using System.Text;
using StellaOps.Router.Common.Enums;
using StellaOps.Router.Common.Frames;
using StellaOps.Router.Common.Models;

using StellaOps.TestKit;
namespace StellaOps.Router.Common.Tests;

/// <summary>
/// Unit tests for <see cref="FrameConverter"/>.
/// </summary>
public sealed class FrameConverterTests
{
    #region ToFrame (RequestFrame) Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_RequestFrame_ReturnsFrameWithRequestType()
    {
        // Arrange
        var request = CreateTestRequestFrame();

        // Act
        var frame = FrameConverter.ToFrame(request);

        // Assert
        frame.Type.Should().Be(FrameType.Request);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_RequestFrame_SetsCorrelationIdFromRequest()
    {
        // Arrange
        var request = CreateTestRequestFrame(correlationId: "test-correlation-123");

        // Act
        var frame = FrameConverter.ToFrame(request);

        // Assert
        frame.CorrelationId.Should().Be("test-correlation-123");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_RequestFrame_UsesRequestIdWhenCorrelationIdIsNull()
    {
        // Arrange
        var request = new RequestFrame
        {
            RequestId = "request-id-456",
            CorrelationId = null,
            Method = "GET",
            Path = "/test"
        };

        // Act
        var frame = FrameConverter.ToFrame(request);

        // Assert
        frame.CorrelationId.Should().Be("request-id-456");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_RequestFrame_SerializesPayload()
    {
        // Arrange
        var request = CreateTestRequestFrame();

        // Act
        var frame = FrameConverter.ToFrame(request);

        // Assert
        frame.Payload.Length.Should().BeGreaterThan(0);
    }

    #endregion

    #region ToRequestFrame Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_ValidRequestFrame_ReturnsRequestFrame()
    {
        // Arrange
        var originalRequest = CreateTestRequestFrame();
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result.Should().NotBeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_WrongFrameType_ReturnsNull()
    {
        // Arrange
        var frame = new Frame
        {
            Type = FrameType.Response,
            CorrelationId = "test",
            Payload = Array.Empty<byte>()
        };

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result.Should().BeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_InvalidJson_ReturnsNull()
    {
        // Arrange
        var frame = new Frame
        {
            Type = FrameType.Request,
            CorrelationId = "test",
            Payload = Encoding.UTF8.GetBytes("invalid json {{{")
        };

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result.Should().BeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesRequestId()
    {
        // Arrange
        var originalRequest = CreateTestRequestFrame(requestId: "unique-request-id");
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.RequestId.Should().Be("unique-request-id");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesMethod()
    {
        // Arrange
        var originalRequest = CreateTestRequestFrame(method: "DELETE");
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Method.Should().Be("DELETE");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesPath()
    {
        // Arrange
        var originalRequest = CreateTestRequestFrame(path: "/api/users/123");
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Path.Should().Be("/api/users/123");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesHeaders()
    {
        // Arrange
        var headers = new Dictionary<string, string>
        {
            ["Content-Type"] = "application/json",
            ["X-Custom-Header"] = "custom-value"
        };
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "POST",
            Path = "/test",
            Headers = headers
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Headers.Should().ContainKey("Content-Type");
        result.Headers["Content-Type"].Should().Be("application/json");
        result.Headers["X-Custom-Header"].Should().Be("custom-value");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesPayload()
    {
        // Arrange
        var payloadBytes = Encoding.UTF8.GetBytes("{\"key\":\"value\"}");
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "POST",
            Path = "/test",
            Payload = payloadBytes
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Payload.ToArray().Should().BeEquivalentTo(payloadBytes);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesTimeoutSeconds()
    {
        // Arrange
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "GET",
            Path = "/test",
            TimeoutSeconds = 60
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.TimeoutSeconds.Should().Be(60);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_RoundTrip_PreservesSupportsStreaming()
    {
        // Arrange
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "GET",
            Path = "/test",
            SupportsStreaming = true
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.SupportsStreaming.Should().BeTrue();
    }

    #endregion

    #region ToFrame (ResponseFrame) Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_ResponseFrame_ReturnsFrameWithResponseType()
    {
        // Arrange
        var response = CreateTestResponseFrame();

        // Act
        var frame = FrameConverter.ToFrame(response);

        // Assert
        frame.Type.Should().Be(FrameType.Response);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_ResponseFrame_SetsCorrelationIdToRequestId()
    {
        // Arrange
        var response = CreateTestResponseFrame(requestId: "req-123");

        // Act
        var frame = FrameConverter.ToFrame(response);

