using Xunit;
using Moq;
using Moq.Protected;
using System.Net;
using System.Net.Http;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Svrnty.MCP.Core;
using CodexMcpServer.Tools;

namespace CodexMcpServer.Tests;

/// <summary>
/// Unit tests for GetDocumentTool following TDD approach.
/// Tests integration with CODEX API /api/documents/{id} endpoint.
/// </summary>
public class GetDocumentToolTests
{
    [Fact]
    public void GetDocumentTool_ShouldHaveCorrectName()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);

        // Act
        var name = tool.Name;

        // Assert
        Assert.Equal("get_document", name);
    }

    [Fact]
    public void GetDocumentTool_ShouldHaveDescription()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);

        // Act
        var description = tool.Description;

        // Assert
        Assert.NotNull(description);
        Assert.NotEmpty(description);
        Assert.Contains("document", description.ToLower());
    }

    [Fact]
    public void GetDocumentTool_ShouldHaveValidSchema()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);

        // Act
        var schema = tool.Schema;

        // Assert
        Assert.NotNull(schema);
        var root = schema.RootElement;
        Assert.Equal(JsonValueKind.Object, root.ValueKind);

        // Schema should define required "id" parameter
        Assert.True(root.TryGetProperty("properties", out var properties));
        Assert.True(properties.TryGetProperty("id", out var idProp));
        Assert.True(idProp.TryGetProperty("type", out var idType));
        Assert.Equal("string", idType.GetString());
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithValidId_ShouldCallCodexApi()
    {
        // Arrange
        var mockResponse = new
        {
            id = "doc123",
            title = "Test Document",
            content = "Document content",
            metadata = new { author = "Test Author" }
        };
        var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
        mockHttpMessageHandler
            .Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.Is<HttpRequestMessage>(req =>
                    req.Method == HttpMethod.Get &&
                    req.RequestUri.ToString().Contains("/api/documents/doc123")
                ),
                ItExpr.IsAny<CancellationToken>()
            )
            .ReturnsAsync(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.OK,
                Content = new StringContent(JsonSerializer.Serialize(mockResponse))
            });

        var httpClient = new HttpClient(mockHttpMessageHandler.Object)
        {
            BaseAddress = new System.Uri("http://localhost:5050")
        };
        var tool = new GetDocumentTool(httpClient);

        var arguments = JsonDocument.Parse("""{"id": "doc123"}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("id", out var id));
        Assert.Equal("doc123", id.GetString());
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithEmptyId_ShouldReturnError()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"id": ""}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out var error));
        Assert.Contains("id", error.GetString().ToLower());
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithNullArguments_ShouldReturnError()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);

        // Act
        var result = await tool.ExecuteAsync(null);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out _));
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithMissingIdProperty_ShouldReturnError()
    {
        // Arrange
        var httpClient = new HttpClient();
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"other": "value"}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out _));
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithNotFound_ShouldReturnError()
    {
        // Arrange
        var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
        mockHttpMessageHandler
            .Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>()
            )
            .ReturnsAsync(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.NotFound,
                Content = new StringContent("Document not found")
            });

        var httpClient = new HttpClient(mockHttpMessageHandler.Object)
        {
            BaseAddress = new System.Uri("http://localhost:5050")
        };
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"id": "nonexistent"}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out _));
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithHttpError_ShouldReturnErrorResponse()
    {
        // Arrange
        var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
        mockHttpMessageHandler
            .Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>()
            )
            .ReturnsAsync(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.InternalServerError,
                Content = new StringContent("Internal server error")
            });

        var httpClient = new HttpClient(mockHttpMessageHandler.Object)
        {
            BaseAddress = new System.Uri("http://localhost:5050")
        };
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"id": "doc123"}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out _));
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_WithInvalidJson_ShouldReturnError()
    {
        // Arrange
        var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
        mockHttpMessageHandler
            .Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>()
            )
            .ReturnsAsync(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.OK,
                Content = new StringContent("invalid json{{{")
            });

        var httpClient = new HttpClient(mockHttpMessageHandler.Object)
        {
            BaseAddress = new System.Uri("http://localhost:5050")
        };
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"id": "doc123"}""");

        // Act
        var result = await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(result);
        var root = result.RootElement;
        Assert.True(root.TryGetProperty("error", out _));
    }

    [Fact]
    public void GetDocumentTool_ShouldImplementIMcpTool()
    {
        // Arrange
        var httpClient = new HttpClient();

        // Act
        var tool = new GetDocumentTool(httpClient);

        // Assert
        Assert.IsAssignableFrom<IMcpTool>(tool);
    }

    [Fact]
    public async Task GetDocumentTool_ExecuteAsync_ShouldUseCorrectEndpoint()
    {
        // Arrange
        string capturedUri = null;
        var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
        mockHttpMessageHandler
            .Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>()
            )
            .ReturnsAsync((HttpRequestMessage req, CancellationToken ct) =>
            {
                capturedUri = req.RequestUri?.ToString();
                return new HttpResponseMessage
                {
                    StatusCode = HttpStatusCode.OK,
                    Content = new StringContent("""{"id": "test123"}""")
                };
            });

        var httpClient = new HttpClient(mockHttpMessageHandler.Object)
        {
            BaseAddress = new System.Uri("http://localhost:5050")
        };
        var tool = new GetDocumentTool(httpClient);
        var arguments = JsonDocument.Parse("""{"id": "test123"}""");

        // Act
        await tool.ExecuteAsync(arguments);

        // Assert
        Assert.NotNull(capturedUri);
        Assert.Contains("/api/documents/test123", capturedUri);
        Assert.DoesNotContain("POST", capturedUri); // Should be GET
    }
}