#ifndef ARGPARSER_SINGLE_ARG_H
#define ARGPARSER_SINGLE_ARG_H

#include <memory>
#include <span>
#include <string>

#include "argument.h"
#include "errors.h"
#include "parse-result.h"
#include "type.h"

namespace argparser {

    template<typename T>
    class single_arg : public arg, public std::enable_shared_from_this<single_arg<T>> {
    public:
        single_arg(std::string name, type_handle_impl<T> type) : arg(std::move(name)), type(type) {}

        [[nodiscard]] T get(const parse_result &pr) const {
            auto v = pr.get_arg(name);
            if (!v.has_value()) {
                throw errors::missing_argument_error(name);
            }
            return std::any_cast<T>(v);
        }

        [[nodiscard]] bool has(const parse_result &pr) const {
            return pr.has_arg(name);
        }

    private:
        type_handle_impl<T> type;

        void do_parse(std::string input, parse_result &pr) const override {
            assert(!pr.get_arg(name).has_value());// a single arg can only be parsed once
            auto val = this->parse_single_value(input, type);
            pr.set_arg(name, std::make_any<T>(val));
        }

        bool get_can_parse_more(parse_result &pr) const override {
            return !pr.get_arg(name).has_value();
        }

        bool get_has_parsed_enough(parse_result &pr) const override {
            return pr.get_arg(name).has_value();
        }
    };

    template<typename T>
    using single_arg_handle = std::shared_ptr<single_arg<T>>;
}// namespace argparser

#endif//ARGPARSER_SINGLE_ARG_H