doublyLinkedList.js

const Table = require('cli-table2');
const chalk = require('chalk');

class Node {
    constructor(data) {
        this.data = data;
        this.next = null;
        this.prev = null;
    }
}

class DoublyLinkedList {
    constructor() {
        this.head = null;
        this.tail = null;
    }

    append(item) {
        let node = new Node(item);

        if (!this.head) {
            this.head = node;
            this.tail = node;
        } else {
            node.prev = this.tail;
            this.tail.next = node;
            this.tail = node
        }
    }

    appendAt(pos, item) {
        let current = this.head;
        let counter = 1;
        let node = new Node(item);
        if (pos == 0) {
            this.head.prev = node
            node.next = this.head
            this.head = node
        } else {
            while (current) {
                current = current.next;
                if (counter == pos) {
                    node.prev = current.prev
                    current.prev.next = node
                    node.next = current
                    current.prev = node
                }
                counter++
            }
        }
    }

    appendAfter(item) {
        // 
    }

    remove(item) {
        let current = this.head;
        while (current) {
            if (current.data === item) {
                if (current == this.head && current == this.tail) {
                    this.head = null;
                    this.tail = null;
                } else if (current == this.head) {
                    this.head = this.head.next
                    this.head.prev = null
                } else if (current == this.tail) {
                    this.tail = this.tail.prev;
                    this.tail.next = null;
                } else {
                    current.prev.next = current.next;
                    current.next.prev = current.prev;
                }
            }
            current = current.next
        }
    }

    removeAt(pos) {
        let current = this.head;
        let counter = 1;
        if (pos == 0) {
            this.head = this.head.next;
            this.head.prev = null;
        } else {
            while (current) {
                current = current.next
                if (current == this.tail) {
                    this.tail = this.tail.prev;
                    this.tail.next = null;
                } else if (counter == pos) {
                    current.prev.next = current.next;
                    current.next.prev = current.prev;
                    break;
                }
                counter++;
            }
        }
    }

    reverse() {
        let current = this.head;
        let prev = null;
        while (current) {
            let next = current.next
            current.next = prev
            current.prev = next
            prev = current
            current = next
        }
        this.tail = this.head
        this.head = prev
    }

    swap(nodeOne, nodeTwo) {
        let current = this.head;
        let counter = 0;
        let firstNode;

        // Make sure we are okay to go
        if (nodeOne === nodeTwo) {
            console.log("ERROR: 'SWAP' both the nodes must be different!");
            return false;
        } else if (nodeOne > nodeTwo) {
            let temp = nodeOne;
            nodeOne = nodeTwo;
            nodeTwo = temp;
        }

        if (nodeOne < 0 || nodeTwo < 0) {
            console.log("ERROR: 'SWAP' both the nodes must be index & index can not be negative!");
            return false;
        }

        // Swap nodes
        while (current !== null) {
            if (counter == nodeOne) {
                firstNode = current;
            } else if (counter == nodeTwo) {
                let temp = current.data;
                current.data = firstNode.data;
                firstNode.data = temp;
            }
            current = current.next;
            counter++;
        }
        return true
    }

    length() {
        let current = this.head;
        let counter = 0;
        while (current !== null) {
            counter++
            current = current.next
        }
        return counter;
    }

    display() {
        let current = this.head;
        let elements = [];
        while (current !== null) {
            elements.push(current.data);
            current = current.next
        }
        return elements.join(" ");
    }

    isEmpty() {
        return this.length() < 1
    }

    traverse(fn) {
        if (!fn || typeof fn !== 'function') {
            console.log("ERROR: 'TRAVERSE' function is undefined!");
            return false;
        }
        let current = this.head;
        while (current !== null) {
            fn(current)
            current = current.next;
        }
        return true;
    }

    traverseReverse(fn) {
        if (!fn || typeof fn !== 'function') {
            console.log("ERROR: 'TRAVERSE_REVERSE' function is undefined!");
            return false;
        }
        let current = this.tail;
        while (current !== null) {
            fn(current)
            current = current.prev;
        }
        return true;
    }

    search(item) {
        let current = this.head;
        let counter = 0;

        while (current) {
            if (current.data == item) {
                return counter
            }
            current = current.next
            counter++
        }
        return false;
    }

	/* 
	* 	EXTRA 
	*/
    prettyPrint() {
        let current = this.head;
        let output = [chalk.red('Head') + ' ->'];
        while (current !== null) {
            output.push(chalk.cyan(current.data));
            current = current.next;
        }
        output.push('<- ' + chalk.red('Tail'));
        this.table(output);
        return true;
    }	// </ PrettyPrint>

    table(output) {
        let table = new Table({
            chars: {
                'top': '─', 'top-mid': '╤', 'top-left': '╔', 'top-right': '╗'
                , 'bottom': '─', 'bottom-mid': '╧', 'bottom-left': '╚', 'bottom-right': '╝'
                , 'left': '│', 'left-mid': '╟', 'mid': '─', 'mid-mid': '┼'
                , 'right': '│', 'right-mid': '╢', 'middle': '│'
            },
            style: { border: ['yellow'] }
        });
        table.push(output);
        console.log(table.toString());
        return true
    } // </ Table>
}

module.exports = DoublyLinkedList