/**
	This file is a part of rexy's general purpose library
	Copyright (C) 2022 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU 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 General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef REXY_COMPAT_CPP17_STRING_BASE_HPP
#define REXY_COMPAT_CPP17_STRING_BASE_HPP

#include "../../string_base.hpp"

#include <utility> //forward
#include <type_traits> //{false,true}_type, declval, enable_if, remove_reference, decay
#include <algorithm> //lexicographically_compare

#include "../../utility.hpp" //strlen, strncmp
#include "../../traits.hpp"

namespace rexy{

	template<class Left, class Right>
	class string_cat_expr;
	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
	class basic_string;
	template<class Char>
	class basic_string_view;

	#define REXY_HAS_MEMFUN_WITH_RET(type, ret, fun, ...) \
		template<class T> \
		struct has_##fun##_f{ \
			static std::false_type check(...); \
			template<class type> \
			static auto check(type* u) -> std::enable_if_t<std::is_convertible_v<decltype(std::declval<type>().fun(__VA_ARGS__)),ret>,std::true_type>; \
	 \
			static constexpr bool value = decltype(check(std::declval<std::remove_reference_t<T>*>()))::value; \
		}; \
		template<class T> \
		static constexpr bool has_##fun##_f_v = has_##fun##_f<T>::value

	#define REXY_HAS_MEMOP_WITH_RET(type, ret, opname, op, ...) \
		template<class T> \
		struct has_##opname##_f{ \
			static std::false_type check(...); \
			template<class type> \
			static auto check(type* u) -> std::enable_if_t<std::is_convertible_v<decltype(std::declval<type>().operator op(__VA_ARGS__)),ret>,std::true_type>; \
	 \
			static constexpr bool value = decltype(check(std::declval<std::remove_reference_t<T>*>()))::value; \
		}; \
		template<class T> \
		static constexpr bool has_##opname##_f_v = has_##opname##_f<T>::value


	REXY_HAS_MEMFUN_WITH_RET(U, typename U::size_type, length);
	REXY_HAS_MEMFUN_WITH_RET(U, typename U::const_pointer, c_str);
	REXY_HAS_MEMOP_WITH_RET(U, typename U::const_reference, indexop, [], 0);
	REXY_HAS_MEMFUN_WITH_RET(U, typename U::const_iterator, begin);
	REXY_HAS_MEMFUN_WITH_RET(U, typename U::const_iterator, end);

	#undef REXY_HAS_MEMFUN_WITH_RET
	#undef REXY_HAS_MEMOP_WITH_RET

	template<class T>
	struct is_basic_string{
		template<class Char, class Alloc>
		static std::true_type check(const basic_string<Char,Alloc>*);
		static std::false_type check(...);

		static constexpr bool value = decltype(check(std::declval<rexy::remove_cvref_t<T>*>()))::value;
	};
	template<class T>
	struct is_basic_string_view{
		template<class Char>
		static std::true_type check(const basic_string_view<Char>*);
		static std::false_type check(...);

		static constexpr bool value = decltype(check(std::declval<rexy::remove_cvref_t<T>*>()))::value;
	};
	template<class T>
	struct is_basic_string_expr{
		template<class Left, class Right>
		static std::true_type check(const string_cat_expr<Left,Right>*);
		static std::false_type check(...);

		static constexpr bool value = decltype(check(std::declval<rexy::remove_cvref_t<T>*>()))::value;
	};

	template<class T>
	struct is_string{
		static constexpr bool value = (is_basic_string<T>::value || is_basic_string_view<T>::value) &&
		                              (has_length_f_v<T> && has_c_str_f_v<T> && has_indexop_f_v<T> && has_begin_f_v<T> && has_end_f_v<T>);
	};
	template<class T>
	static constexpr bool is_string_v = is_string<T>::value;

	template<class... Ts>
	struct are_strings{
		static constexpr bool value = (is_string<Ts>::value && ...);
	};
	template<class... Ts>
	static constexpr bool are_strings_v = are_strings<Ts...>::value;
	template<class T>
	struct is_string_expr{
		static constexpr bool value = is_basic_string_expr<T>::value;
	};
	template<class T>
	static constexpr bool is_string_expr_v = is_string_expr<T>::value;
	template<class... Ts>
	struct are_string_expr{
		static constexpr bool value = (is_string_expr<Ts>::value && ...);
	};
	template<class... Ts>
	static constexpr bool are_string_expr_v = are_string_expr<Ts...>::value;

