import * as fc from 'fast-check';

/**
 * **Feature: backend-frontend-integration, Property 7: Dashboard Stats Accuracy**
 * **Validates: Requirements 6.1**
 * 
 * *For any* dashboard stats query, the returned todayOrderCount SHALL equal the count 
 * of orders created today, and todayGMV SHALL equal the sum of totalAmount for 
 * completed orders today.
 */

// 模拟订单数据结构
interface MockOrder {
  id: string;
  orderNo: string;
  sellerId: string;
  totalAmount: number;
  status: 'PendingPayment' | 'PendingShipment' | 'Shipped' | 'Completed' | 'Cancelled';
  createdAt: Date;
}

// 模拟今日统计结果
interface TodayStats {
  todayOrderCount: number;
  todayGMV: number;
  pendingShipmentCount: number;
}

/**
 * 纯函数：计算今日统计数据
 * 用于属性测试验证业务逻辑的正确性
 */
function calculateTodayStats(orders: MockOrder[], sellerId: string, today: Date): TodayStats {
  // 设置今日开始时间
  const todayStart = new Date(today);
  todayStart.setHours(0, 0, 0, 0);

  // 过滤该商家的订单
  const sellerOrders = orders.filter(order => order.sellerId === sellerId);

  // 今日订单：创建时间在今日的订单
  const todayOrders = sellerOrders.filter(order => order.createdAt >= todayStart);
  const todayOrderCount = todayOrders.length;

  // 今日GMV：今日已完成订单的总额
  const todayCompletedOrders = todayOrders.filter(order => order.status === 'Completed');
  const todayGMV = todayCompletedOrders.reduce((sum, order) => sum + order.totalAmount, 0);

  // 待发货订单数：所有待发货订单（不限于今日）
  const pendingShipmentCount = sellerOrders.filter(
    order => order.status === 'PendingShipment'
  ).length;

  return {
    todayOrderCount,
    todayGMV,
    pendingShipmentCount
  };
}

/**
 * 辅助函数：生成指定日期范围内的随机日期
 */
function randomDateInRange(start: Date, end: Date): Date {
  const startTime = start.getTime();
  const endTime = end.getTime();
  const randomTime = startTime + Math.random() * (endTime - startTime);
  return new Date(randomTime);
}

describe('DashboardService Property Tests', () => {
  // 生成订单状态的arbitrary
  const orderStatusArb = fc.constantFrom(
    'PendingPayment' as const,
    'PendingShipment' as const,
    'Shipped' as const,
    'Completed' as const,
    'Cancelled' as const
  );

  describe('Property 7: Dashboard Stats Accuracy', () => {
    it('今日订单数等于今日创建的订单数量', () => {
      fc.assert(
        fc.property(
          fc.uuid(), // sellerId
          fc.integer({ min: 0, max: 50 }), // 订单数量
          (sellerId, orderCount) => {
            const today = new Date();
            const todayStart = new Date(today);
            todayStart.setHours(0, 0, 0, 0);
            
            // 生成订单：一半今日，一半昨日
            const orders: MockOrder[] = [];
            const yesterday = new Date(today);
            yesterday.setDate(yesterday.getDate() - 1);

            for (let i = 0; i < orderCount; i++) {
              const isToday = i % 2 === 0;
              const createdAt = isToday 
                ? randomDateInRange(todayStart, today)
                : randomDateInRange(yesterday, todayStart);

              orders.push({
                id: `order-${i}`,
                orderNo: `ORDER${String(i).padStart(14, '0')}`,
                sellerId: i % 3 === 0 ? 'other-seller' : sellerId, // 1/3是其他商家
                totalAmount: Math.random() * 1000,
                status: 'Completed',
                createdAt
              });
            }

            const stats = calculateTodayStats(orders, sellerId, today);

            // 手动计算预期的今日订单数
            const expectedTodayCount = orders.filter(
              o => o.sellerId === sellerId && o.createdAt >= todayStart
            ).length;

            return stats.todayOrderCount === expectedTodayCount;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('今日GMV等于今日已完成订单的总额', () => {
      fc.assert(
        fc.property(
          fc.uuid(), // sellerId
          fc.array(
            fc.record({
              totalAmount: fc.integer({ min: 100, max: 100000 }).map(cents => cents / 100),
              status: orderStatusArb,
              isToday: fc.boolean(),
              isSeller: fc.boolean()
            }),
            { minLength: 0, maxLength: 30 }
          ),
          (sellerId, orderData) => {
            const today = new Date();
            const todayStart = new Date(today);
            todayStart.setHours(0, 0, 0, 0);
            const yesterday = new Date(today);
            yesterday.setDate(yesterday.getDate() - 1);

            // 根据生成的数据创建订单
            const orders: MockOrder[] = orderData.map((data, i) => ({
              id: `order-${i}`,
              orderNo: `ORDER${String(i).padStart(14, '0')}`,
              sellerId: data.isSeller ? sellerId : 'other-seller',
              totalAmount: data.totalAmount,
              status: data.status,
              createdAt: data.isToday 
                ? randomDateInRange(todayStart, today)
                : randomDateInRange(yesterday, todayStart)
            }));

            const stats = calculateTodayStats(orders, sellerId, today);

            // 手动计算预期的今日GMV
            const expectedGMV = orders
              .filter(o => 
                o.sellerId === sellerId && 
                o.createdAt >= todayStart && 
                o.status === 'Completed'
              )
              .reduce((sum, o) => sum + o.totalAmount, 0);

