adventofcode2025/lib/day1/command.dart

import "dart:convert";
import "dart:io";

import "package:args/command_runner.dart";

enum Direction { left, right }

class Rotation {
  Direction direction;
  int amount;
  Rotation(this.direction, this.amount);

  @override
  String toString() {
    return '{ direction: ${direction.name}, amount: $amount }';
  }
}

Future<List<Rotation>> parseInputFile(String filePath) async {
  var inputFile = File(filePath);
  var openFile = inputFile.openRead();

  var lines = openFile.transform(utf8.decoder).transform(LineSplitter());

  List<Rotation> inputList = [];
  await for (var line in lines) {
    var dir = line.substring(0, 1);
    var amount = int.parse(line.substring(1, line.length));
    inputList.add(
      Rotation(dir == 'L' ? Direction.left : Direction.right, amount),
    );
  }

  return inputList;
}

class Day1Command extends Command {
  // The [name] and [description] properties must be defined by every
  // subclass.
  @override
  final name = "day1";

  @override
  final description = "Run Advent of Code 2025 Day 1";

  Day1Command() {
    // we can add command specific arguments here.
    // [argParser] is automatically created by the parent class.
  }

  // [run] may also return a Future.
  @override
  Future<void> run() async {
    // [argResults] is set before [run()] is called and contains the flags/options
    // passed to this command.

    if (argResults!.rest.length != 1) {
      print(
        "Expected 1 positional arguments, found ${argResults!.rest.length}",
      );
      exit(1);
    }
    var fileName = argResults!.rest[0];

    print("Parsing file: $fileName");

    var list = await parseInputFile(fileName);

    int dialValue = 50;
    int combinationPart1 = 0;
    int combinationPart2 = 0;

    for (var instruction in list) {
      switch (instruction.direction) {
        case Direction.left:
          // Count full rotations
          combinationPart2 += (instruction.amount / 100).floor();

          // Count additive rotations (remainder + previous value)
          if (dialValue != 0 && (dialValue - (instruction.amount % 100)) <= 0) {
            combinationPart2++;
          }

          // Dial counter-clockwise by amount
          dialValue -= instruction.amount;
        case Direction.right:
          // Dial clockwise by amount
          dialValue += instruction.amount;
          combinationPart2 += (dialValue / 100).floor();
      }

      dialValue = dialValue % 100;
      if (dialValue == 0) {
        combinationPart1++;
      }
    }

    print("Combination - part 1: $combinationPart1");
    print("Combination - part 2: $combinationPart2");
  }
}