/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;

namespace Apache.IoTDB
{
    public class ConcurrentClientQueue
    {
        public ConcurrentQueue<Client> ClientQueue { get; }
        internal IPoolDiagnosticReporter DiagnosticReporter { get; set; }

        public ConcurrentClientQueue(List<Client> clients)
        {
            ClientQueue = new ConcurrentQueue<Client>(clients);
        }
        public ConcurrentClientQueue()
        {
            ClientQueue = new ConcurrentQueue<Client>();
        }
        public void Add(Client client) => Return(client);

        public void Return(Client client)
        {
            Monitor.Enter(ClientQueue);
            try
            {
                ClientQueue.Enqueue(client);
                Monitor.PulseAll(ClientQueue); // wake up all threads waiting on the queue, refresh the waiting time
            }
            finally
            {
                Monitor.Exit(ClientQueue);
            }
            Thread.Sleep(0);
        }
        private int _ref = 0;
        public void AddRef() => Interlocked.Increment(ref _ref);
        public int GetRef() => Volatile.Read(ref _ref);
        public void RemoveRef() => Interlocked.Decrement(ref _ref);
        public int Timeout { get; set; } = 10;
        public Client Take()
        {
            Client client = null;
            Monitor.Enter(ClientQueue);
            try
            {
                while (true)
                {
                    bool timeout = false;
                    if (ClientQueue.IsEmpty)
                    {
                        timeout = !Monitor.Wait(ClientQueue, TimeSpan.FromSeconds(Timeout));
                    }
                    ClientQueue.TryDequeue(out client);

                    if (client != null || timeout)
                    {
                        break;
                    }
                }
            }
            finally
            {
                Monitor.Exit(ClientQueue);
            }
            if (client == null)
            {
                var reasonPhrase = $"Connection pool is empty and wait time out({Timeout}s)";
                if (DiagnosticReporter != null)
                {
                    throw DiagnosticReporter.BuildDepletionException(reasonPhrase);
                }
                throw new TimeoutException(reasonPhrase);
            }
            return client;
        }
    }

    internal interface IPoolDiagnosticReporter
    {
        SessionPoolDepletedException BuildDepletionException(string reasonPhrase);
    }
}