// Ryzom - MMORPG Framework <http://dev.ryzom.com/projects/ryzom/>
// Copyright (C) 2010  Winch Gate Property Limited
//
// 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 (at your option) 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 RZ_LUA_HELPER_H
#define RZ_LUA_HELPER_H


#include "nel/misc/types_nl.h"
#include "nel/misc/smart_ptr.h"

extern "C"
{
	#include <lua.h>
}


class CLuaState;

// ***************************************************************************
/** Helper class to see if a stack is restored at its initial size (or with n return results).
  * Check that the stack size remains unchanged when the object goes out of scope
  */
class CLuaStackChecker
{
public:
	CLuaStackChecker(CLuaState *state, int numWantedResults = 0);
	~CLuaStackChecker();
	/** Increment exception context counter
	  * When an exception is thrown, lua stack checker do any assert bu will
	  * rather restore the lua stack at its original size, and will
	  * let the exception a chance to propagate
	  */
	static void incrementExceptionContextCounter();
	static void decrementExceptionContextCounter();

private:
	CLuaState    *_State;
	int          _FinalWantedSize;
	static uint  _ExceptionContextCounter;

};

// **************************************************************************
/** Helper class to restore the lua stack to the desired size when this object goes out of scope
  */
class CLuaStackRestorer
{
public:
	CLuaStackRestorer(CLuaState *state, int finalSize);
	~CLuaStackRestorer();
private:
	int _FinalSize;
	CLuaState *_State;
};

////////////////
// EXCEPTIONS //
////////////////

class ELuaError : public NLMISC::Exception
{
public:
	ELuaError() { CLuaStackChecker::incrementExceptionContextCounter(); }
	virtual ~ELuaError() throw() { CLuaStackChecker::decrementExceptionContextCounter(); }
	ELuaError(const std::string &reason) : Exception(reason) { CLuaStackChecker::incrementExceptionContextCounter(); }
	// what(), plus append the Reason
	virtual std::string luaWhat() const throw() {return NLMISC::toString("LUAError: %s", what());}
};

// A parse error occured
class ELuaParseError : public ELuaError
{
public:
	ELuaParseError() {}
	ELuaParseError(const std::string &reason) : ELuaError(reason) {}
	virtual ~ELuaParseError() throw() { }
	// what(), plus append the Reason
	virtual std::string luaWhat() const throw() {return NLMISC::toString("ELuaParseError: %s", what());}
};

/** Exception thrown when something went wrong inside a wrapped function called by lua
  */
class ELuaWrappedFunctionException : public ELuaError
{
public:
	ELuaWrappedFunctionException(CLuaState *luaState);
	ELuaWrappedFunctionException(CLuaState *luaState, const std::string &reason);
	ELuaWrappedFunctionException(CLuaState *luaState, const char *format, ...);
	virtual ~ELuaWrappedFunctionException() throw() { }
	virtual const char	*what() const throw() {return _Reason.c_str();}
protected:
	void	init(CLuaState *ls, const std::string &reason);
protected:
	std::string	_Reason;
};

// A execution error occured
class ELuaExecuteError : public ELuaError
{
public:
	ELuaExecuteError() {}
	ELuaExecuteError(const std::string &reason) : ELuaError(reason) {}
	virtual ~ELuaExecuteError() throw() { }
	// what(), plus append the Reason
	virtual std::string luaWhat() const throw() {return NLMISC::toString("ELuaExecuteError: %s", what());}
};

// A bad cast occured when using lua_checkcast
class ELuaBadCast : public ELuaError
{
public:
	ELuaBadCast() {}
	ELuaBadCast(const std::string &reason) : ELuaError(reason) {}
	// what(), plus append the Reason
	virtual std::string luaWhat() const throw() {return NLMISC::toString("ELuaBadCast: %s", what());}
};

// Error when trying to indexate an object that is not a table
class ELuaNotATable : public ELuaError
{
public:
	ELuaNotATable() {}
	ELuaNotATable(const std::string &reason) : ELuaError(reason) {}
	// what(), plus append the Reason
	virtual std::string luaWhat() const throw() {return NLMISC::toString("ELuaNotATable: %s", what());}
};


// ***************************************************************************
// a function to be used with a CLuaState instance
typedef int (* TLuaWrappedFunction) (CLuaState &ls);


