/// <summary>
/// 全域異常處理器
/// </summary>
public class GlobalExceptionHandler : IExceptionHandler
{
    private readonly ILogger<GlobalExceptionHandler> _logger;

    public GlobalExceptionHandler(ILogger<GlobalExceptionHandler> logger)
    {
        _logger = logger;
    }

    public async ValueTask<bool> TryHandleAsync(
        HttpContext httpContext,
        Exception exception,
        CancellationToken cancellationToken)
    {
        _logger.LogError(exception, "發生未處理的異常: {Message}", exception.Message);

        var problemDetails = CreateProblemDetails(exception);

        httpContext.Response.StatusCode = problemDetails.Status ?? 500;
        httpContext.Response.ContentType = "application/problem+json";

        await httpContext.Response.WriteAsJsonAsync(problemDetails, cancellationToken);
        return true;
    }

    private static ProblemDetails CreateProblemDetails(Exception exception)
    {
        return exception switch
        {
            KeyNotFoundException => new ProblemDetails
            {
                Type = "https://httpstatuses.com/404",
                Title = "資源不存在",
                Status = 404,
                Detail = exception.Message
            },
            ArgumentException => new ProblemDetails
            {
                Type = "https://httpstatuses.com/400",
                Title = "參數錯誤",
                Status = 400,
                Detail = exception.Message
            },
            _ => new ProblemDetails
            {
                Type = "https://httpstatuses.com/500",
                Title = "內部伺服器錯誤",
                Status = 500,
                Detail = "發生未預期的錯誤"
            }
        };
    }
}

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "detail": "輸入的資料包含驗證錯誤",
  "errors": {
    "Name": ["產品名稱不能為空"],
    "Price": ["產品價格必須大於 0"]
  }
}

public class TestWebApplicationFactory : WebApplicationFactory<Program>, IAsyncLifetime
{
    private PostgreSqlContainer? _postgresContainer;
    private RedisContainer? _redisContainer;
    private FakeTimeProvider? _timeProvider;

    public PostgreSqlContainer PostgresContainer => _postgresContainer
        ?? throw new InvalidOperationException("PostgreSQL container 尚未初始化");

    public RedisContainer RedisContainer => _redisContainer
        ?? throw new InvalidOperationException("Redis container 尚未初始化");

    public FakeTimeProvider TimeProvider => _timeProvider
        ?? throw new InvalidOperationException("TimeProvider 尚未初始化");

    public async Task InitializeAsync()
    {
        _postgresContainer = new PostgreSqlBuilder()
            .WithImage("postgres:16-alpine")
            .WithDatabase("test_db")
            .WithUsername("testuser")
            .WithPassword("testpass")
            .WithCleanUp(true)
            .Build();

        _redisContainer = new RedisBuilder()
            .WithImage("redis:7-alpine")
            .WithCleanUp(true)
            .Build();

        _timeProvider = new FakeTimeProvider(new DateTimeOffset(2024, 1, 1, 0, 0, 0, TimeSpan.Zero));

        await _postgresContainer.StartAsync();
        await _redisContainer.StartAsync();
    }

    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {
        builder.ConfigureAppConfiguration(config =>
        {
            config.Sources.Clear();
            config.AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["ConnectionStrings:DefaultConnection"] = PostgresContainer.GetConnectionString(),
                ["ConnectionStrings:Redis"] = RedisContainer.GetConnectionString(),
                ["Logging:LogLevel:Default"] = "Warning"
            });
        });

        builder.ConfigureServices(services =>
        {
            // 替換 TimeProvider
            services.Remove(services.Single(d => d.ServiceType == typeof(TimeProvider)));
            services.AddSingleton<TimeProvider>(TimeProvider);
        });

        builder.UseEnvironment("Testing");
    }

    public new async Task DisposeAsync()
    {
        if (_postgresContainer != null) await _postgresContainer.DisposeAsync();
        if (_redisContainer != null) await _redisContainer.DisposeAsync();
        await base.DisposeAsync();
    }
}

[CollectionDefinition("Integration Tests")]
public class IntegrationTestCollection : ICollectionFixture<TestWebApplicationFactory>
{
    public const string Name = "Integration Tests";
}

[Collection("Integration Tests")]
public abstract class IntegrationTestBase : IAsyncLifetime
{
    protected readonly TestWebApplicationFactory Factory;
    protected readonly HttpClient HttpClient;
    protected readonly DatabaseManager DatabaseManager;
    protected readonly IFlurlClient FlurlClient;

    protected IntegrationTestBase(TestWebApplicationFactory factory)
    {
        Factory = factory;
        HttpClient = factory.CreateClient();
        DatabaseManager = new DatabaseManager(factory.PostgresContainer.GetConnectionString());
        FlurlClient = new FlurlClient(HttpClient);
    }

    public virtual async Task InitializeAsync()
    {
        await DatabaseManager.InitializeDatabaseAsync();
    }

    public virtual async Task DisposeAsync()
    {
        await DatabaseManager.CleanDatabaseAsync();
        FlurlClient.Dispose();
    }

    protected void ResetTime()
    {
        Factory.TimeProvider.SetUtcNow(new DateTimeOffset(2024, 1, 1, 0, 0, 0, TimeSpan.Zero));
    }

    protected void AdvanceTime(TimeSpan timeSpan)
    {
        Factory.TimeProvider.Advance(timeSpan);
    }
}

