import 'dart:async';
import 'dart:convert';
import 'dart:math' as math;
import 'dart:typed_data';
import 'dart:ui';

import 'package:dio/dio.dart';
import 'package:floating_window_android/floating_window_android.dart';
import 'package:flutter/material.dart';
import 'package:flutter_background/flutter_background.dart';
import 'package:geolocator/geolocator.dart';
import 'package:libac_dart/nbt/NbtIo.dart';
import 'package:libac_dart/nbt/NbtUtils.dart';
import 'package:libac_dart/nbt/SnbtIo.dart';
import 'package:libac_dart/nbt/Stream.dart';
import 'package:libac_dart/nbt/impl/CompoundTag.dart';
import 'package:libac_dart/nbt/impl/DoubleTag.dart';
import 'package:libac_dart/nbt/impl/ListTag.dart';
import 'package:libac_dart/nbt/impl/StringTag.dart';
import 'package:libac_dart/utils/Converter.dart';
import 'package:libac_dart/utils/TimeUtils.dart';
import 'package:libacflutter/nbt/nbtHelpers.dart';
import 'package:timetrack/consts.dart';
import 'package:wakelock_plus/wakelock_plus.dart';

class SessionData {
  static DateTime StartTime = DateTime(0);
  static DateTime EndTime = DateTime(0);

  static bool IsOnTheClock = false;

  static List<Trip> Trips = [];

  static Delivery? currentDelivery;
  static Trip? currentTrip;
  static List<SmallPosition> positions = [];
  static late StreamSubscription<Position> _listener;
  static Callbacks Calls = Callbacks();
  static String LastSessionID = "";
  static String DisplayError = "";
  static double? TotalPay;
  static bool ContainsTripTimes = true;

  /// Is true if the try-catch is tripped or if not running on Android
  static bool isWeb = false;

  /// This flag is usually set when data is loaded from a saved state. Or when accessed using the Web version of the app.
  static bool IsReadOnly = false;

  static double GetTotalMiles() {
    double total = 0;
    total = _totalMilesTraveled(
      positions,
      minDistanceMeters: 5,
      maxDistanceMeters: 512,
    );
    return total;
  }

  static int GetTotalDeliveries() {
    int total = 0;
    for (var trip in Trips) {
      total += trip.deliveries.length;
    }

    return total;
  }

  static String GetPaidHours() {
    return Duration2Notation(_GetPaidHours());
  }

  static Duration _GetPaidHours() {
    Duration stamp = Duration();
    for (var trip in Trips) {
      stamp += trip.EndTime.difference(trip.StartTime);
    }

    return stamp;
  }

  static String GetUnpaidHours() {
    // This is the inverted value of paid hours. We get total hours and subtract it from the paid hours. This gives us the unpaid hours.
    Time totalHoursWorked = Time.fromNotation(GetPaidHours());

    Duration totalDuration = EndTime.difference(StartTime);
    Time totalTime = Time.fromDuration(totalDuration);

    Time unpaid = totalTime.copy();
    unpaid.subtract(totalHoursWorked);

    return unpaid.toString();
  }

  static String GetTotalMilesAsString() {
    double miles = GetTotalMiles();
    if (miles == 0) return "0.0";
    List<String> split = miles.toString().split(".");
    StringBuilder out = StringBuilder();

    out.append(split[0]);
    out.append(".");
    out.append(split[1].substring(0, 4));

    return out.toString();
  }

  //** Begin AI Generated code */
  /// Converts meters → miles.
  static const _metersPerMile = 1609.344;

  /// Radius of the earth in meters (WGS‑84 mean radius).
  static const _earthRadiusM = 6371000.0;
  static double _haversineMeters(
    double lat1,
    double lon1,
    double lat2,
    double lon2,
  ) {
    final dLat = _deg2rad(lat2 - lat1);
    final dLon = _deg2rad(lon2 - lon1);

    final a =
        math.sin(dLat / 2) * math.sin(dLat / 2) +
        math.cos(_deg2rad(lat1)) *
            math.cos(_deg2rad(lat2)) *
            math.sin(dLon / 2) *
            math.sin(dLon / 2);

    return _earthRadiusM * 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a));
  }

  static double _deg2rad(double deg) => deg * math.pi / 180.0;

