#ifndef ARGPARSER_SINGLE_OPT_H
#define ARGPARSER_SINGLE_OPT_H

#include <cassert>
#include <format>
#include <memory>
#include <optional>
#include <string>

#include "option.h"
#include "parse-result.h"
#include "type.h"

namespace argparser {

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

        std::shared_ptr<option_impl<T>> required() {
            required_ = true;
            return this->shared_from_this();
        }

        std::shared_ptr<option_impl<T>> default_value(T val) {
            this->default_value_ = val;
            this->has_default_value = true;
            return this->shared_from_this();
        }

        void validate(const parse_result &res) const override {
            if (this->required_) {
                if (!res.has_opt(this->name)) {
                    throw errors::missing_option_error(this->name);
                }
            }
        }

        [[nodiscard]] bool consumes_value() const override {
            return true;
        }

        [[nodiscard]] T get(const parse_result &pr) const {
            auto v = pr.get_opt(name);
            if (!v.has_value()) {
                if (has_default_value) {
                    return default_value_;
                }
                throw std::runtime_error(std::format("option {} was not provided", name));
            }
            return std::any_cast<T>(v);
        }

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

    private:
        void do_parse(std::optional<std::string> arg, std::any &val) override {
            assert(arg.has_value());
            const char *parse_end;
            auto begin = &*arg->begin();
            auto end = &*arg->end();
            val = this->type->parse(begin, end, parse_end, internal::parser_allow_undelimited::Any);
            if (parse_end != end) {
                throw errors::type_parsing_error(this->type->get_name(), std::string(begin, end), parse_end - begin, "unexpected input");
            }
        }

        type_handle_impl<T> type;

        bool required_ = false;

        bool has_default_value = false;
        T default_value_;
    };

    template<typename T>
    using option_handle_impl = std::shared_ptr<option_impl<T>>;

}// namespace argparser

#endif//ARGPARSER_SINGLE_OPT_H