using FluentAssertions;
using StellaOps.Cryptography;
using StellaOps.Cryptography.Plugin.OfflineVerification;
using System.Security.Cryptography;
using Xunit;

namespace StellaOps.Cryptography.Plugin.OfflineVerification.Tests;

public class OfflineVerificationProviderTests
{
    private readonly OfflineVerificationCryptoProvider _provider;

    public OfflineVerificationProviderTests()
    {
        _provider = new OfflineVerificationCryptoProvider();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Name_ReturnsCorrectValue()
    {
        // Assert
        _provider.Name.Should().Be("offline-verification");
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData(CryptoCapability.Signing, "ES256", true)]
    [InlineData(CryptoCapability.Signing, "ES384", true)]
    [InlineData(CryptoCapability.Signing, "ES512", true)]
    [InlineData(CryptoCapability.Signing, "RS256", true)]
    [InlineData(CryptoCapability.Signing, "RS384", true)]
    [InlineData(CryptoCapability.Signing, "RS512", true)]
    [InlineData(CryptoCapability.Signing, "PS256", true)]
    [InlineData(CryptoCapability.Signing, "PS384", true)]
    [InlineData(CryptoCapability.Signing, "PS512", true)]
    [InlineData(CryptoCapability.Verification, "ES256", true)]
    [InlineData(CryptoCapability.Verification, "RS256", true)]
    [InlineData(CryptoCapability.Verification, "PS256", true)]
    [InlineData(CryptoCapability.ContentHashing, "SHA-256", true)]
    [InlineData(CryptoCapability.ContentHashing, "SHA-384", true)]
    [InlineData(CryptoCapability.ContentHashing, "SHA-512", true)]
    [InlineData(CryptoCapability.ContentHashing, "SHA256", true)]
    [InlineData(CryptoCapability.PasswordHashing, "PBKDF2", true)]
    [InlineData(CryptoCapability.PasswordHashing, "Argon2id", true)]
    [InlineData(CryptoCapability.Signing, "UNSUPPORTED", false)]
    [InlineData(CryptoCapability.SymmetricEncryption, "AES-256", false)]
    public void Supports_ReturnCorrectResult(CryptoCapability capability, string algorithmId, bool expected)
    {
        // Act
        var result = _provider.Supports(capability, algorithmId);

        // Assert
        result.Should().Be(expected);
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData("SHA-256", "hello world", "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9")]
    [InlineData("SHA-384", "hello world", "fdbd8e75a67f29f701a4e040385e2e23986303ea10239211af907fcbb83578b3e417cb71ce646efd0819dd8c088de1bd")]
    [InlineData("SHA-512", "hello world", "309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f")]
    [InlineData("SHA256", "hello world", "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9")] // Alternative form
    public void GetHasher_ComputesCorrectHash(string algorithmId, string input, string expectedHex)
    {
        // Arrange
        var hasher = _provider.GetHasher(algorithmId);
        var inputBytes = System.Text.Encoding.UTF8.GetBytes(input);

        // Act
        var hash = hasher.ComputeHash(inputBytes);
        var actualHex = Convert.ToHexString(hash).ToLowerInvariant();

        // Assert
        actualHex.Should().Be(expectedHex);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void GetHasher_WithUnsupportedAlgorithm_ThrowsNotSupportedException()
    {
        // Act
        var act = () => _provider.GetHasher("MD5");

        // Assert
        act.Should().Throw<NotSupportedException>()
            .WithMessage("*MD5*");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void GetPasswordHasher_ThrowsNotSupportedException()
    {
        // Act
        var act = () => _provider.GetPasswordHasher("PBKDF2");

        // Assert
        act.Should().Throw<NotSupportedException>()
            .WithMessage("*Password hashing*");
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData("ES256")]
    [InlineData("ES384")]
    [InlineData("ES512")]
    public void CreateEphemeralVerifier_ForEcdsa_VerifiesSignatureCorrectly(string algorithmId)
    {
        // Arrange - Create a real ECDSA key, sign a message
        using var ecdsa = ECDsa.Create();
        var curve = algorithmId switch
        {
            "ES256" => ECCurve.NamedCurves.nistP256,
            "ES384" => ECCurve.NamedCurves.nistP384,
            "ES512" => ECCurve.NamedCurves.nistP521,
            _ => throw new NotSupportedException()
        };
        ecdsa.GenerateKey(curve);

        var hashAlgorithm = algorithmId switch
        {
            "ES256" => HashAlgorithmName.SHA256,
            "ES384" => HashAlgorithmName.SHA384,
            "ES512" => HashAlgorithmName.SHA512,
            _ => throw new NotSupportedException()
        };

        var message = System.Text.Encoding.UTF8.GetBytes("ephemeral verifier test");
        var signature = ecdsa.SignData(message, hashAlgorithm);

        // Export public key in SubjectPublicKeyInfo format
        var publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();

        // Act - Create ephemeral verifier from public key
        var ephemeralVerifier = _provider.CreateEphemeralVerifier(algorithmId, publicKeyBytes);

        // Assert - Verify signature using ephemeral verifier
        var isValid = ephemeralVerifier.VerifyAsync(message, signature, default).GetAwaiter().GetResult();
        isValid.Should().BeTrue("ephemeral verifier should verify signature from original key");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void CreateEphemeralVerifier_ForRsaPkcs1_VerifiesSignatureCorrectly()
    {
        // Arrange - Create a real RSA key, sign a message
        using var rsa = RSA.Create(2048);
        var message = System.Text.Encoding.UTF8.GetBytes("ephemeral rsa verifier test");
        var signature = rsa.SignData(message, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);

