using Xunit;
using Moq;
using System.Threading.Tasks;
using System.Text.Json;

namespace Svrnty.MCP.Core.Tests;

/// <summary>
/// Unit tests for IMcpTool interface following TDD approach.
/// Tests the core abstraction for MCP tools.
/// </summary>
public class IMcpToolTests
{
    [Fact]
    public void IMcpTool_ShouldHaveNameProperty()
    {
        // Arrange - Create a mock implementation
        var mockTool = new Mock<IMcpTool>();
        mockTool.Setup(t => t.Name).Returns("test_tool");

        // Act
        var name = mockTool.Object.Name;

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

    [Fact]
    public void IMcpTool_ShouldHaveDescriptionProperty()
    {
        // Arrange
        var mockTool = new Mock<IMcpTool>();
        mockTool.Setup(t => t.Description).Returns("A test tool");

        // Act
        var description = mockTool.Object.Description;

        // Assert
        Assert.Equal("A test tool", description);
    }

    [Fact]
    public void IMcpTool_ShouldHaveSchemaProperty()
    {
        // Arrange
        var mockTool = new Mock<IMcpTool>();
        var schema = JsonDocument.Parse("""
        {
            "type": "object",
            "properties": {
                "query": { "type": "string" }
            }
        }
        """);
        mockTool.Setup(t => t.Schema).Returns(schema);

        // Act
        var toolSchema = mockTool.Object.Schema;

        // Assert
        Assert.NotNull(toolSchema);
        Assert.Equal("object", toolSchema.RootElement.GetProperty("type").GetString());
    }

    [Fact]
    public async Task IMcpTool_ShouldExecuteAsync()
    {
        // Arrange
        var mockTool = new Mock<IMcpTool>();
        var expectedResult = JsonDocument.Parse("""{"status": "success"}""");
        var arguments = JsonDocument.Parse("""{"query": "test"}""");

        mockTool.Setup(t => t.ExecuteAsync(It.IsAny<JsonDocument>()))
                .ReturnsAsync(expectedResult);

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

        // Assert
        Assert.NotNull(result);
        Assert.Equal("success", result.RootElement.GetProperty("status").GetString());
    }

    [Fact]
    public async Task IMcpTool_ExecuteAsync_ShouldHandleNullArguments()
    {
        // Arrange
        var mockTool = new Mock<IMcpTool>();
        var expectedResult = JsonDocument.Parse("""{"status": "executed"}""");

        mockTool.Setup(t => t.ExecuteAsync(null!))
                .ReturnsAsync(expectedResult);

        // Act
        var result = await mockTool.Object.ExecuteAsync(null!);

        // Assert
        Assert.NotNull(result);
    }

    [Fact]
    public async Task IMcpTool_ExecuteAsync_ShouldReturnJsonResult()
    {
        // Arrange
        var mockTool = new Mock<IMcpTool>();
        var arguments = JsonDocument.Parse("""{"input": "value"}""");
        var expectedResult = JsonDocument.Parse("""{"output": "result"}""");

        mockTool.Setup(t => t.ExecuteAsync(arguments))
                .ReturnsAsync(expectedResult);

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

        // Assert
        Assert.NotNull(result);
        Assert.True(result.RootElement.TryGetProperty("output", out var output));
        Assert.Equal("result", output.GetString());
    }
}