using System.Globalization;
using Google.Protobuf;
using Grpc.Core;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.Secrets.Abstractions;
using ZB.MOM.WW.Secrets.Replicator.Grpc.V1;
using ZB.MOM.WW.Secrets.Replicator.Grpc.Wire;

namespace ZB.MOM.WW.Secrets.Replicator.Grpc.Tests;

/// <summary>
/// Covers the read-only hub service and the domain→wire projection behind it. The contract the
/// proto states is binding here: a name the hub does not hold is omitted, never an error, and
/// every <see cref="StoredSecret"/> field crosses losslessly.
/// </summary>
public sealed class SecretsHubServiceTests
{
    [Fact]
    public async Task GetManifest_returns_every_entry_including_tombstones()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("alpha"));
        store.Seed(Row("beta", isDeleted: true));

        SecretsHubService service = Service(store);

        GetManifestResponse response =
            await service.GetManifest(new GetManifestRequest(), HubServerCallContextStub.Empty());

        Assert.Equal(["alpha", "beta"], response.Entries.Select(e => e.Name).Order());
        ManifestEntry tombstone = response.Entries.Single(e => e.Name == "beta");
        Assert.True(tombstone.IsDeleted);
    }

    [Fact]
    public async Task GetManifest_maps_every_manifest_field()
    {
        var updated = new DateTimeOffset(2026, 8, 7, 13, 45, 12, 345, TimeSpan.FromHours(-5))
            .AddTicks(6789);
        var store = new HubFakeSecretStore();
        store.SeedManifest(new SecretManifestEntry
        {
            Name = new SecretName("db/central"),
            Revision = 42,
            UpdatedUtc = updated,
            IsDeleted = true,
        });

        GetManifestResponse response = await Service(store)
            .GetManifest(new GetManifestRequest(), HubServerCallContextStub.Empty());

        ManifestEntry entry = Assert.Single(response.Entries);
        Assert.Equal("db/central", entry.Name);
        Assert.Equal(42, entry.Revision);
        Assert.Equal(updated.ToString("O", CultureInfo.InvariantCulture), entry.UpdatedUtc);
        Assert.True(entry.IsDeleted);
    }

    [Fact]
    public async Task GetSecrets_omits_names_the_hub_does_not_hold()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("present"));

        var request = new GetSecretsRequest { Names = { "present", "absent" } };

        GetSecretsResponse response =
            await Service(store).GetSecrets(request, HubServerCallContextStub.Empty());

        SecretRow row = Assert.Single(response.Secrets);
        Assert.Equal("present", row.Name);
    }

    [Fact]
    public async Task GetSecrets_returns_tombstoned_rows()
    {
        // A follower needs the tombstone itself to converge on a delete — omitting it would make a
        // deleted secret un-deletable downstream.
        var store = new HubFakeSecretStore();
        store.Seed(Row("gone", isDeleted: true));

        GetSecretsResponse response = await Service(store)
            .GetSecrets(new GetSecretsRequest { Names = { "gone" } }, HubServerCallContextStub.Empty());

        Assert.True(Assert.Single(response.Secrets).IsDeleted);
    }

    [Theory]
    [InlineData("")]
    [InlineData("   ")]
    [InlineData("../etc/passwd")]
    [InlineData("/rooted")]
    [InlineData("has space")]
    [InlineData("double//slash")]
    public async Task GetSecrets_skips_an_invalid_name_instead_of_faulting(string invalid)
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("present"));

        var request = new GetSecretsRequest { Names = { invalid, "present" } };

        GetSecretsResponse response =
            await Service(store).GetSecrets(request, HubServerCallContextStub.Empty());

        Assert.Equal("present", Assert.Single(response.Secrets).Name);
    }

    [Fact]
    public async Task GetSecrets_normalizes_names_before_looking_them_up()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("db/central"));

        GetSecretsResponse response = await Service(store).GetSecrets(
            new GetSecretsRequest { Names = { "  DB/Central  " } }, HubServerCallContextStub.Empty());

        Assert.Equal("db/central", Assert.Single(response.Secrets).Name);
    }

    [Fact]
    public async Task GetSecrets_returns_one_row_per_distinct_name()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("dup"));

