/*
	This file is part of Fennix Kernel.

	Fennix Kernel is free software: you can redistribute it and/or
	modify it under the terms of the GNU General Public License as
	published by the Free Software Foundation, either version 3 of
	the License, or (at your option) any later version.

	Fennix Kernel is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
*/

#pragma once

#include <types.h>
#include <stdexcept>

namespace std
{
	template <typename T>
	class list
	{
	private:
		struct lNode
		{
			T value;
			lNode *prev;
			lNode *next;

			lNode(const T &v, lNode *p = nullptr, lNode *n = nullptr)
				: value(v), prev(p), next(n) {}
		};

		lNode *head;
		lNode *tail;
		size_t size;

	public:
		list() : head(nullptr), tail(nullptr), size(0) {}
		~list() { clear(); }
		list(const list &other) : head(nullptr), tail(nullptr), size(0) { *this = other; }

		void push_back(const T &value)
		{
			lNode *new_node = new lNode(value, tail, nullptr);
			if (empty())
			{
				head = tail = new_node;
			}
			else
			{
				tail->next = new_node;
				tail = new_node;
			}
			++size;
		}

		void pop_back()
		{
			if (empty())
			{
				throw std::runtime_error("list is empty");
			}
			else if (head == tail)
			{
				delete tail;
				head = tail = nullptr;
				--size;
			}
			else
			{
				lNode *old_tail = tail;
				tail = tail->prev;
				tail->next = nullptr;
				delete old_tail;
				--size;
			}
		}

		void push_front(const T &value)
		{
			lNode *new_node = new lNode(value, nullptr, head);
			if (empty())
			{
				head = tail = new_node;
			}
			else
			{
				head->prev = new_node;
				head = new_node;
			}
			++size;
		}

		void pop_front()
		{
			if (empty())
			{
				throw std::runtime_error("list is empty");
			}
			else if (head == tail)
			{
				delete head;
				head = tail = nullptr;
				--size;
			}
			else
			{
				lNode *old_head = head;
				head = head->next;
				head->prev = nullptr;
				delete old_head;
				--size;
			}
		}

		bool empty() const { return size == 0; }

		void clear()
		{
			while (!empty())
				pop_back();
		}

		list &operator=(const list &other)
		{
			if (this != &other)
			{
				clear();
				for (const T &value : other)
				{
					push_back(value);
				}
			}
			return *this;
		}

		class iterator
		{
		private:
			lNode *node;
			friend class list;

		public:
			iterator(lNode *p = nullptr) : node(p) {}
			T &operator*() const { return node->value; }
			T *operator->() const { return &node->value; }

			iterator &operator++()
			{
				node = node->next;
				return *this;
			}

			iterator &operator--()
			{
				node = node->prev;
				return *this;
			}

			iterator operator++(int)
			{
				iterator tmp = *this;
				++*this;
				return tmp;
			}

			iterator operator--(int)
			{
				iterator tmp = *this;
				--*this;
				return tmp;
			}

			bool operator==(const iterator &rhs) const { return node == rhs.node; }
			bool operator!=(const iterator &rhs) const { return node != rhs.node; }
		};

		iterator begin() { return iterator(head); }
		iterator end() { return iterator(nullptr); }

		iterator insert(iterator pos, const T &value)
		{
			if (pos == end())
			{
				push_back(value);
				return iterator(tail);
			}
			else if (pos == begin())
			{
				push_front(value);
				return iterator(head);
			}
			else
			{
				lNode *p = pos.node;
				lNode *new_node = new lNode(value, p->prev, p);
				p->prev->next = new_node;
				p->prev = new_node;
				++size;
				return iterator(new_node);
			}
		}

		iterator erase(iterator pos)
		{
			lNode *p = pos.node;
			iterator next(p->next);
			p->prev->next = p->next;
			p->next->prev = p->prev;
			delete p;
			--size;
			return next;
		}
	};
}