using ChatBot.Models.Dto;
using ChatBot.Services;
using ChatBot.Services.Interfaces;
using ChatBot.Tests.TestUtilities;
using FluentAssertions;
using Moq;

namespace ChatBot.Tests.Services.Interfaces;

public class IHistoryCompressionServiceTests : UnitTestBase
{
    [Fact]
    public void IHistoryCompressionService_ShouldHaveCorrectMethodSignatures()
    {
        // Arrange & Act
        var interfaceType = typeof(IHistoryCompressionService);
        var methods = interfaceType.GetMethods();

        // Assert
        methods.Should().HaveCount(2);

        // CompressHistoryAsync method
        var compressHistoryAsyncMethod = methods.FirstOrDefault(m =>
            m.Name == "CompressHistoryAsync"
        );
        compressHistoryAsyncMethod.Should().NotBeNull();
        compressHistoryAsyncMethod!.ReturnType.Should().Be<Task<List<ChatMessage>>>();
        compressHistoryAsyncMethod.GetParameters().Should().HaveCount(3);
        compressHistoryAsyncMethod
            .GetParameters()[0]
            .ParameterType.Should()
            .Be<List<ChatMessage>>();
        compressHistoryAsyncMethod.GetParameters()[1].ParameterType.Should().Be<int>();
        compressHistoryAsyncMethod
            .GetParameters()[2]
            .ParameterType.Should()
            .Be<CancellationToken>();

        // ShouldCompress method
        var shouldCompressMethod = methods.FirstOrDefault(m => m.Name == "ShouldCompress");
        shouldCompressMethod.Should().NotBeNull();
        shouldCompressMethod!.ReturnType.Should().Be<bool>();
        shouldCompressMethod.GetParameters().Should().HaveCount(2);
        shouldCompressMethod.GetParameters()[0].ParameterType.Should().Be<int>();
        shouldCompressMethod.GetParameters()[1].ParameterType.Should().Be<int>();
    }

    [Fact]
    public void IHistoryCompressionService_ShouldBeImplementedByHistoryCompressionService()
    {
        // Arrange & Act
        var historyCompressionServiceType = typeof(HistoryCompressionService);
        var interfaceType = typeof(IHistoryCompressionService);

        // Assert
        interfaceType.IsAssignableFrom(historyCompressionServiceType).Should().BeTrue();
    }

    [Fact]
    public async Task IHistoryCompressionService_CompressHistoryAsync_ShouldReturnCompressedMessages()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messages = new List<ChatMessage>
        {
            new() { Role = "user", Content = "Message 1" },
            new() { Role = "assistant", Content = "Response 1" },
            new() { Role = "user", Content = "Message 2" },
            new() { Role = "assistant", Content = "Response 2" },
        };
        var targetCount = 2;
        var cancellationToken = CancellationToken.None;
        var expectedCompressedMessages = new List<ChatMessage>
        {
            new() { Role = "user", Content = "Compressed message" },
            new() { Role = "assistant", Content = "Compressed response" },
        };

        mock.Setup(x =>
                x.CompressHistoryAsync(
                    It.IsAny<List<ChatMessage>>(),
                    It.IsAny<int>(),
                    It.IsAny<CancellationToken>()
                )
            )
            .ReturnsAsync(expectedCompressedMessages);

        // Act
        var result = await mock.Object.CompressHistoryAsync(
            messages,
            targetCount,
            cancellationToken
        );

        // Assert
        result.Should().BeEquivalentTo(expectedCompressedMessages);
        mock.Verify(
            x => x.CompressHistoryAsync(messages, targetCount, cancellationToken),
            Times.Once
        );
    }

    [Fact]
    public async Task IHistoryCompressionService_CompressHistoryAsync_ShouldHandleEmptyMessages()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messages = new List<ChatMessage>();
        var targetCount = 5;
        var cancellationToken = CancellationToken.None;
        var expectedCompressedMessages = new List<ChatMessage>();

        mock.Setup(x =>
                x.CompressHistoryAsync(
                    It.IsAny<List<ChatMessage>>(),
                    It.IsAny<int>(),
                    It.IsAny<CancellationToken>()
                )
            )
            .ReturnsAsync(expectedCompressedMessages);

        // Act
        var result = await mock.Object.CompressHistoryAsync(
            messages,
            targetCount,
            cancellationToken
        );

        // Assert
        result.Should().BeEquivalentTo(expectedCompressedMessages);
        mock.Verify(
            x => x.CompressHistoryAsync(messages, targetCount, cancellationToken),
            Times.Once
        );
    }

