using System.Text;
using Shouldly;
using Xunit;
using ZB.MOM.WW.Audit;
using ZB.MOM.WW.OtOpcUa.AdminUI.ApiKeyAck;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
using ZB.MOM.WW.Secrets.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.ApiKeyAck;

/// <summary>
///     lmxopcua#749 — the AdminUI half of the per-key Galaxy ack identity: written ENCRYPTED to the Secrets
///     store under the names the driver reads, listed without touching the password, cleared on request, and
///     audited without the credential.
/// </summary>
public sealed class ApiKeyGalaxyAckIdentityServiceTests
{
    private const string KeyId = "0a1b2c3d4e5f6071";
    private const string Password = "pw-S3cr3t!";

    private readonly InMemorySecretStore _store = new();
    private readonly XorCipher _cipher = new();
    private readonly RecordingAudit _audit = new();
    private readonly RecordingInvalidator _invalidator = new();

    private ApiKeyGalaxyAckIdentityService Service() => new(_store, _cipher, _audit, _invalidator);

    [Fact]
    public async Task Set_writes_both_secrets_encrypted_under_the_driver_names()
    {
        await Service().SetAsync(KeyId, "alice", "CORP", Password, "admin", TestContext.Current.CancellationToken);

        var user = _store.Rows[GalaxyAckIdentitySecrets.UserSecretName(KeyId)];
        var pw = _store.Rows[GalaxyAckIdentitySecrets.PasswordSecretName(KeyId)];
        _cipher.Decrypt(user).ShouldBe("CORP\\alice");
        _cipher.Decrypt(pw).ShouldBe(Password);

        // At rest it is ciphertext, not the password.
        Encoding.UTF8.GetString(pw.Ciphertext).ShouldNotContain(Password);
        pw.Description.ShouldNotBeNull().ShouldNotContain(Password);

        // Password written before the user (a reader never sees a user without its password).
        _store.UpsertOrder.ShouldBe([GalaxyAckIdentitySecrets.PasswordSecretName(KeyId), GalaxyAckIdentitySecrets.UserSecretName(KeyId)]);
        _invalidator.Invalidated.ShouldContain(GalaxyAckIdentitySecrets.PasswordSecretName(KeyId));
    }

    [Fact]
    public async Task List_returns_identity_and_never_decrypts_a_password()
    {
        var svc = Service();
        await svc.SetAsync(KeyId, "alice", "CORP", Password, "admin", TestContext.Current.CancellationToken);
        await svc.SetAsync("ffff0000ffff0000", "bob", null, "", "admin", TestContext.Current.CancellationToken);
        _store.GetCalls.Clear();

        var list = await svc.ListAsync(TestContext.Current.CancellationToken);

        list[KeyId].ShouldBe("CORP\\alice");
        list["ffff0000ffff0000"].ShouldBe("bob");
        _store.GetCalls.ShouldAllBe(n => n.EndsWith("/galaxy-ack-user"));
    }

    [Fact]
    public async Task Clear_removes_both_and_audits_without_the_credential()
    {
        var svc = Service();
        await svc.SetAsync(KeyId, "alice", "CORP", Password, "admin", TestContext.Current.CancellationToken);

        await svc.ClearAsync(KeyId, "admin", TestContext.Current.CancellationToken);

        _store.Rows.ShouldBeEmpty();
        (await svc.ListAsync(TestContext.Current.CancellationToken)).ShouldBeEmpty();
        _audit.Events.Select(e => e.Action).ShouldBe(["apikey.galaxy-ack-identity.set", "apikey.galaxy-ack-identity.clear"]);
        _audit.Events.ShouldAllBe(e => e.Target == KeyId && e.Actor == "admin");
        string.Join("|", _audit.Events.Select(e => e.ToString())).ShouldNotContain(Password);
    }

