using System.Collections;
using System.Collections.Generic;
using System.Threading;

namespace Lucene.Net.Index
{
    /*
     * 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.
     */

    internal class SynchronizedList<T> : IList<T>
    {
        private readonly List<T> _list = new List<T>();

        private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();

        public T this[int index]
        {
            get => _list[index];
            set => _list[index] = value;
        }

        public int Count => _list.Count;

        public bool IsReadOnly => false;

        public void Add(T item)
        {
            _lock.EnterWriteLock();

            try
            {
                _list.Add(item);
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        public void Clear()
        {
            _lock.EnterWriteLock();

            try
            {
                _list.Clear();
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        public bool Contains(T item)
        {
            _lock.EnterReadLock();

            try
            {
                return _list.Contains(item);
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public void CopyTo(T[] array, int arrayIndex)
        {
            _lock.EnterWriteLock();

            try
            {
                _list.CopyTo(array, arrayIndex);
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        public IEnumerator<T> GetEnumerator()
        {
            _lock.EnterReadLock();

            try
            {
                return _list.GetEnumerator();
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public int IndexOf(T item)
        {
            _lock.EnterReadLock();

            try
            {
                return _list.IndexOf(item);
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public void Insert(int index, T item)
        {
            _lock.EnterWriteLock();

            try
            {
                _list.Insert(index, item);
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        public bool Remove(T item)
        {
            _lock.EnterWriteLock();

            try
            {
                return _list.Remove(item);
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        public void RemoveAt(int index)
        {
            _lock.EnterWriteLock();

            try
            {
                _list.RemoveAt(index);
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return _list.GetEnumerator();
        }
    }
}
