/**
 *
 * Ashish Patel
 * e: ashishsushilPatel@gmail.com
 * w: https://ashish.me
 *
 */

const StackNode = require('../models/list-node')

class Stack {
  constructor() {
    this.top = null
    this.size = 0
  }

  isEmpty() {
    return this.top === null
  }

  length() {
    return this.size
  }

  pop() {
    if (!this.isEmpty()) {
      let result = this.top.data
      this.top = this.top.next
      this.size -= 1
      return result
    }
  }

  push(value) {
    if (this.isEmpty()) {
      let node = new StackNode(value)
      this.top = node
    } else {
      let node = new StackNode(value)
      node.next = this.top
      this.top = node
    }
    this.size += 1
  }

  peek() {
    return this.top.data
  }
}

const log = console.log
let stack = new Stack()
stack.push(2)
stack.push(10)
log(stack.peek())
stack.pop()
log(stack.peek())

// test('linked List Stack', () => {
//   expect(linkedListStack('Ashish')).toEqual('Ashish')
// });