/*******************************************************************************

 Copyright (c) 2009, Charles McGarvey
 All rights reserved.
 
 Redistribution   and   use  in  source  and  binary  forms,  with  or  without
 modification, are permitted provided that the following conditions are met:
 
   * Redistributions  of  source  code  must retain the above copyright notice,
     this list of conditions and the following disclaimer.
   * Redistributions  in binary form must reproduce the above copyright notice,
     this  list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
 THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*******************************************************************************/

#ifndef _MOOF_SCRIPT_HH_
#define _MOOF_SCRIPT_HH_

/**
 * @file Script.hh
 * A thin wrapper over Lua.  This is not meant as a complicated binding package
 * between C++ and Lua.  It does not try to make the boundary invisible.  It
 * does not hide the concept of the Lua stack, but rather provides that
 * mechanism with a certain level of abstraction while also providing a cleaner,
 * more consistent API.
 */

#include <list>
#include <map>
#include <string>
#include <vector>

#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/shared_ptr.hpp>

#include <lua.hpp>

#include <Moof/Exception.hh>
#include <Moof/Log.hh>


namespace Mf {


class Script;
typedef boost::shared_ptr<Script> ScriptP;


struct Script
{
	typedef boost::function<int(Script&)> Function;

	enum TYPE
	{
		NONE			= LUA_TNONE,
		NIL				= LUA_TNIL,
		BOOLEAN			= LUA_TBOOLEAN,
		LIGHTUSERDATA	= LUA_TLIGHTUSERDATA,
		NUMBER			= LUA_TNUMBER,
		STRING			= LUA_TSTRING,
		TABLE			= LUA_TTABLE,
		FUNCTION		= LUA_TFUNCTION,
		USERDATA		= LUA_TUSERDATA,
		THREAD			= LUA_TTHREAD
	};

	enum STATUS
	{
		SUCCESS			= 0,
		YIELD			= LUA_YIELD,
		RUNTIME_ERROR	= LUA_ERRRUN,
		SYNTAX_ERROR	= LUA_ERRSYNTAX,
		MEMORY_ERROR	= LUA_ERRMEM,
		HANDLER_ERROR	= LUA_ERRERR,
		FILE_ERROR		= LUA_ERRFILE
	};

	enum PSEUDO_INDEX
	{
		REGISTRY		= LUA_REGISTRYINDEX,
		ENVIRONMENT		= LUA_ENVIRONINDEX,
		GLOBALS			= LUA_GLOBALSINDEX
	};

	/**
	 * This is the most noticeable abstraction on top of the standard Lua API.
	 * A Value object represents a value on the stack.  More specifically, it
	 * represents a position on the stack.  The distinction is only important
	 * when values are moved around on the stack or if the Value represents a
	 * negative index on the stack (the value of which will change as things are
	 * pushed onto and popped from the stack).
	 */

	struct Value
	{
		/**
		 * You have direct access to the index of the value on the stack being
		 * represented.
		 */

		int index;


		/**
		 * A default-constructed Value is invalid until a valid Value is
		 * assigned to it.  The only method that should be called on such a
		 * Value is isValid(), otherwise chaos may ensue.  In this case, the
		 * Value will be invalid even if index is manually changed to a valid
		 * index.  You have to index the script itself to get a valid Value.
		 */
		Value(lua_State* s = 0, int i = 0) :
			index(i),
			state(s) {}

		// check the type of the value
		bool isBoolean() const   { return (bool)lua_isboolean(state, index); }
		bool isFunction() const  { return (bool)lua_isfunction(state, index); }
		bool isNil() const       { return (bool)lua_isnil(state, index); }
		bool isNone() const      { return (bool)lua_isnone(state, index); }
		bool isValid() const     { return state != 0 && !isNone(); }
		bool isNoneOrNil() const { return (bool)lua_isnoneornil(state, index); }
		bool isNumber() const    { return (bool)lua_isnumber(state, index); }
		bool isString() const    { return (bool)lua_isstring(state, index); }
		bool isTable() const     { return (bool)lua_istable(state, index); }
		bool isThread() const    { return (bool)lua_isthread(state, index); }
		bool isData() const      { return (bool)lua_isuserdata(state, index); }
		bool isLightData() const { return (bool)lua_islightuserdata(state, index); }

		/**
		 * Get the type of the value.
		 */

		TYPE getType() const
		{
			return (TYPE)lua_type(state, index);
		}

		/**
		 * Get the name of the type of the value as a string.
		 */

		std::string getTypeName() const
		{
			return std::string(lua_typename(state, (int)getType()));
		}


		/**
		 * Get the length of the value according to the definition given by Lua.
		 */

		size_t getLength() const
		{
			return lua_objlen(state, index);
		}

		int getRealIndex() const
		{
			if (index < 0) return lua_gettop(state) + 1 + index;
			else           return index;
		}