  /// Returns total miles traveled after basic GPS‑noise cleanup.
  ///
  /// * [minDistanceMeters] – drop segments shorter than this (jitter).
  /// * [maxDistanceMeters] – drop segments longer than this (impossible jump).
  static double _totalMilesTraveled(
    List<SmallPosition> positions, {
    double minDistanceMeters = 5,
    double? maxDistanceMeters,
  }) {
    if (positions.length < 2) return 0;

    var meters = 0.0;

    for (var i = 1; i < positions.length; i++) {
      final p1 = positions[i - 1];
      final p2 = positions[i];

      final d = _haversineMeters(
        p1.latitude,
        p1.longitude,
        p2.latitude,
        p2.longitude,
      );

      if (d < minDistanceMeters) continue; // too small → jitter
      if (maxDistanceMeters != null && d > maxDistanceMeters) {
        continue; // glitch
      }

      meters += d;
    }
    return meters / _metersPerMile;
  }
  //** End AI Generated code */

  static Future<bool> Login() async {
    final androidConfig = FlutterBackgroundAndroidConfig(
      notificationTitle: "Time Tracker",
      notificationText:
          "Background notification for keeping TimeTrack running in the background",
      notificationImportance: AndroidNotificationImportance.normal,
    );

    bool success = await FlutterBackground.initialize(
      androidConfig: androidConfig,
    );

    FlutterBackground.enableBackgroundExecution();
    WakelockPlus.enable();

    if (!success) {
      return false;
    }

    bool granted = await FloatingWindowAndroid.isPermissionGranted();
    if (!granted) {
      success = await FloatingWindowAndroid.requestPermission();

      if (!success) return false;
    }

    StartTime = DateTime.now();
    IsOnTheClock = true;

    bool hasGPS;

    LocationPermission perm;
    hasGPS = await Geolocator.isLocationServiceEnabled();
    if (!hasGPS) {
      IsOnTheClock = false;
      return await Future.error("Location services are disabled");
    }

    perm = await Geolocator.checkPermission();
    if (perm == LocationPermission.denied) {
      perm = await Geolocator.requestPermission();
      if (perm == LocationPermission.denied) {
        IsOnTheClock = false;
        return await Future.error("Location permissions are denied");
      }
    }

    if (perm == LocationPermission.deniedForever) {
      IsOnTheClock = false;
      return await Future.error(
        "Location permissions are denied permanently. Login cannot proceed.",
      );
    }

    _listener = Geolocator.getPositionStream(
      locationSettings: TTConsts.LOCATION_SETTINGS,
    ).listen((pos) {
      if (!IsOnTheClock) {
        _listener.cancel();
        return;
      }
      positions.add(SmallPosition.fromPosition(pos));
      SessionData.SaveCacheState();

      SessionData.Calls.dispatch();
    });

    return true;
  }

  static Future<void> Logout() async {
    IsOnTheClock = false;
    currentDelivery = null;
    currentTrip = null;
    _listener.cancel();

    EndTime = DateTime.now();

    FlutterBackground.disableBackgroundExecution();
    WakelockPlus.disable();

    var saveData = await _serializeToNBT();
    ResetAppSession();
    print(SnbtIo.writeToString(saveData));
    Uint8List nbtData = await NbtIo.writeToStream(saveData);

    Trips = [];
    positions = [];

    _upload(nbtData);
  }

  static Future<void> _upload(List<int> nbtData) async {
    Dio dio = Dio();

    Map<String, dynamic> payload = {
      "cmd": "create",
      "type": "nbt",
      "data": base64Encoder.encode(nbtData),
    };

    try {
      var reply = await dio.post(
        TTConsts.SESSION_SERVER,
        data: json.encode(payload),
      );
      if (reply.statusCode == null) {
        throw Exception("Fatal error while uploading");
      }
      if (reply.statusCode! != 200) {
        throw Exception("Fatal error while uploading");
      }

      Map<String, dynamic> replyJs = json.decode(reply.data as String);
      if (replyJs["status"] == "ok") {
        print("Successful upload");
        LastSessionID = replyJs['session'] as String;
        Calls.dispatch();
      }
    } catch (E) {
      // Retry in 2 seconds
      DisplayError =
          "Error: Something went wrong during upload. Retry in 5 seconds...";
      Calls.dispatch();

