package edu.ust.cisc;

import org.springframework.objenesis.ObjenesisException;

import java.util.EmptyStackException; import java.util.Iterator; import java.util.*;

public class CiscStack implements CiscCollection{

public static final int DEFAULT_CAPACITY = 10;
private E[] elementData;
private int size;

public CiscStack() {
    this(DEFAULT_CAPACITY);
}

public CiscStack(int initialCapacity) {
    if(initialCapacity < 0){
        throw new IllegalArgumentException();
    }
    elementData = (E[])new Object[initialCapacity];
    size = 0;
}

public E peek(){
    if(isEmpty()){
        throw new EmptyStackException();
    }
    E item = elementData[size-1];
    return item;
}

public E pop(){
   if(isEmpty()){
       throw new EmptyStackException();
   }
   E item = elementData[size - 1];
   elementData[size -  1] = null;
   size--;
   return item;
}

public void push(E item){
}
@Override
public int size() {
    return size;
}

@Override
public boolean isEmpty() {
    return size == 0;
}

@Override
public boolean contains(Object o) {
    for(int i = 0; i<size; i++){
        if(elementData[i].equals(o)){
            return true;
        }
    }
    return false;
}

@Override
public Iterator<E> iterator() {
    return new CiscStackIterator();
}

private class CiscStackIterator implements Iterator<E> {
    private int nextIndex;
    public CiscStackIterator(){
        nextIndex = size - 1;
    }
    @Override
    public boolean hasNext(){
        return nextIndex>=0;
    }
    @Override
    public E next(){
        E element = elementData[nextIndex];
        nextIndex--;
        return element;
    }
}


@Override
public Object[] toArray() {
    Object[] arr = (E[]) new Object[size];
    int arrIndex = 0;
    for(int i = size-1; i>=0; i--){
        arr[arrIndex] = elementData[i];
        arrIndex++;
    }
    return arr;
}

@Override
public void clear() {
    for(int i = 0; i<size; i++) {
        elementData[i] = null;
    }
    size=0;
}
private void ensureCapacity(int capacity) {
    if(elementData.length < capacity){
        if(elementData.length*2+1 < capacity){
            E[] newList = (E[]) new Object[capacity];
            for(int i=0; i<size; i++){
                newList[i] = elementData[i];
            }
            elementData = newList;
        }
        else{
            E[] newList = (E[]) new Object[(elementData.length*2) +1];
            for(int i = 0; i<size; i++){
                newList[i] = elementData[i];
            }
            elementData = newList;
        }
    }
}

}