// 傳統方式
var url = $"/products?pageSize={pageSize}&page={page}&keyword={keyword}";

// 使用 Flurl
var url = "/products"
    .SetQueryParam("pageSize", 5)
    .SetQueryParam("page", 2)
    .SetQueryParam("keyword", "特殊");

[Fact]
public async Task CreateProduct_使用有效資料_應成功建立產品()
{
    // Arrange
    var request = new ProductCreateRequest { Name = "新產品", Price = 299.99m };

    // Act
    var response = await HttpClient.PostAsJsonAsync("/products", request);

    // Assert
    response.Should().Be201Created()
        .And.Satisfy<ProductResponse>(product =>
        {
            product.Id.Should().NotBeEmpty();
            product.Name.Should().Be("新產品");
            product.Price.Should().Be(299.99m);
        });
}

[Fact]
public async Task CreateProduct_當產品名稱為空_應回傳400BadRequest()
{
    // Arrange
    var invalidRequest = new ProductCreateRequest { Name = "", Price = 100.00m };

    // Act
    var response = await HttpClient.PostAsJsonAsync("/products", invalidRequest);

    // Assert
    response.Should().Be400BadRequest()
        .And.Satisfy<ValidationProblemDetails>(problem =>
        {
            problem.Type.Should().Be("https://tools.ietf.org/html/rfc9110#section-15.5.1");
            problem.Title.Should().Be("One or more validation errors occurred.");
            problem.Errors.Should().ContainKey("Name");
            problem.Errors["Name"].Should().Contain("產品名稱不能為空");
        });
}

[Fact]
public async Task GetById_當產品不存在_應回傳404且包含ProblemDetails()
{
    // Arrange
    var nonExistentId = Guid.NewGuid();

    // Act
    var response = await HttpClient.GetAsync($"/Products/{nonExistentId}");

    // Assert
    response.Should().Be404NotFound()
        .And.Satisfy<ProblemDetails>(problem =>
        {
            problem.Type.Should().Be("https://httpstatuses.com/404");
            problem.Title.Should().Be("產品不存在");
            problem.Status.Should().Be(404);
        });
}

[Fact]
public async Task GetProducts_使用分頁參數_應回傳正確的分頁結果()
{
    // Arrange
    await TestHelpers.SeedProductsAsync(DatabaseManager, 15);

    // Act - 使用 Flurl 建構 QueryString
    var url = "/products"
        .SetQueryParam("pageSize", 5)
        .SetQueryParam("page", 2);

    var response = await HttpClient.GetAsync(url);

    // Assert
    response.Should().Be200Ok()
        .And.Satisfy<PagedResult<ProductResponse>>(result =>
        {
            result.Total.Should().Be(15);
            result.PageSize.Should().Be(5);
            result.Page.Should().Be(2);
            result.Items.Should().HaveCount(5);
        });
}

public static class TestHelpers
{
    public static ProductCreateRequest CreateProductRequest(
        string name = "測試產品",
        decimal price = 100.00m)
    {
        return new ProductCreateRequest { Name = name, Price = price };
    }

    public static async Task SeedProductsAsync(DatabaseManager dbManager, int count)
    {
        var tasks = Enumerable.Range(1, count)
            .Select(i => SeedSpecificProductAsync(dbManager, $"產品 {i:D2}", i * 10.0m));
        await Task.WhenAll(tasks);
    }
}

tests/Integration/
└── SqlScripts/
    └── Tables/
        └── CreateProductsTable.sql

<PackageReference Include="xunit" Version="2.9.3" />
<PackageReference Include="AwesomeAssertions" Version="9.1.0" />
<PackageReference Include="Testcontainers.PostgreSql" Version="4.0.0" />
<PackageReference Include="Testcontainers.Redis" Version="4.0.0" />
<PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.0" />
<PackageReference Include="Flurl" Version="4.0.0" />
<PackageReference Include="Respawn" Version="6.2.1" />

src/
├── Api/                          # WebApi 層
├── Application/                  # 應用服務層
├── Domain/                       # 領域模型
└── Infrastructure/               # 基礎設施層
tests/
└── Integration/
    ├── Fixtures/
    │   ├── TestWebApplicationFactory.cs
    │   ├── IntegrationTestCollection.cs
    │   └── IntegrationTestBase.cs
    ├── Handlers/
    │   ├── GlobalExceptionHandler.cs
    │   └── FluentValidationExceptionHandler.cs
    ├── Helpers/
    │   ├── DatabaseManager.cs
    │   └── TestHelpers.cs
    ├── SqlScripts/
    │   └── Tables/
    └── Controllers/
        └── ProductsControllerTests.cs