namespace Luax
{

	//----------------------------------------------------------------------------------------------------------------
	// 接口

	///
	/// 对不同类型，通过调用GetLuaClassName获得类型名，如果是派生类，GetClassName会被覆盖，指向luax_c_getupvalue。
	///
	template<typename T>
	int LuaxNativeClass<T>::l_GetClassName(lua_State* L)
	{
		LUAX_SETUP(L, "*");

		cc8* type = T::GetLuaxClassName();
		state.Push(type);
		return 1;
	}

	//----------------------------------------------------------------------------------------------------------------

	///
	/// 注册工厂和单例共有的类成员
	/// 
	template<typename T>
	void LuaxNativeClass<T>::RegisterLuaxClass(LuaxState& state)
	{
		luaL_Reg regTable[] = {
			{ "GetClass",     l_GetClass     },
			{ "GetClassName", l_GetClassName },
			{ NULL,           NULL           }
		};

		state.RegisterMethods(regTable);
	}

	///
	/// 工厂类的成员，注册在class table
	///
	template<typename T>
	void LuaxNativeClass<T>::RegisterLuaxFactoryClass(LuaxState& state)
	{
		luaL_Reg regTable[] = {
			{ "GetRefTable", l_GetRefTable },
			{ NULL,          NULL          }
		};

		state.RegisterMethods(regTable);
	}

	///
	/// 单例类的成员，注册在class table
	///
	template<typename T>
	void LuaxNativeClass<T>::RegisterLuaxSingletonClass(LuaxState& state)
	{
		luaL_Reg regTable[] = {
			{ NULL, NULL }
		};

		state.RegisterMethods(regTable);
	}

	template<typename T>
	void LuaxNativeClass<T>::PushLuaxClassTable(LuaxState& state)
	{
		assert(mClassTable);

		mClassTable.PushRef(state);
	}

	template<typename T>
	void LuaxNativeClass<T>::SetLuaxClassTableRef(LuaxState& state, int idx)
	{
		mClassTable.SetRef(state, idx);
	}

	template<typename T>
	LuaxNativeClass<T>::LuaxNativeClass()
	{
	}

	template<typename T>
	LuaxNativeClass<T>::~LuaxNativeClass()
	{
	}

	template<typename T>
	template<typename U>
	void LuaxNativeClass<T>::LuaRetain(LuaxState& state, U* userdata)
	{
		if (PushLuaxRefTable(state))
		{
			if (userdata->PushLuaxUserdata(state))
			{
				lua_pushvalue(state, -1); // copy the userdata
				lua_gettable(state, -3); // get the count (or nil)
				u32 count = state.GetValue<u32>(-1, 0); // get the count (or 0)
				lua_pop(state, 1); // pop the old count
				lua_pushnumber(state, count + 1); // push the new count
				lua_settable(state, -3); // save it in the table: reftable[userdata] = count
			}
		}
	}

	template<typename T>
	template<typename U>
	void LuaxNativeClass<T>::LuaRelease(LuaxState& state, U* userdata)
	{
		if (PushLuaxRefTable(state))
		{
			if (userdata->PushLuaxUserdata(state))
			{
				lua_pushvalue(state, -1); // copy the userdata
				lua_gettable(state, -3); // get the count (or nil)
				u32 count = state.GetValue<u32>(-1, 0); // get the count (or 0)
				lua_pop(state, 1); // pop the old count

				if (count == 0) return; // nothing to do

				if (count > 1) {
					lua_pushnumber(state, count - 1); // push the new count
				}
				else {
					lua_pushnil(state); // maybe cause gc
				}
				lua_settable(state, -3); // save it in the table
			}
		}
	}

	template<typename T>
	bool LuaxNativeClass<T>::PushLuaxUserdata(LuaxState& state)
	{
		assert(!T::IsLuaxClassSingleton());
		if (!mUserdata)
		{
			BindToLua(state);
			return true;
		}
		return mUserdata.PushRef(state);
	}

	template<typename T>
	bool LuaxNativeClass<T>::PushLuaxMemberTable(LuaxState& state)
	{
		int top = state.GetTop();
		if (this->PushLuaxUserdata(state))
		{
			if (lua_getmetatable(state, -1))  // ref table 
			{
				lua_replace(state, -2);
				if (lua_getmetatable(state, -1)) // member table
				{
					lua_replace(state, -2);
					return true;
				}
			}
		}
		state.SetTop(top);
		lua_pushnil(state);
		return false;
	}

	template<typename T>
	bool LuaxNativeClass<T>::PushLuaxRefTable(LuaxState& state)
	{
		// Singleton 
		if (T::IsLuaxClassSingleton())
		{
			if (!this->mSingletonRefTable) {
				lua_newtable(state);
				this->mSingletonRefTable.SetRef(state, -1); // strong ref to member table won't be garbage collected
			}
			else {
				this->mSingletonRefTable.PushRef(state);
			}
			return true;
		}
		// Factory
		else 
		{
			if (this->PushLuaxUserdata(state))
			{
				if (lua_getmetatable(state, -1))
				{
					lua_replace(state, -2);
					return true;
				}
			}
		}
		return false;
	}

