// =============================================================================
// AuthenticationFailuresTests.cs
// Sprint: SPRINT_0352_0001_0001_security_testing_framework
// Task: SEC-0352-005
// OWASP A07:2021 - Identification and Authentication Failures
// =============================================================================

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

namespace StellaOps.Security.Tests.A07_AuthenticationFailures;

/// <summary>
/// Tests for OWASP A07:2021 - Identification and Authentication Failures.
/// Ensures proper authentication practices in Authority and related modules.
/// </summary>
[Trait("Category", "Security")]
[Trait("OWASP", "A07")]
public sealed class AuthenticationFailuresTests : SecurityTestBase
{
    [Fact(DisplayName = "A07-001: Brute force should be rate-limited")]
    public async Task BruteForce_ShouldBeRateLimited()
    {
        // Arrange
        var attempts = 0;
        var blocked = false;

        // Act - simulate rapid authentication attempts
        for (int i = 0; i < 15; i++)
        {
            var result = await SimulateAuthAttempt("user@test.com", "wrong-password");
            attempts++;
            if (result.IsBlocked)
            {
                blocked = true;
                break;
            }
        }

        // Assert
        blocked.Should().BeTrue("Rate limiting should block after multiple failed attempts");
        attempts.Should().BeLessThanOrEqualTo(10, "Should block before 10 attempts");
    }

    [Fact(DisplayName = "A07-002: Weak passwords should be rejected")]
    public void WeakPasswords_ShouldBeRejected()
    {
        // Arrange
        var weakPasswords = new[]
        {
            "password",
            "123456",
            "password123",
            "qwerty",
            "admin",
            "letmein",
            "welcome",
            "abc123"
        };

        // Act & Assert
        foreach (var password in weakPasswords)
        {
            var result = ValidatePasswordStrength(password);
            result.IsStrong.Should().BeFalse($"Weak password '{password}' should be rejected");
        }
    }

    [Fact(DisplayName = "A07-003: Strong passwords should be accepted")]
    public void StrongPasswords_ShouldBeAccepted()
    {
        // Arrange
        var strongPasswords = new[]
        {
            "C0mpl3x!P@ssw0rd#2024",
            "Str0ng$ecur3P@ss!",
            "MyV3ryL0ng&SecurePassword!",
            "!@#$5678Abcdefgh"
        };

        // Act & Assert
        foreach (var password in strongPasswords)
        {
            var result = ValidatePasswordStrength(password);
            result.IsStrong.Should().BeTrue($"Strong password should be accepted");
        }
    }

    [Fact(DisplayName = "A07-004: Session tokens should expire")]
    public void SessionTokens_ShouldExpire()
    {
        // Arrange
        var maxSessionDuration = TimeSpan.FromHours(24);
        var token = CreateSessionToken(issuedAt: DateTimeOffset.UtcNow.AddHours(-25));

        // Act
        var isValid = ValidateSessionToken(token);

        // Assert
        isValid.Should().BeFalse("Expired session tokens should be rejected");
    }

    [Fact(DisplayName = "A07-005: Session tokens should be revocable")]
    public void SessionTokens_ShouldBeRevocable()
    {
        // Arrange
        var token = CreateSessionToken(issuedAt: DateTimeOffset.UtcNow);
        ValidateSessionToken(token).Should().BeTrue("Fresh token should be valid");

        // Act
        RevokeSessionToken(token);

        // Assert
        ValidateSessionToken(token).Should().BeFalse("Revoked token should be rejected");
    }

    [Fact(DisplayName = "A07-006: Failed logins should not reveal user existence")]
    public void FailedLogins_ShouldNotRevealUserExistence()
    {
        // Arrange & Act
        var existingUserError = SimulateAuthAttempt("existing@test.com", "wrong").Result.ErrorMessage;
        var nonExistentUserError = SimulateAuthAttempt("nonexistent@test.com", "wrong").Result.ErrorMessage;

        // Assert - error messages should be identical
        existingUserError.Should().Be(nonExistentUserError,
            "Error messages should not reveal whether user exists");
    }

    [Fact(DisplayName = "A07-007: MFA should be supported")]
    public void Mfa_ShouldBeSupported()
    {
        // Arrange
        var mfaMethods = GetSupportedMfaMethods();

        // Assert
        mfaMethods.Should().NotBeEmpty("MFA should be supported");
        mfaMethods.Should().Contain("TOTP", "TOTP should be a supported MFA method");
    }

    [Fact(DisplayName = "A07-008: Account lockout should be implemented")]
    public async Task AccountLockout_ShouldBeImplemented()
    {
        // Arrange
        var userId = "test-lockout@test.com";
        
