using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using Opc.Ua;
using Shouldly;
using Xunit;
using ZB.MOM.WW.Secrets.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Browser.Tests;

/// <summary>
///     Review 2026-10-21 R06:O-5 — the AdminUI browse refused <c>Certificate</c> auth "in v1", so a
///     certificate-authenticated upstream could not be browsed at all. The browse now builds its identity through
///     the same <see cref="OpcUaUserIdentityFactory"/> the runtime driver uses (incl. the <c>secret:</c> resolution
///     of the credential fields, fail-closed), so it presents exactly the credentials the deployed driver will.
/// </summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientBrowserCertificateAuthTests
{
    private sealed class OneSecret(string name, string value) : ISecretResolver
    {
        public Task<string?> GetAsync(SecretName secretName, CancellationToken ct) =>
            Task.FromResult<string?>(secretName.Value == name ? value : null);
    }

    private static string WritePfx(string password)
    {
        using var rsa = RSA.Create(2048);
        var req = new CertificateRequest("CN=OpcUaClientBrowserCertAuthTests", rsa, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
        var cert = req.CreateSelfSigned(DateTimeOffset.UtcNow.AddMinutes(-5), DateTimeOffset.UtcNow.AddHours(1));
        var path = Path.Combine(Path.GetTempPath(), $"opcua-browse-cert-{Guid.NewGuid():N}.pfx");
        File.WriteAllBytes(path, cert.Export(X509ContentType.Pfx, password));
        return path;
    }

    /// <summary>Certificate auth is no longer refused: a missing cert path fails on the certificate itself.</summary>
    [Fact]
    public async Task OpenAsync_with_certificate_auth_fails_on_the_certificate_not_a_refusal()
    {
        var json = """{"EndpointUrl":"opc.tcp://127.0.0.1:1","AuthType":"Certificate"}""";

        var ex = await Should.ThrowAsync<InvalidOperationException>(
            () => new OpcUaClientDriverBrowser().OpenAsync(json, TestContext.Current.CancellationToken));

        ex.Message.ShouldContain("UserCertificatePath");
        ex.Message.ShouldNotContain("does not support");
    }

    /// <summary>A valid PFX whose password is a <c>secret:</c> ref resolves through the injected store.</summary>
    [Fact]
    public async Task A_certificate_identity_is_built_with_its_secret_password_resolved()
    {
        var path = WritePfx("s3cret-pw");
        try
        {
            var opts = new OpcUaClientDriverOptions
            {
                AuthType = OpcUaAuthType.Certificate,
                UserCertificatePath = path,
                UserCertificatePassword = "secret:opcua/browse-cert",
            };

            var identity = await OpcUaClientDriverBrowser.BuildBrowseUserIdentityAsync(
                opts, new OneSecret("opcua/browse-cert", "s3cret-pw"), TestContext.Current.CancellationToken);

            identity.TokenType.ShouldBe(UserTokenType.Certificate);
        }
        finally
        {
            try { File.Delete(path); } catch { /* best-effort */ }
        }
    }

    /// <summary>With no secret store, a <c>secret:</c> ref fails closed instead of being sent as the literal.</summary>
    [Fact]
    public async Task A_secret_ref_with_no_secret_store_fails_closed()
    {
        var opts = new OpcUaClientDriverOptions
        {
            AuthType = OpcUaAuthType.Username,
            Username = "op",
            Password = "secret:opcua/pw",
        };

        var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
            OpcUaClientDriverBrowser.BuildBrowseUserIdentityAsync(opts, null, TestContext.Current.CancellationToken));
        ex.Message.ShouldContain("fail-closed");
    }

    /// <summary>Positive control: a literal password is used as-is (no store needed).</summary>
    [Fact]
    public async Task A_literal_username_password_needs_no_store()
    {
        var opts = new OpcUaClientDriverOptions { AuthType = OpcUaAuthType.Username, Username = "op", Password = "pw" };

        var identity = await OpcUaClientDriverBrowser.BuildBrowseUserIdentityAsync(opts, null, TestContext.Current.CancellationToken);

        identity.TokenType.ShouldBe(UserTokenType.UserName);
    }
}