        // Export public key in SubjectPublicKeyInfo format
        var publicKeyBytes = rsa.ExportSubjectPublicKeyInfo();

        // Act - Create ephemeral verifier from public key
        var ephemeralVerifier = _provider.CreateEphemeralVerifier("RS256", publicKeyBytes);

        // Assert - Verify signature using ephemeral verifier
        var isValid = ephemeralVerifier.VerifyAsync(message, signature, default).GetAwaiter().GetResult();
        isValid.Should().BeTrue("ephemeral RSA verifier should verify PKCS1 signature from original key");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void CreateEphemeralVerifier_ForRsaPss_VerifiesSignatureCorrectly()
    {
        // Arrange - Create a real RSA key, sign a message
        using var rsa = RSA.Create(2048);
        var message = System.Text.Encoding.UTF8.GetBytes("ephemeral rsa pss verifier test");
        var signature = rsa.SignData(message, HashAlgorithmName.SHA256, RSASignaturePadding.Pss);

        // Export public key in SubjectPublicKeyInfo format
        var publicKeyBytes = rsa.ExportSubjectPublicKeyInfo();

        // Act - Create ephemeral verifier from public key
        var ephemeralVerifier = _provider.CreateEphemeralVerifier("PS256", publicKeyBytes);

        // Assert - Verify signature using ephemeral verifier
        var isValid = ephemeralVerifier.VerifyAsync(message, signature, default).GetAwaiter().GetResult();
        isValid.Should().BeTrue("ephemeral RSA verifier should verify PSS signature from original key");
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData("ES256")]
    [InlineData("PS256")]
    public void EphemeralVerifier_SignAsync_ThrowsNotSupportedException(string algorithmId)
    {
        // Arrange - Create a dummy public key
        byte[] publicKeyBytes;
        if (algorithmId.StartsWith("ES"))
        {
            using var ecdsa = ECDsa.Create();
            publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();
        }
        else
        {
            using var rsa = RSA.Create(2048);
            publicKeyBytes = rsa.ExportSubjectPublicKeyInfo();
        }

        var ephemeralVerifier = _provider.CreateEphemeralVerifier(algorithmId, publicKeyBytes);

        // Act
        var message = System.Text.Encoding.UTF8.GetBytes("test");
        var act = async () => await ephemeralVerifier.VerifyAsync(message, System.Text.Encoding.UTF8.GetBytes("invalid-signature"), default);

        // Assert - should return false, not throw
        var result = act().GetAwaiter().GetResult();
        result.Should().BeFalse();
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData("ES256")]
    [InlineData("PS256")]
    public void EphemeralVerifier_WithTamperedMessage_FailsVerification(string algorithmId)
    {
        // Arrange - Create key and sign original message
        byte[] publicKeyBytes;
        byte[] signature;
        var originalMessage = System.Text.Encoding.UTF8.GetBytes("original message");
        var tamperedMessage = System.Text.Encoding.UTF8.GetBytes("tampered message");

        if (algorithmId.StartsWith("ES"))
        {
            using var ecdsa = ECDsa.Create();
            signature = ecdsa.SignData(originalMessage, HashAlgorithmName.SHA256);
            publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();
        }
        else
        {
            using var rsa = RSA.Create(2048);
            var padding = algorithmId.StartsWith("PS") ? RSASignaturePadding.Pss : RSASignaturePadding.Pkcs1;
            signature = rsa.SignData(originalMessage, HashAlgorithmName.SHA256, padding);
            publicKeyBytes = rsa.ExportSubjectPublicKeyInfo();
        }

        var ephemeralVerifier = _provider.CreateEphemeralVerifier(algorithmId, publicKeyBytes);

        // Act
        var isValid = ephemeralVerifier.VerifyAsync(tamperedMessage, signature, default).GetAwaiter().GetResult();

        // Assert
        isValid.Should().BeFalse("ephemeral verifier should fail with tampered message");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void CreateEphemeralVerifier_WithUnsupportedAlgorithm_ThrowsNotSupportedException()
    {
        // Arrange - Create a dummy public key
        using var ecdsa = ECDsa.Create();
        var publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();

        // Act
        var act = () => _provider.CreateEphemeralVerifier("UNSUPPORTED", publicKeyBytes);

        // Assert
        act.Should().Throw<NotSupportedException>()
            .WithMessage("*UNSUPPORTED*");
    }

    [Trait("Category", TestCategories.Unit)]
        [Theory]
    [InlineData("ES256")]
    [InlineData("PS256")]
    public void EphemeralVerifier_HasCorrectProperties(string algorithmId)
    {
        // Arrange - Create a dummy public key
        byte[] publicKeyBytes;
        using (var ecdsa = ECDsa.Create())
        {
            publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();
using StellaOps.TestKit;
        }

        // Act
        var ephemeralVerifier = _provider.CreateEphemeralVerifier(algorithmId, publicKeyBytes);

        // Assert
        ephemeralVerifier.KeyId.Should().Be("ephemeral");
        ephemeralVerifier.AlgorithmId.Should().Be(algorithmId);
    }
}