    [Theory]
    [InlineData("")]
    [InlineData("CORP\\alice")]
    public async Task Set_rejects_missing_or_domain_qualified_user(string user)
    {
        await Should.ThrowAsync<ArgumentException>(() => Service().SetAsync(KeyId, user, null, Password, "admin", default));
        _store.Rows.ShouldBeEmpty();
    }

    [Fact]
    public async Task Set_rejects_a_malformed_key_id()
    {
        await Should.ThrowAsync<ArgumentException>(() => Service().SetAsync("../x", "alice", null, Password, "admin", default));
        _store.Rows.ShouldBeEmpty();
    }

    /// <summary>Reversible stand-in for the AES-GCM envelope cipher — enough to prove the value is not stored in clear.</summary>
    private sealed class XorCipher : ISecretCipher
    {
        public StoredSecret Encrypt(SecretName name, string plaintext, SecretContentType contentType) => new()
        {
            Name = name, ContentType = contentType,
            Ciphertext = Encoding.UTF8.GetBytes(plaintext).Select(b => (byte)(b ^ 0x5A)).ToArray(),
            Nonce = [], Tag = [], WrappedDek = [], WrapNonce = [], WrapTag = [],
            KekId = "test", Revision = 0, CreatedUtc = DateTimeOffset.UtcNow, UpdatedUtc = DateTimeOffset.UtcNow,
        };

        public string Decrypt(StoredSecret secret) =>
            Encoding.UTF8.GetString(secret.Ciphertext.Select(b => (byte)(b ^ 0x5A)).ToArray());

        public StoredSecret Rewrap(StoredSecret secret, IMasterKeyProvider oldKek, IMasterKeyProvider newKek) =>
            throw new NotSupportedException();
    }

    private sealed class RecordingAudit : IAuditWriter
    {
        public List<AuditEvent> Events { get; } = [];
        public Task WriteAsync(AuditEvent evt, CancellationToken ct = default) { Events.Add(evt); return Task.CompletedTask; }
    }

    private sealed class RecordingInvalidator : ISecretCacheInvalidator
    {
        public List<string> Invalidated { get; } = [];
        public void Invalidate(SecretName name) => Invalidated.Add(name.Value);
    }

    private sealed class InMemorySecretStore : ISecretStore
    {
        public Dictionary<string, StoredSecret> Rows { get; } = new();
        public List<string> UpsertOrder { get; } = [];
        public List<string> GetCalls { get; } = [];

        public Task<StoredSecret?> GetAsync(SecretName name, CancellationToken ct)
        {
            GetCalls.Add(name.Value);
            return Task.FromResult(Rows.TryGetValue(name.Value, out var r) ? r : null);
        }

        public Task UpsertAsync(StoredSecret row, CancellationToken ct)
        {
            UpsertOrder.Add(row.Name.Value);
            Rows[row.Name.Value] = row;
            return Task.CompletedTask;
        }

        public Task<bool> DeleteAsync(SecretName name, string? actor, CancellationToken ct) =>
            Task.FromResult(Rows.Remove(name.Value));

        public Task<IReadOnlyList<SecretMetadata>> ListAsync(bool includeDeleted, CancellationToken ct) =>
            Task.FromResult<IReadOnlyList<SecretMetadata>>(Rows.Values.Select(r => new SecretMetadata
            {
                Name = r.Name, ContentType = r.ContentType, KekId = r.KekId, Revision = r.Revision,
                CreatedUtc = r.CreatedUtc, UpdatedUtc = r.UpdatedUtc,
            }).ToList());

        public Task<IReadOnlyList<SecretManifestEntry>> GetManifestAsync(CancellationToken ct) => throw new NotSupportedException();
        public Task ApplyReplicatedAsync(StoredSecret row, CancellationToken ct) => throw new NotSupportedException();
        public Task<bool> ApplyRewrapAsync(StoredSecret rewrappedRow, byte[] expectedCurrentWrappedDek, CancellationToken ct) => throw new NotSupportedException();
    }
}