/**
	This file is a part of rexy's matrix client
	Copyright (C) 2019-2020 rexy712

	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 RAII_STRING_BASE_HPP
#define RAII_STRING_BASE_HPP

#include <type_traits> //is_same, integral_contant, enable_if, etc
#include <utility> //forward
#include <cstdlib> //size_t

namespace raii{

	class string_expr{};

	//Base of all RAII strings. Its use is allowing passing of raii strings to functions without knowing the exact type
	class string_base : public string_expr
	{
	protected:
		size_t m_length = 0;
		size_t m_cap = 0;
		char* m_data = nullptr;

	protected:
		constexpr string_base(void) = default;
		constexpr string_base(size_t len):
			m_cap(len){}
		//Initialize without copying
		constexpr string_base(char* data, size_t len):
			m_cap(len), m_data(data){}
		constexpr string_base(char* data, size_t len, size_t cap):
			m_length(len), m_cap(cap), m_data(data){}
		//Copy ctor (do nothing)
		string_base(const string_base&){}
		~string_base(void) = default;

	public:
		//Stop managing stored pointer. Does not free.
		char* release(void);

		//Length of string not including null terminator
		constexpr size_t length(void)const{return m_length;}
		constexpr size_t capacity(void)const{return m_cap;}
		//direct access to managed pointer
		constexpr char* get(void){return m_data;}
		constexpr const char* get(void)const{return m_data;}
		constexpr operator char*(void){return m_data;}
		constexpr operator const char*(void)const{return m_data;}
		//true if m_data is not null
		constexpr operator bool(void)const{return m_data;}

		char& operator[](size_t i);
		const char& operator[](size_t i)const;
	};


	//Supplies all functions that string_base can't implement
	template<class Allocator>
	class string_intermediary : public string_base
	{
	public:
		using allocator_type = Allocator;

	public:
		string_intermediary(void) = default;
		string_intermediary(char* data, size_t len);
		string_intermediary(const char* data, size_t len);
		string_intermediary(char* data, size_t len, size_t cap);
		string_intermediary(const char* data);
		string_intermediary(size_t len);
		string_intermediary(size_t len, size_t cap);

		//normal copy and move ctors
		string_intermediary(const string_intermediary& b);
		string_intermediary(string_intermediary&& s);

		string_intermediary(const string_base& b);

		//dtor
		~string_intermediary(void);

		string_intermediary& operator=(const string_intermediary& s);
		string_intermediary& operator=(string_intermediary&& s);
		//Copy from c string
		string_intermediary& operator=(const char* c);
		//Copy from other string_base
		string_intermediary& operator=(const string_base& s);

		//Replace managed pointer. Frees existing value
		void reset(char* val = nullptr);
		void reset(char* val, size_t len);
		bool resize(size_t newsize);
		void append(const char* data, size_t len);
		void append(const char* data);
		void append(const string_base& s);

	private:
		string_intermediary& _copy_string(const char* s, size_t len);
	};

	//Like an expression template but not really
	template<class Left, class Right>
	class string_cat_expr : public string_expr
	{
	private:
		Left m_l;
		Right m_r;

	public:
		template<class T, class U>
		constexpr string_cat_expr(T&& l, U&& r);
		constexpr string_cat_expr(const string_cat_expr& s);
		constexpr string_cat_expr(string_cat_expr&& s);

		constexpr size_t length(void)const;
		template<class Alloc>
		operator string_intermediary<Alloc>(void);
		constexpr const Left& left(void)const;
		constexpr const Right& right(void)const;
	};

	class static_string : public string_base
	{
	public:
		constexpr static_string(void) = default;
		template<size_t N>
		constexpr static_string(const char(&str)[N]);
		constexpr static_string(const char* str, size_t len);
		static_string(const char* c);
		constexpr static_string(const static_string& s);
		constexpr static_string(static_string&& s);
		~static_string(void) = default;

		static_string& operator=(const char* c);
		static_string& operator=(const static_string& s);
		static_string& operator=(static_string&&) = delete;
	};


	namespace detail{
		std::true_type is_string_helper(string_expr);
		std::false_type is_string_helper(...);
		template<class T>
		struct is_string{
			static constexpr bool value = std::is_same<std::true_type,decltype(is_string_helper(std::declval<T>()))>::value;
		};
		std::true_type is_string_base(string_base*);
		std::false_type is_string_base(...);
		template<class T>
		struct is_concrete_string{
			static constexpr bool value = std::is_same<std::true_type,decltype(is_string_base(std::declval<typename std::decay<T>::type*>()))>::value;
		};
		template<class... Args>
		std::true_type is_tuple_helper(std::tuple<Args...>);
		std::false_type is_tuple_helper(...);
		template<class T>
		struct is_tuple{
			static constexpr bool value = std::is_same<std::true_type,decltype(is_tuple_helper(std::declval<T>()))>::value;
		};

		//check for member function 'length'
		template<class T>
		struct has_len{
			template<class U, class V>
			struct check;

			template<class U>
			static std::true_type test(check<U,decltype(&U::length)>*);
			template<class U>
			static std::false_type test(...);

			static constexpr bool value = std::is_same<std::true_type,decltype(test<T>(0))>::value;
		};
		template<class Targ>
		struct appender
		{
		private:
			Targ& m_targ;
		public:
			appender(Targ& t);
			template<class L, class R>
			void operator()(const string_cat_expr<L,R>& str);
			void operator()(const string_base& str);
		};
	}
}

