///
///    This file is part of ILNumerics Community Edition.
///
///    ILNumerics Community Edition - high performance computing for applications.
///    Copyright (C) 2006 - 2012 Haymo Kutschbach, http://ilnumerics.net
///
///    ILNumerics Community Edition is free software: you can redistribute it and/or modify
///    it under the terms of the GNU General Public License version 3 as published by
///    the Free Software Foundation.
///
///    ILNumerics Community Edition is distributed in the hope that it will be useful,
///    but WITHOUT ANY WARRANTY; without even the implied warranty of
///    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
///    GNU General Public License for more details.
///
///    You should have received a copy of the GNU General Public License
///    along with ILNumerics Community Edition. See the file License.txt in the root
///    of your distribution package. If not, see <http://www.gnu.org/licenses/>.
///
///    In addition this software uses the following components and/or licenses: 
///
///    =================================================================================
///    The Open Toolkit Library License
///    
///    Copyright (c) 2006 - 2009 the Open Toolkit library.
///    
///    Permission is hereby granted, free of charge, to any person obtaining a copy
///    of this software and associated documentation files (the "Software"), to deal
///    in the Software without restriction, including without limitation the rights to 
///    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
///    the Software, and to permit persons to whom the Software is furnished to do
///    so, subject to the following conditions:
///
///    The above copyright notice and this permission notice shall be included in all
///    copies or substantial portions of the Software.
///
///    =================================================================================
///    

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

namespace ILNumerics.Data {
    public sealed class ILIntList {

        private static readonly int INITIAL_CAPACITY = 4; 
        private static Queue<ILIntList> s_cache = new Queue<ILIntList>();
        private static object s_lock = new object();
        public static ILIntList Create() {
            lock (s_lock) {
                ILIntList ret;
                if (s_cache.Count > 0) {
                    ret = s_cache.Dequeue();
                    System.Diagnostics.Debug.Assert(ret.m_data.Length >= INITIAL_CAPACITY && ret.Count == 0);
                    return ret;
                } else {
                    return new ILIntList();
                }
            }
        }

        public static ILIntList Create(int initialCapacity) {
            
            lock (s_lock) {
                ILIntList ret;
                if (s_cache.Count > 0) {
                    ret = s_cache.Dequeue();
                    System.Diagnostics.Debug.Assert(ret.m_data.Length >= INITIAL_CAPACITY && ret.Count == 0);
                    return ret;
                } else {
                    return new ILIntList();
                }
            }
        }

        private static void Cache(ILIntList list) {
            lock (s_lock) {
                list.Clear();
                s_cache.Enqueue(list);
                System.Diagnostics.Debug.Assert(list.m_data.Length >= INITIAL_CAPACITY && list.Count == 0);
            }
        }

        int[] m_data; 
        int m_count;
        int[] m_initialData; 

        internal ILIntList( ILDenseArray<int> array ) {
            m_count = array.D.NumberOfElements; 
            m_data = ILMemoryPool.Pool.New<int>(m_count);
            m_initialData = new int[INITIAL_CAPACITY]; 
            System.Array.Copy(array.GetArrayForRead(), m_data, m_count); 
        }

        private ILIntList() {
            m_count = 0;
            m_data = new int[INITIAL_CAPACITY];
            m_initialData = m_data;
        }
        private ILIntList(int initialCapacity) {
            m_count = 0;
            m_data = new int[initialCapacity];
            m_initialData = null; 
        }


        public int this[int index] {
            get {
                //if (index >= m_count) 
                //    throw new IndexOutOfRangeException(); 
                return m_data[index];
            }
            set { m_data[index] = value; }
        }

        public int Count {
            get { return m_count; }
        }

        public IEnumerator<int> GetEnumerator() {
            for (int i = 0; i < m_count; i++) {
                yield return m_data[i]; 
            }
        }

        internal bool Contains( int val ) {
            for (int i = 0; i < m_count; i++) {
                if (m_data[i] == val) return true; 
            }
            return false; 
        }

        internal void Add( int val ) {
            if (m_count == m_data.Length) {
                doubleCapacity(); 
            }
            m_data[m_count++] = val; 
        }

        private void doubleCapacity() {
            // we always give our data array at least INITIAL_CAPACITY elements
            int[] newArr = ILMemoryPool.Pool.New<int>(m_data.Length * 2); 
            System.Array.Copy(m_data,newArr,m_count);
            if (m_data != m_initialData)
                ILMemoryPool.Pool.RegisterObject(m_data);
            m_data = newArr; 
        }
        /// <summary>
        /// caution! This may bring the current instance of ILIntList in an UNUSABLE and inconsistent state! 
        /// </summary>
        /// <returns>internal int[] data array</returns>
        internal int[] GetArray() {
            return m_data; 
        }
        /// <summary>
        /// transfers internal data to new array and disposes this list 
        /// </summary>
        /// <returns></returns>
        internal ILRetArray<int> ToTempArray() {
            ILSize newDims = new ILSize(1, m_count); 
            ILRetArray<int> ret = new ILRetArray<int>(new Storage.ILDenseStorage<int>(m_data,newDims));
            if (m_data == m_initialData) {
                m_data = new int[INITIAL_CAPACITY];
                m_initialData = m_data;
            } else {
                m_data = m_initialData;
            }
            Cache(this); 
            return ret; 
        }

        internal void Clear() {
            if (m_data.Length > INITIAL_CAPACITY) {
                ILMemoryPool.Pool.RegisterObject(m_data);
                m_data = m_initialData;
            } 
            m_count = 0; 
        }

        internal void Dispose() {
            Cache(this); 
        }

    }
}