Advent Of Code 2020 Day 12 in dart

aoc2020_12.dart

void main() {
  final List<Object> solutions = [
    SolutionA(),
    SolutionB()
  ];
  solutions.forEach((s) => print(s.toString()));
}

// Full inputs at https://adventofcode.com/2020/day/12/input
const inputsDay12 = """F10
N3
F7
R90
F11""";

enum Action { N, S, E, W, L, R, F }
var charAction = {
  'N': Action.N,
  'S': Action.S,
  'E': Action.E,
  'W': Action.W,
  'L': Action.L,
  'R': Action.R,
  'F': Action.F
};
List<Instruction> _parseInputs(String inputs) => inputs
    .split('\n')
    .where((element) => element.isNotEmpty)
    .map((e) => Instruction.fromString(e))
    .toList();
var _inputs = _parseInputs(inputsDay12);

class Instruction {
  final Action action;
  final int distance;
  Instruction.fromString(String input)
      : action = charAction[input.split('')[0]],
        distance = int.parse(input.split('').skip(1).join(''));
  @override
  String toString() => "$action$distance";
}

enum Direction {
  N,
  S,
  E,
  W,
}
var directions = [Direction.N, Direction.E, Direction.S, Direction.W];
var actionDirection = {
  Action.N: Direction.N,
  Action.E: Direction.E,
  Action.S: Direction.S,
  Action.W: Direction.W
};

enum ShipVersion { One, Two }

class Ship {
  final shipVersion;
  int _x = 0;
  int _y = 0;
  Direction direction;
  int _rX = 10;
  int _rY = 1;
  Ship({this.shipVersion = ShipVersion.Two}) : direction = Direction.E;

  instruct(Instruction instruction) {
    Direction moveDirection;
    Action action = instruction.action;
    int distanceOrDegree = instruction.distance;
    if (shipVersion == ShipVersion.One) {
      if (action == Action.R || action == Action.L) {
        turn(distanceOrDegree, isLeft: action == Action.L);
      } else {
        if (action != Action.F) {
          moveDirection = actionDirection[action];
        }
        move(distanceOrDegree, moveDirection);
      }
    } else if (shipVersion == ShipVersion.Two) {
      if (action == Action.R || action == Action.L) {
        rotate(distanceOrDegree, isLeft: action == Action.L);
      } else {
        if (action == Action.F) {
          move(distanceOrDegree * _rX, _rX >= 0 ? Direction.E : Direction.W);
          move(distanceOrDegree * _rY, _rY >= 0 ? Direction.N : Direction.S);
        } else {
          moveDirection = actionDirection[action];
          moveWaypoint(distanceOrDegree, moveDirection);
        }
      }
    }
    // print(this.toString());
  }

  rotate(int degree, {isLeft = false}) {
    var deg = (360 + (isLeft ? -degree : degree)) % 360;
    var prevRX = _rX;
    var prevRY = _rY;
    if (deg == 90 || deg == 270) {
      _rX = prevRY;
      _rY = prevRX;
    }
    if (deg == 90) {
      _rY = -_rY;
    } else if (deg == 180) {
      _rX = -_rX;
      _rY = -_rY;
    } else if (deg == 270) {
      _rX = -_rX;
    }
  }

  turn(int degree, {isLeft = false}) {
    var index = directions.indexOf(direction), inc = degree ~/ 90;
    index += inc * (isLeft ? -1 : 1);
    index = index % directions.length;
    direction = directions[index];
  }

  moveWaypoint(int instructionDistance, Direction instructionDirection) {
    var dir = instructionDirection != null ? instructionDirection : direction;
    switch (dir) {
      case Direction.N:
        _rY += instructionDistance;
        break;
      case Direction.S:
        _rY -= instructionDistance;
        break;
      case Direction.E:
        _rX += instructionDistance;
        break;
      case Direction.W:
        _rX -= instructionDistance;
        break;
    }
  }

  move(int instructionDistance, Direction instructionDirection) {
    var dir = instructionDirection != null ? instructionDirection : direction;
    switch (dir) {
      case Direction.N:
      case Direction.S:
        _y += instructionDistance;
        break;
      case Direction.E:
      case Direction.W:
        _x += instructionDistance;
        break;
    }
  }

  get absX => _x < 0 ? -_x : _x;
  get absY => _y < 0 ? -_y : _y;
  get absRX => _rX < 0 ? -_rX : _rX;
  get absRY => _rY < 0 ? -_rY : _rY;

  @override
  String toString() => "${_x >= 0 ? 'east' : 'west'} $absX,"
      " ${_y >= 0 ? 'north' : 'south'} $absY"
      " -> $direction"
      " (WP: ${_rX >= 0 ? 'east' : 'west'} $absRX, ${_rY >= 0 ? 'north' : 'south'} $absRY)";
}

abstract class AdventSolution {
  final int day;
  final String name;
  AdventSolution(this.day, this.name);

  // implement in subclass
  String getSolution();

  @override
  String toString() {
    return "Advent Of Code, "
        "Day $day "
        "${name.isNotEmpty ? name : ''} "
        "solution: ${getSolution()}";
  }
}

abstract class _Day12Solution extends AdventSolution {
  _Day12Solution(name) : super(12, name);
}

class SolutionA extends _Day12Solution {
  SolutionA() : super('A');

  String getSolution() {
    var ship = Ship(shipVersion: ShipVersion.One);
    _inputs.forEach(ship.instruct);
    return (ship.absX + ship.absY).toString();
  }
}

class SolutionB extends _Day12Solution {
  SolutionB() : super('B');

  String getSolution() {
    var ship = Ship();
    _inputs.forEach(ship.instruct);
    return (ship.absX + ship.absY).toString();
  }
}