/** 
 * @file llioutil.h
 * @author Phoenix
 * @date 2005-10-05
 * @brief Helper classes for dealing with IOPipes
 *
 * Copyright (c) 2005-$CurrentYear$, Linden Research, Inc.
 * $License$
 */

#ifndef LL_LLIOUTIL_H
#define LL_LLIOUTIL_H

#include "llbuffer.h"
#include "lliopipe.h"
#include "llpumpio.h"

/** 
 * @class LLIOFlush
 * @brief This class is used as a mini chain head which drains the buffer.
 * @see LLIOPipe
 *
 * An instance of this class acts as a useful chain head when all data
 * is known, and you simply want to get the chain moving.
 */
class LLIOFlush : public LLIOPipe
{
public:
	LLIOFlush() {}
	virtual ~LLIOFlush() {}

protected:
	/* @name LLIOPipe virtual implementations
	 */
	//@{
	/** 
	 * @brief Process the data in buffer
	 */
	EStatus process_impl(
		const LLChannelDescriptors& channels,
		buffer_ptr_t& buffer,
		bool& eos,
		LLSD& context,
		LLPumpIO* pump);
	//@}
protected:
};

/** 
 * @class LLIOSleep
 * @brief This is a simple helper class which will hold a chain and
 * process it later using pump mechanisms
 * @see LLIOPipe
 */
class LLIOSleep : public LLIOPipe
{
public:
	LLIOSleep(F64 sleep_seconds) : mSeconds(sleep_seconds) {}
	virtual ~LLIOSleep() {}

protected:
	/* @name LLIOPipe virtual implementations
	 */
	//@{
	/** 
	 * @brief Process the data in buffer
	 */
	EStatus process_impl(
		const LLChannelDescriptors& channels,
		buffer_ptr_t& buffer,
		bool& eos,
		LLSD& context,
		LLPumpIO* pump);
	//@}
protected:
	F64 mSeconds;
};

/** 
 * @class LLIOAddChain
 * @brief Simple pipe that just adds a chain to a pump.
 * @see LLIOPipe
 */
class LLIOAddChain : public LLIOPipe
{
public:
	LLIOAddChain(const LLPumpIO::chain_t& chain, F32 timeout) :
		mChain(chain),
		mTimeout(timeout)
	{}
	virtual ~LLIOAddChain() {}

protected:
	/* @name LLIOPipe virtual implementations
	 */
	//@{
	/** 
	 * @brief Process the data in buffer
	 */
	EStatus process_impl(
		const LLChannelDescriptors& channels,
		buffer_ptr_t& buffer,
		bool& eos,
		LLSD& context,
		LLPumpIO* pump);
	//@}

protected:
	LLPumpIO::chain_t mChain;
	F32 mTimeout;
};

/** 
 * @class LLChangeChannel
 * @brief This class changes the channel of segments in the buffer
 * @see LLBufferArray
 *
 * This class is useful for iterating over the segments in a buffer
 * array and changing each channel that matches to a different
 * channel.
 * Example:
 * <code>
 * set_in_to_out(LLChannelDescriptors channels, LLBufferArray* buf)
 * {
 *   std::for_each(
 *     buf->beginSegment(),
 *     buf->endSegment(),
 *     LLChangeChannel(channels.in(), channels.out()));
 * }
 * </code>
 */
class LLChangeChannel //: public unary_function<T, void>
{
public:
	/** 
	 * @brief Constructor for iterating over a segment range to change channel.
	 *
	 * @param is The channel to match when looking at a segment.
	 * @param becomes The channel to set the segment when a match is found.
	 */
	LLChangeChannel(S32 is, S32 becomes);

	/** 
	 * @brief Do the work of changing the channel
	 */
	void operator()(LLSegment& segment);

protected:
	S32 mIs;
	S32 mBecomes;
};


#endif // LL_LLIOUTIL_H