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using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Threading.Tasks;
using NUnit.Framework;
using Opc.Ua.Security.Certificates;
using Opc.Ua.Tests;

namespace Opc.Ua.Core.Tests.Security.Identity
{
    [TestFixture]
    [Category("Identity")]
    [Parallelizable]
    public sealed class IssuedIdentityTokenHandlerTests
    {
        [TestCase(Namespaces.OpcUa + "UserToken#GenericWSS", IssuedTokenType.GenericWSS, "Generic WSS Token")]
        [TestCase(Namespaces.OpcUa + "UserToken#SAML", IssuedTokenType.SAML, "SAML Token")]
        [TestCase(Profiles.JwtUserToken, IssuedTokenType.JWT, "JWT")]
        [TestCase(Namespaces.OpcUa + "UserToken#KerberosBinary", IssuedTokenType.KerberosBinary, "Kerberos Token")]
        [TestCase("urn:custom", IssuedTokenType.Unknown, "Issued Token")]
        public void IssuedTokenTypeAndDisplayNameFollowProfileUri(
            string profileUri,
            IssuedTokenType expectedType,
            string expectedDisplayName)
        {
            var handler = new IssuedIdentityTokenHandler(profileUri, [1, 2, 3]);

            Assert.That(handler.TokenType, Is.EqualTo(UserTokenType.IssuedToken));
            Assert.That(handler.IssuedTokenType, Is.EqualTo(expectedType));
            Assert.That(handler.DisplayName, Is.EqualTo(expectedDisplayName));
            Assert.That(handler.IssuedTokenTypeProfileUri, Is.EqualTo(profileUri));
        }

        [Test]
        public void ConstructorDefaultsPolicyIdToJwtProfile()
        {
            var token = new IssuedIdentityToken();

            var handler = new IssuedIdentityTokenHandler(token);

            Assert.That(handler.IssuedTokenType, Is.EqualTo(IssuedTokenType.JWT));
            Assert.That(token.PolicyId, Is.EqualTo(Profiles.JwtUserToken));
        }

        [Test]
        public void DecryptedTokenDataUsesDefensiveCopiesAndClearsPreviousValue()
        {
            byte[] original = [1, 2, 3];
            var handler = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, original);

            byte[] firstCopy = handler.DecryptedTokenData!;
            firstCopy![0] = 99;
            handler.DecryptedTokenData = [4, 5];

            Assert.That(handler.DecryptedTokenData, Is.EqualTo(new byte[] { 4, 5 }));
            Assert.That(firstCopy, Is.EqualTo(new byte[] { 99, 2, 3 }));
            handler.DecryptedTokenData = null;
            Assert.That(handler.DecryptedTokenData, Is.Null);
        }

        [Test]
        public async Task EncryptAndDecryptWithSecurityNoneRoundTripsTokenDataAsync()
        {
            var handler = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, [0x10, 0x20, 0x30]);
            IServiceMessageContext context = ServiceMessageContext.Create(NUnitTelemetryContext.Create());

            await handler.EncryptAsync(null!, [], SecurityPolicies.None, context).ConfigureAwait(false);
            Assert.That(((IssuedIdentityToken)handler.Token).EncryptionAlgorithm, Is.EqualTo(string.Empty));
            Assert.That(((IssuedIdentityToken)handler.Token).TokenData.ToArray(), Is.EqualTo(new byte[] { 0x10, 0x20, 0x30 }));

            var encryptedToken = new IssuedIdentityToken
            {
                PolicyId = Profiles.JwtUserToken,
                TokenData = new byte[] { 0x10, 0x20, 0x30 }.ToByteString()
            };
            handler = new IssuedIdentityTokenHandler(encryptedToken);
            await handler.DecryptAsync(null!, null!, SecurityPolicies.None, context).ConfigureAwait(false);

            Assert.That(handler.DecryptedTokenData, Is.EqualTo(new byte[] { 0x10, 0x20, 0x30 }));
        }

        [Test]
        public async Task EccEncryptionReleasesTemporaryNonceAndIssuerHandlesAsync(
            [Values] bool missingTokenData,
            [Values] bool rsaDh)
        {
            string policyUri = rsaDh ? SecurityPolicies.RSA_DH_AesGcm : SecurityPolicies.ECC_nistP256;
            SecurityPolicyInfo? policy = SecurityPolicies.Default.GetInfo(policyUri);
            IServiceMessageContext context = ServiceMessageContext.Create(NUnitTelemetryContext.Create());
            if (policy == null)
            {
                var unsupported = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, [1, 2, 3]);
                ServiceResultException error = await Assert.ThrowsAsync<ServiceResultException>(
                    async () => await unsupported.EncryptAsync(null!, [], policyUri, context).ConfigureAwait(false));
                Assert.That(error.StatusCode, Is.EqualTo(StatusCodes.BadSecurityPolicyRejected));
                return;
            }