      Timer(Duration(seconds: 5), () {
        _upload(nbtData);
      });
    }
  }

  static void ResetAppSession() {
    IsOnTheClock = false;
    StartTime = DateTime.fromMillisecondsSinceEpoch(0);
    Trips = [];
    currentDelivery = null;
    currentTrip = null;
    positions = [];
    EndTime = DateTime.fromMillisecondsSinceEpoch(0);
    LastSessionID = "";
    DisplayError = "";
    IsReadOnly = false;
    ContainsTripTimes = true;

    Calls.dispatch();
  }

  /// This function attempts to load the saved state from cache.
  ///
  /// This will return true when a session exists; false when no session exists, or is empty.
  static Future<bool> LoadSavedCacheState() async {
    CompoundTag ct = await NBTHelper.GetNBT(name: "appstate");
    // Restore various flags now.
    if (ct.isEmpty) {
      ResetAppSession();
      return false;
    }

    await _deserialize(ct);

    return true;
  }

  /// Saves the current session based on various factors.
  static Future<void> SaveCacheState() async {
    CompoundTag ct = IsOnTheClock ? await _serializeToNBT() : CompoundTag();
    await NBTHelper.CommitNBT(data: ct, name: "appstate");
  }

  static Future<void> _deserialize(CompoundTag ct) async {
    IsOnTheClock = NbtUtils.readBoolean(ct, "inprog");
    StartTime = DateTime.parse(ct.get("start")!.asString());
    if (ct.containsKey("end")) {
      EndTime = DateTime.parse(ct.get("end")!.asString());
    } else {
      EndTime = DateTime(0);
    }
    TotalPay = ct.get("totalPay")!.asDouble();

    ListTag poses = ct.get("pos")! as ListTag;
    for (var pos in poses.value) {
      positions.add(await SmallPosition.fromNBT(pos.asCompoundTag()));
    }

    ListTag trips = ct.get("trips") as ListTag;
    for (var trip in trips.value) {
      Trips.add(await Trip.fromNBT(trip.asCompoundTag()));
    }

    if (ct.containsKey("current_trip")) {
      currentTrip = await Trip.fromNBT(ct.get("current_trip")!.asCompoundTag());
    }

    if (ct.containsKey("current_delivery")) {
      currentDelivery = await Delivery.fromNBT(
        ct.get("current_delivery")!.asCompoundTag(),
      );
    }
  }

  /// This private function will turn all the data into NBT, for both the cache state, and newer usage, for storing it on the server in a more compact format.
  static Future<CompoundTag> _serializeToNBT() async {
    CompoundTag ct = CompoundTag();

    NbtUtils.writeBoolean(ct, "inprog", IsOnTheClock);
    // No need to write the contains trip times flag, it is set during deserialization.  For inprog sessions, it will be set to true by the system.
    ct.put("start", StringTag.valueOf(StartTime.toIso8601String()));
    if (EndTime.year < 2000) {
      // We have a end time
      ct.put("end", StringTag.valueOf(EndTime.toIso8601String()));
    }

    ListTag posX = ListTag();
    for (var pos in positions) {
      posX.add(await pos.toNBT());
    }
    ct.put("pos", posX);

    ListTag myTrips = ListTag();
    for (var trip in Trips) {
      myTrips.add(await trip.toNBT());
    }
    ct.put("trips", myTrips);

    // This format supports saving current trip and current delivery.
    if (currentDelivery != null) {
      ct.put("current_delivery", await currentDelivery!.toNBT());
    }

    if (currentTrip != null) {
      ct.put("current_trip", await currentTrip!.toNBT());
    }

    if (TotalPay != null) {
      ct.put("totalPay", DoubleTag.valueOf(TotalPay!));
    }

    return ct;
  }

  static Map<String, dynamic> SaveData() {
    Map<String, dynamic> saveData = {};

    List<Map<String, dynamic>> trips = [];
    for (var trip in Trips) {
      trips.add(trip.toJsonMap());
    }

    List<Map<String, dynamic>> posx = [];
    for (var pos in positions) {
      posx.add(pos.toMap());
    }

    saveData["trips"] = trips;
    saveData["positions"] = posx;
    saveData["start"] = StartTime.toIso8601String();
    saveData["end"] = EndTime.toIso8601String();
    if (TotalPay != null) saveData["totalPay"] = TotalPay;

    return saveData;
  }

  static Future<bool> DownloadData() async {
    Dio dio = Dio();
    Map<String, dynamic> payload = {"cmd": "get", "id": LastSessionID};

