DLL

import { inheritLeadingComments } from '../../../../../../Library/Caches/typescript/4.9/node_modules/@babel/types/lib/index.js';
import LinkedListNode from './linked-list-node.js';

export default class DoublyLinkedList {
    #head =null
    #tail =null
    #count = 0

    addFirst(value) {
      const node = new LinkedListNode(value);
      if(!this.#head){
         this.#head=node;
         this.#tail = node;
      } else {
      node.next = this.#head;
      this.#head.prev = node;
      this.#head = node;
      }
      this.#count++;
    }

    addLast(value) {
      const node = new LinkedListNode(value);
      if(!this.#head) {
         this.#head = node;
      } else {
         this.#tail.next = node;
         node.prev = this.#tail;
      }
      this.#tail = node;
      this.#count++;
    }

    removeFirst(){
      if(!this.#head){
         throw new Error('No head');
      }
      if(this.count === 1){
         const val = this.#head.value;
         this.#head = null;
         this.#tail = null;
         this.#count--;
         return val;
      } else {
      const val = this.#head.value;
      this.#head = this.#head.next;
      this.#head.prev = null;
      this.#count--;
      return val;
      }
    }

    removeLast() {
      if(!this.#tail){
         throw new Error('No tail');
      }
      if(this.count === 1){
         const val = this.#tail.value;
         this.#head = null;
         this.#tail = null;
         this.#count--;
         return val;
      } else {
         const val = this.#tail.value;
         this.#tail.prev.next = null;
         this.#count--;
         return val;
      }
    }

    values() {
      let result = [];
      while(this.#head){
         result.push(this.#head.value);
         this.#head = this.#head.next;
      }
      return result;
    }

    insertAfter(node, val) {
      const newNode = new LinkedListNode(val);
      if(node === this.#tail){
         this.#tail.next = newNode;
         newNode.prev = this.#tail;
         this.#tail = newNode;
         this.#count++;
      } else {
      node.next.prev = newNode;
      newNode.prev = node;
      newNode.next = node.next;
      node.next = newNode;
      this.#count++;
      }
    }
    insertBefore(node,val){
      const newNode = new LinkedListNode(val);
      if(node === this.#head){
         newNode.next = this.#head;
         this.#head.prev = newNode;
         this.#head = newNode;
         this.#count++;
      } else {
      node.prev.next = newNode;
      newNode.next = node;
      node.prev = newNode;
      this.#count++;
      }

    }
    find(val) {
      let ref = this.#head;
      while(ref){
         if(ref.value === val) {
            return ref;
         }
         ref = ref.next;
      }
      return null;

    }

    valuesRev () { //gives the values in reverse order to check the validity of refrences.
      let result = [];
      while(this.#tail){
         result.push(this.#tail.value);
         this.#tail = this.#tail.prev;
      }
      return result;
    }

    get count() {
      return this.#count;
    }
    get head() {
      return this.#head;
    }
    get tail() {
      return this.#tail;
    }
}