﻿/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace DotPulsar.Internal
{
    using DotPulsar.Internal.Abstractions;
    using DotPulsar.Internal.Requests;
    using PulsarApi;
    using System;
    using System.Threading.Tasks;

    public sealed class RequestResponseHandler : IDisposable
    {
        private readonly RequestId _requestId;
        private readonly Awaiter<IRequest, BaseCommand> _requests;
        private readonly EnumLookup<BaseCommand.Type, Func<BaseCommand, IRequest>> _getResponseIdentifier;

        public RequestResponseHandler()
        {
            _requestId = new RequestId();
            _requests = new Awaiter<IRequest, BaseCommand>();

            _getResponseIdentifier = new EnumLookup<BaseCommand.Type, Func<BaseCommand, IRequest>>(cmd => throw new Exception($"CommandType '{cmd.CommandType}' not supported as request/response type"));
            _getResponseIdentifier.Set(BaseCommand.Type.Connected, cmd => new ConnectRequest());
            _getResponseIdentifier.Set(BaseCommand.Type.SendError, cmd => new SendRequest(cmd.SendError.ProducerId, cmd.SendError.SequenceId));
            _getResponseIdentifier.Set(BaseCommand.Type.SendReceipt, cmd => new SendRequest(cmd.SendReceipt.ProducerId, cmd.SendReceipt.SequenceId));
            _getResponseIdentifier.Set(BaseCommand.Type.ProducerSuccess, cmd => StandardRequest.WithRequestId(cmd.ProducerSuccess.RequestId));
            _getResponseIdentifier.Set(BaseCommand.Type.CloseConsumer, cmd => StandardRequest.WithConsumerId(cmd.CloseConsumer.RequestId, cmd.CloseConsumer.ConsumerId));
            _getResponseIdentifier.Set(BaseCommand.Type.CloseProducer, cmd => StandardRequest.WithProducerId(cmd.CloseProducer.RequestId, cmd.CloseProducer.ProducerId));
            _getResponseIdentifier.Set(BaseCommand.Type.LookupResponse, cmd => StandardRequest.WithRequestId(cmd.LookupTopicResponse.RequestId));
            _getResponseIdentifier.Set(BaseCommand.Type.GetLastMessageIdResponse, cmd => StandardRequest.WithRequestId(cmd.GetLastMessageIdResponse.RequestId));
            _getResponseIdentifier.Set(BaseCommand.Type.GetOrCreateSchemaResponse, cmd => StandardRequest.WithRequestId(cmd.GetOrCreateSchemaResponse.RequestId));
            _getResponseIdentifier.Set(BaseCommand.Type.Success, cmd => StandardRequest.WithRequestId(cmd.Success.RequestId));
            _getResponseIdentifier.Set(BaseCommand.Type.Error, cmd => !_requestId.IsPastInitialId() ? new ConnectRequest() : StandardRequest.WithRequestId(cmd.Error.RequestId));
        }

        public void Dispose()
            => _requests.Dispose();

        public Task<BaseCommand> Outgoing(CommandProducer command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithProducerId(command.RequestId, command.ProducerId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandCloseProducer command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithProducerId(command.RequestId, command.ProducerId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandSubscribe command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithConsumerId(command.RequestId, command.ConsumerId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandUnsubscribe command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithConsumerId(command.RequestId, command.ConsumerId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandCloseConsumer command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithConsumerId(command.RequestId, command.ConsumerId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandSend command)
        {
            var request = new SendRequest(command.ProducerId, command.SequenceId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandGetOrCreateSchema command)
        {
            command.RequestId = _requestId.FetchNext();
            var request = StandardRequest.WithRequestId(command.RequestId);
            return _requests.CreateTask(request);
        }

        public Task<BaseCommand> Outgoing(CommandConnect _1)
            => _requests.CreateTask(new ConnectRequest());

        public Task<BaseCommand> Outgoing(CommandLookupTopic command)
        {
            command.RequestId = _requestId.FetchNext();
            return _requests.CreateTask(StandardRequest.WithRequestId(command.RequestId));
        }

        public Task<BaseCommand> Outgoing(CommandSeek command)
        {
            command.RequestId = _requestId.FetchNext();
            return _requests.CreateTask(StandardRequest.WithConsumerId(command.RequestId, command.ConsumerId, BaseCommand.Type.Seek));
        }

        public Task<BaseCommand> Outgoing(CommandGetLastMessageId command)
        {
            command.RequestId = _requestId.FetchNext();
            return _requests.CreateTask(StandardRequest.WithRequestId(command.RequestId));
        }

        public void Incoming(BaseCommand command)
        {
            var identifier = _getResponseIdentifier.Get(command.CommandType)(command);

            if (identifier is not null)
                _requests.SetResult(identifier, command);
        }

        public void Incoming(CommandCloseConsumer command)
        {
            var requests = _requests.Keys;
            foreach (var request in requests)
            {
                if (request.SenderIsConsumer(command.ConsumerId))
                {
                    if (request.IsCommandType(BaseCommand.Type.Seek))
                        _requests.SetResult(request, new BaseCommand { CommandType = BaseCommand.Type.Success });
                    else
                        _requests.Cancel(request);
                }
            }
        }

        public void Incoming(CommandCloseProducer command)
        {
            var requests = _requests.Keys;
            foreach (var request in requests)
            {
                if (request.SenderIsProducer(command.ProducerId))
                    _requests.Cancel(request);
            }
        }
    }
}