package org.terst.nav

import android.util.Log
import android.annotation.SuppressLint
import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.app.Service
import android.content.Context
import android.content.Intent
import android.location.Location
import android.os.IBinder
import android.os.Looper
import androidx.core.app.NotificationCompat
import com.google.android.gms.location.*
import kotlinx.coroutines.channels.BufferOverflow
import kotlinx.coroutines.flow.MutableSharedFlow
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.SharedFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.update
import org.terst.nav.nmea.NmeaParser
import org.terst.nav.nmea.NmeaStreamManager
import org.terst.nav.sensors.DepthData
import org.terst.nav.sensors.HeadingData
import org.terst.nav.sensors.WindData
import org.terst.nav.gps.GpsPosition
import kotlinx.coroutines.flow.collectLatest
import kotlinx.coroutines.tasks.await
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.cancel
import kotlinx.coroutines.launch

data class GpsData(
    val latitude: Double,
    val longitude: Double,
    val speedOverGround: Float, // m/s
    val courseOverGround: Float // degrees
) {
    fun toLocation(): Location {
        val location = Location("GpsData")
        location.latitude = latitude
        location.longitude = longitude
        location.speed = speedOverGround
        location.bearing = courseOverGround
        return location
    }
}

class LocationService : Service() {

    private lateinit var fusedLocationClient: FusedLocationProviderClient
    private lateinit var locationCallback: LocationCallback
    private lateinit var anchorAlarmManager: AnchorAlarmManager
    private lateinit var barometerSensorManager: BarometerSensorManager
    private lateinit var nmeaParser: NmeaParser
    private lateinit var nmeaStreamManager: NmeaStreamManager
    private val serviceScope = CoroutineScope(Dispatchers.IO + SupervisorJob())

    private val NOTIFICATION_CHANNEL_ID = "location_service_channel"
    private val NOTIFICATION_ID = 123

    private var isAlarmTriggered = false // To prevent repeated alarm triggering

    override fun onCreate() {
        super.onCreate()
        Log.d("LocationService", "Service created")
        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
        anchorAlarmManager = AnchorAlarmManager(this) // Initialize with service context
        barometerSensorManager = BarometerSensorManager(this)
        nmeaParser = NmeaParser()
        nmeaStreamManager = NmeaStreamManager(nmeaParser, serviceScope)
        createNotificationChannel()

        // Observe barometer status and update our public state
        serviceScope.launch {
            barometerSensorManager.barometerStatus.collect { status ->
                _barometerStatus.value = status
            }
        }

        // Collect NMEA GPS positions
        serviceScope.launch {
            nmeaStreamManager.nmeaGpsPosition.collectLatest { gpsPosition ->
                _nmeaGpsPositionFlow.emit(gpsPosition)
            }
        }

        // Collect NMEA Wind Data
        serviceScope.launch {
            nmeaStreamManager.nmeaWindData.collectLatest { windData ->
                _nmeaWindDataFlow.emit(windData)
            }
        }

        // Collect NMEA Depth Data
        serviceScope.launch {
            nmeaStreamManager.nmeaDepthData.collectLatest { depthData ->
                _nmeaDepthDataFlow.emit(depthData)
            }
        }

        // Collect NMEA Heading Data
        serviceScope.launch {
            nmeaStreamManager.nmeaHeadingData.collectLatest { headingData ->
                _nmeaHeadingDataFlow.emit(headingData)
            }
        }

        // Mock tidal current data generator
        serviceScope.launch {
            while (true) {
                val currents = MockTidalCurrentGenerator.generateMockCurrents()
                _tidalCurrentState.update { it.copy(currents = currents) }
                kotlinx.coroutines.delay(60000) // Update every minute
            }
        }

        locationCallback = object : LocationCallback() {
            override fun onLocationResult(locationResult: LocationResult) {
                locationResult.lastLocation?.let { location ->
                    val gpsData = GpsData(
                        latitude = location.latitude,
                        longitude = location.longitude,
                        speedOverGround = location.speed,
                        courseOverGround = location.bearing
                    )
                    serviceScope.launch {
                        _locationFlow.emit(gpsData) // Emit to shared flow (Android system GPS)
                    }

