Linked List

"""Модуль связного списка"""


class LinkedListItem:
    """Узел связного списка"""

    def __init__(self, data=None):
        self.content = data
        self.next_item = None
        self.previous_item = None

    @property
    def next_item(self):
        """Следующий элемент"""
        return self._next

    @next_item.setter
    def next_item(self, value):
        self._next = value
        if value is not None and value.previous_item != self:
            value.previous_item = self

    @property
    def previous_item(self):
        """Предыдущий элемент"""
        return self._previous

    @previous_item.setter
    def previous_item(self, value):
        self._previous = value
        if value is not None and value.next_item != self:
            value.next_item = self

    def __repr__(self):
        return str(self.content)


class LinkedList:
    """Связный список"""

    def __init__(self, *args):
        self.first_item = None
        if len(args) > 0:
            self.append(*args)

    @property
    def last(self):
        """Последний элемент"""
        if self.first_item is None:
            return None
        return self.first_item.previous_item.content

    def append_left(self, item):
        """Добавление слева"""
        list_item = LinkedListItem(item)
        if self.first_item is None:
            self.first_item = list_item
            list_item.next_item = list_item
        else:
            self.first_item.previous_item = list_item
            self.first_item = list_item
        return self

    def append_right(self, item):
        """Добавление справа"""
        list_item = LinkedListItem(item)
        if self.first_item is None:
            self.first_item = list_item
            list_item.next_item = list_item
        else:
            self.first_item.previous_item.next_item = list_item
            self.first_item.previous_item = list_item
        return self

    def append(self, *args):
        """Добавление справа"""
        for item in args:
            self.append_right(item)
        return self

    def remove(self, item):
        """Удаление первого вхождения"""
        if self.first_item is None:
            raise ValueError("List is empty")

        flag = True
        for current_item in self:
            if current_item.content == item:
                flag = False
                if current_item.next_item == current_item:
                    self.first_item = None
                else:
                    if current_item == self.first_item:
                        self.first_item = current_item.next_item
                    current_item.previous_item.next_item = current_item.next_item
                    current_item.next_item.previous_item = current_item.previous_item
                    break
        if flag:
            raise ValueError("Item not found")
        return self

    def insert(self, previous, item):
        """Вставка справа от первого вхождения"""
        if self.first_item is None:
            self.append(item)
        else:
            for current_item in self:
                if current_item.content == previous:
                    list_item = LinkedListItem(item)
                    list_item.next_item = current_item.next_item
                    list_item.previous_item = current_item
                    current_item.next_item = list_item
                    break
        return self

    def __len__(self):
        count = 0
        current_item = self.first_item
        while current_item is not None:
            count += 1
            current_item = current_item.next_item
            if current_item == self.first_item:
                break
        return count

    def __iter__(self):
        current_item = self.first_item
        while current_item is not None and self.first_item is not None:
            yield current_item
            current_item = current_item.next_item
            if current_item == self.first_item:
                break

    def __getitem__(self, index: int):
        if index < 0:
            index = len(self) + index
        if index < 0 or index >= len(self):
            raise IndexError("Index out of range")

        current_index = 0
        current_item = self.first_item
        while current_index != index:
            current_item = current_item.next_item
            current_index += 1
            if current_item == self.first_item:
                break

        return current_item.content

    def __contains__(self, item):
        for current_item in self:
            if current_item.content == item:
                return True
        return False

    def __repr__(self):
        return str(self)

    def __str__(self):
        string_list = []
        for item in self:
            string_list.append(str(item))
        return '[' + ', '.join(string_list) + ']'