import 'package:flutter_test/flutter_test.dart';

import 'package:qiangbao_accounting/models/account.dart';

void main() {
  group('余额反算 initialBalanceFor', () {
    // 后端公式：balance = initialBalance + totalIncome - totalExpense
    test('无收支时目标余额就是期初余额', () {
      expect(
        initialBalanceFor(targetBalance: 5000, totalIncome: 0, totalExpense: 0),
        5000,
      );
    });

    test('有收入时需扣除收入', () {
      // 收入 8000，想让余额显示 5000 → 期初 = 5000 - 8000 = -3000
      expect(
        initialBalanceFor(targetBalance: 5000, totalIncome: 8000, totalExpense: 0),
        -3000,
      );
    });

    test('有支出时需加回支出', () {
      // 支出 1200，想让余额显示 5000 → 期初 = 5000 + 1200 = 6200
      expect(
        initialBalanceFor(targetBalance: 5000, totalIncome: 0, totalExpense: 1200),
        6200,
      );
    });

    test('收支都有时综合换算', () {
      // 收 8000 支 1200，目标 5000 → 5000 - 8000 + 1200 = -1800
      expect(
        initialBalanceFor(targetBalance: 5000, totalIncome: 8000, totalExpense: 1200),
        -1800,
      );
    });

    test('换算后余额能被后端公式还原（往返一致）', () {
      const target = 12345.67;
      const income = 8000.0;
      const expense = 3456.78;
      final initial = initialBalanceFor(
        targetBalance: target,
        totalIncome: income,
        totalExpense: expense,
      );
      // 模拟后端计算
      final balance = initial + income - expense;
      expect(balance, closeTo(target, 0.001));
    });

    test('目标余额非法时返回 0', () {
      expect(
        initialBalanceFor(targetBalance: double.nan, totalIncome: 100, totalExpense: 0),
        0,
      );
      expect(
        initialBalanceFor(targetBalance: double.infinity, totalIncome: 0, totalExpense: 0),
        0,
      );
    });
  });

  group('AccountInfo.fromJson 防御性', () {
    test('字段缺失时不抛异常并按公式兜底算余额', () {
      final a = AccountInfo.fromJson({
        'id': '3',
        'initialBalance': '1000',
        'totalIncome': 500,
        'totalExpense': '200.5',
        // name / balance 缺失
      });
      expect(a.id, 3);
      expect(a.name, '默认账户');
      expect(a.initialBalance, 1000);
      expect(a.totalIncome, 500);
      expect(a.totalExpense, 200.5);
      expect(a.balance, 1000 + 500 - 200.5); // 本地兜底计算
    });

    test('后端给了 balance 时优先使用后端值', () {
      final a = AccountInfo.fromJson({
        'initialBalance': 1000,
        'totalIncome': 500,
        'totalExpense': 200,
        'balance': 9999, // 故意与公式不一致
      });
      expect(a.balance, 9999);
    });

    test('完全空对象返回零值账户', () {
      final a = AccountInfo.fromJson({});
      expect(a.balance, 0);
      expect(a.totalIncome, 0);
      expect(a.totalExpense, 0);
    });
  });
}