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

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:geolocator/geolocator.dart';
import 'package:libac_dart/nbt/Stream.dart';
import 'package:timetrack/consts.dart';

class SessionData {
  static DateTime StartTime = 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 = "";

  /// 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 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<void> Login() async {
    StartTime = DateTime.now();
    IsOnTheClock = true;

    bool hasGPS;

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

    if (perm == LocationPermission.deniedForever) {
      IsOnTheClock = false;
      return 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.Calls.dispatch();
    });
  }

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

    var saveData = SaveData();
    print(saveData);

    Trips = [];
    positions = [];

    Dio dio = Dio();
    Map<String, dynamic> payload = {"cmd": "create", "data": saveData};

    var reply = await dio.post(
      TTConsts.SESSION_SERVER,
      data: json.encode(payload),
    );
    Map<String, dynamic> replyJs = json.decode(reply.data as String);
    if (replyJs["status"] == "ok") {
      print("Successful upload");
      LastSessionID = replyJs['session'] as String;
      Calls.dispatch();
    }
  }

  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>> _pos = [];
    for (var pos in positions) {
      _pos.add(pos.toMap());
    }

    saveData["trips"] = _trips;
    saveData["positions"] = _pos;

    return saveData;
  }

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

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

    LoadData(reply.data as String);
  }

  static void LoadData(String js) {
    Map<String, dynamic> _js = json.decode(js);
    if (_js.containsKey("error")) {
      LastSessionID = "";
      return;
    }
    List<Map<String, dynamic>> _trips =
        _js['trips'] as List<Map<String, dynamic>>;
    List<Map<String, dynamic>> _pos =
        _js['positions'] as List<Map<String, dynamic>>;

    for (var trip in _trips) {
      Trips.add(Trip.fromJsonMap(trip));
    }

    for (var position in _pos) {
      positions.add(SmallPosition.fromMap(position));
    }

    IsReadOnly = true;
  }

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

    return pos;
  }

  static Trip GetNewTrip() {
    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() {
    currentDelivery = null;
    currentTrip = null;
  }
}

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

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

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

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

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

    return delivery;
  }
}

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

  DateTime StartTime = 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.toString()};
    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);
    trip.deliveries = [];
    List<Map<String, dynamic>> _dropOffs =
        jsx['deliveries'] as List<Map<String, dynamic>>;

    for (var dropOff in _dropOffs) {
      trip.deliveries.add(Delivery.fromMap(dropOff));
    }

    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,
    );
  }
}