        // Assert
        frame.CorrelationId.Should().Be("req-123");
    }

    #endregion

    #region ToResponseFrame Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_ValidResponseFrame_ReturnsResponseFrame()
    {
        // Arrange
        var originalResponse = CreateTestResponseFrame();
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result.Should().NotBeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_WrongFrameType_ReturnsNull()
    {
        // Arrange
        var frame = new Frame
        {
            Type = FrameType.Request,
            CorrelationId = "test",
            Payload = Array.Empty<byte>()
        };

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result.Should().BeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_InvalidJson_ReturnsNull()
    {
        // Arrange
        var frame = new Frame
        {
            Type = FrameType.Response,
            CorrelationId = "test",
            Payload = Encoding.UTF8.GetBytes("not valid json")
        };

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result.Should().BeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_RoundTrip_PreservesRequestId()
    {
        // Arrange
        var originalResponse = CreateTestResponseFrame(requestId: "original-req-id");
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.RequestId.Should().Be("original-req-id");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_RoundTrip_PreservesStatusCode()
    {
        // Arrange
        var originalResponse = CreateTestResponseFrame(statusCode: 404);
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.StatusCode.Should().Be(404);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_RoundTrip_PreservesHeaders()
    {
        // Arrange
        var headers = new Dictionary<string, string>
        {
            ["Content-Type"] = "application/json",
            ["Cache-Control"] = "no-cache"
        };
        var originalResponse = new ResponseFrame
        {
            RequestId = "test-id",
            StatusCode = 200,
            Headers = headers
        };
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.Headers["Content-Type"].Should().Be("application/json");
        result.Headers["Cache-Control"].Should().Be("no-cache");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_RoundTrip_PreservesPayload()
    {
        // Arrange
        var payloadBytes = Encoding.UTF8.GetBytes("{\"result\":\"success\"}");
        var originalResponse = new ResponseFrame
        {
            RequestId = "test-id",
            StatusCode = 200,
            Payload = payloadBytes
        };
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.Payload.ToArray().Should().BeEquivalentTo(payloadBytes);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_RoundTrip_PreservesHasMoreChunks()
    {
        // Arrange
        var originalResponse = new ResponseFrame
        {
            RequestId = "test-id",
            StatusCode = 200,
            HasMoreChunks = true
        };
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.HasMoreChunks.Should().BeTrue();
    }

    #endregion

    #region Edge Cases

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_EmptyPayload_ReturnsEmptyPayload()
    {
        // Arrange
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "GET",
            Path = "/test",
            Payload = Array.Empty<byte>()
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Payload.IsEmpty.Should().BeTrue();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToRequestFrame_NullHeaders_ReturnsEmptyHeaders()
    {
        // Arrange
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "GET",
            Path = "/test"
        };
        var frame = FrameConverter.ToFrame(originalRequest);

        // Act
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result!.Headers.Should().NotBeNull();
        result.Headers.Should().BeEmpty();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToResponseFrame_EmptyPayload_ReturnsEmptyPayload()
    {
        // Arrange
        var originalResponse = new ResponseFrame
        {
            RequestId = "test-id",
            StatusCode = 204,
            Payload = Array.Empty<byte>()
        };
        var frame = FrameConverter.ToFrame(originalResponse);

        // Act
        var result = FrameConverter.ToResponseFrame(frame);

        // Assert
        result!.Payload.IsEmpty.Should().BeTrue();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void ToFrame_LargePayload_Succeeds()
    {
        // Arrange
        var largePayload = new byte[1024 * 1024]; // 1MB
        Random.Shared.NextBytes(largePayload);
        var originalRequest = new RequestFrame
        {
            RequestId = "test-id",
            Method = "POST",
            Path = "/upload",
            Payload = largePayload
        };

        // Act
        var frame = FrameConverter.ToFrame(originalRequest);
        var result = FrameConverter.ToRequestFrame(frame);

        // Assert
        result.Should().NotBeNull();
        result!.Payload.ToArray().Should().BeEquivalentTo(largePayload);
    }

    #endregion

    #region Helper Methods

    private static RequestFrame CreateTestRequestFrame(
        string? requestId = null,
        string? correlationId = null,
        string method = "GET",
        string path = "/test")
    {
        return new RequestFrame
        {
            RequestId = requestId ?? Guid.NewGuid().ToString("N"),
            CorrelationId = correlationId,
            Method = method,
            Path = path
        };
    }

    private static ResponseFrame CreateTestResponseFrame(
        string? requestId = null,
        int statusCode = 200)
    {
        return new ResponseFrame
        {
            RequestId = requestId ?? Guid.NewGuid().ToString("N"),
            StatusCode = statusCode
        };
    }

    #endregion
}