    // Send the data, and get the response
    try {
      var reply = await dio.post(
        TTConsts.SESSION_SERVER,
        data: json.encode(payload),
      );

      String cType = reply.headers.value("Content-Type") ?? "application/json";

      if (cType == "application/json") {
        return LoadData(reply.data as Map<String, dynamic>);
      } else if (cType == "application/nbt") {
        print("Data is in NBT Format");
        Uint8List lst = base64Encoder.decode(reply.data as String);
        // Convert this to a CompoundTag
        CompoundTag ct = await NbtIo.readFromStream(lst) as CompoundTag;
        _deserialize(ct);
        return true;
      } else
        return false;
    } catch (E, stack) {
      print(E);

      print(stack);

      return false;
    }
  }

  static bool LoadData(Map<String, dynamic> jsMap) {
    if (jsMap.containsKey("error")) {
      LastSessionID = "";
      return false;
    }
    List<dynamic> trips = jsMap['trips'] as List<dynamic>;
    List<dynamic> pos = jsMap['positions'] as List<dynamic>;

    for (var trip in trips) {
      Trips.add(Trip.fromJsonMap(trip as Map<String, dynamic>));
    }

    for (var position in pos) {
      positions.add(SmallPosition.fromMap(position as Map<String, dynamic>));
    }

    if (jsMap.containsKey("start")) {
      StartTime = DateTime.parse(jsMap['start'] as String);
    }

    if (jsMap.containsKey("end")) {
      EndTime = DateTime.parse(jsMap["end"] as String);
    }

    if (jsMap.containsKey("totalPay")) {
      TotalPay = jsMap["totalPay"] as double;
    } else {
      TotalPay = null;
    }

    IsReadOnly = true;

    return true;
  }

  static Future<Position> GetNewLocation() async {
    Position pos = await Geolocator.getCurrentPosition(
      locationSettings: TTConsts.LOCATION_SETTINGS,
    );

    return pos;
  }

  static Trip GetNewTrip() {
    if (currentTrip != null) {
      currentTrip!.EndTime = DateTime.now();
    }
    currentTrip = Trip();
    Trips.add(currentTrip!);
    return currentTrip!;
  }

  static Delivery GetNewDelivery() {
    if (currentTrip != null) {
      var dropOff = currentTrip!.startNewDelivery();
      currentDelivery = dropOff;
      return dropOff;
    } else {
      throw Exception("A delivery cannot exist without a trip");
    }
  }

  static void EndTrip() {
    if (currentTrip != null) {
      currentTrip!.EndTime = DateTime.now();
    }
    currentDelivery = null;
    currentTrip = null;
  }

  /// [a] should be the Start Time,
  ///
  /// [b] is the end time
  static String GetTotalTimeWorked(DateTime a, DateTime b) {
    Duration diff = b.difference(a);
    return Duration2Notation(diff);
  }

  static String Duration2Notation(Duration time) {
    Time tm = Time.fromDuration(time);

    return tm.toString();
  }
}

class Delivery {
  SmallPosition? endLocation;
  DateTime StartTime = DateTime.now();

  Delivery() {
    StartTime = DateTime.now();
  }

  Future<void> MarkEndLocation() async {
    var pos = await SessionData.GetNewLocation();
    endLocation = SmallPosition.fromPosition(pos);
  }

  Map<String, dynamic> toJsonMap() {
    return {
      "start": StartTime.toIso8601String(),
      "endPos": endLocation?.toMap() ?? "incomplete",
    };
  }

  static Delivery fromMap(Map<String, dynamic> jsx) {
    Delivery delivery = Delivery();
    delivery.StartTime = DateTime.parse(jsx['start'] as String);
    if (jsx['endPos'] is String) {
      delivery.endLocation = null;
    } else {
      delivery.endLocation = SmallPosition.fromMap(
        jsx['endPos'] as Map<String, dynamic>,
      );
    }

    return delivery;
  }

  Future<CompoundTag> toNBT() async {
    CompoundTag ct = CompoundTag();
    ct.put("start", StringTag.valueOf(StartTime.toIso8601String()));
    if (endLocation != null) {
      ct.put("endPos", await endLocation!.toNBT());
    }

    return ct;
  }

  static Future<Delivery> fromNBT(CompoundTag ct) async {
    Delivery delivery = Delivery();
    delivery.StartTime = DateTime.parse(ct.get("start")!.asString());
    if (ct.containsKey("endPos")) {
      delivery.endLocation = await SmallPosition.fromNBT(
        ct.get("endPos") as CompoundTag,
      );
    }

    return delivery;
  }
}

class Trip {
  List<Delivery> deliveries = [];

