/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2022, Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <cruft/util/cast.hpp>
#include <cruft/util/bool.hpp>
#include <cruft/util/concepts/string.hpp>
#include <cruft/util/debug/assert.hpp>
#include <cruft/util/parse/value.hpp>

#include <optional>
#include <string>
#include <functional>


namespace cruft::cmdopt2 {
    struct argument_t {
        std::string name;
        std::optional<std::string> description;
        bool required_ = false;

        using acceptor1_t = std::function<void(char const *)>;
        std::optional<acceptor1_t> acceptor1;
    };


    template <typename T>
    concept parseable = std::is_arithmetic_v<T> or std::is_same_v<T, cruft::tribool>;


    template <typename BaseT>
    struct ops_t : argument_t {
        template <typename ValueT>
        requires (!std::is_convertible_v<ValueT, acceptor1_t>)
        BaseT bind (ValueT&&) = delete;

        template <typename ValueT>
        BaseT
        bind (ValueT &ref)
        {
            CHECK (!acceptor1);
            if constexpr (parseable<ValueT>) {
                acceptor1 = [&ref] (char const* str) { ref = parse::from_string<ValueT> (str); };
            } else {
                acceptor1 = [&ref] (char const* str) { ref = str; };
            }
            return get ();
        }

        template <typename ValueT>
        BaseT
        bind (std::optional<ValueT> &ref)
        {
            CHECK (!acceptor1);

            if constexpr (parseable<ValueT>) {
                acceptor1 = [&ref] (char const* str) { ref = parse::from_string<ValueT> (str); };
            } else {
                acceptor1 = [&ref] (char const* str) { ref = str; };
            }

            return get ();
        }

        template <typename ValueT>
        BaseT
        bind (std::vector<ValueT> &ref)
        {
            if (!repeat_)
                throw std::logic_error ("vector argument with non-repeatable argument");

            if constexpr (parseable<ValueT>) {
                acceptor1 = [&ref] (char const* str) {
                    ref.emplace_back (parse::from_string<ValueT> (str));
                };
            } else {
                acceptor1 = [&ref] (char const* str) {
                    ref.emplace_back (str);
                };
            }

            return get ();
        }

        BaseT
        bind (acceptor1_t _acceptor1)
        {
            CHECK (!acceptor1);
            acceptor1 = std::move (_acceptor1);
            return get ();
        }

        BaseT
        get (void) const
        {
            return reinterpret_cast<BaseT const&> (*this);
        }

        BaseT
        acceptor (acceptor1_t _acceptor) const
        {
            BaseT res = get ();
            res.acceptor1 = _acceptor;
            return res;
        }

        bool required (void) const
        {
            return required_;
        }

        BaseT required (bool val) const
        {
            BaseT res = get ();
            res.required_ = val;
            return res;
        }

        bool repeat_;
        BaseT repeat (bool val) const
        {
            BaseT res = get ();
            res.repeat_ = val;
            return res;
        }
    };

    struct positional_t : public ops_t<positional_t> {
        positional_t ignore (void) const;
    };

    positional_t positional (char const *name);
    positional_t positional (std::string_view name);
    positional_t positional (std::string const &name);
    positional_t positional (std::string &&name);


    struct keyword_t : public ops_t<keyword_t> {
        using acceptor0_t = std::function<void(void)>;
        std::optional<acceptor0_t> acceptor0;

        using ops_t::acceptor;
        keyword_t acceptor (acceptor0_t);

        keyword_t ignore (void) const;

        keyword_t flag (void) const;
        keyword_t flag (std::string_view long_) const;
        keyword_t flag (char short_) const;

        keyword_t count   (int  &) const;
        keyword_t present (bool &) const;

        std::optional<char> short_;
        std::optional<std::string> long_;
    };

    keyword_t keyword (char const *name);
    keyword_t keyword (std::string_view name);
    keyword_t keyword (std::string const &name);
    keyword_t keyword (std::string &&name);
}