	///
	/// 创建userdata，并以此添加ref table，member table和class table。
	///     ref table 是kv强引用table，保存对其他userdata的引用计数（通过userdata作为key，计数为value），以及成员引用
	///     member table 保存lua创建的实例的成员
	///     class table 所有本类型的实例共有的函数表
	///
	template<typename T>
	void LuaxNativeClass<T>::BindToLua(LuaxState& state)
	{
		// 单例不能绑定userdata
		assert(!T::IsLuaxClassSingleton());
		assert(!mUserdata);

		// 创建userdata并留在栈顶
		state.PushPtrUserData(this);

		lua_newtable(state); // ref table，无法在lua处访问，用来管理C对象的生命周期
		lua_newtable(state); // member table，lua中创建的对象成员都保存在这里
		PushLuaxClassTable(state); // class table

		// stack:
		// -1: class table
		// -2: member table
		// -3: ref table
		// -4: userdata

		int top = state.GetTop();
		int memberTable = top - 1;
		int refTable = top - 2;

		// ref table 注册 __tostring
		lua_pushcfunction(state, l___tostring);
		lua_setfield(state, refTable, "__tostring");

		// ref table 的 __index 和 __newindex 设为 member table
		lua_pushvalue(state, memberTable);
		lua_setfield(state, refTable, "__index");

		lua_pushvalue(state, memberTable);
		lua_setfield(state, refTable, "__newindex");

		lua_pushcfunction(state, l___gc);
		lua_setfield(state, refTable, "__gc");

		// 设置元表
		lua_setmetatable(state, -2); // class is meta of member
		lua_setmetatable(state, -2); // member is meta of ref
		lua_setmetatable(state, -2); // ref is meta of userdata

		// 设置一个userdata的弱引用，方便通过PushLuaUserdata方法返回lua对象
		mUserdata.SetRef(state, -1);
		assert(mUserdata);
	}

	///
	/// 成员引用管理
	///
	template<typename T>
	void LuaxNativeClass<T>::SetMemberRef(LuaxState& state, LuaxMemberRef& memRef, int idx)
	{
		ClearMemberRef(state, memRef);
		if (!lua_isnil(state, idx))
		{
			idx = state.AbsIndex(idx);
			if (PushLuaxRefTable(state))
			{
				lua_pushvalue(state, idx);
				memRef.refID = luaL_ref(state, -2);
				state.Pop(); // ref table
			}
		}
	}

	template<typename T>
	bool LuaxNativeClass<T>::PushMemberRef(LuaxState& state, LuaxMemberRef& memRef)
	{
		if (memRef)
		{
			if (PushLuaxRefTable(state))
			{
				lua_rawgeti(state, -1, memRef.refID);
				lua_replace(state, -2); // ref table
				if (lua_isnil(state, -1))
					goto failed;
				return true;
			}
		}
		lua_pushnil(state);
	failed:
		memRef.refID = LUA_NOREF;
		return false;
	}

	template<typename T>
	void LuaxNativeClass<T>::ClearMemberRef(LuaxState& state, LuaxMemberRef& memRef)
	{
		if (memRef)
		{
			if (PushLuaxRefTable(state))
			{
				luaL_unref(state, -1, memRef.refID);
				state.Pop(); // ref table
			}
			memRef.refID = LUA_NOREF;
		}
	}

	//--------------------------------------------------------------------------------------------------------------

	///
	/// 释放工厂创建的实例
	///
	template<typename T>
	int LuaxNativeClass<T>::l___gc(lua_State* L)
	{
		LUAX_SETUP(L, "U");
		T* self = state.GetLuaUserdata<T>(1);
		delete self;
		return 0;
	}

	///
	/// 输出格式如下:
	/// 地址 类名
	///
	template<typename T>
	int LuaxNativeClass<T>::l___tostring(lua_State* L)
	{
		// params: 
		// 1: userdata

		LUAX_STATE(L);
		T* self = state.GetLuaUserdata<T>(1);
		if (self)
		{
			cc8* classname = "";
			lua_getfield(state, 1, "GetClassName");
			if (state.IsType(-1, LUA_TFUNCTION))
			{
				lua_pushvalue(L, 1); // userdata 
				state.Call(1, 1); // 派生类的GetClassName函数
				classname = state.GetValue<cc8*>(-1, "");
			}
			else
			{
				classname = T::GetLuaxClassName();
			}
			lua_pushfstring(L, "%s: %p", classname, self);
			return 1;
		}
		return 0;
	}

#ifdef LUAX_ENABLE_NATIVE_EXTEND

	///
	/// 派生出子类，在lua里对派生类的成员和行为进行重新设计，但是保证了userdata的统一。Native class的派生提供Ctor支持，在
	/// native实体创建后可以使用Ctor进行初始化，派生类拥有和基类一样的New参数列表，且native对象是一样的类型。
	///
	template<typename T>
	int LuaxNativeClass<T>::l_ExtendFactory(lua_State* L)
	{
		// upvalues:
		// 1: base class 