// ***************************************************************************
/** C++ version of a lua state
  */
class CLuaState : public NLMISC::CRefCount
{
public:
	typedef NLMISC::CRefPtr<CLuaState>   TRefPtr;

	// Create a new environement
	CLuaState();
	~CLuaState();


	/// \name Registering
	// @{
	// register a wrapped function
	void				registerFunc(const char *name, TLuaWrappedFunction function);
	// @}


	/// \name Script execution
	// @{

	/** Parse a script and push as a function in top of the LUA stack
	 *	\throw ELuaParseError
	 *	\param dbgSrc is a string for debug. Should be a filename (preceded with '@'), or a short script.
	 */
	void				loadScript(const std::string &code, const std::string &dbgSrc);

	/** Execute a script from a string, possibly throwing an exception if there's a parse error
	 *	\throw ELuaParseError, ELuaExecuteError
	 */
	void				executeScript(const std::string &code, int numRet = 0);

	/** Execute a script from a string. If an errors occurs it is printed in the log
	 *	\return true if script execution was successful
	 */
	bool				executeScriptNoThrow(const std::string &code, int numRet = 0);

	/** Load a Script from a File (maybe in a BNP), and execute it
	 *	\return false if file not found
	 *	\throw ELuaParseError, ELuaExecuteError
	 */
	bool				executeFile(const std::string &pathName);

	/** execute a very Small Script (a function call for instance)
	 *	It is different from doString() in such there is a cache (where the key is the script itself)
	 *	so that the second time this script is executed, there is no parsing
	 *	Note: I experienced optim with about 10 times faster than a executeScript() on a simple "a= a+1;" script
	 *	\throw ELuaParseError, ELuaExecuteError
	 */
	void				executeSmallScript(const std::string &script);

	// @}


	/// \name Stack Manipulation
	// @{
	// stack manipulation (indices start at 1)
	void				setTop(int index);     // set new size of stack
	void				clear() { setTop(0); }
	int					getTop();
	bool				empty() { return getTop() == 0; }
	void				pushValue(int index);  // copie nth element of stack to the top of the stack
	void				remove(int index);     // remove nth element of stack
	void				insert(int index);     // insert last element of the stack before the given position
	void				replace(int index);    // replace nth element of the stack with the top of the stack
	void				pop(int numElem = 1);  // remove n elements from the top of the stack
	// test the type of an element in the stack
	// return one of the following values :
	// LUA_TNIL
	// LUA_TNUMBER
	// LUA_TBOOLEAN
	// LUA_TSTRING
	// LUA_TTABLE
	// LUA_TFUNCTION
	// LUA_TUSERDATA
	// LUA_TTHREAD
	// LUA_TLIGHTUSERDATA
	int					type(int index = -1);
	const char			*getTypename(int type);
	bool				isNil(int index = -1);
	bool				isBoolean(int index = -1);
	bool				isNumber(int index = -1);
	bool				isString(int index = -1);
	bool				isTable(int index = -1);
	bool				isFunction(int index = -1);
	bool				isCFunction(int index = -1);
	bool				isUserData(int index = -1);
	bool				isLightUserData(int index = -1);
	// converting then getting a value from the stack
	bool				toBoolean(int index = -1);
	lua_Number			toNumber(int index = -1);
	const char			*toString(int index = -1);
	void				toString(int index, std::string &str);		// convert to a std::string, with a NULL check.
	size_t				strlen(int index = -1);
	lua_CFunction		toCFunction(int index = -1);
	void				*toUserData(int index = -1);
	const void			*toPointer(int index = -1);
	/** Helper functions : get value of the wanted type in the top table after conversion
	* A default value is used if the stack entry is NULL.
	* If conversion fails then an exception is thrown (with optional msg)
	*/
	bool				getTableBooleanValue(const char *name, bool        defaultValue= false);
	double				getTableNumberValue(const char *name,  double      defaultValue= 0);
	const char			*getTableStringValue(const char *name, const char *defaultValue= NULL);
	// pushing value onto the stack
	void				push(bool value);
	void				push(lua_Number value);
	void				push(const char *str);
	void				push(const char *str, int length);
	void				push(const std::string &str);
	void				pushNil();
	void				push(lua_CFunction f);
	void                push(TLuaWrappedFunction function);
	void				pushLightUserData(void *);			// push a light user data (use newUserData to push a full userdata)
	// metatables
	bool				getMetaTable(int index = -1);
	bool				setMetaTable(int index = -1);  // set the metatable at top of stack to the object at 'index' (usually -2), then pop the metatable
	                                                   // even if asignment failed
	// comparison
	bool				equal(int index1, int index2);
	bool				rawEqual(int index1, int index2);
	bool				lessThan(int index1, int index2);
	// concatenation of the n element at the top of the stack (using lua semantic)
	void				concat(int numElem);
	// tables
	void				newTable(); // create a new table at top of the stack
	void				getTable(int index); // get value from a table at index 'index' (key is at top)
	void				rawGet(int index);
	void				setTable(int index); // set (key, value) from top of the stack into the given table
	                                         // both key and value are poped
	void				rawSet(int index);
	bool				next(int index);  // table traversal
	// UserData
	void				*newUserData(uint size);
	// seting value by int index in a table
	void				rawSetI(int index, int n);
	void				rawGetI(int index, int n);
	/** Calling functions (it's up to the caller to clear the results)
	  * The function should have been pushed on the stack
	  */
	void				call(int nargs, int nresults);
	int					pcall(int nargs, int nresults, int errfunc = 0);
	/** Helper : Execute a function by name. Lookup for the function is done in the table at the index 'funcTableIndex'
	  * the behaviour is the same than with call of pcall.
	  */
	int                 pcallByName(const char *functionName, int nargs, int nresults, int funcTableIndex = LUA_GLOBALSINDEX, int errfunc = 0);

