import 'package:aoc2020/model/point.dart';
import 'package:tuple/tuple.dart';

enum Direction { N, NE, E, SE, S, SW, W, NW }

class Dir {
  static int get dirs => Direction.values.length;
  static int get dirStep => 360 ~/ dirs;
  static List<Direction> get dirEnum => Direction.values;
  static List<String> get dir => Direction.values.map((dir) => dir.toString().substring(dir.toString().indexOf('.') + 1)).toList();
  static String string(Direction dir) => dir.toString().substring(dir.toString().indexOf('.') + 1);
  static Direction stringToEnum(String str) => dirEnum[dir.indexOf(str)];
}

class Pos {
  static final Pos _singleton = Pos._internal();
  Point _loc;
  Point _waypoint;
  Direction _dir;

  Map<Direction, Point> moveOffset = {
    Direction.N: Point(-1, 0),
    Direction.NE: Point(-1, 1),
    Direction.E: Point(0, 1),
    Direction.SE: Point(1, 1),
    Direction.S: Point(1, 0),
    Direction.SW: Point(1, -1),
    Direction.W: Point(0, -1),
    Direction.NW: Point(-1, -1),
  };

  // factory Pos({Point loc, Direction dir}) {
  //   _singleton.loc = loc;
  //   _singleton.dir = dir;
  //   return _singleton;
  // }

  factory Pos() {
    return _singleton;
  }

  // singleton's constructor
  Pos._internal() {
    reset();
  }

  void reset() {
    _loc = Point(0, 0);
    _waypoint = Point(-1, 10); // relative to _loc
    _dir = Direction.E;
  }

  int get ns => _loc.item1;
  int get ew => _loc.item2;

  void move(Tuple2<String, int> _move) {
    var _direction = (_move.item1 == 'F') ? _dir : Dir.stringToEnum(_move.item1);
    _loc += (moveOffset[_direction] * _move.item2);
  }

  void moveSec2(Tuple2<String, int> _move) {
    if (_move.item1 == 'F') {
      _loc += (_waypoint * _move.item2);
    } else {
      _waypoint += (moveOffset[Dir.stringToEnum(_move.item1)] * _move.item2);
    }
  }

  void rotate(Tuple2<String, int> _rotate) {
    switch (_rotate.item1) {
      case 'L':
        left(deg: _rotate.item2);
        break;
      case 'R':
        right(deg: _rotate.item2);
        break;
      default:
        print('ERROR');
    }
  }

  void rotateSec2(Tuple2<String, int> _rotate) {
    var _deg = _rotate.item2 % 360;
    if (_rotate.item1 == 'L') _deg = 360 - _deg;
    switch (_deg) {
      case 90:
        _waypoint = Point(_waypoint.item2, -_waypoint.item1);
        break;
      case 180:
        _waypoint = Point(-_waypoint.item1, -_waypoint.item2);
        break;
      case 270:
        _waypoint = Point(-_waypoint.item2, _waypoint.item1);
        break;
    }
  }

  void _rotateDeg(int deg) {
    var count = (deg ~/ Dir.dirStep) % Dir.dirs;
    var _newDirIndex = Dir.dirEnum.indexOf(_dir) + count;
    _newDirIndex = _newDirIndex < 0 ? Dir.dirs - count : _newDirIndex;
    _newDirIndex %= Dir.dirs;
    _dir = Dir.dirEnum[_newDirIndex];
  }

  void left({int deg = 90}) => _rotateDeg(-deg);
  void right({int deg = 90}) => _rotateDeg(deg);

  @override
  String toString() => '{$_loc:$_dir} $_waypoint';
}