		// params: 
		// 1: class name 

		int baseClass = lua_upvalueindex(1);

		lua_newtable(L); // class table 

		int inheritClass = lua_gettop(L);

		// .GetClassName()
		cc8* type = lua_tostring(L, 1);
		lua_pushstring(L, type);
		lua_pushcclosure(L, luax_c_getupvalue, 1); 
		lua_setfield(L, -2, "GetClassName");

		// .GetClass()
		lua_pushvalue(L, inheritClass);
		lua_pushcclosure(L, luax_c_getupvalue, 1);
		lua_setfield(L, -2, "GetClass");

		// .Extend()
		lua_pushvalue(L, inheritClass);
		lua_pushcclosure(L, l_ExtendFactory, 1);
		lua_setfield(L, -2, "Extend");

		// .New() 
		lua_pushvalue(L, inheritClass); 
		lua_getfield(L, baseClass, "New");
		lua_pushcclosure(L, l_New, 2);
		lua_setfield(L, -2, "New");

		// __base = baseClass
		lua_pushvalue(L, baseClass);
		lua_setfield(L, -2, "__base");

		// __index = inheritClass
		lua_pushvalue(L, inheritClass);
		lua_setfield(L, -2, "__index"); 

		// metatable is baseClass
		lua_pushvalue(L, baseClass);
		lua_setmetatable(L, inheritClass);

		return 1;
	}

	template<typename T>
	int LuaxNativeClass<T>::l_ExtendSingleton(lua_State* L)
	{
		// upvalues:
		// 1: base class 

		// params: 
		// 1: class name 

		int baseClass = lua_upvalueindex(1); 

		lua_newtable(L); // class name 

		int inheritClass = lua_gettop(L);

		// .GetClassName()
		cc8* type = lua_tostring(L, 1);
		lua_pushstring(L, type);
		lua_pushcclosure(L, luax_c_getupvalue, 1);
		lua_setfield(L, -2, "GetClassName");

		// .GetClass()
		lua_pushvalue(L, inheritClass);
		lua_pushcclosure(L, luax_c_getupvalue, 1);
		lua_setfield(L, -2, "GetClass");

		// .Extend()
		lua_pushvalue(L, inheritClass);
		lua_pushcclosure(L, l_ExtendFactory, 1);
		lua_setfield(L, -2, "Extend");

		// __base = baseClass
		lua_pushvalue(L, baseClass);
		lua_setfield(L, -2, "__base");

		// __index = inheritClass
		lua_pushvalue(L, inheritClass);
		lua_setfield(L, -2, "__index");

		// metatable is baseClass
		lua_pushvalue(L, baseClass);
		lua_setmetatable(L, inheritClass);

		return 1;
	}

#endif

	template<typename T> 
	int LuaxNativeClass<T>::l_GetClass(lua_State* L)
	{
		LUAX_STATE(L);
		if (!mClassTable)
			lua_pushnil(L);
		else
			mClassTable.PushRef(state);
		return 1;
	}

	template<typename T>
	int LuaxNativeClass<T>::l_GetRefTable(lua_State* L)
	{
		LUAX_STATE(L);
		T* self = state.GetLuaUserdata<T>(1);
		bool success = self->PushLuaxRefTable(state);
		if (!success)
			lua_pushnil(L);
		return 1;
	}

	template<typename T>
	int LuaxNativeClass<T>::l_New(lua_State* L)
	{
		LUAX_STATE(L);

		// upvalues:
		// 1: class table 
		// 2: original New()

		// stack:
		// -1~-n: args

		int n = lua_gettop(L); // n args
		
		lua_pushvalue(L, lua_upvalueindex(2));
		if (state.IsType(-1, LUA_TFUNCTION))
		{
			// stack:
			// -1: New
			// -2~-1-n: args

			state.PushValues(-1 - n, n);

			// stack:
			// -1~-n: args
			// -n-1: New
			// -n-2~-1-2n: args

			state.Call(n, 1);
			
			// stack: 
			// -1: userdata 
			// -2~-1-n: args

			// reset member table's metatable to class table
			if (state.IsType(-1, LUA_TUSERDATA))
			{
				if (lua_getmetatable(L, -1)) // ref table
				{
					if (lua_getmetatable(L, -1)) // member table
					{
						lua_pushvalue(L, lua_upvalueindex(1)); // class table 
						lua_setmetatable(L, -2);
						state.Pop(); // member table
					}
					state.Pop(); // ref table
				}

				// stack: 
				// -1: userdata
				// -2~-1-n: args

				int args = state.AbsIndex(-1 - n);

				// 尝试调用Ctor函数
				lua_getfield(L, lua_upvalueindex(1), "Ctor");

				if (state.IsType(-1, LUA_TFUNCTION))
				{
					lua_pushvalue(L, -2); // userdata
					state.PushValues(args, n);
					state.Call(n + 1, 0);
				}
				else
					state.Pop();

			}

			return 1;
		}
		return 0;
	}

	template<typename T> LuaxStrongRef LuaxNativeClass<T>::mClassTable;        // class table
	template<typename T> LuaxStrongRef LuaxNativeClass<T>::mSingletonRefTable; // 单例

}