                    // Check for anchor drag if anchor watch is active
                    checkAnchorDrag(location)
                }
            }
        }
    }

    /**
     * Checks if the current location is outside the anchor watch circle.
     */
    private fun checkAnchorDrag(location: Location) {
        _anchorWatchState.update { currentState ->
            if (currentState.isActive && currentState.anchorLocation != null) {
                val isDragging = currentState.isDragging(location)
                if (isDragging) {
                    Log.w("AnchorWatch", "!!! ANCHOR DRAG DETECTED !!! Distance: ${currentState.anchorLocation.distanceTo(location)}m, Radius: ${currentState.watchCircleRadiusMeters}m")
                    if (!isAlarmTriggered) {
                        anchorAlarmManager.startAlarm()
                        isAlarmTriggered = true
                    }
                } else {
                    Log.d("AnchorWatch", "Anchor holding. Distance: ${currentState.anchorLocation.distanceTo(location)}m, Radius: ${currentState.watchCircleRadiusMeters}m")
                    if (isAlarmTriggered) {
                        anchorAlarmManager.stopAlarm()
                        isAlarmTriggered = false
                    }
                }
            } else {
                // If anchor watch is not active, ensure alarm is stopped
                if (isAlarmTriggered) {
                    anchorAlarmManager.stopAlarm()
                    isAlarmTriggered = false
                }
            }
            currentState
        }
    }

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        when (intent?.action) {
            ACTION_START_FOREGROUND_SERVICE -> {
                Log.d("LocationService", "Starting foreground service")
                startForeground(NOTIFICATION_ID, createNotification())
                serviceScope.launch {
                    _currentPowerMode.emit(PowerMode.FULL) // Set initial power mode to FULL
                    startLocationUpdatesInternal(PowerMode.FULL)
                }
                barometerSensorManager.start()
                nmeaStreamManager.start(NMEA_GATEWAY_IP, NMEA_GATEWAY_PORT)
            }
            ACTION_STOP_FOREGROUND_SERVICE -> {
                Log.d("LocationService", "Stopping foreground service")
                stopLocationUpdatesInternal()
                barometerSensorManager.stop()
                nmeaStreamManager.stop()
                stopSelf()
            }
            ACTION_START_ANCHOR_WATCH -> {
                Log.d("LocationService", "Received ACTION_START_ANCHOR_WATCH")
                val radius = intent.getDoubleExtra(EXTRA_WATCH_RADIUS, AnchorWatchState.DEFAULT_WATCH_CIRCLE_RADIUS_METERS)
                serviceScope.launch {
                    startAnchorWatch(radius)
                    setPowerMode(PowerMode.ANCHOR_WATCH)
                }
            }
            ACTION_STOP_ANCHOR_WATCH -> {
                Log.d("LocationService", "Received ACTION_STOP_ANCHOR_WATCH")
                stopAnchorWatch()
                setPowerMode(PowerMode.FULL) // Revert to full power mode after stopping anchor watch
            }
            ACTION_UPDATE_WATCH_RADIUS -> {
                Log.d("LocationService", "Received ACTION_UPDATE_WATCH_RADIUS")
                val radius = intent.getDoubleExtra(EXTRA_WATCH_RADIUS, AnchorWatchState.DEFAULT_WATCH_CIRCLE_RADIUS_METERS)
                updateWatchCircleRadius(radius)
            }
            ACTION_TOGGLE_TIDAL_VISIBILITY -> {
                val isVisible = intent.getBooleanExtra(EXTRA_TIDAL_VISIBILITY, false)
                _tidalCurrentState.update { it.copy(isVisible = isVisible) }
            }
        }
        return START_NOT_STICKY
    }

