleConfig(destNum: Int, configType: Int) = request(
        destNum,
        { service, packetId, dest -> service.getModuleConfig(packetId, dest, configType) },
        "Request getModuleConfig error",
    )

    fun setRingtone(ringtone: String) {
        val destNum = destNode.value?.num ?: return
        _radioConfigState.update { it.copy(ringtone = ringtone) }
        meshService?.setRingtone(destNum, ringtone)
    }

    private fun getRingtone(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.getRingtone(packetId, dest) },
        "Request getRingtone error"
    )

    fun setCannedMessages(messages: String) {
        val destNum = destNode.value?.num ?: return
        _radioConfigState.update { it.copy(cannedMessageMessages = messages) }
        meshService?.setCannedMessages(destNum, messages)
    }

    private fun getCannedMessages(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.getCannedMessages(packetId, dest) },
        "Request getCannedMessages error"
    )

    private fun requestShutdown(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.requestShutdown(packetId, dest) },
        "Request shutdown error"
    )

    private fun requestReboot(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.requestReboot(packetId, dest) },
        "Request reboot error"
    )

    private fun requestFactoryReset(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.requestFactoryReset(packetId, dest) },
        "Request factory reset error"
    )

    private fun requestNodedbReset(destNum: Int) = request(
        destNum,
        { service, packetId, dest -> service.requestNodedbReset(packetId, dest) },
        "Request NodeDB reset error"
    )

    private fun sendAdminRequest(destNum: Int) {
        val route = radioConfigState.value.route
        _radioConfigState.update { it.copy(route = "") } // setter (response is PortNum.ROUTING_APP)

        when (route) {
            AdminRoute.REBOOT.name -> requestReboot(destNum)
            AdminRoute.SHUTDOWN.name -> with(radioConfigState.value) {
                if (metadata != null && !metadata.canShutdown) {
                    sendError(R.string.cant_shutdown)
                } else {
                    requestShutdown(destNum)
                }
            }

            AdminRoute.FACTORY_RESET.name -> requestFactoryReset(destNum)
            AdminRoute.NODEDB_RESET.name -> requestNodedbReset(destNum)
        }
    }

    fun setFixedPosition(position: Position) {
        val destNum = destNode.value?.num ?: return
        try {
            meshService?.setFixedPosition(destNum, position)
        } catch (ex: RemoteException) {
            errormsg("Set fixed position error: ${ex.message}")
        }
    }

    fun removeFixedPosition() = setFixedPosition(Position(0.0, 0.0, 0))

    fun importProfile(
        uri: Uri,
        onResult: (DeviceProfile) -> Unit,
    ) = viewModelScope.launch(Dispatchers.IO) {
        try {
            app.contentResolver.openInputStream(uri).use { inputStream ->
                val bytes = inputStream?.readBytes()
                val protobuf = DeviceProfile.parseFrom(bytes)
                onResult(protobuf)
            }
        } catch (ex: Exception) {
            errormsg("Import DeviceProfile error: ${ex.message}")
            sendError(ex.customMessage)
        }
    }

    fun exportProfile(uri: Uri, profile: DeviceProfile) = viewModelScope.launch {
        writeToUri(uri, profile)
    }

    private suspend fun writeToUri(uri: Uri, message: MessageLite) = withContext(Dispatchers.IO) {
        try {
            app.contentResolver.openFileDescriptor(uri, "wt")?.use { parcelFileDescriptor ->
                FileOutputStream(parcelFileDescriptor.fileDescriptor).use { outputStream ->
                    message.writeTo(outputStream)
                }
            }
            setResponseStateSuccess()
        } catch (ex: Exception) {
            errormsg("Can't write file error: ${ex.message}")
            sendError(ex.customMessage)
        }
    }

