using AutoMapper;
using IM_API.Dtos.Auth;
using IM_API.Dtos.User;
using IM_API.Exceptions;
using IM_API.Interface.Services;
using IM_API.Models;
using IM_API.Services;
using IM_API.Tools;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Moq;
using System;
using System.Threading;
using System.Threading.Tasks;
using Xunit;

public class AuthServiceTests
{
    // ---------- 辅助：创建独立的 InMemory DbContext ----------
    private ImContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<ImContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        var context = new ImContext(options);
        return context;
    }

    // ---------- 可用于模拟 SaveChanges 抛异常的 DbContext ----------
    private class ThrowOnSaveImContext : ImContext
    {
        private readonly bool _throw;
        public ThrowOnSaveImContext(DbContextOptions<ImContext> options, bool throwOnSave) : base(options)
        {
            _throw = throwOnSave;
        }

        public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
        {
            if (_throw) throw new InvalidOperationException("Simulated DB save error");
            return base.SaveChangesAsync(cancellationToken);
        }
    }

    // ---------- 默认 AutoMapper（简易映射配置） ----------
    private IMapper CreateMapper()
    {
        var config = new MapperConfiguration(cfg =>
        {
            cfg.CreateMap<RegisterRequestDto, User>();
            cfg.CreateMap<User, UserInfoDto>();
        });
        return config.CreateMapper();
    }

    // ---------- 创建 Service（允许注入自定义 mapper） ----------
    private AuthService CreateService(ImContext context, IMapper mapper = null)
    {
        var loggerMock = new Mock<ILogger<AuthService>>();
        var mapperToUse = mapper ?? CreateMapper();
        var mockCache = new Mock<ICacheService>();
        return new AuthService(context, loggerMock.Object, mapperToUse,mockCache.Object);
    }

    // --------------------- 测试用例 ---------------------

    [Fact]
    public async Task LoginAsync_ShouldReturnUser_WhenValidCredentials()
    {
        var context = CreateDbContext();
        context.Users.Add(new User { Id = 1, Username = "Tom", Password = "123456", NickName = "测试用户" });
        await context.SaveChangesAsync();

        var service = CreateService(context);

        var result = await service.LoginAsync(new LoginRequestDto
        {
            Username = "Tom",
            Password = "123456"
        });

        Assert.NotNull(result);
        Assert.Equal(1, result.Id);
        Assert.Equal("Tom", result.Username);
    }

    [Fact]
    public async Task LoginAsync_ShouldThrowException_WhenInvalidCredentials()
    {
        var context = CreateDbContext();
        var service = CreateService(context);

        await Assert.ThrowsAsync<BaseException>(async () =>
        {
            await service.LoginAsync(new LoginRequestDto
            {
                Username = "NotExist",
                Password = "wrong"
            });
        });
    }

    [Fact]
    public async Task LoginAsync_IsCaseSensitive_ForUsername()
    {
        // 说明：当前实现是精确匹配 => 区分大小写
        var context = CreateDbContext();
        context.Users.Add(new User { Id = 10, Username = "Tom", Password = "p" });
        await context.SaveChangesAsync();

        var service = CreateService(context);

        // 使用小写用户名应失败（表明当前逻辑区分大小写）
        await Assert.ThrowsAsync<BaseException>(async () =>
        {
            await service.LoginAsync(new LoginRequestDto { Username = "tom", Password = "p" });
        });
    }

    [Fact]
    public async Task RegisterAsync_ShouldPersistUserAndReturnDto_WhenNewUser()
    {
        var context = CreateDbContext();
        var service = CreateService(context);

        var request = new RegisterRequestDto
        {
            Username = "Jerry",
            Password = "123456"
        };

        var result = await service.RegisterAsync(request);

        // 返回值正确
        Assert.NotNull(result);
        Assert.Equal("Jerry", result.Username);
        Assert.True(result.Id > 0);

        // DB 中确实存在该用户
        var persisted = await context.Users.FirstOrDefaultAsync(u => u.Username == "Jerry");
        Assert.NotNull(persisted);
        Assert.Equal("Jerry", persisted.Username);
    }

    [Fact]
    public async Task RegisterAsync_ShouldThrowException_WhenUserExists()
    {
        var context = CreateDbContext();
        context.Users.Add(new User { Username = "Tom", Password = "12223" });
        await context.SaveChangesAsync();

        var service = CreateService(context);

        var request = new RegisterRequestDto { Username = "Tom", Password = "123" };

        await Assert.ThrowsAsync<BaseException>(() => service.RegisterAsync(request));
    }

    [Fact]
    public async Task RegisterAsync_ShouldThrow_WhenMapperThrows()
    {
        var context = CreateDbContext();

        var mapperMock = new Mock<IMapper>();
        mapperMock.Setup(m => m.Map<User>(It.IsAny<RegisterRequestDto>()))
                  .Throws(new Exception("mapper failure"));

        var service = CreateService(context, mapperMock.Object);

        var req = new RegisterRequestDto { Username = "A", Password = "B" };

        var ex = await Assert.ThrowsAsync<Exception>(() => service.RegisterAsync(req));
        Assert.Contains("mapper failure", ex.Message);
    }

    [Fact]
    public async Task RegisterAsync_ShouldPropagateSaveException_WhenSaveFails()
    {
        var options = new DbContextOptionsBuilder<ImContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        // 使用自定义上下文在 SaveChanges 时抛异常
        var throwingContext = new ThrowOnSaveImContext(options, throwOnSave: true);

        var service = CreateService(throwingContext);

        var req = new RegisterRequestDto { Username = "X", Password = "P" };

        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => service.RegisterAsync(req));
        Assert.Contains("Simulated DB save error", ex.Message);
    }

    [Fact]
    public async Task RegisterAsync_NullDto_ThrowsNullReferenceException_CurrentBehavior()
    {
        // 说明：当前实现没有对 dto 为 null 做检查，会触发 NullReferenceException。
        // 建议：在生产代码中改为抛 ArgumentNullException 或者进行参数校验并返回明确错误。
        var context = CreateDbContext();
        var service = CreateService(context);

        await Assert.ThrowsAsync<NullReferenceException>(async () =>
        {
            await service.RegisterAsync(null);
        });
    }
}