        // Act - trigger lockout
        for (int i = 0; i < 10; i++)
        {
            await SimulateAuthAttempt(userId, "wrong-password");
        }

        var accountStatus = GetAccountStatus(userId);

        // Assert
        accountStatus.IsLocked.Should().BeTrue("Account should be locked after multiple failures");
        accountStatus.LockoutDuration.Should().BeGreaterThan(TimeSpan.Zero);
    }

    [Fact(DisplayName = "A07-009: Password reset tokens should be single-use")]
    public void PasswordResetTokens_ShouldBeSingleUse()
    {
        // Arrange
        var resetToken = GeneratePasswordResetToken("user@test.com");

        // Act - use token once
        var firstUse = UsePasswordResetToken(resetToken, "NewP@ssw0rd!");
        var secondUse = UsePasswordResetToken(resetToken, "AnotherP@ss!");

        // Assert
        firstUse.Should().BeTrue("First use of reset token should succeed");
        secondUse.Should().BeFalse("Second use of reset token should fail");
    }

    [Fact(DisplayName = "A07-010: Default credentials should be changed")]
    public void DefaultCredentials_ShouldBeChanged()
    {
        // Arrange
        var defaultCredentials = new[]
        {
            ("admin", "admin"),
            ("root", "root"),
            ("admin", "password"),
            ("administrator", "administrator")
        };

        // Act & Assert
        foreach (var (username, password) in defaultCredentials)
        {
            var result = SimulateAuthAttempt(username, password).Result;
            result.IsSuccess.Should().BeFalse($"Default credential {username}/{password} should not work");
        }
    }

    // Helper methods

    private static async Task<AuthResult> SimulateAuthAttempt(string username, string password)
    {
        await Task.Delay(1); // Simulate async operation
        
        // Simulate rate limiting after 5 attempts
        var attempts = GetAttemptCount(username);
        if (attempts >= 5)
        {
            return new AuthResult(false, true, "Authentication failed");
        }
        
        IncrementAttemptCount(username);
        return new AuthResult(false, false, "Authentication failed");
    }

    private static int GetAttemptCount(string username)
    {
        // Simulated - would use actual rate limiter
        return _attemptCounts.GetValueOrDefault(username, 0);
    }

    private static void IncrementAttemptCount(string username)
    {
        _attemptCounts[username] = _attemptCounts.GetValueOrDefault(username, 0) + 1;
    }

    private static readonly Dictionary<string, int> _attemptCounts = new();

    private static PasswordValidationResult ValidatePasswordStrength(string password)
    {
        var hasUpperCase = password.Any(char.IsUpper);
        var hasLowerCase = password.Any(char.IsLower);
        var hasDigit = password.Any(char.IsDigit);
        var hasSpecial = password.Any(c => !char.IsLetterOrDigit(c));
        var isLongEnough = password.Length >= 12;

        var isStrong = hasUpperCase && hasLowerCase && hasDigit && hasSpecial && isLongEnough;
        return new PasswordValidationResult(isStrong);
    }

    private static string CreateSessionToken(DateTimeOffset issuedAt)
    {
        return $"session_{issuedAt.ToUnixTimeSeconds()}_{Guid.NewGuid()}";
    }

    private static readonly HashSet<string> _revokedTokens = new();

    private static bool ValidateSessionToken(string token)
    {
        if (_revokedTokens.Contains(token)) return false;
        
        // Extract issued time
        var parts = token.Split('_');
        if (parts.Length < 2 || !long.TryParse(parts[1], out var issuedUnix)) return false;
        
        var issuedAt = DateTimeOffset.FromUnixTimeSeconds(issuedUnix);
        var age = DateTimeOffset.UtcNow - issuedAt;
        
        return age < TimeSpan.FromHours(24);
    }

    private static void RevokeSessionToken(string token)
    {
        _revokedTokens.Add(token);
    }

    private static string[] GetSupportedMfaMethods()
    {
        return new[] { "TOTP", "WebAuthn", "SMS", "Email" };
    }

    private static AccountStatus GetAccountStatus(string userId)
    {
        var attempts = _attemptCounts.GetValueOrDefault(userId, 0);
        return new AccountStatus(attempts >= 10, TimeSpan.FromMinutes(15));
    }

    private static readonly HashSet<string> _usedResetTokens = new();

    private static string GeneratePasswordResetToken(string email)
    {
        return $"reset_{email}_{Guid.NewGuid()}";
    }

    private static bool UsePasswordResetToken(string token, string newPassword)
    {
        if (_usedResetTokens.Contains(token)) return false;
        _usedResetTokens.Add(token);
        return true;
    }

    private record AuthResult(bool IsSuccess, bool IsBlocked, string ErrorMessage);
    private record PasswordValidationResult(bool IsStrong);
    private record AccountStatus(bool IsLocked, TimeSpan LockoutDuration);
}