            // 使用近似比较处理浮点数精度问题
            return Math.abs(stats.todayGMV - expectedGMV) < 0.01;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('待发货订单数等于状态为PendingShipment的订单数量', () => {
      fc.assert(
        fc.property(
          fc.uuid(), // sellerId
          fc.array(
            fc.record({
              status: orderStatusArb,
              isSeller: fc.boolean()
            }),
            { minLength: 0, maxLength: 30 }
          ),
          (sellerId, orderData) => {
            const today = new Date();

            const orders: MockOrder[] = orderData.map((data, i) => ({
              id: `order-${i}`,
              orderNo: `ORDER${String(i).padStart(14, '0')}`,
              sellerId: data.isSeller ? sellerId : 'other-seller',
              totalAmount: Math.random() * 1000,
              status: data.status,
              createdAt: today
            }));

            const stats = calculateTodayStats(orders, sellerId, today);

            // 手动计算预期的待发货订单数
            const expectedPending = orders.filter(
              o => o.sellerId === sellerId && o.status === 'PendingShipment'
            ).length;

            return stats.pendingShipmentCount === expectedPending;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('空订单列表返回零统计', () => {
      fc.assert(
        fc.property(
          fc.uuid(),
          (sellerId) => {
            const today = new Date();
            const stats = calculateTodayStats([], sellerId, today);

            return (
              stats.todayOrderCount === 0 &&
              stats.todayGMV === 0 &&
              stats.pendingShipmentCount === 0
            );
          }
        ),
        { numRuns: 100 }
      );
    });

    it('不同商家的统计数据相互独立', () => {
      fc.assert(
        fc.property(
          fc.uuid(),
          fc.uuid(),
          fc.array(
            fc.record({
              totalAmount: fc.integer({ min: 100, max: 100000 }).map(cents => cents / 100),
              status: orderStatusArb
            }),
            { minLength: 1, maxLength: 20 }
          ),
          (sellerId1, sellerId2, orderData) => {
            // 确保两个商家ID不同
            if (sellerId1 === sellerId2) return true;

            const today = new Date();
            const todayStart = new Date(today);
            todayStart.setHours(0, 0, 0, 0);

            // 创建订单，分配给两个商家
            const orders: MockOrder[] = orderData.map((data, i) => ({
              id: `order-${i}`,
              orderNo: `ORDER${String(i).padStart(14, '0')}`,
              sellerId: i % 2 === 0 ? sellerId1 : sellerId2,
              totalAmount: data.totalAmount,
              status: data.status,
              createdAt: randomDateInRange(todayStart, today)
            }));

            const stats1 = calculateTodayStats(orders, sellerId1, today);
            const stats2 = calculateTodayStats(orders, sellerId2, today);

            // 验证：两个商家的订单数之和等于总订单数
            const totalOrders = orders.filter(o => o.createdAt >= todayStart).length;
            
            return stats1.todayOrderCount + stats2.todayOrderCount === totalOrders;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('GMV只计算已完成订单，不包括其他状态', () => {
      fc.assert(
        fc.property(
          fc.uuid(),
          fc.integer({ min: 100, max: 10000 }).map(cents => cents / 100),
          (sellerId, amount) => {
            const today = new Date();
            const todayStart = new Date(today);
            todayStart.setHours(0, 0, 0, 0);

            // 创建不同状态的订单，金额相同
            const statuses: Array<'PendingPayment' | 'PendingShipment' | 'Shipped' | 'Completed' | 'Cancelled'> = [
              'PendingPayment',
              'PendingShipment',
              'Shipped',
              'Completed',
              'Cancelled'
            ];

            const orders: MockOrder[] = statuses.map((status, i) => ({
              id: `order-${i}`,
              orderNo: `ORDER${String(i).padStart(14, '0')}`,
              sellerId,
              totalAmount: amount,
              status,
              createdAt: randomDateInRange(todayStart, today)
            }));

            const stats = calculateTodayStats(orders, sellerId, today);

            // GMV应该只等于一个已完成订单的金额
            return Math.abs(stats.todayGMV - amount) < 0.01;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('昨日订单不计入今日统计', () => {
      fc.assert(
        fc.property(
          fc.uuid(),
          fc.integer({ min: 1, max: 20 }),
          (sellerId, orderCount) => {
            const today = new Date();
            const todayStart = new Date(today);
            todayStart.setHours(0, 0, 0, 0);
            const yesterday = new Date(today);
            yesterday.setDate(yesterday.getDate() - 1);
            const yesterdayStart = new Date(yesterday);
            yesterdayStart.setHours(0, 0, 0, 0);

            // 只创建昨日的订单
            const orders: MockOrder[] = [];
            for (let i = 0; i < orderCount; i++) {
              orders.push({
                id: `order-${i}`,
                orderNo: `ORDER${String(i).padStart(14, '0')}`,
                sellerId,
                totalAmount: Math.random() * 1000,
                status: 'Completed',
                createdAt: randomDateInRange(yesterdayStart, todayStart)
              });
            }

            const stats = calculateTodayStats(orders, sellerId, today);

            // 今日订单数和GMV应该都是0
            return stats.todayOrderCount === 0 && stats.todayGMV === 0;
          }
        ),
        { numRuns: 100 }
      );
    });
  });
});