    fun installProfile(protobuf: DeviceProfile) = with(protobuf) {
        meshService?.beginEditSettings()
        if (hasLongName() || hasShortName()) {
            destNode.value?.user?.let {
                val user = MeshProtos.User.newBuilder()
                    .setId(it.id)
                    .setLongName(if (hasLongName()) longName else it.longName)
                    .setShortName(if (hasShortName()) shortName else it.shortName)
                    .setIsLicensed(it.isLicensed)
                    .build()
                setOwner(user)
            }
        }
        if (hasChannelUrl()) {
            try {
                setChannels(channelUrl)
            } catch (ex: Exception) {
                errormsg("DeviceProfile channel import error", ex)
                sendError(ex.customMessage)
            }
        }
        if (hasConfig()) {
            val descriptor = ConfigProtos.Config.getDescriptor()
            config.allFields.forEach { (field, value) ->
                val newConfig = ConfigProtos.Config.newBuilder()
                    .setField(descriptor.findFieldByName(field.name), value)
                    .build()
                setConfig(newConfig)
            }
        }
        if (hasFixedPosition()) {
            setFixedPosition(Position(fixedPosition))
        }
        if (hasModuleConfig()) {
            val descriptor = ModuleConfigProtos.ModuleConfig.getDescriptor()
            moduleConfig.allFields.forEach { (field, value) ->
                val newConfig = ModuleConfigProtos.ModuleConfig.newBuilder()
                    .setField(descriptor.findFieldByName(field.name), value)
                    .build()
                setModuleConfig(newConfig)
            }
        }
        meshService?.commitEditSettings()
    }

    fun clearPacketResponse() {
        requestIds.value = hashSetOf()
        _radioConfigState.update { it.copy(responseState = ResponseState.Empty) }
    }

    fun setResponseStateLoading(route: Enum<*>) {
        val destNum = destNode.value?.num ?: return

        _radioConfigState.update {
            RadioConfigState(
                isLocal = it.isLocal,
                connected = it.connected,
                route = route.name,
                metadata = it.metadata,
                responseState = ResponseState.Loading(),
            )
        }

        when (route) {
            ConfigRoute.USER -> getOwner(destNum)

            ConfigRoute.CHANNELS -> {
                getChannel(destNum, 0)
                getConfig(destNum, ConfigRoute.LORA.type)
                // channel editor is synchronous, so we don't use requestIds as total
                setResponseStateTotal(maxChannels + 1)
            }

            is AdminRoute -> {
                getConfig(destNum, AdminProtos.AdminMessage.ConfigType.SESSIONKEY_CONFIG_VALUE)
                setResponseStateTotal(2)
            }

            is ConfigRoute -> {
                if (route == ConfigRoute.LORA) {
                    getChannel(destNum, 0)
                }
                getConfig(destNum, route.type)
            }

            is ModuleRoute -> {
                if (route == ModuleRoute.CANNED_MESSAGE) {
                    getCannedMessages(destNum)
                }
                if (route == ModuleRoute.EXT_NOTIFICATION) {
                    getRingtone(destNum)
                }
                getModuleConfig(destNum, route.type)
            }
        }
    }

    private fun setResponseStateTotal(total: Int) {
        _radioConfigState.update { state ->
            if (state.responseState is ResponseState.Loading) {
                state.copy(responseState = state.responseState.copy(total = total))
            } else {
                state // Return the unchanged state for other response states
            }
        }
    }

    private fun setResponseStateSuccess() {
        _radioConfigState.update { state ->
            if (state.responseState is ResponseState.Loading) {
                state.copy(responseState = ResponseState.Success(true))
            } else {
                state // Return the unchanged state for other response states
            }
        }
    }

    private val Exception.customMessage: String get() = "${javaClass.simpleName}: $message"
    private fun sendError(error: String) = setResponseStateError(UiText.DynamicString(error))
    private fun sendError(@StringRes id: Int) = setResponseStateError(UiText.StringResource(id))
    private fun setResponseStateError(error: UiText) {
        _radioConfigState.update { it.copy(responseState = ResponseState.Error(error)) }
    }

    private fun incrementCompleted() {
        _radioConfigState.update { state ->
            if (state.responseState is ResponseState.Loading) {
                val increment = state.responseState.completed + 1
                state.copy(responseState = state.responseState.copy(completed = increment))
            } else {
                state // Return the unchanged state for other response states
            }
        }
    }

