import 'package:flutter_test/flutter_test.dart';
import 'package:tane/domain/crop_calendar.dart';

void main() {
  test('an empty month set packs to null, not 0', () {
    expect(monthsToMask(const []), isNull);
    expect(monthsToMask(const [0, 13, -1]), isNull); // out of range ignored
  });

  test('months round-trip through the mask, ascending and deduped', () {
    final mask = monthsToMask(const [9, 3, 4, 3]);
    expect(maskToMonths(mask), [3, 4, 9]);
  });

  test('every single month packs to a distinct bit', () {
    for (var m = 1; m <= 12; m++) {
      expect(maskToMonths(monthsToMask([m])), [m]);
    }
  });

  test('maskToMonths of null or 0 is empty', () {
    expect(maskToMonths(null), isEmpty);
    expect(maskToMonths(0), isEmpty);
  });

  test('maskHasMonth reflects set bits', () {
    final mask = monthsToMask(const [3, 9]);
    expect(maskHasMonth(mask, 3), isTrue);
    expect(maskHasMonth(mask, 9), isTrue);
    expect(maskHasMonth(mask, 4), isFalse);
    expect(maskHasMonth(null, 3), isFalse);
    expect(maskHasMonth(mask, 0), isFalse);
  });

  test('toggleMonth adds, removes, and clears to null when empty', () {
    var mask = toggleMonth(null, 3);
    expect(maskToMonths(mask), [3]);
    mask = toggleMonth(mask, 9);
    expect(maskToMonths(mask), [3, 9]);
    mask = toggleMonth(mask, 3);
    expect(maskToMonths(mask), [9]);
    mask = toggleMonth(mask, 9);
    expect(mask, isNull); // last month removed → null, not 0
  });
}