	//Compare
	template<class Str1, class Str2, std::enable_if_t<are_strings<Str1, Str2>::value,int> = 0>
	constexpr bool operator==(const Str1& left, const Str2& right){
		if(left.length() != right.length()){
			return false;
		}
		return !rexy::strncmp(left.c_str(), right.c_str(), left.length()+1);
	}
	template<class Str1, std::enable_if_t<are_strings<Str1>::value,int> = 0>
	constexpr bool operator==(const Str1& left, typename std::decay_t<Str1>::const_pointer right){
		if(right == nullptr){
			return false;
		}
		const rexy::basic_string_view rstr(right);
		if(rstr.length() != left.length()){
			return false;
		}
		return !rexy::strncmp(left.c_str(), rstr.c_str(), left.length());
	}
	template<class Str1, std::enable_if_t<are_strings<Str1>::value,int> = 0>
	constexpr bool operator==(typename std::decay_t<Str1>::const_pointer left, const Str1& right){
		if(left == nullptr){
			return false;
		}
		const rexy::basic_string_view lstr(left);
		if(lstr.length() != right.length()){
			return false;
		}
		return !rexy::strncmp(lstr.c_str(), right.c_str(), right.length());
	}
	template<class Str1, class Str2, std::enable_if_t<are_strings<Str1, Str2>::value,int> = 0>
	constexpr bool operator!=(const Str1& left, const Str2& right)noexcept{
		return !(left == right);
	}
	template<class Str1, std::enable_if_t<are_strings<Str1>::value,int> = 0>
	constexpr bool operator!=(const Str1& left, typename std::decay_t<Str1>::const_pointer right)noexcept{
		return !(left == right);
	}
	template<class Str1, std::enable_if_t<are_strings<Str1>::value,int> = 0>
	constexpr bool operator!=(typename std::decay_t<Str1>::const_pointer left, const Str1& right)noexcept{
		return !(left == right);
	}
	template<class Str1, class Str2, std::enable_if_t<are_string<Str1,Str2>::value,int> = 0>
	constexpr bool operator<(const Str1& left, const Str2& right)noexcept{
		return std::lexicographical_compare(left.begin(), left.end(), right.begin(), right.end());
	}
	template<class Str1, class Str2, std::enable_if_t<are_string<Str1,Str2>::value,int> = 0>
	constexpr bool operator<=(const Str1& left, const Str2& right)noexcept{
		return !(right < left);
	}
	template<class Str1, class Str2, std::enable_if_t<are_string<Str1,Str2>::value,int> = 0>
	constexpr bool operator>(const Str1& left, const Str2& right)noexcept{
		return (right < left);
	}
	template<class Str1, class Str2, std::enable_if_t<are_string<Str1,Str2>::value,int> = 0>
	constexpr bool operator>=(const Str1& left, const Str2& right)noexcept{
		return !(left < right);
	}

	//String + string concat
	template<class Left, class Right, std::enable_if_t<are_strings<Left, Right>::value,int> = 0>
	constexpr auto operator+(Left&& l, Right&& r)
		//uses deduction guide whereas std::is_nothrow_constructible couldn't
		noexcept(noexcept(::new (nullptr) string_cat_expr(std::forward<Left>(l), std::forward<Right>(r))))
	{
		return string_cat_expr(std::forward<Left>(l), std::forward<Right>(r));
	}
	//String + char pointer
	template<class Right, std::enable_if_t<is_string<Right>::value,int> = 0>
	constexpr auto operator+(typename std::decay_t<Right>::const_pointer left, Right&& right)
		noexcept(noexcept(::new (nullptr) string_cat_expr(rexy::basic_string_view(left), std::forward<Right>(right))))
	{
		return string_cat_expr(rexy::basic_string_view(left), std::forward<Right>(right));
	}
	//Char pointer + string
	template<class Left, std::enable_if_t<is_string<Left>::value,int> = 0>
	constexpr auto operator+(Left&& left, typename std::decay_t<Left>::const_pointer right)
		noexcept(noexcept(::new (nullptr) string_cat_expr(std::forward<Left>(left), rexy::basic_string_view(right))))
	{
		return rexy::string_cat_expr(std::forward<Left>(left), rexy::basic_string_view(right));
	}


