/*
 * 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 2020, Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <iterator>

namespace cruft::iterator {
    ///////////////////////////////////////////////////////////////////////////
    /// An iterator that converts the value_type of an underlying iterator to
    /// a requested type.
    template <typename ValueT, typename IteratorT>
    class cast {
    public:
        cast (IteratorT _inner)
            : m_inner (_inner)
        { ; }

        using iterator_category = typename std::iterator_traits<IteratorT>::iterator_category;
        using value_type = ValueT;
        using difference_type = typename std::iterator_traits<IteratorT>::difference_type;
        using pointer = value_type*;
        using reference = value_type&;

        class wrapper {
        public:
            using inner_value     = typename std::iterator_traits<IteratorT>::value;
            using inner_pointer   = typename std::iterator_traits<IteratorT>::pointer;
            using inner_reference = typename std::iterator_traits<IteratorT>::reference;

            reference
            operator= (ValueT const &val)
            {
                _value = static_cast<inner_value> (val);
                return _value;
            }

            reference operator= (ValueT &&val)
            {
                _value = static_cast<inner_value> (val);
            }

            inner_pointer
            operator-> ()
            { return &_value; }

        private:
            inner_reference _value;
        };


        wrapper operator*  (void) { return wrapper (*m_inner); };
        wrapper operator-> (void) { return wrapper (*m_inner); };

        cast& operator++ (void)
        {
            ++m_inner;
            return *this;
        }

    private:
        IteratorT m_inner;
    };
}