using FsCheck;
using FsCheck.Xunit;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using Microsoft.Extensions.Logging;
using Moq;
using VendingMachine.Application.DTOs.Coupon;
using VendingMachine.Application.Services;
using VendingMachine.Domain.Entities;
using VendingMachine.Infrastructure.Data;
using VendingMachine.Infrastructure.Services;

namespace VendingMachine.Tests;

/// <summary>
/// 优惠券模块属性测试
/// </summary>
public class CouponPropertyTests
{
    /// <summary>
    /// 创建内存数据库上下文
    /// </summary>
    private static AppDbContext CreateDbContext(string dbName)
    {
        var options = new DbContextOptionsBuilder<AppDbContext>()
            .UseInMemoryDatabase(databaseName: dbName)
            .ConfigureWarnings(w => w.Ignore(InMemoryEventId.TransactionIgnoredWarning))
            .Options;
        return new AppDbContext(options);
    }

    // Feature: vending-machine-app, Property 13: 优惠券兑换正确性
    // 对于任意优惠券兑换操作，如果用户积分 >= 优惠券所需积分，则兑换成功且用户积分减少对应数量；
    // 如果用户积分 < 优惠券所需积分，则兑换失败且用户积分不变。
    // **Validates: Requirements 6.2, 6.3**
    [Property(MaxTest = 100)]
    public bool RedeemCoupon_WhenSufficientPoints_ShouldSucceedAndDeductPoints(
        PositiveInt balanceRaw, PositiveInt costRaw)
    {
        // 确保积分充足：balance >= cost
        var cost = (costRaw.Get % 500) + 1;
        var balance = cost + (balanceRaw.Get % 1000);

        var dbName = $"RedeemSufficient_{Guid.NewGuid()}";
        using var db = CreateDbContext(dbName);
        var logger = Mock.Of<ILogger<CouponService>>();

        var user = new User
        {
            Uid = "testuser00001",
            Phone = "13800000001",
            AreaCode = "+86",
            Nickname = "测试用户",
            PointsBalance = balance
        };
        var template = new CouponTemplate
        {
            Id = "coupon001",
            NameZhCn = "测试优惠券",
            NameZhTw = "測試優惠券",
            NameEn = "Test Coupon",
            Type = CouponType.DirectDiscount,
            DiscountAmount = 5m,
            PointsCost = cost,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            IsActive = true,
            IsStamp = false
        };
        db.Users.Add(user);
        db.CouponTemplates.Add(template);
        db.SaveChanges();

        var service = new CouponService(db, logger);
        var result = service.RedeemCouponAsync("testuser00001", "coupon001").GetAwaiter().GetResult();

        db.Entry(user).Reload();

        // 兑换成功且积分正确扣减
        return result.Success
            && result.Data != null
            && result.Data.Redeemed
            && user.PointsBalance == balance - cost;
    }

    [Property(MaxTest = 100)]
    public bool RedeemCoupon_WhenInsufficientPoints_ShouldFailAndKeepPoints(
        PositiveInt balanceRaw, PositiveInt extraRaw)
    {
        // 确保积分不足：balance < cost
        var balance = (balanceRaw.Get % 100) + 1;
        var cost = balance + (extraRaw.Get % 500) + 1;

        var dbName = $"RedeemInsufficient_{Guid.NewGuid()}";
        using var db = CreateDbContext(dbName);
        var logger = Mock.Of<ILogger<CouponService>>();

        var user = new User
        {
            Uid = "testuser00001",
            Phone = "13800000001",
            AreaCode = "+86",
            Nickname = "测试用户",
            PointsBalance = balance
        };
        var template = new CouponTemplate
        {
            Id = "coupon001",
            NameZhCn = "测试优惠券",
            NameZhTw = "測試優惠券",
            NameEn = "Test Coupon",
            Type = CouponType.DirectDiscount,
            DiscountAmount = 5m,
            PointsCost = cost,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            IsActive = true,
            IsStamp = false
        };
        db.Users.Add(user);
        db.CouponTemplates.Add(template);
        db.SaveChanges();

        var balanceBefore = user.PointsBalance;

        var service = new CouponService(db, logger);
        var result = service.RedeemCouponAsync("testuser00001", "coupon001").GetAwaiter().GetResult();

        db.Entry(user).Reload();

        // 兑换失败且积分不变
        return !result.Success
            && user.PointsBalance == balanceBefore;
    }

    // Feature: vending-machine-app, Property 14: 优惠券状态分类与标识
    // 对于任意用户优惠券列表，每张优惠券应被正确分类为"可使用""已使用"或"已过期"，
    // 且已使用和已过期的优惠券应带有对应状态标识。
    // **Validates: Requirements 6.6, 6.7**
    [Property(MaxTest = 100)]
    public bool CouponStatus_ShouldBeCorrectlyClassified(PositiveInt seed)
    {
        var dbName = $"CouponStatus_{Guid.NewGuid()}";
        using var db = CreateDbContext(dbName);
        var logger = Mock.Of<ILogger<CouponService>>();

        var user = new User
        {
            Uid = "testuser00001",
            Phone = "13800000001",
            AreaCode = "+86",
            Nickname = "测试用户",
            PointsBalance = 1000
        };
        db.Users.Add(user);

        var template = new CouponTemplate
        {
            Id = "tpl001",
            NameZhCn = "测试券",
            NameZhTw = "測試券",
            NameEn = "Test",
            Type = CouponType.DirectDiscount,
            DiscountAmount = 5m,
            PointsCost = 10,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            IsActive = true,
            IsStamp = false
        };
        db.CouponTemplates.Add(template);