		/**
		 * Get a pointer value (for userdata, tables, threads, and functions).
		 */

		const void* getIdentifier() const
		{
			return lua_topointer(state, index);
		}


		bool operator == (const Value& rhs) const
		{
			return (bool)lua_equal(state, index, rhs.index);
		}
		bool operator != (const Value& rhs) const
		{
			return !(*this == rhs);
		}
		bool operator < (const Value& rhs) const
		{
			return (bool)lua_lessthan(state, index, rhs.index);
		}
		bool operator <= (const Value& rhs) const
		{
			return *this < rhs || *this == rhs;
		}
		bool operator > (const Value& rhs) const
		{
			return !(*this <= rhs);
		}
		bool operator >= (const Value& rhs) const
		{
			return !(*this < rhs);
		}
		operator bool () const
		{
			return (bool)lua_toboolean(state, index);
		}

		Value& operator = (const Value& rhs)
		{
			rhs.pushCopy();
			replaceWithTop();
			return *this;
		}


		/**
		 * Convert the underlying value to a C++ type.
		 */

		template <typename T>
		bool get(T& value) const
		{
			if (isNumber())
			{
				value = (T)lua_tointeger(state, index);
				return true;
			}
			return false;
		}

		bool get(float& value) const
		{
			if (isNumber())
			{
				value = (float)lua_tonumber(state, index);
				return true;
			}
			return false;
		}
		bool get(double& value) const
		{
			if (isNumber())
			{
				value = (double)lua_tonumber(state, index);
				return true;
			}
			return false;
		}

		bool get(bool& value) const
		{
			if (isBoolean())
			{
				value = (bool)lua_toboolean(state, index);
				return true;
			}
			return false;
		}

		bool get(std::string& value) const
		{
			if (isString())
			{
				size_t size;
				const char* str = lua_tolstring(state, index, &size);
				value.assign(str, size);
				return true;
			}
			return false;
		}

		template <typename T>
		bool get(std::vector<T>& array) const
		{
			if (!isTable()) return false;

			array.clear();

			Value	value(state, -1);
			int		realIndex = getRealIndex();

			bool done = false;
			for (int i = 1; !done; ++i)
			{
				lua_rawgeti(state, realIndex, i);

				T v;
				if (value.get(v)) array.push_back(v);
				else              done = true;

				lua_pop(state, 1);
			}

			return true;
		}

		template <typename T>
		bool get(std::map<std::string,T>& dictionary) const
		{
			if (!isTable()) return false;

			dictionary.clear();

			Value	key(state, -2);
			Value	value(state, -1);
			int		realIndex = getRealIndex();

			lua_pushnil(state);
			while (lua_next(state, realIndex) != 0)
			{
				std::string k;
				if (!key.isNumber() && key.get(k))
				{
					T v;
					if (value.get(v)) dictionary[k] = v;
				}
				lua_pop(state, 1);
			}
			lua_pop(state, 1);

			return true;
		}



		/**
		 * Copy the value and push the copy to the stack.
		 */

		void pushCopy() const
		{
			lua_pushvalue(state, index);
		}

		/**
		 * Replace this value with the value at the top of the stack.
		 */

		void replaceWithTop()
		{
			lua_replace(state, index);
		}

		void remove()
		{
			lua_remove(state, index);
		}

		/**
		 * Inserts the top-most value on the stack at position index, shifting other
		 * values as needed.
		 */

		void insertTopHere()
		{
			lua_insert(state, index);
		}

		
		void pushMetatable() const
		{
			lua_getmetatable(state, index);
		}

		void pushField() const
		{
			lua_gettable(state, index);
		}

		void pushField(const std::string& name) const
		{
			lua_getfield(state, index, name.c_str());
		}


	private:

		lua_State* state;
	};


	Script() :
		state_(luaL_newstate())
	{
		lua_pushlightuserdata(state_, this);
		lua_setfield(state_, LUA_REGISTRYINDEX, "_script_obj");
	}

	~Script()
	{
		if (isMainThread_) lua_close(state_);
	}


	static ScriptP alloc()
	{
		return ScriptP(new Script);
	}


	void importStandardLibraries()
	{
		luaL_openlibs(state_);
	}

	void importFunction(const std::string& name, const Function& function)
	{
		push(function);
		lua_setglobal(state_, name.c_str());
	}


	STATUS doString(const std::string& commands)
	{
		return (STATUS)luaL_dostring(state_, commands.c_str());
	}

	STATUS doFile(const std::string& file)
	{
		return (STATUS)luaL_dofile(state_, file.c_str());
	}


	/**
	 * Thread-handling methods.
	 */

	Script pushNewThread()
	{
		return Script(state_);
	}

	void pushThread()
	{
		lua_pushthread(state_);
	}

	STATUS resume(int nargs)
	{
		return (STATUS)lua_resume(state_, nargs);
	}

	STATUS getStatus() const
	{
		return (STATUS)lua_status(state_);
	}

	int yield(int results)
	{
		return lua_yield(state_, results);
	}

	bool isMainThread() const
	{
		return isMainThread_;
	}


	/**
	 * Get significant values.
	 */

	Value getGlobalTable() const
	{
		return Value(state_, GLOBALS);
	}

	Value getRegistryTable() const
	{
		return Value(state_, REGISTRY);
	}

	Value getEnvironmentTable() const
	{
		return Value(state_, ENVIRONMENT);
	}

	Value getTop() const
	{
		return Value(state_, lua_gettop(state_));
	}

	/**
	 * Get the size of the stack; this is also the index of the top-most value.
	 */

