// The MIT License (MIT) 

// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_STACK_GET_HPP
#define SOL_STACK_GET_HPP

#include "stack_core.hpp"
#include "usertype_traits.hpp"
#include "inheritance.hpp"
#include "overload.hpp"
#include "error.hpp"
#include <memory>
#include <functional>
#include <utility>

namespace sol {
	namespace stack {

		template<typename T, typename>
		struct getter {
			static T& get(lua_State* L, int index, record& tracking) {
				return getter<T&>{}.get(L, index, tracking);
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<std::is_floating_point<T>::value>> {
			static T get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<T>(lua_tonumber(L, index));
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<meta::all<std::is_integral<T>, std::is_signed<T>>::value>> {
			static T get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<T>(lua_tointeger(L, index));
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<meta::all<std::is_integral<T>, std::is_unsigned<T>>::value>> {
			static T get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<T>(lua_tointeger(L, index));
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<std::is_enum<T>::value>> {
			static T get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<T>(lua_tointegerx(L, index, nullptr));
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<std::is_base_of<reference, T>::value || std::is_base_of<stack_reference, T>::value>> {
			static T get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return T(L, index);
			}
		};

		template<>
		struct getter<userdata_value> {
			static userdata_value get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return userdata_value(lua_touserdata(L, index));
			}
		};

		template<>
		struct getter<lightuserdata_value> {
			static lightuserdata_value get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return lightuserdata_value(lua_touserdata(L, index));
			}
		};

		template<typename T>
		struct getter<light<T>> {
			static light<T> get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return light<T>(static_cast<T*>(lua_touserdata(L, index)));
			}
		};

		template<typename T>
		struct getter<user<T>> {
			static T& get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return *static_cast<T*>(lua_touserdata(L, index));
			}
		};

		template<typename T>
		struct getter<user<T*>> {
			static T* get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<T*>(lua_touserdata(L, index));
			}
		};

		template<>
		struct getter<type> {
			static type get(lua_State *L, int index, record& tracking) {
				tracking.use(1);
				return static_cast<type>(lua_type(L, index));
			}
		};

		template<>
		struct getter<bool> {
			static bool get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return lua_toboolean(L, index) != 0;
			}
		};

		template<>
		struct getter<std::string> {
			static std::string get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				std::size_t len;
				auto str = lua_tolstring(L, index, &len);
				return std::string( str, len );
			}
		};

		template <>
		struct getter<string_detail::string_shim> {
			string_detail::string_shim get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				size_t len;
				const char* p = lua_tolstring(L, index, &len);
				return string_detail::string_shim(p, len);
			}
		};

		template<>
		struct getter<const char*> {
			static const char* get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return lua_tostring(L, index);
			}
		};

		template<>
		struct getter<meta_function> {
			static meta_function get(lua_State *L, int index, record& tracking) {
				tracking.use(1);
				const char* name = getter<const char*>{}.get(L, index, tracking);
				for (std::size_t i = 0; i < meta_function_names.size(); ++i)
					if (meta_function_names[i] == name)
						return static_cast<meta_function>(i);
				return meta_function::construct;
			}
		};

		template<>
		struct getter<char> {
			static char get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				size_t len;
				auto str = lua_tolstring(L, index, &len);
				return len > 0 ? str[0] : '\0';
			}
		};

		template<>
		struct getter<std::wstring> {
			static std::wstring get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return{};
			}
		};

#if 0

		template<>
		struct getter<std::u16string> {
			static std::u16string get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return{};
			}
		};

		template<>
		struct getter<std::u32string> {
			static std::u32string get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return{};
			}
		};

		template<>
		struct getter<wchar_t> {
			static wchar_t get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				auto str = getter<std::wstring>{}.get(L, index);
				return str.size() > 0 ? str[0] : '\0';
			}
		};

		template<>
		struct getter<char16_t> {
			static char get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				auto str = getter<std::u16string>{}.get(L, index);
				return str.size() > 0 ? str[0] : '\0';
			}
		};

		template<>
		struct getter<char32_t> {
			static char32_t get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				auto str = getter<std::u32string>{}.get(L, index);
				return str.size() > 0 ? str[0] : '\0';
			}
		};