	//String + expr concat
	template<class Left, class Right, std::enable_if_t<is_string<Left>::value && is_string_expr<Right>::value,int> = 0>
	constexpr auto operator+(Left&& left, Right&& right){
		return string_cat_expr(std::forward<Left>(left), std::forward<Right>(right));
	}
	//Expr + string
	template<class Left, class Right, std::enable_if_t<is_string_expr<Left>::value && is_string<Right>::value,int> = 0>
	constexpr auto operator+(Left&& left, Right&& right){
		return string_cat_expr(std::forward<Left>(left), std::forward<Right>(right));
	}
	//Expr + expr
	template<class Left, class Right, std::enable_if_t<are_string_expr<Left,Right>::value,int> = 0>
	constexpr auto operator+(Left&& left, Right&& right){
		return string_cat_expr(std::forward<Left>(left), std::forward<Right>(right));
	}
	//Expr + char pointer
	template<class Left, std::enable_if_t<is_string_expr<Left>::value,int> = 0>
	constexpr auto operator+(Left&& left, typename std::decay_t<Left>::const_pointer right){
		return string_cat_expr(std::forward<Left>(left), rexy::basic_string_view(right));
	}
	//char pointer + Expr
	template<class Right, std::enable_if_t<is_string_expr<Right>::value,int> = 0>
	constexpr auto operator+(typename std::decay_t<Right>::const_pointer left, Right&& right){
		return string_cat_expr(rexy::basic_string_view(left), std::forward<Right>(right));
	}

	//String concat assignment
	template<class Left, class Right, std::enable_if_t<are_strings<Left,Right>::value,int> = 0>
	decltype(auto) operator+=(Left& l, Right&& r)
		noexcept(noexcept(l + std::forward<Right>(r)) && std::is_nothrow_assignable<Left, decltype(l + std::forward<Right>(r))>::value)
	{
		return l = (l + std::forward<Right>(r));
	}
	template<class Left, class Right, std::enable_if_t<is_string<Left>::value && is_string_expr<Right>::value,int> = 0>
	decltype(auto) operator+=(Left& l, Right&& r)
		noexcept(noexcept(l + std::forward<Right>(r)) && std::is_nothrow_assignable<Left, decltype(l + std::forward<Right>(r))>::value)
	{
		return l = (l + std::forward<Right>(r));
	}
	template<class Left, std::enable_if_t<is_string<Left>::value, int> = 0>
	decltype(auto) operator+=(Left& l, typename std::decay_t<Left>::const_pointer r)
		noexcept(noexcept(l + r) && std::is_nothrow_assignable<Left, decltype(l + r)>::value)
	{
		return l = (l + r);
	}

	template<class T, class Char, std::enable_if_t<is_string<T>::value, int> = 0>
	constexpr std::size_t find_first_of(T&& t, const Char* c, std::size_t start, std::size_t size){
		if(start > t.length()){
			return rexy::npos;
		}
		for(auto it = t.cbegin() + start;it != t.cend();++it){
			for(std::size_t i = 0;i < size;++i){
				if(*it == c[i]){
					return it - t.cbegin();
				}
			}
		}
		return rexy::npos;
	}

	template<class T, class Char, std::enable_if_t<is_string<T>::value, int> = 0>
	constexpr std::size_t find_last_of(T&& t, const Char* c, std::size_t start, std::size_t size){
		if(start > t.length()){
			return rexy::npos;
		}

		const auto b = t.cend() - 1;
		const auto e = t.cbegin() - 1 - start;

		for(auto it = b;it != e;--it){
			for(std::size_t i = 0;i < size;++i){
				if(*it == c[i]){
					return it - t.cbegin();
				}
			}
		}
		return rexy::npos;
	}

}

#endif