	int getSize() const
	{
		return lua_gettop(state_);
	}

	void setSize(int size)
	{
		lua_settop(state_, size);
	}

	void clear()
	{
		setSize(0);
	}


	/**
	 * Makes sure there is at least extra more places on the stack.  Returns
	 * false if space couldn't be created.  Just like with the regular Lua API,
	 * you are responsible to make sure the stack is big enough to hold whatever
	 * you want to push on it.  This is usually only an issue if you're pushing
	 * stuff in a loop.
	 */

	bool checkStack(int extra)
	{
		return (bool)lua_checkstack(state_, extra);
	}


	/**
	 * Concatenates the top-most n values on the stack.
	 */

	void concat(int n)
	{
		lua_concat(state_, n);
	}


	/**
	 * Push some values onto the stack.
	 */

	template <typename T>
	void push(T value)
	{
		lua_pushinteger(state_, lua_Integer(value));
	}

	void push(bool value)
	{
		lua_pushboolean(state_, int(value));
	}

	void push(float value)
	{
		lua_pushnumber(state_, (lua_Number)value);
	}
	void push(double value)
	{
		lua_pushnumber(state_, (lua_Number)value);
	}

	void push(const std::string& value)
	{
		lua_pushlstring(state_, value.c_str(), value.length());
	}
	void push(const char* value, size_t length)
	{
		lua_pushlstring(state_, value, length);
	}

	void push(const Function& function)
	{
		functions_.push_back(function);

		lua_pushlightuserdata(state_, (void*)&functions_.back());
		lua_pushcclosure(state_, dispatchCall, 1);
	}

	void push(void* data)
	{
		lua_pushlightuserdata(state_, data);
	}

	void pushNil()
	{
		lua_pushnil(state_);
	}

	void pushFromThread(Script& thread, int n)
	{
		lua_xmove(thread.state_, state_, n);
	}

	STATUS pushCode(const std::string& filename)
	{
		return (STATUS)luaL_loadfile(state_, filename.c_str());
	}

	STATUS pushCode(const std::string& name, const char* buffer, size_t size)
	{
		return (STATUS)luaL_loadbuffer(state_, buffer, size, name.c_str());
	}

	void* pushNewData(size_t size)
	{
		return lua_newuserdata(state_, size);
	}

	void pushNewTable()
	{
		lua_newtable(state_);
	}


	/**
	 * Call a function on the stack.  The correct procedure is to push a
	 * function onto the stack followed by nargs arguments.  This method will
	 * pop them off upon return, leaving up to nresults return values (default
	 * is any number of return values, depending on the callee).
	 */

	STATUS call(int nargs, int nresults = LUA_MULTRET)
	{
		return (STATUS)lua_pcall(state_, nargs, nresults, 0);
	}


	/**
	 * Pops n values from the top of the stack.
	 */

	void pop(int n = 1)
	{
		lua_pop(state_, n);
	}


	/**
	 * Index into the stack to get a Value.
	 */

	Value operator [] (int index) const
	{
		return Value(state_, index);
	}


	/**
	 * Getting and setting fields of a table.
	 */

	void get(const std::string& field,  int index = GLOBALS) const
	{
		lua_getfield(state_, index, field.c_str());
	}

	void set(const std::string& field, int index = GLOBALS)
	{
		lua_setfield(state_, index, field.c_str());
	}


	/**
	 * Control over the garbage collection process.
	 */

	void collectAll()
	{
		lua_gc(state_, LUA_GCCOLLECT, 0);
	}

	void stopCollector()
	{
		lua_gc(state_, LUA_GCSTOP, 0);
	}

	void restartCollector()
	{
		lua_gc(state_, LUA_GCRESTART, 0);
	}

	int getUsedMemory() const
	{
		// in kilobytes
		return lua_gc(state_, LUA_GCCOUNT, 0);
	}

	void collectStep(int step)
	{
		lua_gc(state_, LUA_GCSTEP, step);
	}

	void tuneCollector(int pause, int step)
	{
		lua_gc(state_, LUA_GCSETPAUSE, pause);
		lua_gc(state_, LUA_GCSETSTEPMUL, step);
	}



	struct Exception : public Mf::Exception
	{
		explicit Exception(unsigned error) :
			Mf::Exception(error) {}

		void raise()
		{
			throw *this;
		}
	};


private:

	Script(lua_State* state) :
		state_(lua_newthread(state)),
		isMainThread_(false) {}

	static int dispatchCall(lua_State* state)
	{
		const Function* function = (const Function*)lua_touserdata(state,
				lua_upvalueindex(1));

		lua_getfield(state, LUA_REGISTRYINDEX, "_script_obj");
		Script* script = (Script*)lua_touserdata(state, -1);
		lua_pop(state, 1);

		return (*function)(*script);
	}

	lua_State*			state_;
	bool				isMainThread_;
	std::list<Function>	functions_;
};


} // namespace Mf

#endif // _MOOF_SCRIPT_HH_

/** vim: set ts=4 sw=4 tw=80: *************************************************/