adventofcode2025/lib/day2/command.dart

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

import "package:args/command_runner.dart";

class Day2Command extends Command {
  // The [name] and [description] properties must be defined by every
  // subclass.
  @override
  final name = "day2";

  @override
  final description = "Run Advent of Code 2025 Day 2";

  Day2Command() {
    // 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}",
      );
    }
    var filePath = argResults!.rest[0];

    print("Parsing file: $filePath");

    var inputFile = File(filePath);
    var openFile = await inputFile.readAsString();
    var part1Answer = openFile
        .trim()
        .split(',')
        .expand((range) {
          var extents = range.split('-');
          if (extents.length != 2) {
            throw Exception(
              "Expected range with 2 parts, but got ${extents.length} parts: {range}",
            );
          }
          var numRange = [int.parse(extents[0]), int.parse(extents[1])];
          List<int> createRange(int from, int to) =>
              List.generate(to - from + 1, (i) => i + from);
          return createRange(numRange[0], numRange[1]);
        })
        .map((id) => id.toString())
        .where((id) => id.length.isEven)
        .where((id) {
          var first_half = id.substring(0, (id.length / 2).floor());
          var second_half = id.substring((id.length / 2).floor(), id.length);
          return first_half == second_half;
        })
        .map((id) => int.parse(id))
        .reduce((id1, id2) => id1 + id2);
    print("Part 1 Answer: $part1Answer");
  }
}