/** 
 * @file llapr.h
 * @author Phoenix
 * @date 2004-11-28
 * @brief Helper functions for using the apache portable runtime library.
 *
 * $LicenseInfo:firstyear=2004&license=viewergpl$
 * 
 * Copyright (c) 2004-2009, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 * 
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

#ifndef LL_LLAPR_H
#define LL_LLAPR_H

#if LL_LINUX || LL_SOLARIS
#include <sys/param.h>  // Need PATH_MAX in APR headers...
#endif

#include <boost/noncopyable.hpp>

#include "apr_thread_proc.h"
#include "apr_thread_mutex.h"
#include "apr_getopt.h"
#include "apr_signal.h"
#include "apr_atomic.h"
#include "llstring.h"

class AIAPRPool;
class AIVolatileAPRPool;

/** 
 * @class LLScopedLock
 * @brief Small class to help lock and unlock mutexes.
 *
 * This class is used to have a stack level lock once you already have
 * an apr mutex handy. The constructor handles the lock, and the
 * destructor handles the unlock. Instances of this class are
 * <b>not</b> thread safe.
 */
class LL_COMMON_API LLScopedLock : private boost::noncopyable
{
public:
	/**
	 * @brief Constructor which accepts a mutex, and locks it.
	 *
	 * @param mutex An allocated APR mutex. If you pass in NULL,
	 * this wrapper will not lock.
	 */
	LLScopedLock(apr_thread_mutex_t* mutex);

	/**
	 * @brief Destructor which unlocks the mutex if still locked.
	 */
	~LLScopedLock();

	/** 
	 * @brief Check lock.
	 */
	bool isLocked() const { return mLocked; }

	/** 
	 * @brief This method unlocks the mutex.
	 */
	void unlock();

protected:
	bool mLocked;
	apr_thread_mutex_t* mMutex;
};

template <typename Type> class LLAtomic32
{
public:
	LLAtomic32<Type>() {};
	LLAtomic32<Type>(Type x) {apr_atomic_set32(&mData, apr_uint32_t(x)); };
	~LLAtomic32<Type>() {};

	operator const Type() { apr_uint32_t data = apr_atomic_read32(&mData); return Type(data); }
	Type operator =(const Type& x) { apr_atomic_set32(&mData, apr_uint32_t(x)); return Type(mData); }
	void operator -=(Type x) { apr_atomic_sub32(&mData, apr_uint32_t(x)); }
	void operator +=(Type x) { apr_atomic_add32(&mData, apr_uint32_t(x)); }
	Type operator ++(int) { return apr_atomic_inc32(&mData); } // Type++
	Type operator --(int) { return apr_atomic_dec32(&mData); } // Type--
	
private:
	apr_uint32_t mData;
};

typedef LLAtomic32<U32> LLAtomicU32;
typedef LLAtomic32<S32> LLAtomicS32;

// File IO convenience functions.
// Returns NULL if the file fails to openm sets *sizep to file size of not NULL
// abbreviated flags
#define LL_APR_R (APR_READ) // "r"
#define LL_APR_W (APR_CREATE|APR_TRUNCATE|APR_WRITE) // "w"
#define LL_APR_RB (APR_READ|APR_BINARY) // "rb"
#define LL_APR_WB (APR_CREATE|APR_TRUNCATE|APR_WRITE|APR_BINARY) // "wb"
#define LL_APR_RPB (APR_READ|APR_WRITE|APR_BINARY) // "r+b"
#define LL_APR_WPB (APR_CREATE|APR_TRUNCATE|APR_READ|APR_WRITE|APR_BINARY) // "w+b"

//
//apr_file manager
//which: 1)only keeps one file open;
//       2)closes the open file in the destruction function
//       3)informs the apr_pool to clean the memory when the file is closed.
//Note: please close an open file at the earliest convenience. 
//      especially do not put some time-costly operations between open() and close().
//      otherwise it might lock the APRFilePool.
//there are two different apr_pools the APRFile can use:
//      1, a temperary pool passed to an APRFile function, which is used within this function and only once.
//      2, a global pool.
//

class LL_COMMON_API LLAPRFile : boost::noncopyable
{
	// make this non copyable since a copy closes the file
private:
	apr_file_t* mFile ;
	AIVolatileAPRPool* mVolatileFilePoolp;	// (Thread local) APR pool currently in use.
	AIAPRPool* mRegularFilePoolp;		// ...or a regular pool.

public:
	enum access_t {
		global,		// Use a global pool for long-lived file accesses. This should really only happen from the main thread.
		local		// Use a thread-local volatile pool for short file accesses.
	};

	LLAPRFile() ;
	LLAPRFile(const std::string& filename, apr_int32_t flags, access_t access_type);
	~LLAPRFile() ;

	apr_status_t open(const std::string& filename, apr_int32_t flags, access_t access_type, S32* sizep = NULL);
	apr_status_t close() ;

	// Returns actual offset, -1 if seek fails
	S32 seek(apr_seek_where_t where, S32 offset);
	apr_status_t eof() { return apr_file_eof(mFile);}

	// Returns bytes read/written, 0 if read/write fails:
	S32 read(void* buf, S32 nbytes);
	S32 write(const void* buf, S32 nbytes);
	
	apr_file_t* getFileHandle() {return mFile;}	

//
//*******************************************************************************************************************************
//static components
//
private:
	static S32 seek(apr_file_t* file, apr_seek_where_t where, S32 offset);
public:
	// returns false if failure:
	static bool remove(const std::string& filename);
	static bool rename(const std::string& filename, const std::string& newname);
	static bool isExist(const std::string& filename, apr_int32_t flags = APR_READ);
	static S32 size(const std::string& filename);
	static bool makeDir(const std::string& dirname);
	static bool removeDir(const std::string& dirname);

	// Returns bytes read/written, 0 if read/write fails:
	static S32 readEx(const std::string& filename, void *buf, S32 offset, S32 nbytes);
	static S32 writeEx(const std::string& filename, void *buf, S32 offset, S32 nbytes);
//*******************************************************************************************************************************
};

/**
 * @brief Function which approprately logs error or remains quiet on
 * APR_SUCCESS.
 * @return Returns <code>true</code> if status is an error condition.
 */
bool LL_COMMON_API ll_apr_warn_status(apr_status_t status);

void LL_COMMON_API ll_apr_assert_status(apr_status_t status);

#endif // LL_LLAPR_H