    override fun onBind(intent: Intent?): IBinder? {
        return null // Not a bound service
    }

    override fun onDestroy() {
        super.onDestroy()
        Log.d("LocationService", "Service destroyed")
        stopLocationUpdatesInternal()
        anchorAlarmManager.stopAlarm()
        barometerSensorManager.stop()
        nmeaStreamManager.stop() // Stop NMEA stream when service is destroyed
        _anchorWatchState.value = AnchorWatchState(isActive = false)
        isAlarmTriggered = false // Reset alarm trigger state
        serviceScope.cancel() // Cancel the coroutine scope
    }


    @SuppressLint("MissingPermission")
    private fun startLocationUpdatesInternal(powerMode: PowerMode) {
        Log.d("LocationService", "Requesting location updates with PowerMode: ${powerMode.name}, interval: ${powerMode.gpsUpdateIntervalMillis}ms")
        val locationRequest = LocationRequest.Builder(Priority.PRIORITY_HIGH_ACCURACY, powerMode.gpsUpdateIntervalMillis)
            .setMinUpdateIntervalMillis(powerMode.gpsUpdateIntervalMillis / 2) // Half the interval for minUpdateInterval
            .build()
        fusedLocationClient.requestLocationUpdates(
            locationRequest,
            locationCallback,
            Looper.getMainLooper()
        )
    }

    private fun stopLocationUpdatesInternal() {
        Log.d("LocationService", "Removing location updates")
        fusedLocationClient.removeLocationUpdates(locationCallback)
    }

    fun setPowerMode(powerMode: PowerMode) {
        serviceScope.launch {
            if (_currentPowerMode.value != powerMode) {
                // Emit the new power mode first
                _currentPowerMode.emit(powerMode)
                Log.d("LocationService", "Power mode changing to ${powerMode.name}. Restarting location updates.")
                // Stop current updates if running
                stopLocationUpdatesInternal()
                // Start new updates with the new power mode's interval
                startLocationUpdatesInternal(powerMode)
            } else {
                Log.d("LocationService", "Power mode already ${powerMode.name}. No change needed.")
            }
        }
    }

    private fun createNotificationChannel() {
        val serviceChannel = NotificationChannel(
            NOTIFICATION_CHANNEL_ID,
            "Location Service Channel",
            NotificationManager.IMPORTANCE_LOW
        )
        val manager = getSystemService(NotificationManager::class.java) as NotificationManager
        manager.createNotificationChannel(serviceChannel)
    }

    private fun createNotification(): Notification {
        val notificationIntent = Intent(this, MainActivity::class.java)
        val pendingIntent = PendingIntent.getActivity(
            this,
            0,
            notificationIntent,
            PendingIntent.FLAG_IMMUTABLE
        )

        return NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
            .setContentTitle("Sailing Companion")
            .setContentText("Tracking your location in the background...")
            .setSmallIcon(R.drawable.ic_anchor)
            .setContentIntent(pendingIntent)
            .build()
    }

    /**
     * Starts the anchor watch with the current location as the anchor point.
     * @param radiusMeters The watch circle radius in meters.
     */
    @SuppressLint("MissingPermission")
    suspend fun startAnchorWatch(radiusMeters: Double = AnchorWatchState.DEFAULT_WATCH_CIRCLE_RADIUS_METERS) {
        val lastLocation = fusedLocationClient.lastLocation.await()
        lastLocation?.let { location ->
            _anchorWatchState.update { AnchorWatchState(
                anchorLocation = location,
                watchCircleRadiusMeters = radiusMeters,
                setTimeMillis = System.currentTimeMillis(),
                isActive = true
            ) }
            Log.i("AnchorWatch", "Anchor watch started at lat: ${location.latitude}, lon: ${location.longitude} with radius: ${radiusMeters}m")
        } ?: run {
            Log.e("AnchorWatch", "Could not start anchor watch: Last known location is null.")
            // Handle error, e.g., show a toast to the user
        }
    }