        GetSecretsResponse response = await Service(store).GetSecrets(
            new GetSecretsRequest { Names = { "dup", "dup", "DUP" } }, HubServerCallContextStub.Empty());

        Assert.Single(response.Secrets);
        Assert.Equal(1, store.GetCallCount);
    }

    [Fact]
    public async Task GetSecrets_on_an_empty_request_reads_nothing()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("present"));

        GetSecretsResponse response = await Service(store)
            .GetSecrets(new GetSecretsRequest(), HubServerCallContextStub.Empty());

        Assert.Empty(response.Secrets);
        Assert.Equal(0, store.GetCallCount);
    }

    [Fact]
    public async Task GetSecrets_serves_a_request_exactly_at_the_cap()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("n1"));
        store.Seed(Row("n2"));
        store.Seed(Row("n3"));

        var request = new GetSecretsRequest { Names = { "n1", "n2", "n3" } };

        GetSecretsResponse response = await Service(store, maxNamesPerRequest: 3)
            .GetSecrets(request, HubServerCallContextStub.Empty());

        Assert.Equal(3, response.Secrets.Count);
    }

    [Fact]
    public async Task GetSecrets_refuses_a_request_over_the_cap()
    {
        var store = new HubFakeSecretStore();
        store.Seed(Row("n1"));

        var request = new GetSecretsRequest { Names = { "n1", "n2", "n3", "n4" } };

        RpcException error = await Assert.ThrowsAsync<RpcException>(
            () => Service(store, maxNamesPerRequest: 3).GetSecrets(request, HubServerCallContextStub.Empty()));

        Assert.Equal(StatusCode.ResourceExhausted, error.StatusCode);
    }

    [Fact]
    public async Task GetSecrets_over_the_cap_reads_nothing_at_all()
    {
        // The refusal has to land BEFORE the sequential store loop — a cap that stops the response
        // after doing the reads would defend nothing.
        var store = new HubFakeSecretStore();
        store.Seed(Row("n1"));

        var request = new GetSecretsRequest { Names = { "n1", "n1", "n1" } };

        await Assert.ThrowsAsync<RpcException>(
            () => Service(store, maxNamesPerRequest: 2).GetSecrets(request, HubServerCallContextStub.Empty()));

        Assert.Equal(0, store.GetCallCount);
    }

    [Fact]
    public async Task GetSecrets_cap_refusal_states_the_cap_and_the_count_but_never_a_name()
    {
        var store = new HubFakeSecretStore();
        var request = new GetSecretsRequest { Names = { "db/central", "db/site-a", "db/site-b" } };

        RpcException error = await Assert.ThrowsAsync<RpcException>(
            () => Service(store, maxNamesPerRequest: 2).GetSecrets(request, HubServerCallContextStub.Empty()));

        Assert.Contains("2", error.Status.Detail, StringComparison.Ordinal);
        Assert.Contains("3", error.Status.Detail, StringComparison.Ordinal);
        foreach (string name in request.Names)
        {
            Assert.DoesNotContain(name, error.Status.Detail, StringComparison.OrdinalIgnoreCase);
        }
    }

    [Fact]
    public async Task GetSecrets_falls_back_to_the_default_cap_when_options_carry_a_nonpositive_one()
    {
        // Registration validates the cap, so this only happens when the options were built some
        // other way — and the safe reading of "0" is the default, never "no cap".
        var store = new HubFakeSecretStore();
        var request = new GetSecretsRequest();
        for (int i = 0; i <= SecretsGrpcHubServerOptions.DefaultMaxNamesPerRequest; i++)
        {
            request.Names.Add($"n{i}");
        }

        RpcException error = await Assert.ThrowsAsync<RpcException>(
            () => Service(store, maxNamesPerRequest: 0).GetSecrets(request, HubServerCallContextStub.Empty()));

        Assert.Equal(StatusCode.ResourceExhausted, error.StatusCode);
    }

    [Fact]
    public async Task GetSecrets_hands_the_call_cancellation_token_to_the_store()
    {
        using var cts = new CancellationTokenSource();
        await cts.CancelAsync();

        var store = new HubFakeSecretStore();
        store.Seed(Row("present"));

        await Service(store).GetSecrets(
            new GetSecretsRequest { Names = { "present" } },
            HubServerCallContextStub.WithCancellation(cts.Token));

