using AVEVA.Historian.Client.Grpc;
using AVEVA.Historian.Client.Models;
using AVEVA.Historian.Client.Wcf;
using Google.Protobuf;
using ArchestrA.Grpc.Contract.Retrieval;
using GrpcHistory = ArchestrA.Grpc.Contract.History;

namespace AVEVA.Historian.Client.Tests;

/// <summary>
/// Unit coverage for the 2023 R2 RemoteGrpc transport — the parts that do not require a live
/// server: channel address/port resolution, metadata, transport routing, and the invariant that
/// gRPC request messages carry the same native byte buffers the WCF path uses.
/// </summary>
public sealed class HistorianGrpcTransportTests
{
    private static HistorianClientOptions Options(
        string host = "histserver",
        int port = HistorianClientOptions.DefaultPort,
        bool tls = false,
        string? dnsIdentity = null,
        bool compression = false) => new()
        {
            Host = host,
            Port = port,
            Transport = HistorianTransport.RemoteGrpc,
            GrpcUseTls = tls,
            ServerDnsIdentity = dnsIdentity,
            Compression = compression,
            IntegratedSecurity = true
        };

    [Fact]
    public void ResolvePort_DefaultWcfPort_SubstitutesGrpcDefault()
    {
        Assert.Equal(HistorianClientOptions.DefaultGrpcPort, HistorianGrpcChannelFactory.ResolvePort(Options(port: HistorianClientOptions.DefaultPort)));
    }

    [Fact]
    public void ResolvePort_ExplicitPort_IsHonoured()
    {
        Assert.Equal(443, HistorianGrpcChannelFactory.ResolvePort(Options(port: 443)));
    }

    [Fact]
    public void ResolveAddress_Plaintext_UsesHttpAndHost()
    {
        Assert.Equal("http://histserver:32565", HistorianGrpcChannelFactory.ResolveAddress(Options()));
    }

    [Fact]
    public void ResolveAddress_Tls_UsesHttpsAndHostWhenNoDnsIdentity()
    {
        Assert.Equal("https://histserver:32565", HistorianGrpcChannelFactory.ResolveAddress(Options(tls: true)));
    }

    [Fact]
    public void ResolveAddress_Tls_PrefersDnsIdentityForCertMatch()
    {
        string address = HistorianGrpcChannelFactory.ResolveAddress(Options(host: "10.0.0.5", tls: true, dnsIdentity: "localhost"));
        Assert.Equal("https://localhost:32565", address);
    }

    [Fact]
    public void Create_CompressionDisabled_EmitsNoEncodingHeader()
    {
        using HistorianGrpcConnection connection = HistorianGrpcChannelFactory.Create(Options(compression: false));
        Assert.DoesNotContain(connection.Metadata, e => e.Key == "grpc-internal-encoding-request");
    }

    [Fact]
    public void Create_CompressionEnabled_AdvertisesGzipRequestEncoding()
    {
        using HistorianGrpcConnection connection = HistorianGrpcChannelFactory.Create(Options(compression: true));
        global::Grpc.Core.Metadata.Entry entry = Assert.Single(connection.Metadata, e => e.Key == "grpc-internal-encoding-request");
        Assert.Equal("gzip", entry.Value);
    }

    [Fact]
    public void StartQueryRequest_CarriesNativeDataQueryBufferUnchanged()
    {
        // The gRPC envelope must wrap the exact bytes the WCF StartQuery2 path sends, so the
        // already-reverse-engineered DataQueryRequest serializer is reused verbatim.
        HistorianDataQueryRequest request = HistorianWcfReadOrchestrator.BuildDataQueryRequest(
            "Tag.Counter", new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc), new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc), 100);
        byte[] nativeBuffer = HistorianDataQueryProtocol.SerializeFullHistoryRequest(request);

        var message = new StartQueryRequest
        {
            UiHandle = 7,
            UiQueryRequestType = HistorianDataQueryProtocol.QueryRequestTypeData,
            BtRequestBuffer = ByteString.CopyFrom(nativeBuffer)
        };