    /**
     * Stops the anchor watch.
     */
    fun stopAnchorWatch() {
        _anchorWatchState.update { AnchorWatchState(isActive = false) }
        Log.i("AnchorWatch", "Anchor watch stopped.")
        anchorAlarmManager.stopAlarm()
        isAlarmTriggered = false
    }

    /**
     * Updates the watch circle radius.
     */
    fun updateWatchCircleRadius(radiusMeters: Double) {
        _anchorWatchState.update { it.copy(watchCircleRadiusMeters = radiusMeters) }
        Log.d("AnchorWatch", "Watch circle radius updated to ${radiusMeters}m.")
    }

    companion object {
        const val ACTION_START_FOREGROUND_SERVICE = "ACTION_START_FOREGROUND_SERVICE"
        const val ACTION_STOP_FOREGROUND_SERVICE = "ACTION_STOP_FOREGROUND_SERVICE"
        const val ACTION_START_ANCHOR_WATCH = "ACTION_START_ANCHOR_WATCH"
        const val ACTION_STOP_ANCHOR_WATCH = "ACTION_STOP_ANCHOR_WATCH"
        const val ACTION_UPDATE_WATCH_RADIUS = "ACTION_UPDATE_WATCH_RADIUS"
        const val ACTION_TOGGLE_TIDAL_VISIBILITY = "ACTION_TOGGLE_TIDAL_VISIBILITY"
        const val EXTRA_WATCH_RADIUS = "extra_watch_radius"
        const val EXTRA_TIDAL_VISIBILITY = "extra_tidal_visibility"

        // NMEA Gateway configuration (example values - these should ideally be configurable by the user)
        private const val NMEA_GATEWAY_IP = "192.168.1.1" // Placeholder IP address
        private const val NMEA_GATEWAY_PORT = 10110      // Default NMEA port

        // Publicly accessible flows
        val locationFlow: SharedFlow<GpsData>
            get() = _locationFlow
        val anchorWatchState: StateFlow<AnchorWatchState>
            get() = _anchorWatchState
        val tidalCurrentState: StateFlow<TidalCurrentState>
            get() = _tidalCurrentState
        val barometerStatus: StateFlow<BarometerStatus>
            get() = _barometerStatus

        // NMEA Data Flows
        val nmeaGpsPositionFlow: SharedFlow<GpsPosition>
            get() = _nmeaGpsPositionFlow
        val nmeaWindDataFlow: SharedFlow<WindData>
            get() = _nmeaWindDataFlow
        val nmeaDepthDataFlow: SharedFlow<DepthData>
            get() = _nmeaDepthDataFlow
        val nmeaHeadingDataFlow: SharedFlow<HeadingData>
            get() = _nmeaHeadingDataFlow

        private val _locationFlow = MutableSharedFlow<GpsData>(replay = 1)
        private val _anchorWatchState = MutableStateFlow(AnchorWatchState())
        private val _tidalCurrentState = MutableStateFlow(TidalCurrentState())
        private val _barometerStatus = MutableStateFlow(BarometerStatus())

        // Private NMEA Data Flows
        private val _nmeaGpsPositionFlow = MutableSharedFlow<GpsPosition>(
            replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST
        )
        private val _nmeaWindDataFlow = MutableSharedFlow<WindData>(
            replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST
        )
        private val _nmeaDepthDataFlow = MutableSharedFlow<DepthData>(
            replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST
        )
        private val _nmeaHeadingDataFlow = MutableSharedFlow<HeadingData>(
            replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST
        )

        private val _currentPowerMode = MutableStateFlow(PowerMode.FULL)
        val currentPowerMode: StateFlow<PowerMode>
            get() = _currentPowerMode
    }
}