#endif // For a distant future

		template<>
		struct getter<nil_t> {
			static nil_t get(lua_State*, int, record& tracking) {
				tracking.use(1);
				return nil;
			}
		};

		template<>
		struct getter<std::nullptr_t> {
			static std::nullptr_t get(lua_State*, int, record& tracking) {
				tracking.use(1);
				return nullptr;
			}
		};

		template<>
		struct getter<nullopt_t> {
			static nullopt_t get(lua_State*, int, record& tracking) {
				tracking.use(1);
				return nullopt;
			}
		};

		template<>
		struct getter<this_state> {
			static this_state get(lua_State* L, int, record& tracking) {
				tracking.use(0);
				return this_state{ L };
			}
		};

		template<>
		struct getter<lua_CFunction> {
			static lua_CFunction get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return lua_tocfunction(L, index);
			}
		};

		template<>
		struct getter<c_closure> {
			static c_closure get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return c_closure(lua_tocfunction(L, index), -1);
			}
		};

		template<>
		struct getter<error> {
			static error get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				size_t sz = 0;
				const char* err = lua_tolstring(L, index, &sz);
				if (err == nullptr) {
					return error(detail::direct_error, "");
				}
				return error(detail::direct_error, std::string(err, sz));
			}
		};

		template<>
		struct getter<void*> {
			static void* get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				return lua_touserdata(L, index);
			}
		};

		template<typename T>
		struct getter<T*> {
			static T* get_no_nil(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				void** pudata = static_cast<void**>(lua_touserdata(L, index));
				void* udata = *pudata;
				return get_no_nil_from(L, udata, index, tracking);
			}

			static T* get_no_nil_from(lua_State* L, void* udata, int index, record&) {
				if (detail::has_derived<T>::value && luaL_getmetafield(L, index, &detail::base_class_cast_key()[0]) != 0) {
					void* basecastdata = lua_touserdata(L, -1);
					detail::inheritance_cast_function ic = (detail::inheritance_cast_function)basecastdata;
					// use the casting function to properly adjust the pointer for the desired T
					udata = ic(udata, detail::id_for<T>::value);
					lua_pop(L, 1);
				}
				T* obj = static_cast<T*>(udata);
				return obj;
			}

			static T* get(lua_State* L, int index, record& tracking) {
				type t = type_of(L, index);
				if (t == type::nil) {
					tracking.use(1);
					return nullptr;
				}
				return get_no_nil(L, index, tracking);
			}
		};

		template<typename T>
		struct getter<non_null<T*>> {
			static T* get(lua_State* L, int index, record& tracking) {
				return getter<T*>::get_no_nil(L, index, tracking);
			}
		};

		template<typename T>
		struct getter<T&> {
			static T& get(lua_State* L, int index, record& tracking) {
				return *getter<T*>::get_no_nil(L, index, tracking);
			}
		};

		template<typename T>
		struct getter<T, std::enable_if_t<is_unique_usertype<T>::value>> {
			typedef typename unique_usertype_traits<T>::type P;
			typedef typename unique_usertype_traits<T>::actual_type Real;

			static Real& get(lua_State* L, int index, record& tracking) {
				tracking.use(1);
				P** pref = static_cast<P**>(lua_touserdata(L, index));
				detail::special_destruct_func* fx = static_cast<detail::special_destruct_func*>(static_cast<void*>(pref + 1));
				Real* mem = static_cast<Real*>(static_cast<void*>(fx + 1));
				return *mem;
			}
		};

		template<typename T>
		struct getter<std::reference_wrapper<T>> {
			static T& get(lua_State* L, int index, record& tracking) {
				return getter<T&>{}.get(L, index, tracking);
			}
		};

		template<typename... Args>
		struct getter<std::tuple<Args...>> {
			template <std::size_t... I>
			static decltype(auto) apply(std::index_sequence<I...>, lua_State* L, int index, record& tracking) {
				return std::tuple<decltype(stack::get<Args>(L, index))...>{stack::get<Args>(L, index + tracking.used, tracking)...};
			}

			static decltype(auto) get(lua_State* L, int index, record& tracking) {
				return apply(std::make_index_sequence<sizeof...(Args)>(), L, index, tracking);
			}
		};

		template<typename A, typename B>
		struct getter<std::pair<A, B>> {
			static decltype(auto) get(lua_State* L, int index, record& tracking) {
				return std::pair<decltype(stack::get<A>(L, index)), decltype(stack::get<B>(L, index))>{stack::get<A>(L, index, tracking), stack::get<B>(L, index + tracking.used, tracking)};
			}
		};

	} // stack
} // sol

#endif // SOL_STACK_GET_HPP