// =============================================================================
// A01_BrokenAccessControl/AuthorizationBypassTests.cs
// OWASP A01:2021 - Broken Access Control
// Tests for authorization bypass vulnerabilities
// =============================================================================

using FluentAssertions;
using StellaOps.Security.Tests.Infrastructure;

namespace StellaOps.Security.Tests.A01_BrokenAccessControl;

/// <summary>
/// Tests for broken access control vulnerabilities including:
/// - Horizontal privilege escalation (accessing other users' data)
/// - Vertical privilege escalation (accessing admin functions)
/// - IDOR (Insecure Direct Object Reference)
/// - Path-based access control bypass
/// </summary>
[Trait("Category", "Security")]
[Trait("OWASP", "A01")]
[OwaspCategory("A01:2021", "Broken Access Control")]
public class AuthorizationBypassTests : SecurityTestBase
{
    [Fact]
    public void Should_Reject_Cross_Tenant_Access_Attempt()
    {
        // Arrange
        var tenantA = GenerateTestTenantId();
        var tenantB = GenerateTestTenantId();
        var userFromTenantA = GenerateTestUserId();
        
        // Act & Assert
        // Simulates checking that a user from Tenant A cannot access Tenant B resources
        // In real implementation, this would test the actual authorization service
        tenantA.Should().NotBe(tenantB, "Test setup: tenants should be different");
        
        // The authorization check should prevent cross-tenant access
        var authorizationResult = SimulateCrossTenantAccessCheck(tenantA, tenantB, userFromTenantA);
        authorizationResult.Should().BeFalse("Cross-tenant access should be denied");
    }

    [Fact]
    public void Should_Reject_IDOR_Attack_On_Resource_Id()
    {
        // Arrange
        var authenticatedUserId = GenerateTestUserId();
        var otherUserId = GenerateTestUserId();
        
        // Act - Attempt to access another user's resource by ID manipulation
        var canAccessOtherUserResource = SimulateIdorCheck(authenticatedUserId, otherUserId);
        
        // Assert
        canAccessOtherUserResource.Should().BeFalse(
            "User should not access resources of another user via IDOR");
    }

    [Fact]
    public void Should_Reject_Admin_Function_Access_By_Regular_User()
    {
        // Arrange
        var regularUserId = GenerateTestUserId();
        var isAdmin = false;
        
        // Act - Attempt to access admin-only function
        var canAccessAdminFunction = SimulateAdminFunctionCheck(regularUserId, isAdmin);
        
        // Assert
        canAccessAdminFunction.Should().BeFalse(
            "Regular user should not access admin functions");
    }

    [Theory]
    [InlineData("/api/admin/users", false)]
    [InlineData("/api/admin/settings", false)]
    [InlineData("/api/admin/audit-logs", false)]
    [InlineData("/api/v1/scans", true)] // Regular endpoint - should be accessible
    public void Should_Enforce_Path_Based_Authorization(string path, bool shouldBeAccessible)
    {
        // Arrange
        var regularUserId = GenerateTestUserId();
        
        // Act
        var canAccess = SimulatePathBasedAuth(path, regularUserId, isAdmin: false);
        
        // Assert
        canAccess.Should().Be(shouldBeAccessible,
            $"Path {path} should {(shouldBeAccessible ? "" : "not ")}be accessible to regular users");
    }

    [Fact]
    public void Should_Prevent_Parameter_Tampering_For_Ownership()
    {
        // Arrange
        var authenticatedUserId = GenerateTestUserId();
        var tamperedOwnerId = GenerateTestUserId(); // Attacker tries to claim ownership
        
        // Act - Simulate API call where attacker modifies owner_id parameter
        var result = SimulateOwnershipTamperingCheck(authenticatedUserId, tamperedOwnerId);
        
        // Assert
        result.Should().BeFalse("Parameter tampering for ownership should be rejected");
    }

    [Fact]
    public void Should_Enforce_Method_Level_Authorization()
    {
        // Arrange
        var userId = GenerateTestUserId();
        var resourceId = Guid.NewGuid();
        
        // User has READ but not WRITE permission
        var readAllowed = true;
        var writeAllowed = false;
        
        // Act & Assert
        SimulateMethodAuth(userId, resourceId, "GET", readAllowed).Should().BeTrue();
        SimulateMethodAuth(userId, resourceId, "DELETE", writeAllowed).Should().BeFalse(
            "User with read-only permission should not delete resources");
    }

    [Fact]
    public void Should_Validate_JWT_Claims_For_Authorization()
    {
        // Arrange - JWT with tampered claims
        var tamperedToken = MaliciousPayloads.JwtAttacks.NoneAlgorithm;
        
        // Act & Assert
        var action = () => ValidateJwtForAuth(tamperedToken);
        action.Should().Throw<Exception>("Tampered JWT should be rejected");
    }

    #region Simulation Helpers

    private static bool SimulateCrossTenantAccessCheck(Guid requestorTenant, Guid targetTenant, Guid userId)
    {
        // In real implementation, this would call the authorization service
        // For test purposes, we verify the logic exists
        return requestorTenant == targetTenant;
    }

    private static bool SimulateIdorCheck(Guid authenticatedUserId, Guid resourceOwnerId)
    {
        // Proper IDOR protection requires ownership verification
        return authenticatedUserId == resourceOwnerId;
    }

    private static bool SimulateAdminFunctionCheck(Guid userId, bool isAdmin)
    {
        // Admin functions require admin role
        return isAdmin;
    }

    private static bool SimulatePathBasedAuth(string path, Guid userId, bool isAdmin)
    {
        // Admin paths require admin role
        if (path.StartsWith("/api/admin", StringComparison.OrdinalIgnoreCase))
        {
            return isAdmin;
        }
        return true;
    }

    private static bool SimulateOwnershipTamperingCheck(Guid authenticatedUserId, Guid claimedOwnerId)
    {
        // The claimed owner must match the authenticated user
        return authenticatedUserId == claimedOwnerId;
    }

    private static bool SimulateMethodAuth(Guid userId, Guid resourceId, string method, bool hasPermission)
    {
        // Method-level authorization check
        return hasPermission;
    }

    private static void ValidateJwtForAuth(string token)
    {
        // Simulate JWT validation that should reject invalid tokens
        if (token.EndsWith('.') || token.Split('.').Length != 3)
        {
            throw new InvalidOperationException("Invalid JWT format");
        }
        
        var parts = token.Split('.');
        if (string.IsNullOrEmpty(parts[2]))
        {
            throw new InvalidOperationException("JWT signature is missing");
        }
    }

    #endregion
}