using Grpc.Core;
using MxGateway.Contracts.Proto;

namespace MxGateway.Server.Grpc;

public sealed class MxAccessGrpcRequestValidator
{
    public void ValidateOpenSession(OpenSessionRequest request)
    {
        ArgumentNullException.ThrowIfNull(request);

        if (request.CommandTimeout is not null && request.CommandTimeout.ToTimeSpan() <= TimeSpan.Zero)
        {
            throw InvalidArgument("Command timeout must be greater than zero when provided.");
        }
    }

    public void ValidateCloseSession(CloseSessionRequest request)
    {
        ArgumentNullException.ThrowIfNull(request);
        RequireSessionId(request.SessionId);
    }

    public void ValidateStreamEvents(StreamEventsRequest request)
    {
        ArgumentNullException.ThrowIfNull(request);
        RequireSessionId(request.SessionId);
    }

    public void ValidateInvoke(MxCommandRequest request)
    {
        ArgumentNullException.ThrowIfNull(request);
        RequireSessionId(request.SessionId);

        if (request.Command is null)
        {
            throw InvalidArgument("Invoke requires a command payload.");
        }

        if (request.Command.Kind is MxCommandKind.Unspecified)
        {
            throw InvalidArgument("Invoke requires a command kind.");
        }

        ValidateCommandPayload(request.Command);
    }

    private static void RequireSessionId(string sessionId)
    {
        if (string.IsNullOrWhiteSpace(sessionId))
        {
            throw InvalidArgument("Session id is required.");
        }
    }

    private static void ValidateCommandPayload(MxCommand command)
    {
        MxCommand.PayloadOneofCase expectedPayload = ExpectedPayload(command.Kind);
        if (command.PayloadCase != expectedPayload)
        {
            throw InvalidArgument(
                $"Command kind {command.Kind} requires payload {expectedPayload} but received {command.PayloadCase}.");
        }
    }

    private static MxCommand.PayloadOneofCase ExpectedPayload(MxCommandKind kind)
    {
        return kind switch
        {
            MxCommandKind.Register => MxCommand.PayloadOneofCase.Register,
            MxCommandKind.Unregister => MxCommand.PayloadOneofCase.Unregister,
            MxCommandKind.AddItem => MxCommand.PayloadOneofCase.AddItem,
            MxCommandKind.AddItem2 => MxCommand.PayloadOneofCase.AddItem2,
            MxCommandKind.RemoveItem => MxCommand.PayloadOneofCase.RemoveItem,
            MxCommandKind.Advise => MxCommand.PayloadOneofCase.Advise,
            MxCommandKind.UnAdvise => MxCommand.PayloadOneofCase.UnAdvise,
            MxCommandKind.AdviseSupervisory => MxCommand.PayloadOneofCase.AdviseSupervisory,
            MxCommandKind.AddBufferedItem => MxCommand.PayloadOneofCase.AddBufferedItem,
            MxCommandKind.SetBufferedUpdateInterval => MxCommand.PayloadOneofCase.SetBufferedUpdateInterval,
            MxCommandKind.Suspend => MxCommand.PayloadOneofCase.Suspend,
            MxCommandKind.Activate => MxCommand.PayloadOneofCase.Activate,
            MxCommandKind.Write => MxCommand.PayloadOneofCase.Write,
            MxCommandKind.Write2 => MxCommand.PayloadOneofCase.Write2,
            MxCommandKind.WriteSecured => MxCommand.PayloadOneofCase.WriteSecured,
            MxCommandKind.WriteSecured2 => MxCommand.PayloadOneofCase.WriteSecured2,
            MxCommandKind.AuthenticateUser => MxCommand.PayloadOneofCase.AuthenticateUser,
            MxCommandKind.ArchestraUserToId => MxCommand.PayloadOneofCase.ArchestraUserToId,
            MxCommandKind.Ping => MxCommand.PayloadOneofCase.Ping,
            MxCommandKind.GetSessionState => MxCommand.PayloadOneofCase.GetSessionState,
            MxCommandKind.GetWorkerInfo => MxCommand.PayloadOneofCase.GetWorkerInfo,
            MxCommandKind.DrainEvents => MxCommand.PayloadOneofCase.DrainEvents,
            MxCommandKind.ShutdownWorker => MxCommand.PayloadOneofCase.ShutdownWorker,
            _ => MxCommand.PayloadOneofCase.None,
        };
    }

    private static RpcException InvalidArgument(string detail)
    {
        return new RpcException(new Status(StatusCode.InvalidArgument, detail));
    }
}