    private fun processPacketResponse(packet: MeshProtos.MeshPacket) {
        val data = packet.decoded
        if (data.requestId !in requestIds.value) return
        val route = radioConfigState.value.route

        val destNum = destNode.value?.num ?: return
        val debugMsg = "requestId: ${data.requestId.toUInt()} to: ${destNum.toUInt()} received %s"

        if (data?.portnumValue == Portnums.PortNum.ROUTING_APP_VALUE) {
            val parsed = MeshProtos.Routing.parseFrom(data.payload)
            debug(debugMsg.format(parsed.errorReason.name))
            if (parsed.errorReason != MeshProtos.Routing.Error.NONE) {
                sendError(getStringResFrom(parsed.errorReasonValue))
            } else if (packet.from == destNum && route.isEmpty()) {
                requestIds.update { it.apply { remove(data.requestId) } }
                if (requestIds.value.isEmpty()) {
                    setResponseStateSuccess()
                } else {
                    incrementCompleted()
                }
            }
        }
        if (data?.portnumValue == Portnums.PortNum.ADMIN_APP_VALUE) {
            val parsed = AdminProtos.AdminMessage.parseFrom(data.payload)
            debug(debugMsg.format(parsed.payloadVariantCase.name))
            if (destNum != packet.from) {
                sendError("Unexpected sender: ${packet.from.toUInt()} instead of ${destNum.toUInt()}.")
                return
            }
            when (parsed.payloadVariantCase) {
                AdminProtos.AdminMessage.PayloadVariantCase.GET_DEVICE_METADATA_RESPONSE -> {
                    _radioConfigState.update { it.copy(metadata = parsed.getDeviceMetadataResponse) }
                    incrementCompleted()
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_CHANNEL_RESPONSE -> {
                    val response = parsed.getChannelResponse
                    // Stop once we get to the first disabled entry
                    if (response.role != ChannelProtos.Channel.Role.DISABLED) {
                        _radioConfigState.update { state ->
                            state.copy(channelList = state.channelList.toMutableList().apply {
                                add(response.index, response.settings)
                            })
                        }
                        incrementCompleted()
                        if (response.index + 1 < maxChannels && route == ConfigRoute.CHANNELS.name) {
                            // Not done yet, request next channel
                            getChannel(destNum, response.index + 1)
                        }
                    } else {
                        // Received last channel, update total and start channel editor
                        setResponseStateTotal(response.index + 1)
                    }
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_OWNER_RESPONSE -> {
                    _radioConfigState.update { it.copy(userConfig = parsed.getOwnerResponse) }
                    incrementCompleted()
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_CONFIG_RESPONSE -> {
                    val response = parsed.getConfigResponse
                    if (response.payloadVariantCase.number == 0) { // PAYLOADVARIANT_NOT_SET
                        sendError(response.payloadVariantCase.name)
                    }
                    _radioConfigState.update { it.copy(radioConfig = response) }
                    incrementCompleted()
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_MODULE_CONFIG_RESPONSE -> {
                    val response = parsed.getModuleConfigResponse
                    if (response.payloadVariantCase.number == 0) { // PAYLOADVARIANT_NOT_SET
                        sendError(response.payloadVariantCase.name)
                    }
                    _radioConfigState.update { it.copy(moduleConfig = response) }
                    incrementCompleted()
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_CANNED_MESSAGE_MODULE_MESSAGES_RESPONSE -> {
                    _radioConfigState.update {
                        it.copy(cannedMessageMessages = parsed.getCannedMessageModuleMessagesResponse)
                    }
                    incrementCompleted()
                }

                AdminProtos.AdminMessage.PayloadVariantCase.GET_RINGTONE_RESPONSE -> {
                    _radioConfigState.update { it.copy(ringtone = parsed.getRingtoneResponse) }
                    incrementCompleted()
                }

                else -> debug("No custom processing needed for ${parsed.payloadVariantCase}")
            }

            if (AdminRoute.entries.any { it.name == route }) {
                sendAdminRequest(destNum)
            }
            requestIds.update { it.apply { remove(data.requestId) } }
        }
    }
}