import 'dart:math';

import 'package:cookit/src/planning/week_fill.dart';
import 'package:flutter_test/flutter_test.dart';

import '../support/fixtures.dart';

void main() {
  final days = [for (var d = 19; d <= 25; d++) DateTime.utc(2026, 10, d)];
  final recipes = [for (var i = 0; i < 5; i++) recipe(id: 'r$i', name: 'R$i')];

  test('fills each empty day with a different Recipe, never one already in the week', () {
    final filled = fillWeek(
      emptyDays: days.take(3).toList(),
      candidates: recipes,
      inWeek: {'r0'},
      recent: const {},
      random: Random(1),
    );
    expect(filled.keys, days.take(3));
    final ids = filled.values.map((r) => r.id).toList();
    expect(ids.toSet(), hasLength(3));
    expect(ids, isNot(contains('r0')));
  });

  test('recently planned Recipes come only after the others', () {
    for (var seed = 0; seed < 20; seed++) {
      final filled = fillWeek(
        emptyDays: days.take(4).toList(),
        candidates: recipes,
        inWeek: const {},
        recent: {'r0', 'r1'},
        random: Random(seed),
      );
      final ids = filled.values.map((r) => r.id).toList();
      expect(ids.take(3).toSet(), {'r2', 'r3', 'r4'});
      expect(ids.last, anyOf('r0', 'r1'));
    }
  });

  test('days stay empty when the Recipes run out', () {
    final filled = fillWeek(
      emptyDays: days,
      candidates: recipes.take(2).toList(),
      inWeek: const {},
      recent: const {},
      random: Random(2),
    );
    expect(filled, hasLength(2));
  });

  test('pickReplacement skips the week and returns null when nothing is left', () {
    final pick = pickReplacement(
      candidates: recipes,
      inWeek: {'r0', 'r1', 'r2', 'r3'},
      recent: const {},
      random: Random(),
    );
    expect(pick?.id, 'r4');
    expect(
      pickReplacement(candidates: recipes, inWeek: {for (final r in recipes) r.id}, recent: const {}, random: Random()),
      isNull,
    );
  });
}