using System;

namespace TEST
{
    public sealed class ObjectPool<T> : IPool<T>
        where T : class
    {

        private readonly Func<T> _creater = null;
        private readonly Action<T> _rester = null;
        private readonly T[] _objs = null;
        private readonly int _capcity;

        private int _remainer;

        public ObjectPool(int capcity, Func<T> creater = null, Action<T> rester = null)
        {
            _capcity = _remainer = capcity;
            _creater = creater;
            _rester = rester;
            _objs = new T[capcity];
            for (int i = 0; i < capcity; i++)
                _objs[i] = creater();

        }

        public int Capcity { get { return _capcity; } }
        public int Remainer { get { return _remainer; } }

        public T Fetch()
        {
            if (_remainer <= 0)
                throw new Exception();

            lock (_objs)
            {
                return _objs[--_remainer];
            }
        }
        public void Store(T obj)
        {
            if (_remainer >= _capcity)
                throw new Exception();

            if (_rester != null)
                _rester(obj);
            lock (_objs)
            {
                _objs[_remainer++] = obj;
            }
        }
    }
}