            using Certificate sender = CreateSigningCertificate("CN=Issued Token Sender", rsaDh);
            using Certificate receiver = CreateSigningCertificate("CN=Issued Token Receiver", rsaDh);
            using Certificate issuerTemplate = CreateSigningCertificate("CN=Issued Token Issuer", rsaDh, ca: true);
            X509Certificate2 issuerNative = issuerTemplate.AsX509Certificate2();
            using var issuer = Certificate.From(issuerNative);
            using var chain = new CertificateCollection { sender, issuer };
            using var receiverKey = Nonce.CreateNonce(policy);
            using var temporarySenderKey = Nonce.CreateNonce(policy);
            byte[] expected = [0x10, 0x20, 0x30];
            byte[] nonce = Nonce.CreateRandomNonceData(32);
            var handler = new IssuedIdentityTokenHandler(
                new IssuedIdentityToken { PolicyId = Profiles.JwtUserToken },
                null,
                _ => temporarySenderKey)
            {
                DecryptedTokenData = missingTokenData ? null : expected
            };

            if (missingTokenData)
            {
                ServiceResultException error = await Assert.ThrowsAsync<ServiceResultException>(
                    async () => await handler.EncryptAsync(
                        receiver, nonce, policyUri, context, receiverKey, sender, chain, true).ConfigureAwait(false));
                Assert.That(error.StatusCode, Is.EqualTo(StatusCodes.BadIdentityTokenInvalid));
            }
            else
            {
                await handler.EncryptAsync(
                    receiver, nonce, policyUri, context, receiverKey, sender, chain, true).ConfigureAwait(false);
                using var decryptor = EncryptedSecret.CreateForEcc(
                    context, policyUri, chain, receiver, receiverKey, sender, null!);
                (bool success, byte[]? secret) = await decryptor.TryDecryptAsync(
                    ((IssuedIdentityToken)handler.Token).TokenData.ToArray(), nonce).ConfigureAwait(false);
                Assert.That(success, Is.True);
                Assert.That(secret, Is.EqualTo(expected));
                CryptoUtils.ZeroMemory(secret);
            }

            Assert.That(chain, Has.Count.EqualTo(2));
            Assert.That(chain[1].Thumbprint, Is.EqualTo(issuer.Thumbprint));
            chain.Dispose();
            issuer.Dispose();
            byte[] retainedSecret = temporarySenderKey.GenerateSecret(receiverKey, null)!;
            try
            {
                Assert.Multiple(() =>
                {
                    Assert.That(retainedSecret?.Length, Is.Null,
                        "The temporary sender agreement key must be released.");
                    Assert.That(issuerNative.Handle, Is.EqualTo(IntPtr.Zero),
                        "The filtered issuer collection must not retain an extra owning handle.");
                    Assert.That(sender.HasPrivateKey, Is.True);
                    Assert.That(receiver.HasPrivateKey, Is.True);
                });
            }
            finally
            {
                if (retainedSecret != null)
                {
                    CryptoUtils.ZeroMemory(retainedSecret);
                }
            }
        }

        [Test]
        public void UpdatePolicyChangesPolicyAndProfile()
        {
            var handler = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, [1]);
            var policy = new UserTokenPolicy
            {
                PolicyId = "issued",
                IssuedTokenType = Namespaces.OpcUa + "UserToken#SAML"
            };

            handler.UpdatePolicy(policy);

            Assert.That(handler.Token.PolicyId, Is.EqualTo("issued"));
            Assert.That(handler.IssuedTokenTypeProfileUri, Is.EqualTo(policy.IssuedTokenType));
            Assert.That(handler.IssuedTokenType, Is.EqualTo(IssuedTokenType.SAML));
        }

        [Test]
        public async Task SignAndVerifyAreNoOpsForIssuedTokensAsync()
        {
            var handler = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, [1]);

            SignatureData signature = await handler
                .SignAsync([1, 2, 3], SecurityPolicies.None)
                .ConfigureAwait(false);
            bool verified = await handler
                .VerifyAsync([1, 2, 3], signature, SecurityPolicies.None)
                .ConfigureAwait(false);

            Assert.That(signature, Is.Null);
            Assert.That(verified, Is.True);
        }

        [Test]
        public void CloneCopiesTokenAndEqualsComparesTokenData()
        {
            var handler = new IssuedIdentityTokenHandler(Profiles.JwtUserToken, [7, 8, 9])
            {
                DecryptedTokenData = [7, 8, 9]
            };

            var clone = (IssuedIdentityTokenHandler)handler.Clone();

            Assert.That(clone, Is.Not.SameAs(handler));
            Assert.That(clone.IssuedTokenTypeProfileUri, Is.EqualTo(handler.IssuedTokenTypeProfileUri));
            Assert.That(clone.DecryptedTokenData, Is.EqualTo(handler.DecryptedTokenData));
            bool equalsClone = handler.Equals(clone);
            bool equalsOtherHandler = handler.Equals(new UserNameIdentityTokenHandler("user", [1]));
            Assert.That(equalsClone, Is.True);
            Assert.That(equalsOtherHandler, Is.False);
        }

        private static Certificate CreateSigningCertificate(string subject, bool rsa, bool ca = false)
        {
            ICertificateBuilder builder = CertificateBuilder.Create(subject);
            if (ca)
            {
                builder.SetCAConstraint();
            }
            return rsa ? builder.CreateForRSA() : builder.SetECCurve(ECCurve.NamedCurves.nistP256).CreateForECDsa();
        }
    }
}