  DateTime StartTime = DateTime(0);
  DateTime EndTime = DateTime(0);

  Trip() {
    StartTime = DateTime.now();
  }

  Delivery startNewDelivery() {
    var delivery = Delivery();
    deliveries.add(delivery);

    return delivery;
  }

  Map<String, dynamic> toJsonMap() {
    Map<String, Object> trip = {
      "start": StartTime.toIso8601String(),
      "end": EndTime.toIso8601String(),
    };
    List<Map<String, dynamic>> dropOffs = [];
    for (var delivery in deliveries) {
      dropOffs.add(delivery.toJsonMap());
    }

    trip["deliveries"] = dropOffs;

    return trip;
  }

  static Trip fromJsonMap(Map<String, dynamic> jsx) {
    Trip trip = Trip();
    trip.StartTime = DateTime.parse(jsx['start'] as String);
    if (jsx.containsKey("end")) {
      trip.EndTime = DateTime.parse(jsx['end'] as String);
    } else {
      SessionData.ContainsTripTimes = false;
    }
    trip.deliveries = [];
    List<dynamic> dropOffs = jsx['deliveries'] as List<dynamic>;

    for (var dropOff in dropOffs) {
      trip.deliveries.add(Delivery.fromMap(dropOff as Map<String, dynamic>));
    }

    return trip;
  }

  Future<CompoundTag> toNBT() async {
    CompoundTag ct = CompoundTag();

    ct.put("start", StringTag.valueOf(StartTime.toIso8601String()));
    if (EndTime.year < 2000) {
      ct.put("end", StringTag.valueOf(EndTime.toIso8601String()));
    }

    ListTag drops = ListTag();
    for (var drop in deliveries) {
      drops.add(await drop.toNBT());
    }
    ct.put("deliveries", drops);

    return ct;
  }

  static Future<Trip> fromNBT(CompoundTag tag) async {
    Trip trip = Trip();

    // Deserialize the Trip
    trip.StartTime = DateTime.parse(tag.get("start")!.asString());
    if (!tag.containsKey("end")) {
      SessionData.ContainsTripTimes = false;
    }

    ListTag drops = tag.get("deliveries")! as ListTag;
    for (var drop in drops.value) {
      Delivery del = await Delivery.fromNBT(drop.asCompoundTag());
      trip.deliveries.add(del);
    }

    return trip;
  }
}

class Callbacks {
  VoidCallback? HomeCallback;
  VoidCallback? MapCallback;
  VoidCallback? UpdateSettingsCallback;
  VoidCallback? WorkDataCallback;

  void dispatch() {
    if (HomeCallback != null) HomeCallback!();
    if (MapCallback != null) MapCallback!();
    if (UpdateSettingsCallback != null) UpdateSettingsCallback!();
    if (WorkDataCallback != null) WorkDataCallback!();
  }
}

/// A simple wrapper for a position that strips away unnecessary information to create a more compact piece of save data
class SmallPosition {
  double latitude;
  double longitude;

  SmallPosition({required this.latitude, required this.longitude});

  static SmallPosition fromPosition(Position position) {
    return SmallPosition(
      latitude: position.latitude,
      longitude: position.longitude,
    );
  }

  Map<String, dynamic> toMap() {
    return {"latitude": latitude, "longitude": longitude};
  }

  static SmallPosition fromMap(Map<String, dynamic> map) {
    return SmallPosition(
      latitude: map['latitude'] as double,
      longitude: map['longitude'] as double,
    );
  }

  Future<CompoundTag> toNBT() async {
    CompoundTag ct = CompoundTag();
    ct.put("latitude", DoubleTag.valueOf(latitude));
    ct.put("longitude", DoubleTag.valueOf(longitude));

    return ct;
  }

  static Future<SmallPosition> fromNBT(CompoundTag ct) async {
    return SmallPosition(
      latitude: ct.get("latitude")?.asDouble() ?? 0,
      longitude: ct.get("longitude")?.asDouble() ?? 0,
    );
  }
}