using System.Security.Cryptography.X509Certificates;
using Opc.Ua;
using Opc.Ua.Configuration;
using Opc.Ua.Security.Certificates;
using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.IntegrationTests;

/// <summary>Exercises the target certificate manager with real issuer stores and signed certificates.</summary>
public sealed class Sdk2CertificateValidationTests
{
    [Theory]
    [InlineData("valid")]
    [InlineData("expired")]
    [InlineData("revoked")]
    [InlineData("missing-issuer")]
    [InlineData("bad-issuer-usage")]
    public async Task Trust_and_certificate_failures_keep_the_configured_rejection_policy(string scenario)
    {
        var ct = TestContext.Current.CancellationToken;
        await using var pki = await ValidationPki.CreateAsync(scenario, ct);
        var result = await pki.Configuration.CertificateManager.ValidateAsync(pki.Leaf, ct: ct);
        if (scenario == "valid") result.IsValid.ShouldBeTrue(result.ToString());
        else
        {
            result.IsValid.ShouldBeFalse();
            var expected = scenario switch
            {
                "expired" => StatusCodes.BadCertificateTimeInvalid,
                "revoked" => StatusCodes.BadCertificateRevoked,
                "missing-issuer" => StatusCodes.BadCertificateChainIncomplete,
                _ => StatusCodes.BadCertificateIssuerUseNotAllowed,
            };
            (result.StatusCode == expected || result.Errors.Any(e => e.StatusCode == expected)).ShouldBeTrue(
                $"Expected {expected}; actual {result.StatusCode}: {string.Join(", ", result.Errors)}");
        }
        pki.Configuration.SecurityConfiguration.AutoAcceptUntrustedCertificates.ShouldBeFalse();
    }

    [Theory]
    [InlineData(true)]
    [InlineData(false)]
    public async Task A_trusted_chain_does_not_bypass_endpoint_identity_checks(bool wrongUri)
    {
        await using var pki = await ValidationPki.CreateAsync("valid", TestContext.Current.CancellationToken);
        (await pki.Configuration.CertificateManager.ValidateAsync(pki.Leaf, ct: TestContext.Current.CancellationToken))
            .IsValid.ShouldBeTrue();
        var endpoint = new ConfiguredEndpoint(null, new EndpointDescription
        {
            EndpointUrl = wrongUri ? "opc.tcp://localhost:4840" : "opc.tcp://other.invalid:4840",
            Server = new ApplicationDescription { ApplicationUri = wrongUri ? "urn:wrong-application" : ValidationPki.PeerUri },
        }, EndpointConfiguration.Create(pki.Configuration));
        var error = Should.Throw<ServiceResultException>(() =>
        {
            if (wrongUri) pki.Configuration.CertificateManager.ValidateApplicationUri(pki.Leaf, endpoint);
            else pki.Configuration.CertificateManager.ValidateDomains(pki.Leaf, endpoint);
        });
        error.StatusCode.ShouldBe(wrongUri ? StatusCodes.BadCertificateUriInvalid : StatusCodes.BadCertificateHostNameInvalid);
    }

    private sealed class ValidationPki : IAsyncDisposable
    {
        internal const string PeerUri = "urn:Sdk2ValidationPeer";
        private readonly string _root = Path.Combine(Path.GetTempPath(), $"otua-validation-{Guid.NewGuid():N}");
        private ApplicationInstance? _application;
        private Certificate? _issuer;
        internal Certificate Leaf { get; private set; } = null!;
        internal ApplicationConfiguration Configuration { get; private set; } = null!;

        internal static async Task<ValidationPki> CreateAsync(string scenario, CancellationToken ct)
        {
            var pki = new ValidationPki();
            try
            {
                var now = DateTime.UtcNow;
                var issuerBuilder = CertificateBuilder.Create("CN=Sdk2ValidationIssuer")
                    .SetNotBefore(now.AddDays(-10)).SetNotAfter(now.AddDays(365)).SetCAConstraint(-1);
                if (scenario == "bad-issuer-usage")
                    issuerBuilder.AddExtension(new X509KeyUsageExtension(X509KeyUsageFlags.DigitalSignature, true));
                pki._issuer = issuerBuilder.SetRSAKeySize(2048).CreateForRSA();
                var names = new SubjectAlternativeNameBuilder();
                names.AddUri(new Uri(PeerUri)); names.AddDnsName("localhost");
                pki.Leaf = CertificateBuilder.Create("CN=Sdk2ValidationPeer")
                    .SetNotBefore(now.AddDays(-2)).SetNotAfter(scenario == "expired" ? now.AddDays(-1) : now.AddDays(30))
                    .AddExtension(names.Build()).SetIssuer(pki._issuer).SetRSAKeySize(2048).CreateForRSA();
                if (scenario != "missing-issuer")
                {
                    var certs = Path.Combine(pki._root, "trusted", "certs"); Directory.CreateDirectory(certs);
                    await File.WriteAllBytesAsync(Path.Combine(certs, "issuer.der"), pki._issuer.RawData, ct);
                    if (scenario == "revoked")
                    {
                        var crls = Path.Combine(pki._root, "trusted", "crl"); Directory.CreateDirectory(crls);
                        var crl = new X509CRL(CrlBuilder.Create(pki._issuer.SubjectName).AddRevokedCertificate(pki.Leaf).CreateForRSA(pki._issuer));
                        await File.WriteAllBytesAsync(Path.Combine(crls, "issuer.crl"), crl.RawData, ct);
                    }
                }
                var telemetry = DefaultTelemetry.Create(_ => { });
                var security = TestClientSecurity.Build(pki._root); security.AutoAcceptUntrustedCertificates = false;
                pki.Configuration = new ApplicationConfiguration(telemetry)
                {
                    ApplicationName = "Sdk2Validation", ApplicationUri = "urn:Sdk2Validation", ApplicationType = ApplicationType.Client,
                    SecurityConfiguration = security, ClientConfiguration = new ClientConfiguration(),
                };
                pki._application = new ApplicationInstance(telemetry) { ApplicationConfiguration = pki.Configuration };
                await pki.Configuration.ValidateAsync(ApplicationType.Client, ct);
                return pki;
            }
            catch { await pki.DisposeAsync(); throw; }
        }

        public async ValueTask DisposeAsync()
        {
            if (_application is not null) await _application.DisposeAsync();
            Leaf?.Dispose(); _issuer?.Dispose();
            if (Directory.Exists(_root)) Directory.Delete(_root, true);
        }
    }
}