import 'package:flutter_test/flutter_test.dart';
import 'package:household_keeper/features/tasks/domain/frequency.dart';
import 'package:household_keeper/features/tasks/domain/relative_date.dart';
import 'package:household_keeper/features/tasks/domain/scheduling.dart';

void main() {
  group('calculateNextDueDate', () {
    test('daily adds 1 day', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 3, 15),
        intervalType: IntervalType.daily,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 3, 16));
    });

    test('everyNDays(3) adds 3 days', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 3, 15),
        intervalType: IntervalType.everyNDays,
        intervalDays: 3,
      );
      expect(result, DateTime(2026, 3, 18));
    });

    test('weekly adds 7 days', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 3, 15),
        intervalType: IntervalType.weekly,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 3, 22));
    });

    test('biweekly adds 14 days', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 3, 15),
        intervalType: IntervalType.biweekly,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 3, 29));
    });

    test('monthly from Jan 15 gives Feb 15', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 1, 15),
        intervalType: IntervalType.monthly,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 2, 15));
    });

    test('monthly from Jan 31 gives Feb 28 (clamping)', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 1, 31),
        intervalType: IntervalType.monthly,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 2, 28));
    });

    test('monthly from Feb 28 (anchor 31) gives Mar 31 (anchor memory)', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 2, 28),
        intervalType: IntervalType.monthly,
        intervalDays: 1,
        anchorDay: 31,
      );
      expect(result, DateTime(2026, 3, 31));
    });

    test('quarterly from Jan 15 gives Apr 15', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 1, 15),
        intervalType: IntervalType.quarterly,
        intervalDays: 1,
      );
      expect(result, DateTime(2026, 4, 15));
    });

    test('yearly from 2026-03-15 gives 2027-03-15', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 3, 15),
        intervalType: IntervalType.yearly,
        intervalDays: 1,
      );
      expect(result, DateTime(2027, 3, 15));
    });

    test('everyNMonths(2) adds 2 months', () {
      final result = calculateNextDueDate(
        currentDueDate: DateTime(2026, 1, 15),
        intervalType: IntervalType.everyNMonths,
        intervalDays: 2,
      );
      expect(result, DateTime(2026, 3, 15));
    });
  });

  group('catchUpToPresent', () {
    test('skips past occurrences to reach today or future', () {
      // Task was due Jan 1, weekly interval. Today is Mar 15.
      // Should advance past all missed weeks to the next week on/after Mar 15.
      final result = catchUpToPresent(
        nextDue: DateTime(2026, 1, 1),
        today: DateTime(2026, 3, 15),
        intervalType: IntervalType.weekly,
        intervalDays: 1,
      );
      // Jan 1 + 11 weeks = Mar 19 (first Thursday on/after Mar 15)
      expect(result.isAfter(DateTime(2026, 3, 14)), isTrue);
      expect(result.isBefore(DateTime(2026, 3, 22)), isTrue);
    });

    test('returns date unchanged if already in future', () {
      final futureDate = DateTime(2026, 4, 1);
      final result = catchUpToPresent(
        nextDue: futureDate,
        today: DateTime(2026, 3, 15),
        intervalType: IntervalType.weekly,
        intervalDays: 1,
      );
      expect(result, futureDate);
    });
  });

  group('formatRelativeDate', () {
    final today = DateTime(2026, 3, 15);

    test('today returns "Heute"', () {
      expect(formatRelativeDate(DateTime(2026, 3, 15), today), 'Heute');
    });

    test('tomorrow returns "Morgen"', () {
      expect(formatRelativeDate(DateTime(2026, 3, 16), today), 'Morgen');
    });

    test('3 days from now returns "in 3 Tagen"', () {
      expect(formatRelativeDate(DateTime(2026, 3, 18), today), 'in 3 Tagen');
    });

    test('1 day overdue returns "Uberfaellig seit 1 Tag"', () {
      expect(
        formatRelativeDate(DateTime(2026, 3, 14), today),
        'Uberfaellig seit 1 Tag',
      );
    });

    test('5 days overdue returns "Uberfaellig seit 5 Tagen"', () {
      expect(
        formatRelativeDate(DateTime(2026, 3, 10), today),
        'Uberfaellig seit 5 Tagen',
      );
    });
  });
}