using FluentAssertions;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Moq;
using StellaOps.Microservice;
using StellaOps.Router.Common.Models;
using Xunit;

namespace StellaOps.Microservice.Tests;

/// <summary>
/// Tests for EndpointDiscoveryService - verifies integration of discovery + YAML loading + merging.
/// </summary>
public class EndpointDiscoveryServiceTests
{
    private readonly Mock<IEndpointDiscoveryProvider> _discoveryProviderMock;
    private readonly Mock<IMicroserviceYamlLoader> _yamlLoaderMock;
    private readonly Mock<IEndpointOverrideMerger> _mergerMock;
    private readonly ILogger<EndpointDiscoveryService> _logger;
    private readonly EndpointDiscoveryService _service;

    public EndpointDiscoveryServiceTests()
    {
        _discoveryProviderMock = new Mock<IEndpointDiscoveryProvider>();
        _yamlLoaderMock = new Mock<IMicroserviceYamlLoader>();
        _mergerMock = new Mock<IEndpointOverrideMerger>();
        _logger = NullLogger<EndpointDiscoveryService>.Instance;

        _service = new EndpointDiscoveryService(
            _discoveryProviderMock.Object,
            _yamlLoaderMock.Object,
            _mergerMock.Object,
            _logger);
    }

    [Fact]
    public void DiscoverEndpoints_CallsDiscoveryProvider()
    {
        var codeEndpoints = new List<EndpointDescriptor>();
        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _mergerMock
            .Setup(x => x.Merge(It.IsAny<IReadOnlyList<EndpointDescriptor>>(), It.IsAny<MicroserviceYamlConfig?>()))
            .Returns(codeEndpoints);

        _service.DiscoverEndpoints();

        _discoveryProviderMock.Verify(x => x.DiscoverEndpoints(), Times.Once);
    }

    [Fact]
    public void DiscoverEndpoints_CallsYamlLoader()
    {
        var codeEndpoints = new List<EndpointDescriptor>();
        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _mergerMock
            .Setup(x => x.Merge(It.IsAny<IReadOnlyList<EndpointDescriptor>>(), It.IsAny<MicroserviceYamlConfig?>()))
            .Returns(codeEndpoints);

        _service.DiscoverEndpoints();

        _yamlLoaderMock.Verify(x => x.Load(), Times.Once);
    }

    [Fact]
    public void DiscoverEndpoints_PassesCodeEndpointsAndYamlConfigToMerger()
    {
        var codeEndpoints = new List<EndpointDescriptor>
        {
            CreateEndpoint("GET", "/api/test")
        };
        var yamlConfig = new MicroserviceYamlConfig
        {
            Endpoints =
            [
                new EndpointOverrideConfig { Method = "GET", Path = "/api/test" }
            ]
        };

        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _yamlLoaderMock
            .Setup(x => x.Load())
            .Returns(yamlConfig);
        _mergerMock
            .Setup(x => x.Merge(codeEndpoints, yamlConfig))
            .Returns(codeEndpoints);

        _service.DiscoverEndpoints();

        _mergerMock.Verify(x => x.Merge(codeEndpoints, yamlConfig), Times.Once);
    }

    [Fact]
    public void DiscoverEndpoints_ReturnsMergedEndpoints()
    {
        var codeEndpoints = new List<EndpointDescriptor>
        {
            CreateEndpoint("GET", "/api/test", TimeSpan.FromSeconds(10))
        };
        var mergedEndpoints = new List<EndpointDescriptor>
        {
            CreateEndpoint("GET", "/api/test", TimeSpan.FromMinutes(5))
        };

        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _mergerMock
            .Setup(x => x.Merge(It.IsAny<IReadOnlyList<EndpointDescriptor>>(), It.IsAny<MicroserviceYamlConfig?>()))
            .Returns(mergedEndpoints);

        var result = _service.DiscoverEndpoints();

        result.Should().BeSameAs(mergedEndpoints);
    }

    [Fact]
    public void DiscoverEndpoints_ContinuesWithNullYamlConfig_WhenLoaderReturnsNull()
    {
        var codeEndpoints = new List<EndpointDescriptor>
        {
            CreateEndpoint("GET", "/api/test")
        };

        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _yamlLoaderMock
            .Setup(x => x.Load())
            .Returns((MicroserviceYamlConfig?)null);
        _mergerMock
            .Setup(x => x.Merge(codeEndpoints, null))
            .Returns(codeEndpoints);

        var result = _service.DiscoverEndpoints();

        _mergerMock.Verify(x => x.Merge(codeEndpoints, null), Times.Once);
        result.Should().BeSameAs(codeEndpoints);
    }

    [Fact]
    public void DiscoverEndpoints_ContinuesWithNullYamlConfig_WhenLoaderThrows()
    {
        var codeEndpoints = new List<EndpointDescriptor>
        {
            CreateEndpoint("GET", "/api/test")
        };

        _discoveryProviderMock
            .Setup(x => x.DiscoverEndpoints())
            .Returns(codeEndpoints);
        _yamlLoaderMock
            .Setup(x => x.Load())
            .Throws(new Exception("YAML parsing failed"));
        _mergerMock
            .Setup(x => x.Merge(codeEndpoints, null))
            .Returns(codeEndpoints);

        var result = _service.DiscoverEndpoints();

        // Should not throw, should continue with null config
        _mergerMock.Verify(x => x.Merge(codeEndpoints, null), Times.Once);
        result.Should().BeSameAs(codeEndpoints);
    }

    private static EndpointDescriptor CreateEndpoint(
        string method,
        string path,
        TimeSpan? timeout = null)
    {
        return new EndpointDescriptor
        {
            ServiceName = "test-service",
            Version = "1.0.0",
            Method = method,
            Path = path,
            DefaultTimeout = timeout ?? TimeSpan.FromSeconds(30)
        };
    }
}