        // 创建三种状态的优惠券
        var available = new UserCoupon
        {
            Id = "uc_avail",
            CouponTemplateId = "tpl001",
            UserId = "testuser00001",
            Status = CouponStatus.Available,
            ExpireAt = DateTime.UtcNow.AddDays(30)
        };
        var used = new UserCoupon
        {
            Id = "uc_used",
            CouponTemplateId = "tpl001",
            UserId = "testuser00001",
            Status = CouponStatus.Used,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            UsedAt = DateTime.UtcNow.AddDays(-1)
        };
        var expired = new UserCoupon
        {
            Id = "uc_expired",
            CouponTemplateId = "tpl001",
            UserId = "testuser00001",
            Status = CouponStatus.Expired,
            ExpireAt = DateTime.UtcNow.AddDays(-1)
        };
        db.UserCoupons.AddRange(available, used, expired);
        db.SaveChanges();

        var service = new CouponService(db, logger);
        var result = service.GetMyCouponsAsync("testuser00001", null, "zh-CN").GetAwaiter().GetResult();

        if (!result.Success || result.Data == null)
            return false;

        var coupons = result.Data;

        // 验证三种状态都存在且正确分类
        var availableCoupon = coupons.FirstOrDefault(c => c.Id == "uc_avail");
        var usedCoupon = coupons.FirstOrDefault(c => c.Id == "uc_used");
        var expiredCoupon = coupons.FirstOrDefault(c => c.Id == "uc_expired");

        return availableCoupon != null && availableCoupon.Status == "available"
            && usedCoupon != null && usedCoupon.Status == "used"
            && expiredCoupon != null && expiredCoupon.Status == "expired";
    }

    // Feature: vending-machine-app, Property 15: 印花兑换权限取决于会员状态
    // 对于任意用户点击印花优惠券兑换按钮，会员用户应执行兑换流程，非会员用户应被拒绝。
    // **Validates: Requirements 7.3, 7.4**
    [Property(MaxTest = 100)]
    public bool StampRedeem_MemberShouldSucceed_NonMemberShouldFail(bool isMember, PositiveInt balanceRaw)
    {
        var balance = (balanceRaw.Get % 1000) + 100; // 确保积分充足

        var dbName = $"StampPermission_{Guid.NewGuid()}";
        using var db = CreateDbContext(dbName);
        var logger = Mock.Of<ILogger<CouponService>>();

        var user = new User
        {
            Uid = "testuser00001",
            Phone = "13800000001",
            AreaCode = "+86",
            Nickname = "测试用户",
            IsMember = isMember,
            MembershipType = isMember ? MembershipType.Monthly : MembershipType.None,
            PointsBalance = balance
        };
        var stamp = new CouponTemplate
        {
            Id = "stamp001",
            NameZhCn = "节日印花",
            NameZhTw = "節日印花",
            NameEn = "Holiday Stamp",
            Type = CouponType.DirectDiscount,
            DiscountAmount = 10m,
            PointsCost = 0,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            IsActive = true,
            IsStamp = true
        };
        db.Users.Add(user);
        db.CouponTemplates.Add(stamp);
        db.SaveChanges();

        var service = new CouponService(db, logger);
        var result = service.RedeemStampCouponAsync("testuser00001", "stamp001").GetAwaiter().GetResult();

        if (isMember)
        {
            // 会员应兑换成功
            return result.Success && result.Data != null && result.Data.Redeemed;
        }
        else
        {
            // 非会员应被拒绝
            return !result.Success;
        }
    }

    // Feature: vending-machine-app, Property 16: 印花兑换幂等性
    // 对于任意会员用户和印花优惠券，第一次兑换应成功，后续重复兑换应被拒绝。
    // **Validates: Requirements 7.5, 7.6**
    [Property(MaxTest = 100)]
    public bool StampRedeem_ShouldBeIdempotent_SecondAttemptRejected(PositiveInt seed)
    {
        var dbName = $"StampIdempotent_{Guid.NewGuid()}";
        using var db = CreateDbContext(dbName);
        var logger = Mock.Of<ILogger<CouponService>>();

        var user = new User
        {
            Uid = "testuser00001",
            Phone = "13800000001",
            AreaCode = "+86",
            Nickname = "测试用户",
            IsMember = true,
            MembershipType = MembershipType.Monthly,
            PointsBalance = 1000
        };
        var stamp = new CouponTemplate
        {
            Id = "stamp001",
            NameZhCn = "节日印花",
            NameZhTw = "節日印花",
            NameEn = "Holiday Stamp",
            Type = CouponType.DirectDiscount,
            DiscountAmount = 10m,
            PointsCost = 0,
            ExpireAt = DateTime.UtcNow.AddDays(30),
            IsActive = true,
            IsStamp = true
        };
        db.Users.Add(user);
        db.CouponTemplates.Add(stamp);
        db.SaveChanges();

        var service = new CouponService(db, logger);

        // 第一次兑换应成功
        var firstResult = service.RedeemStampCouponAsync("testuser00001", "stamp001").GetAwaiter().GetResult();

        // 第二次兑换应被拒绝
        var secondResult = service.RedeemStampCouponAsync("testuser00001", "stamp001").GetAwaiter().GetResult();

        return firstResult.Success
            && firstResult.Data != null
            && firstResult.Data.Redeemed
            && !secondResult.Success;
    }
}