import EmptyStackException from './EmptyStackException'
import List from './List'

/**
 * @see http://download.oracle.com/javase/6/docs/api/java/util/Stack.html
 *
 * @extends {List}
 * @constructor
 * @private
 */
export default function Stack () {
  /**
   * @type {Array}
   * @private
   */
  this.array_ = []
};
Stack.prototype = new List()

/**
 * @override
 */
Stack.prototype.add = function (e) {
  this.array_.push(e)
  return true
}

/**
 * @override
 */
Stack.prototype.get = function (index) {
  if (index < 0 || index >= this.size()) {
    throw new Error()
  }

  return this.array_[index]
}

/**
 * Pushes an item onto the top of this stack.
 * @param {Object} e
 * @return {Object}
 */
Stack.prototype.push = function (e) {
  this.array_.push(e)
  return e
}

/**
 * Pushes an item onto the top of this stack.
 * @param {Object} e
 * @return {Object}
 */
Stack.prototype.pop = function (e) {
  if (this.array_.length === 0) {
    throw new EmptyStackException()
  }

  return this.array_.pop()
}

/**
 * Looks at the object at the top of this stack without removing it from the
 * stack.
 * @return {Object}
 */
Stack.prototype.peek = function () {
  if (this.array_.length === 0) {
    throw new EmptyStackException()
  }

  return this.array_[this.array_.length - 1]
}

/**
 * Tests if this stack is empty.
 * @return {boolean} true if and only if this stack contains no items; false
 *         otherwise.
 */
Stack.prototype.empty = function () {
  if (this.array_.length === 0) {
    return true
  } else {
    return false
  }
}

/**
 * @return {boolean}
 */
Stack.prototype.isEmpty = function () {
  return this.empty()
}

/**
 * Returns the 1-based position where an object is on this stack. If the object
 * o occurs as an item in this stack, this method returns the distance from the
 * top of the stack of the occurrence nearest the top of the stack; the topmost
 * item on the stack is considered to be at distance 1. The equals method is
 * used to compare o to the items in this stack.
 *
 * NOTE: does not currently actually use equals. (=== is used)
 *
 * @param {Object} o
 * @return {number} the 1-based position from the top of the stack where the
 *         object is located; the return value -1 indicates that the object is
 *         not on the stack.
 */
Stack.prototype.search = function (o) {
  return this.array_.indexOf(o)
}

/**
 * @return {number}
 * @export
 */
Stack.prototype.size = function () {
  return this.array_.length
}

/**
 * @return {Array}
 */
Stack.prototype.toArray = function () {
  var array = []

  for (var i = 0, len = this.array_.length; i < len; i++) {
    array.push(this.array_[i])
  }

  return array
}