using System.Security.Claims;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Moq;
using Xunit;
using FluentAssertions;
using YarpGateway.Config;
using YarpGateway.Middleware;

namespace YarpGateway.Tests.Unit.Middleware;

public class JwtTransformMiddlewareTests
{
    private readonly Mock<ILogger<JwtTransformMiddleware>> _loggerMock;
    private readonly JwtConfig _jwtConfig;

    public JwtTransformMiddlewareTests()
    {
        _jwtConfig = new JwtConfig
        {
            Authority = "https://auth.example.com",
            Audience = "yarp-gateway"
        };
        _loggerMock = new Mock<ILogger<JwtTransformMiddleware>>();
    }


    private JwtTransformMiddleware CreateMiddleware()
    {
        var jwtConfigOptions = Options.Create(_jwtConfig);
        return new JwtTransformMiddleware(
            next: Mock.Of<RequestDelegate>(),
            jwtConfig: jwtConfigOptions,
            logger: _loggerMock.Object
        );
    }



    private DefaultHttpContext CreateAuthenticatedContext(string? tenantId = "tenant-1", string? userId = "user-1")
    {
        var context = new DefaultHttpContext();
        
        var claims = new List<Claim>();
        
        if (!string.IsNullOrEmpty(tenantId))
        {
            claims.Add(new Claim("tenant", tenantId));
        }
        
        if (!string.IsNullOrEmpty(userId))
        {
            claims.Add(new Claim(ClaimTypes.NameIdentifier, userId));
            claims.Add(new Claim("sub", userId));
        }
        
        claims.Add(new Claim(ClaimTypes.Name, "testuser"));
        claims.Add(new Claim("name", "Test User"));
        claims.Add(new Claim(ClaimTypes.Role, "admin"));
        claims.Add(new Claim("role", "user"));

        var identity = new ClaimsIdentity(claims, JwtBearerDefaults.AuthenticationScheme);
        var principal = new ClaimsPrincipal(identity);
        
        context.User = principal;
        
        return context;
    }

    private DefaultHttpContext CreateUnauthenticatedContext()
    {
        var context = new DefaultHttpContext();
        context.User = new ClaimsPrincipal();
        return context;
    }

    [Fact]
    public async Task InvokeAsync_WithAuthenticatedUser_ShouldExtractTenantClaim()
    {
        // Arrange
        var context = CreateAuthenticatedContext(tenantId: "tenant-123");
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers["X-Tenant-Id"].Should().Contain("tenant-123");
    }

    [Fact]
    public async Task InvokeAsync_WithAuthenticatedUser_ShouldExtractUserId()
    {
        // Arrange
        var context = CreateAuthenticatedContext(userId: "user-456");
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers["X-User-Id"].Should().Contain("user-456");
    }

    [Fact]
    public async Task InvokeAsync_WithAuthenticatedUser_ShouldExtractUserName()
    {
        // Arrange
        var context = CreateAuthenticatedContext();
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers["X-User-Name"].Should().Contain("Test User");
    }

    [Fact]
    public async Task InvokeAsync_WithAuthenticatedUser_ShouldExtractRoles()
    {
        // Arrange
        var context = CreateAuthenticatedContext();
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers["X-Roles"].Should().Contain("admin,user");
    }

    [Fact]
    public async Task InvokeAsync_WithUnauthenticatedUser_ShouldNotSetHeaders()
    {
        // Arrange
        var context = CreateUnauthenticatedContext();
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers.Should().NotContainKey("X-Tenant-Id");
        context.Request.Headers.Should().NotContainKey("X-User-Id");
    }

    [Fact]
    public async Task InvokeAsync_WithMissingTenantClaim_ShouldLogWarning()
    {
        // Arrange
        var context = CreateAuthenticatedContext(tenantId: null!);
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert - should not throw, just log warning
        context.Request.Headers.Should().NotContainKey("X-Tenant-Id");
    }

    [Fact]
    public async Task InvokeAsync_WithTenantClaimUsingTenantIdType_ShouldExtractCorrectly()
    {
        // Arrange
        var context = new DefaultHttpContext();
        var claims = new List<Claim>
        {
            new Claim("tenant_id", "tenant-using-id-type"),
            new Claim(ClaimTypes.NameIdentifier, "user-1")
        };
        var identity = new ClaimsIdentity(claims, JwtBearerDefaults.AuthenticationScheme);
        context.User = new ClaimsPrincipal(identity);
        
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert
        context.Request.Headers["X-Tenant-Id"].Should().Contain("tenant-using-id-type");
    }

    [Fact]
    public async Task InvokeAsync_ShouldRemoveExistingXHeaders_PreventHeaderInjection()
    {
        // Arrange
        var context = CreateAuthenticatedContext();
        // Simulate header injection attempt
        context.Request.Headers["X-Tenant-Id"] = "injected-tenant";
        
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert - the injected header should be removed and replaced with JWT value
        context.Request.Headers["X-Tenant-Id"].Should().Contain("tenant-1");
    }

    [Fact]
    public async Task InvokeAsync_WithMultipleTenantClaims_ShouldPrioritizeTenantType()
    {
        // Arrange
        var context = new DefaultHttpContext();
        var claims = new List<Claim>
        {
            new Claim("tenant", "tenant-from-claim"),
            new Claim("tenant_id", "tenant-id-claim"),
            new Claim(ClaimTypes.NameIdentifier, "user-1")
        };
        var identity = new ClaimsIdentity(claims, JwtBearerDefaults.AuthenticationScheme);
        context.User = new ClaimsPrincipal(identity);
        
        var middleware = CreateMiddleware();

        // Act
        await middleware.InvokeAsync(context);

        // Assert - should prioritize "tenant" over "tenant_id"
        context.Request.Headers["X-Tenant-Id"].Should().Contain("tenant-from-claim");
    }

    [Fact]
    public async Task InvokeAsync_WithEmptyClaims_ShouldNotThrow()
    {
        // Arrange
        var context = new DefaultHttpContext();
        var identity = new ClaimsIdentity(Array.Empty<Claim>(), JwtBearerDefaults.AuthenticationScheme);
        context.User = new ClaimsPrincipal(identity);
        
        var middleware = CreateMiddleware();

        // Act & Assert - should not throw
        await middleware.InvokeAsync(context);
    }
}