#pragma once

#include <QString>
#include <QList>
#include <iostream>
#include <functional>
#include "data_types.h"


namespace validate {
	template<typename T> class Validator {
	public:
		virtual bool check(T value) const {
			return false;
		}
		virtual void getDepict(datas::IDataObject& self_description) { }
	};
	template<typename T> class ValidatorReceiver {
	public:
		virtual void append(Validator<T> inst) { }
	};




	template<typename... args_type> struct ValidateTemplet;
	template<> struct ValidateTemplet<> { };
	template<typename head_type, typename... rest_type>
	struct ValidateTemplet<head_type, rest_type...> : public ValidateTemplet<rest_type...> {
	private:
		QList<Validator<head_type>> validator_list;

	public:
		void add(Validator<head_type> vinst) {
			validator_list << vinst;
		}
		bool check(head_type value) {
			for (auto u : validator_list)
				if (!u.check(value))
					return false;
			return true;
		}
	};




	template<int idx, typename... args_type> struct ElmPos;

	template<typename head_type, typename... rest_type>
	struct ElmPos<0, ValidateTemplet<head_type, rest_type...>> {
		using value_type = head_type;
		using templet_type = ValidateTemplet<head_type, rest_type...>;
	};
	template<int idx, typename head_type, typename... rest_type>
	struct ElmPos<idx, ValidateTemplet<head_type, rest_type...>> {
		using value_type = typename ElmPos<idx - 1, ValidateTemplet<rest_type...>>::value_type;
		using templet_type = typename ElmPos<idx - 1, ValidateTemplet<rest_type...>>::templet_type;
	};

	template<int idx, typename head_type, typename... rest_type>
	void __validator_insert_helper(ValidateTemplet<head_type, rest_type...>& target,
		Validator<typename ElmPos<idx, ValidateTemplet<head_type, rest_type...>>::value_type> inst) {
		using templet_type = typename ElmPos<idx, ValidateTemplet<head_type, rest_type...>>::templet_type;
		target.templet_type::add(inst);
	}




	template<int n, typename... args_type> class SlicePosition;

	template<typename S, typename T> class SliceValidator : public Validator<S> {
	private:
		std::function<T(S)> _proc_conv;
		Validator<T> _sub_validator;

	public:
		SliceValidator(std::function<T(S)> proc, Validator<T> vinst)
			: _proc_conv(proc), _sub_validator(vinst) { }

		virtual bool check(S value) const {
			auto t_value = _proc_conv(value);
			return _sub_validator.check(t_value);
		}
	};
	template<int n, typename... args_type> class ArgsPosition
		: public ValidatorReceiver<typename ElmPos<n, ValidateTemplet<args_type...>>::value_type> {
	public:
		using param_type = typename ElmPos<n, ValidateTemplet<args_type...>>::value_type;

		ArgsPosition(ValidateTemplet<args_type...>& target) :_templet_bind(target) { }

		ArgsPosition<n, args_type...>& operator&(Validator<param_type> vinst) {
			append(vinst);
			return *this;
		}

		template<typename slice_type>
		SlicePosition<n, param_type, slice_type, ArgsPosition<n, args_type...>>
			slice(std::function<slice_type(param_type)> slice_fun) {
			return SlicePosition<n, param_type, slice_type, ArgsPosition<n, args_type...>>(*this, slice_fun);
		}

		// ValidatorReceiver
		virtual void append(Validator<param_type> inst) {
			__validator_insert_helper<n, args_type...>(_templet_bind, inst);
		}

	private:
		ValidateTemplet<args_type...>& _templet_bind;
	};
	template<int n, typename s_type, typename t_type, typename... args_type>
	class SlicePosition<n, s_type, t_type, ArgsPosition<n, args_type...>> : public ValidatorReceiver<t_type> {
	public:
		SlicePosition(ValidatorReceiver<s_type>& host, std::function<t_type(s_type)> func)
			:_conv_func(func), _prev_bind(host) { }

		SlicePosition<n, s_type, t_type, ArgsPosition<n, args_type...>>& operator&(Validator<t_type> vinst) {
			append(vinst);
			return *this;
		}

		template<typename slice_type>
		SlicePosition<n, t_type, slice_type, ArgsPosition<n, args_type...>>
			slice(std::function<slice_type(t_type)> slice_fun) {
			return SlicePosition<n, t_type, slice_type, ArgsPosition<n, args_type...>>(*this, slice_fun);
		}

		// ValidatorReceiver
		virtual void append(Validator<t_type> inst) {
			SliceValidator<s_type, t_type> mid_validator(_conv_func, inst);
			_prev_bind.append(mid_validator);
		}

	private:
		std::function<t_type(s_type)> _conv_func;
		ValidatorReceiver<s_type>& _prev_bind;
	};




	template<void* func, typename... types> struct ValidateHelper;
	template<void* func, typename return_type, typename... args_type>
	struct ValidateHelper<func, return_type, args_type...> : public ValidateTemplet<args_type...> {
		template<int n> ArgsPosition<n, args_type...> pos() {
			return ArgsPosition<n, args_type...>(*this);
		}
	};

}