#include "raii/string_base.tpp"

namespace{
	constexpr inline raii::static_string operator"" _ss(const char* str, size_t len){
		return raii::static_string(str, len);
	}
}
template<class Str1, class Str2, typename std::enable_if<raii::detail::is_concrete_string<Str1>::value&&raii::detail::is_concrete_string<Str2>::value,void>::type* = nullptr>
bool operator==(Str1&& left, Str2&& right){
	return left && right && left.length() == right.length() && !strcmp(left.get(), right.get());
}
template<class Str1, class Str2, typename std::enable_if<raii::detail::is_concrete_string<Str1>::value&&raii::detail::is_concrete_string<Str2>::value,void>::type* = nullptr>
bool operator!=(Str1&& left, Str2&& right){
	return !(left == right);
}

template<class Right, typename std::enable_if<raii::detail::is_string<Right>::value && std::is_rvalue_reference<Right&&>::value,void>::type* = nullptr>
constexpr auto operator+(const char* left, Right&& right){
	return raii::string_cat_expr<raii::static_string,typename std::remove_reference<Right>::type>(raii::static_string(left), std::move(right));
}
template<class Right, typename std::enable_if<raii::detail::is_string<Right>::value && !std::is_rvalue_reference<Right&&>::value,void>::type* = nullptr>
constexpr auto operator+(const char* left, Right&& right){
	return raii::string_cat_expr<raii::static_string,decltype(std::forward<Right>(right))>(raii::static_string(left), std::forward<Right>(right));
}

template<class Left, typename std::enable_if<raii::detail::is_string<Left>::value && std::is_rvalue_reference<Left&&>::value,void>::type* = nullptr>
constexpr auto operator+(Left&& left, const char* right){
	return raii::string_cat_expr<typename std::remove_reference<Left>::type,raii::static_string>(std::move(left), raii::static_string(right));
}
template<class Left, typename std::enable_if<raii::detail::is_string<Left>::value && !std::is_rvalue_reference<Left&&>::value,void>::type* = nullptr>
constexpr auto operator+(Left&& left, const char* right){
	return raii::string_cat_expr<decltype(std::forward<Left>(left)),raii::static_string>(std::forward<Left>(left), raii::static_string(right));
}

template<class Left,
         class Right,
         typename std::enable_if<
         	raii::detail::is_string<Left>::value &&
         	raii::detail::is_string<Right>::value &&
         	std::is_rvalue_reference<Left&&>::value &&
         	std::is_rvalue_reference<Right&&>::value,
         void>::type* = nullptr>
constexpr auto operator+(Left&& l, Right&& r){
	return raii::string_cat_expr<typename std::remove_reference<Left>::type,typename std::remove_reference<Right>::type>(std::move(l), std::move(r));
}
template<class Left,
         class Right,
         typename std::enable_if<
         	raii::detail::is_string<Left>::value &&
         	raii::detail::is_string<Right>::value &&
         	!std::is_rvalue_reference<Left&&>::value &&
         	!std::is_rvalue_reference<Right&&>::value,
         void>::type* = nullptr>
constexpr auto operator+(Left&& l, Right&& r){
	return raii::string_cat_expr<decltype(std::forward<Left>(l)),decltype(std::forward<Right>(r))>(std::forward<Left>(l), std::forward<Right>(r));
}
template<class Left,
         class Right,
         typename std::enable_if<
         	raii::detail::is_string<Left>::value &&
         	raii::detail::is_string<Right>::value &&
         	std::is_rvalue_reference<Left&&>::value &&
         	!std::is_rvalue_reference<Right&&>::value,
         void>::type* = nullptr>
constexpr auto operator+(Left&& l, Right&& r){
	return raii::string_cat_expr<typename std::remove_reference<Left>::type,decltype(std::forward<Right>(r))>(std::move(l), std::forward<Right>(r));
}
template<class Left,
         class Right,
         typename std::enable_if<
         	raii::detail::is_string<Left>::value &&
         	raii::detail::is_string<Right>::value &&
         	!std::is_rvalue_reference<Left&&>::value &&
         	std::is_rvalue_reference<Right&&>::value,
         void>::type* = nullptr>
constexpr auto operator+(Left&& l, Right&& r){
	return raii::string_cat_expr<decltype(std::forward<Left>(l)),typename std::remove_reference<Right>::type>(std::forward<Left>(l), std::move(r));
}

template<class Left, class Right, typename std::enable_if<raii::detail::is_string<Left>::value&&raii::detail::is_string<Right>::value,void>::type* = nullptr>
decltype(auto) operator+=(Left& l, Right&& r){
	return l = (l + std::forward<Right>(r));
}
template<class Left, typename std::enable_if<raii::detail::is_string<Left>::value,void>::type* = nullptr>
decltype(auto) operator+=(Left& l, const char* r){
	return l = (l + r);
}

#ifdef RAII_BINARY_HPP
#include "raii/binary_string_conv.hpp"
#endif

#endif