/*
 * ArcEmu MMORPG Server
 * Copyright (C) 2008-2010 <http://www.ArcEmu.com/>
 *
 * Circular Buffer Class
 * Based on the Bip Buffer concept, from http://www.codeproject.com/KB/IP/bipbuffer.aspx
 * Implementation Copyright (C) 2008-2010 Burlex
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef _NETLIB_CIRCULARBUFFER_H
#define _NETLIB_CIRCUALRBUFFER_H

class CircularBuffer
{
		// allocated whole block pointer
		uint8* m_buffer;
		uint8* m_bufferEnd;

		// region A pointer, and size
		uint8* m_regionAPointer;
		size_t m_regionASize;

		// region size
		uint8* m_regionBPointer;
		size_t m_regionBSize;

		// pointer magic!
		inline size_t GetAFreeSpace() { return (m_bufferEnd - m_regionAPointer - m_regionASize); }
		inline size_t GetSpaceBeforeA() { return (m_regionAPointer - m_buffer); }
		inline size_t GetSpaceAfterA() { return (m_bufferEnd - m_regionAPointer - m_regionASize); }
		inline size_t GetBFreeSpace() { if(m_regionBPointer == NULL) { return 0; } return (m_regionAPointer - m_regionBPointer - m_regionBSize); }

	public:

		/** Constructor
		*/
		CircularBuffer();

		/** Destructor
		*/
		~CircularBuffer();

		/** Read bytes from the buffer
		* @param destination pointer to destination where bytes will be written
		* @param bytes number of bytes to read
		* @return true if there was enough data, false otherwise
		*/
		bool Read(void* destination, size_t bytes);
		void AllocateB();

		/** Write bytes to the buffer
		* @param data pointer to the data to be written
		* @param bytes number of bytes to be written
		* @return true if was successful, otherwise false
		*/
		bool Write(const void* data, size_t bytes);

		/** Returns the number of available bytes left.
		*/
		size_t GetSpace();

		/** Returns the number of bytes currently stored in the buffer.
		*/
		size_t GetSize();

		/** Returns the number of contiguous bytes (that can be pushed out in one operation)
		*/
		size_t GetContiguiousBytes();

		/** Removes len bytes from the front of the buffer
		* @param len the number of bytes to "cut"
		*/
		void Remove(size_t len);

		/** Returns a pointer at the "end" of the buffer, where new data can be written
		*/
		void* GetBuffer();

		/** Allocate the buffer with room for size bytes
		* @param size the number of bytes to allocate
		*/
		void Allocate(size_t size);

		/** Increments the "writen" pointer forward len bytes
		* @param len number of bytes to step
		*/
		void IncrementWritten(size_t len);			// known as "commit"

		/** Returns a pointer at the "beginning" of the buffer, where data can be pulled from
		*/
		void* GetBufferStart();
};

#endif		// _NETLIB_CIRCULARBUFFER_H

