﻿/*
 * 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 Abstractions;
    using Events;
    using System;
    using System.Threading;

    public sealed class Channel : IChannel
    {
        private readonly Lock _senderLock;
        private readonly Guid _correlationId;
        private readonly IRegisterEvent _eventRegister;
        private readonly IEnqueue<MessagePackage> _enqueue;

        public Channel(Guid correlationId, IRegisterEvent eventRegister, IEnqueue<MessagePackage> enqueue)
        {
            _senderLock = new Lock();
            _correlationId = correlationId;
            _eventRegister = eventRegister;
            _enqueue = enqueue;
        }

        public void Received(MessagePackage message)
            => _enqueue.Enqueue(message);

        public void Activated()
            => _eventRegister.Register(new ChannelActivated(_correlationId));

        public void ClosedByServer()
        {
            _senderLock.Disable();
            _eventRegister.Register(new ChannelClosedByServer(_correlationId));
        }

        public void Connected()
            => _eventRegister.Register(new ChannelConnected(_correlationId));

        public void Deactivated()
            => _eventRegister.Register(new ChannelDeactivated(_correlationId));

        public void Disconnected()
        {
            _senderLock.Disable();
            _eventRegister.Register(new ChannelDisconnected(_correlationId));
        }

        public void ReachedEndOfTopic()
            => _eventRegister.Register(new ChannelReachedEndOfTopic(_correlationId));

        public void Unsubscribed()
            => _eventRegister.Register(new ChannelUnsubscribed(_correlationId));

        public IDisposable SenderLock()
            => _senderLock.Enter();

        private sealed class Lock : IDisposable
        {
            private readonly object _lock;
            private bool _canSend;

            public Lock()
            {
                _lock = new object();
                _canSend = true;
            }

            public void Disable()
            {
                Monitor.Enter(_lock);
                _canSend = false;
                Monitor.Exit(_lock);
            }

            public IDisposable Enter()
            {
                Monitor.Enter(_lock);

                if (_canSend)
                    return this;

                Monitor.Exit(_lock);
                throw new OperationCanceledException();
            }

            public void Dispose()
                => Monitor.Exit(_lock);
        }
    }
}