using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Blizzard
{
    /// <summary>
    /// Represents a collection of re-usable MySQLConnection instances.
    /// </summary>
    sealed class MySQLConnectionPool
    {
        /// <summary>
        /// Pool of MySQLConnection instances.
        /// </summary>
        private Stack<MySQLConnection> pool;

        /// <summary>
        /// Initializes the object pool to the specified size.
        /// </summary>
        /// <param name="capacity">Maximum number of MySQLConnection objects the pool can hold.</param>
        public MySQLConnectionPool(Int32 capacity)
        {
            this.pool = new Stack<MySQLConnection>(capacity);
        }

        /// <summary>
        /// Removes a MySQLConnection instance from the pool.
        /// </summary>
        /// <returns>MySQLConnection removed from the pool.</returns>
        public MySQLConnection Pop()
        {
            lock (this.pool)
            {
                if (this.pool.Count > 0)
                {
                    return this.pool.Pop();
                }
                else
                {
                    return null;
                }
            }
        }

        /// <summary>
        /// Add a MySQLConnection instance to the pool.
        /// </summary>
        /// <param name="item">MySQLConnection instance to add to the pool.</param>
        public void Push(MySQLConnection item)
        {
            lock (this.pool)
            {
                if (item == null)
                {
                    throw new ArgumentNullException("Items added to a MySQLConnectionPool cannot be null");
                }
                else
                {
                    this.pool.Push(item);
                }
            }
        }

        /// <summary>
        /// Removes all instances of MySQLConnection from the pool.
        /// </summary>
        public void Clear()
        {
            lock (this.pool)
            {
                this.pool.Clear();
            }
        }
    }
}