    [Fact]
    public async Task IHistoryCompressionService_CompressHistoryAsync_ShouldHandleLargeMessageList()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messages = new List<ChatMessage>();
        for (int i = 0; i < 100; i++)
        {
            messages.Add(new() { Role = "user", Content = $"Message {i}" });
        }
        var targetCount = 10;
        var cancellationToken = CancellationToken.None;
        var expectedCompressedMessages = new List<ChatMessage>
        {
            new() { Role = "user", Content = "Compressed summary" },
        };

        mock.Setup(x =>
                x.CompressHistoryAsync(
                    It.IsAny<List<ChatMessage>>(),
                    It.IsAny<int>(),
                    It.IsAny<CancellationToken>()
                )
            )
            .ReturnsAsync(expectedCompressedMessages);

        // Act
        var result = await mock.Object.CompressHistoryAsync(
            messages,
            targetCount,
            cancellationToken
        );

        // Assert
        result.Should().BeEquivalentTo(expectedCompressedMessages);
        mock.Verify(
            x => x.CompressHistoryAsync(messages, targetCount, cancellationToken),
            Times.Once
        );
    }

    [Fact]
    public async Task IHistoryCompressionService_CompressHistoryAsync_ShouldHandleCancellationToken()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messages = new List<ChatMessage>
        {
            new() { Role = "user", Content = "Test message" },
        };
        var targetCount = 1;
        var cancellationToken = new CancellationToken(true); // Cancelled token
        var expectedCompressedMessages = new List<ChatMessage>();

        mock.Setup(x =>
                x.CompressHistoryAsync(
                    It.IsAny<List<ChatMessage>>(),
                    It.IsAny<int>(),
                    It.IsAny<CancellationToken>()
                )
            )
            .ReturnsAsync(expectedCompressedMessages);

        // Act
        var result = await mock.Object.CompressHistoryAsync(
            messages,
            targetCount,
            cancellationToken
        );

        // Assert
        result.Should().BeEquivalentTo(expectedCompressedMessages);
        mock.Verify(
            x => x.CompressHistoryAsync(messages, targetCount, cancellationToken),
            Times.Once
        );
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldReturnTrue_WhenMessageCountExceedsThreshold()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = 15;
        var threshold = 10;
        var expectedResult = true;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldReturnFalse_WhenMessageCountIsBelowThreshold()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = 5;
        var threshold = 10;
        var expectedResult = false;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldReturnFalse_WhenMessageCountEqualsThreshold()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = 10;
        var threshold = 10;
        var expectedResult = false;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldHandleZeroValues()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = 0;
        var threshold = 0;
        var expectedResult = false;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldHandleNegativeValues()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = -5;
        var threshold = -10;
        var expectedResult = false;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldCompress_ShouldHandleLargeValues()
    {
        // Arrange
        var mock = new Mock<IHistoryCompressionService>();
        var messageCount = int.MaxValue;
        var threshold = int.MaxValue - 1;
        var expectedResult = true;

        mock.Setup(x => x.ShouldCompress(It.IsAny<int>(), It.IsAny<int>())).Returns(expectedResult);

        // Act
        var result = mock.Object.ShouldCompress(messageCount, threshold);

        // Assert
        result.Should().Be(expectedResult);
        mock.Verify(x => x.ShouldCompress(messageCount, threshold), Times.Once);
    }

    [Fact]
    public void IHistoryCompressionService_ShouldBePublicInterface()
    {
        // Arrange & Act
        var interfaceType = typeof(IHistoryCompressionService);

        // Assert
        interfaceType.IsPublic.Should().BeTrue();
        interfaceType.IsInterface.Should().BeTrue();
    }

    [Fact]
    public void IHistoryCompressionService_ShouldHaveCorrectNamespace()
    {
        // Arrange & Act
        var interfaceType = typeof(IHistoryCompressionService);

        // Assert
        interfaceType.Namespace.Should().Be("ChatBot.Services.Interfaces");
    }

    [Fact]
    public void IHistoryCompressionService_ShouldHaveCorrectGenericConstraints()
    {
        // Arrange & Act
        var interfaceType = typeof(IHistoryCompressionService);
        var methods = interfaceType.GetMethods();

        // Assert
        // All methods should be public
        methods.All(m => m.IsPublic).Should().BeTrue();

        // CompressHistoryAsync should have default parameter for CancellationToken
        var compressMethod = methods.First(m => m.Name == "CompressHistoryAsync");
        compressMethod.GetParameters()[2].HasDefaultValue.Should().BeTrue();
        // Note: Default value for CancellationToken in interface might be null
        compressMethod.GetParameters()[2].DefaultValue.Should().BeNull();
    }
}