        // The fake does not honour the token, so what is pinned here is the propagation itself: a
        // real store sees the caller's cancellation, and an abandoned call stops costing reads.
        Assert.True(store.LastCancellationToken.IsCancellationRequested);
        Assert.Equal(cts.Token, store.LastCancellationToken);
    }

    [Fact]
    public void DomainToWire_maps_a_fully_populated_row_field_by_field()
    {
        // Deliberately non-UTC offsets: DateTimeOffset carries an offset that a UTC-instant
        // representation would silently normalize away.
        var created = new DateTimeOffset(2026, 1, 2, 3, 4, 5, 678, TimeSpan.FromHours(-5)).AddTicks(9012);
        var updated = new DateTimeOffset(2026, 8, 7, 9, 10, 11, 121, TimeSpan.FromHours(5.5)).AddTicks(3456);
        var deleted = new DateTimeOffset(2026, 8, 7, 9, 30, 0, TimeSpan.FromHours(9));

        var row = new StoredSecret
        {
            Name = new SecretName("db/central"),
            Description = "central connection string",
            ContentType = SecretContentType.ConnectionString,
            Ciphertext = [1, 2, 3, 4],
            Nonce = [5, 6, 7],
            Tag = [8, 9],
            WrappedDek = [10, 11, 12],
            WrapNonce = [13, 14],
            WrapTag = [15],
            KekId = "kek-2026-08",
            Revision = 7,
            IsDeleted = true,
            DeletedUtc = deleted,
            CreatedUtc = created,
            UpdatedUtc = updated,
            CreatedBy = "alice",
            UpdatedBy = "bob",
        };

        SecretRow wire = DomainToWire.ToWire(row);

        Assert.Equal("db/central", wire.Name);
        Assert.Equal("central connection string", wire.Description);
        Assert.Equal("ConnectionString", wire.ContentType);
        Assert.Equal(new byte[] { 1, 2, 3, 4 }, wire.Ciphertext.ToByteArray());
        Assert.Equal(new byte[] { 5, 6, 7 }, wire.Nonce.ToByteArray());
        Assert.Equal(new byte[] { 8, 9 }, wire.Tag.ToByteArray());
        Assert.Equal(new byte[] { 10, 11, 12 }, wire.WrappedDek.ToByteArray());
        Assert.Equal(new byte[] { 13, 14 }, wire.WrapNonce.ToByteArray());
        Assert.Equal(new byte[] { 15 }, wire.WrapTag.ToByteArray());
        Assert.Equal("kek-2026-08", wire.KekId);
        Assert.Equal(7, wire.Revision);
        Assert.True(wire.IsDeleted);
        Assert.Equal(deleted.ToString("O", CultureInfo.InvariantCulture), wire.DeletedUtc);
        Assert.Equal(created.ToString("O", CultureInfo.InvariantCulture), wire.CreatedUtc);
        Assert.Equal(updated.ToString("O", CultureInfo.InvariantCulture), wire.UpdatedUtc);
        Assert.Equal("alice", wire.CreatedBy);
        Assert.Equal("bob", wire.UpdatedBy);
    }

    [Fact]
    public void DomainToWire_leaves_nullable_fields_absent_rather_than_empty()
    {
        StoredSecret row = Row("minimal");

        SecretRow wire = DomainToWire.ToWire(row);

        Assert.False(wire.HasDescription);
        Assert.False(wire.HasDeletedUtc);
        Assert.False(wire.HasCreatedBy);
        Assert.False(wire.HasUpdatedBy);
    }

    [Fact]
    public void DomainToWire_distinguishes_an_empty_string_from_a_null()
    {
        StoredSecret row = Row("empties") with { Description = string.Empty, CreatedBy = string.Empty };

        SecretRow wire = DomainToWire.ToWire(row);

        Assert.True(wire.HasDescription);
        Assert.Equal(string.Empty, wire.Description);
        Assert.True(wire.HasCreatedBy);
        Assert.Equal(string.Empty, wire.CreatedBy);
    }

    [Theory]
    [InlineData(SecretContentType.Text, "Text")]
    [InlineData(SecretContentType.ConnectionString, "ConnectionString")]
    [InlineData(SecretContentType.Json, "Json")]
    [InlineData(SecretContentType.BinaryBase64, "BinaryBase64")]
    public void DomainToWire_writes_the_content_type_member_name(SecretContentType type, string expected)
    {
        SecretRow wire = DomainToWire.ToWire(Row("typed") with { ContentType = type });

