pragma solidity ^0.8.0;

import "solidity-linked-list/contracts/StructuredLinkedList.sol";

contract MyContract {
    using StructuredLinkedList for StructuredLinkedList.List;

    StructuredLinkedList.List list;

    // your stuff
}

/**
 * @dev Checks if the list exists
 * @param self stored linked list from contract
 * @return bool true if list exists, false otherwise
 */
function listExists(List storage self) internal view returns (bool);

/**
 * @dev Checks if the node exists
 * @param self stored linked list from contract
 * @param _node a node to search for
 * @return bool true if node exists, false otherwise
 */
function nodeExists(List storage self, uint256 _node) internal view returns (bool);

/**
 * @dev Returns the number of elements in the list
 * @param self stored linked list from contract
 * @return uint256
 */
function sizeOf(List storage self) internal view returns (uint256);

/**
 * @dev Returns the links of a node as a tuple
 * @param self stored linked list from contract
 * @param _node id of the node to get
 * @return bool, uint256, uint256 true if node exists or false otherwise, previous node, next node
 */
function getNode(List storage self, uint256 _node) internal view returns (bool, uint256, uint256);

/**
 * @dev Returns the link of a node `_node` in direction `_direction`.
 * @param self stored linked list from contract
 * @param _node id of the node to step from
 * @param _direction direction to step in
 * @return bool, uint256 true if node exists or false otherwise, node in _direction
 */
function getAdjacent(List storage self, uint256 _node, bool _direction) internal view returns (bool, uint256);

/**
 * @dev Returns the link of a node `_node` in direction `_NEXT`.
 * @param self stored linked list from contract
 * @param _node id of the node to step from
 * @return bool, uint256 true if node exists or false otherwise, next node
 */
function getNextNode(List storage self, uint256 _node) internal view returns (bool, uint256);

/**
 * @dev Returns the link of a node `_node` in direction `_PREV`.
 * @param self stored linked list from contract
 * @param _node id of the node to step from
 * @return bool, uint256 true if node exists or false otherwise, previous node
 */
function getPreviousNode(List storage self, uint256 _node) internal view returns (bool, uint256);

/**
 * @dev Can be used before `insert` to build an ordered list.
 * @dev Get the node and then `insertBefore` or `insertAfter` basing on your list order.
 * @dev If you want to order basing on other than `structure.getValue()` override this function
 * @param self stored linked list from contract
 * @param _structure the structure instance
 * @param _value value to seek
 * @return uint256 next node with a value less than _value
 */
function getSortedSpot(List storage self, address _structure, uint256 _value) internal view returns (uint256);

/**
 * @dev Insert node `_new` beside existing node `_node` in direction `_NEXT`.
 * @param self stored linked list from contract
 * @param _node existing node
 * @param _new  new node to insert
 * @return bool true if success, false otherwise
 */
function insertAfter(List storage self, uint256 _node, uint256 _new) internal returns (bool);

/**
 * @dev Insert node `_new` beside existing node `_node` in direction `_PREV`.
 * @param self stored linked list from contract
 * @param _node existing node
 * @param _new  new node to insert
 * @return bool true if success, false otherwise
 */
function insertBefore(List storage self, uint256 _node, uint256 _new) internal returns (bool);

/**
 * @dev Removes an entry from the linked list
 * @param self stored linked list from contract
 * @param _node node to remove from the list
 * @return uint256 the removed node
 */
function remove(List storage self, uint256 _node) internal returns (uint256);

/**
 * @dev Pushes an entry to the head of the linked list
 * @param self stored linked list from contract
 * @param _node new entry to push to the head
 * @return bool true if success, false otherwise
 */
function pushFront(List storage self, uint256 _node) internal returns (bool);

/**
 * @dev Pushes an entry to the tail of the linked list
 * @param self stored linked list from contract
 * @param _node new entry to push to the tail
 * @return bool true if success, false otherwise
 */
function pushBack(List storage self, uint256 _node) internal returns (bool);

/**
 * @dev Pops the first entry from the head of the linked list
 * @param self stored linked list from contract
 * @return uint256 the removed node
 */
function popFront(List storage self) internal returns (uint256);

/**
 * @dev Pops the first entry from the tail of the linked list
 * @param self stored linked list from contract
 * @return uint256 the removed node
 */
function popBack(List storage self) internal returns (uint256);