	// push a C closure (pop n element from the stack and associate with the function)
	void				pushCClosure(lua_CFunction function, int n);
	// @}


	/// \name Misc
	// @{
	/** Retrieve pointer to a CLuaState environment from its lua_State pointer, or NULL
      * if there no such environment
	  */
	static CLuaState	*fromStatePointer(lua_State *state);
	// Get state pointer. The state should not be closed (this object has ownership)
	lua_State			*getStatePointer() const {return _State;}
	// check that an index is valid when accessing the stack
	// an assertion is raised if the index is not valid
	void				checkIndex(int index);

	// registering C function to use with a lua state pointer
	void				registerFunc(const char *name, lua_CFunction function);

	// Garbage collector
	int					getGCCount();      // get memory in use in KB
	int					getGCThreshold();  // get max memory in KB
	void				setGCThreshold(int kb);   // set max memory in KB (no-op with ref-counted version)

	// handle garbage collector for ref-counted version of lua (no-op with standard version, in which case gc handling is automatic)
	void				handleGC();

	/** For Debug: get the Stack context of execution (filename / line)
	 *	\param stackLevel: get the context of execution of the given stackLevel.
	 *		0 for the current function
	 *		1 for the function that called 0
	 *		2 ....
	 *	NB: if called from a C function called from LUA, remember that stackLevel 0 is the current function.
	 *		Hence if you want to know what LUA context called you, pass stackLevel=1!
	 *	\param ret string cleared if any error, else filled with formated FileName / LineNumber
	 */
	void				getStackContext(std::string &ret, uint stackLevel);
	// @}

	// for debug : dump the current content of the stack (no recursion)
	void				dumpStack();
	static void			dumpStack(lua_State *ls);
	void				getStackAsString(std::string &dest);


private:
	lua_State			*_State;

	// Small Script Cache
	uint						_SmallScriptPool;
	typedef std::map<std::string, uint>	TSmallScriptCache;
	TSmallScriptCache			_SmallScriptCache;
	static const char *			_NELSmallScriptTableName;

private:
	// this object isn't intended to be copied
	CLuaState(const CLuaState &/* other */):NLMISC::CRefCount() { nlassert(0); }
	CLuaState &operator=(const CLuaState &/* other */) { nlassert(0); return *this; }

	void				executeScriptInternal(const std::string &code, const std::string &dbgSrc, int numRet = 0);

};


// Access to lua function
// one should not include lua.h directly because if a debugger is present, lua
// function pointer will be taken from a dynamic library.



//=============================================================================================
// include implementation
#define RZ_INCLUDE_LUA_HELPER_INLINE
	#include "lua_helper_inline.h"
#undef RZ_INCLUDE_LUA_HELPER_INLINE


#endif