        Assert.Equal(expected, wire.ContentType);
    }

    private static SecretsHubService Service(ISecretStore store, int? maxNamesPerRequest = null)
    {
        var options = new SecretsGrpcHubServerOptions { BearerToken = "irrelevant-to-the-service" };
        if (maxNamesPerRequest is int max)
        {
            options.MaxNamesPerRequest = max;
        }

        return new SecretsHubService(store, Options.Create(options), NullLogger<SecretsHubService>.Instance);
    }

    private static StoredSecret Row(string name, bool isDeleted = false) => new()
    {
        Name = new SecretName(name),
        ContentType = SecretContentType.Text,
        Ciphertext = [1],
        Nonce = [2],
        Tag = [3],
        WrappedDek = [4],
        WrapNonce = [5],
        WrapTag = [6],
        KekId = "kek",
        Revision = 1,
        IsDeleted = isDeleted,
        DeletedUtc = isDeleted ? DateTimeOffset.UnixEpoch : null,
        CreatedUtc = DateTimeOffset.UnixEpoch,
        UpdatedUtc = DateTimeOffset.UnixEpoch,
    };
}

/// <summary>
/// An in-memory <see cref="ISecretStore"/>. Only the two read members the hub adapts are
/// implemented; the write half throws, which is itself part of the pull-only pin — a hub that ever
/// started writing would fail loudly in these tests.
/// </summary>
internal sealed class HubFakeSecretStore : ISecretStore
{
    private readonly Dictionary<string, StoredSecret> _rows = new(StringComparer.Ordinal);
    private readonly List<SecretManifestEntry> _manifestOverride = [];

    /// <summary>How many single-row reads the service issued.</summary>
    public int GetCallCount { get; private set; }

    /// <summary>The cancellation token the service passed on the most recent read.</summary>
    public CancellationToken LastCancellationToken { get; private set; }

    /// <summary>Adds a row, and the manifest entry derived from it.</summary>
    public void Seed(StoredSecret row) => _rows[row.Name.Value] = row;

    /// <summary>Adds a manifest entry with no backing row, for manifest-shape assertions.</summary>
    public void SeedManifest(SecretManifestEntry entry) => _manifestOverride.Add(entry);

    /// <inheritdoc/>
    public Task<StoredSecret?> GetAsync(SecretName name, CancellationToken ct)
    {
        GetCallCount++;
        LastCancellationToken = ct;
        return Task.FromResult(_rows.GetValueOrDefault(name.Value));
    }

    /// <inheritdoc/>
    public Task<IReadOnlyList<SecretManifestEntry>> GetManifestAsync(CancellationToken ct)
    {
        if (_manifestOverride.Count > 0)
        {
            return Task.FromResult<IReadOnlyList<SecretManifestEntry>>(_manifestOverride);
        }

        IReadOnlyList<SecretManifestEntry> entries = _rows.Values
            .Select(r => new SecretManifestEntry
            {
                Name = r.Name,
                Revision = r.Revision,
                UpdatedUtc = r.UpdatedUtc,
                IsDeleted = r.IsDeleted,
            })
            .ToList();

        return Task.FromResult(entries);
    }

    /// <inheritdoc/>
    public Task UpsertAsync(StoredSecret row, CancellationToken ct) => throw new NotSupportedException();

    /// <inheritdoc/>
    public Task<bool> DeleteAsync(SecretName name, string? actor, CancellationToken ct) =>
        throw new NotSupportedException();

    /// <inheritdoc/>
    public Task<IReadOnlyList<SecretMetadata>> ListAsync(bool includeDeleted, CancellationToken ct) =>
        throw new NotSupportedException();

    /// <inheritdoc/>
    public Task ApplyReplicatedAsync(StoredSecret row, CancellationToken ct) =>
        throw new NotSupportedException();

    /// <inheritdoc/>
    public Task<bool> ApplyRewrapAsync(
        StoredSecret rewrappedRow, byte[] expectedCurrentWrappedDek, CancellationToken ct) =>
        throw new NotSupportedException();
}