//

// © Copyright Henrik Ravn 2004

//

// Use, modification and distribution are subject to the Boost Software License, Version 1.0. 

// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//

using System;

using System.Diagnostics;

namespace DotZLib

{

	/// <summary>

	/// This class implements a circular buffer

	/// </summary>

	internal class CircularBuffer

	{

        #region Private data

        private int _capacity;

        private int _head;

        private int _tail;

        private int _size;

        private byte[] _buffer;

        #endregion

        public CircularBuffer(int capacity)

        {    

            Debug.Assert( capacity > 0 );

            _buffer = new byte[capacity];

            _capacity = capacity;

            _head = 0;

            _tail = 0;

            _size = 0;

        }

        public int Size { get { return _size; } }

        public int Put(byte[] source, int offset, int count)

        {

            Debug.Assert( count > 0 );

            int trueCount = Math.Min(count, _capacity - Size);

            for (int i = 0; i < trueCount; ++i)

                _buffer[(_tail+i) % _capacity] = source[offset+i];

            _tail += trueCount;

            _tail %= _capacity;

            _size += trueCount;

            return trueCount;

        }

        public bool Put(byte b)

        {

            if (Size == _capacity) // no room

                return false;

            _buffer[_tail++] = b;

            _tail %= _capacity;

            ++_size;

            return true;

        }

        public int Get(byte[] destination, int offset, int count)

        {

            int trueCount = Math.Min(count,Size);

            for (int i = 0; i < trueCount; ++i)

                destination[offset + i] = _buffer[(_head+i) % _capacity];

            _head += trueCount;

            _head %= _capacity;

            _size -= trueCount;

            return trueCount;

        }

        public int Get()

        {

            if (Size == 0)

                return -1;

            int result = (int)_buffer[_head++ % _capacity];

            --_size;

            return result;

        }

    }

}