        // Round-trip through protobuf and confirm the native buffer survives byte-for-byte.
        byte[] wire = message.ToByteArray();
        var decoded = StartQueryRequest.Parser.ParseFrom(wire);
        Assert.Equal(nativeBuffer, decoded.BtRequestBuffer.ToByteArray());
        Assert.Equal(7u, decoded.UiHandle);
        Assert.Equal((uint)HistorianDataQueryProtocol.QueryRequestTypeData, decoded.UiQueryRequestType);
    }

    [Fact]
    public void InterfaceVersionResponses_ExposeErrorAndVersion_AsProbeExpects()
    {
        // R0.4 ProbeAsync reads uiError/uiVersion off each service's GetInterfaceVersion response.
        // Pin that field mapping (success = uiError 0 + uiVersion > 0) via a protobuf round-trip.
        var history = GrpcHistory.GetInterfaceVersionResponse.Parser.ParseFrom(
            new GrpcHistory.GetInterfaceVersionResponse { UiError = 0, UiVersion = 12 }.ToByteArray());
        var retrieval = GetRetrievalInterfaceVersionResponse.Parser.ParseFrom(
            new GetRetrievalInterfaceVersionResponse { UiError = 0, UiVersion = 4 }.ToByteArray());

        Assert.Equal(0u, history.UiError);
        Assert.Equal(12u, history.UiVersion);
        Assert.Equal(0u, retrieval.UiError);
        Assert.Equal(4u, retrieval.UiVersion);
    }

    [Fact]
    public void GetSystemParameterMessages_CarryHandleNameAndValue_AsStatusClientExpects()
    {
        // R0.3 sends {uiHandle, strParameterName} and reads strParameterValue when status succeeds.
        var request = ArchestrA.Grpc.Contract.Status.GetSystemParameterRequest.Parser.ParseFrom(
            new ArchestrA.Grpc.Contract.Status.GetSystemParameterRequest { UiHandle = 9, StrParameterName = "HistorianVersion" }.ToByteArray());
        Assert.Equal(9u, request.UiHandle);
        Assert.Equal("HistorianVersion", request.StrParameterName);

        var response = ArchestrA.Grpc.Contract.Status.GetSystemParameterResponse.Parser.ParseFrom(
            new ArchestrA.Grpc.Contract.Status.GetSystemParameterResponse
            {
                Status = new ArchestrA.Grpc.Contract.RequestStatus.Status { BSuccess = true },
                StrParameterValue = "20.0.000"
            }.ToByteArray());
        Assert.True(response.Status.BSuccess);
        Assert.Equal("20.0.000", response.StrParameterValue);
    }

    [Fact]
    public void BuildTagNamesBuffer_EncodesCountThenLengthPrefixedUtf16Names()
    {
        // R0.2 request framing: uint count + per-name(uint charCount + UTF-16LE). Golden bytes.
        byte[] buffer = AVEVA.Historian.Client.Grpc.HistorianGrpcTagClient.BuildTagNamesBuffer(["AB", "C"]);

        byte[] expected =
        [
            0x02, 0x00, 0x00, 0x00,             // count = 2
            0x02, 0x00, 0x00, 0x00,             // "AB" char count = 2
            0x41, 0x00, 0x42, 0x00,             // 'A','B' UTF-16LE
            0x01, 0x00, 0x00, 0x00,             // "C" char count = 1
            0x43, 0x00                          // 'C' UTF-16LE
        ];
        Assert.Equal(expected, buffer);
    }

    [Fact]
    public void OpenConnectionRequest_CarriesNativeOpen2BufferUnchanged()
    {
        byte[] open2 = HistorianNativeHandshake.BuildOpenConnection3Request(
            "histserver", Guid.NewGuid(), HistorianWcfAuthChainHelper.NativeIntegratedReadOnlyConnectionMode);

        var message = new GrpcHistory.OpenConnectionRequest { BtConnectionRequest = ByteString.CopyFrom(open2) };
        var decoded = GrpcHistory.OpenConnectionRequest.Parser.ParseFrom(message.ToByteArray());

        Assert.Equal(open2, decoded.BtConnectionRequest.ToByteArray());
    }
}