#pragma once

#include <hpr/container/dynamic_array.hpp>

#include <memory>


namespace hpr
{

    template <typename Type>
    class TreeNode
    {

    public:

        using value_type = Type;
        using pointer = Type*;
        using reference = Type&;
        using const_pointer = Type const*;
        using const_reference = Type const&;

    protected:

        pointer p_data;

        darray<TreeNode*> p_descendants;
        TreeNode* p_ancestor;

    public:

        friend constexpr
        void swap(TreeNode& main, TreeNode& other) noexcept
        {
            using std::swap;
            swap(main.p_data, other.p_data);
            swap(main.p_descendants, other.p_descendants);
            swap(main.p_ancestor, other.p_ancestor);
        }

        inline
        TreeNode() :
            p_data {new value_type {}},
            p_descendants {},
            p_ancestor {}
        {}

        inline
        TreeNode(const TreeNode& node) :
            p_data {new value_type {*node.p_data}},
            p_descendants {},
            p_ancestor {}
        {}

        inline
        TreeNode(TreeNode&& node)  noexcept :
            p_data {},
            p_descendants {},
            p_ancestor {}
        {
            swap(*this, node);
            /*std::swap(p_data, node.p_data);
            std::swap(p_descendants, node.p_descendants);
            std::swap(p_ancestor, node.p_ancestor);*/
        }

        inline
        TreeNode& operator=(TreeNode other)
        {
            swap(*this, other);
            return *this;
        }

        inline explicit
        TreeNode(const value_type& data) :
            p_data {new value_type {data}},
            p_descendants {},
            p_ancestor {}
        {}

        inline
        TreeNode(const value_type& data, const darray<TreeNode*>& descendants, TreeNode* ancestor) :
            p_data {new value_type {data}},
            p_descendants {descendants},
            p_ancestor {ancestor}
        {
            for (auto descendant : p_descendants)
                descendant->ancestor(this);
        }

        inline
        TreeNode(const value_type& data, const darray<TreeNode*>& descendants) :
            p_data {new value_type {data}},
            p_descendants {descendants},
            p_ancestor {}
        {
            for (auto descendant : p_descendants)
                descendant->ancestor(this);
        }

        virtual
        ~TreeNode()
        {
            delete p_data;
            //delete p_ancestor;
        }

        // Member functions

        inline
        pointer data()
        {
            return p_data;
        }

        inline
        void ancestor(TreeNode* node)
        {
            p_ancestor = node;
        }

        inline
        TreeNode* ancestor()
        {
            return p_ancestor;
        }

        inline
        void descendants(const darray<TreeNode*>& descendants)
        {
            p_descendants = descendants;
        }

        inline
        darray<TreeNode*>& descendants()
        {
            return p_descendants;
        }

        darray<TreeNode*> traverse_descendants()
        {
            std::function<darray<TreeNode*>(TreeNode*)> collect = [&](TreeNode* node)
            {
                darray<TreeNode*> ds;

                if (!node->descendants().is_empty())
                {
                    for (TreeNode* dnode: node->descendants())
                    {
                        ds.push(dnode);
                        if (!dnode->descendants().is_empty())
                            ds.push(collect(dnode));
                    }
                }

                return ds;
            };

            return collect(this);
        }

        darray<TreeNode*> traverse_ancestors()
        {
            std::function<darray<TreeNode*>(TreeNode*)> collect = [&](TreeNode* node)
            {
                darray<TreeNode*> ds;

                if (node->p_ancestor)
                {
                    ds.push(node);
                    ds.push(collect(node->p_ancestor));
                }

                return ds;
            };

            return collect(this);
        }
    };

} // end namespace hpr