package calculator;
import java.util.Scanner;

public class CustomArrayList {
    private Object[] arr;
    private int count;
    private static final int INITIAL_CAPACITY = 4;

    /** Initializes the array-based list – allocate memory **/

    public CustomArrayList() {
        arr = new Object[INITIAL_CAPACITY];
        count = 0;
    }
    /**
     * @return the actual list length
     */

    public int getLength() {
        return count;
    }

/**
 * Adds element to the list
 * @param item - the element you want to add
 */

public void add(Object item) {
    add(count, item);
}

/**
 * Inserts the specified element at given position in this list
 * @param index - index at which the specified element is to be inserted
 * @param item - element to be inserted
 * @throws IndexOutOfBoundsException
 */

public void add(int index, Object item) {
    if (index>count || index<0) {
        throw new IndexOutOfBoundsException(
            "Invalid index: " + index);
    }

    Object[] extendedArr = arr;
    if (count + 1 == arr.length) {
        extendedArr = new Object[arr.length * 2];
    }

    System.arraycopy(arr, 0, extendedArr, 0, index);
    count++;
    System.arraycopy(
        arr, index, extendedArr, index+1, count-index-1);
    extendedArr[index] = item;
    arr = extendedArr;
	}

/**
 * Returns the index of the first occurrence of the specified element in this list.
 * @param item - the element you are searching
 * @return the index of given element or -1 is not found
 */

public int indexOf(Object item) {
    if (item == null) {
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == null)
                return i;
        }
    } else {
        for (int i = 0; i < arr.length; i++)
            if (item.equals(arr[i]))
                return i;
    }
    return -1;
}

/**
 * Clears the list
 */

public void clear() {
    arr = new Object[0];
    count = 0;
}

/**
 * Checks if an element exists
 * @param item – the item to be checked
 * @return if the item exists
 */

public boolean contains(Object item) {
    int index = indexOf(item);
    boolean found = (index != -1);
    return found;
}

/**
 * @return the object on given position
 */

public Object elementAt(int index) {
    if (index>=count || index<0) {
        throw new IndexOutOfBoundsException(
            "Invalid index: " + index);
    }
    return arr[index];
	}
/**
 * Removes the element at the specified index
 * @param index - the index, whose element you want to remove
 * @return the removed element
 */

public Object remove(int index) {
    if (index>=count || index<0) {
        throw new IndexOutOfBoundsException(
            "Invalid index: " + index);
    }

    Object item = arr[index];
    System.arraycopy(arr, index+1, arr, index, count-index+1);
    arr[count - 1] = null;
    count--;
    return item;
}

/**
 * Removes the specified item and returns its index or -1
 * if item does not exists
 * @param item - the item you want to remove
*/

public int remove(Object item) {
    int index = indexOf(item);
    if (index == -1) {
        return index;
    }

    System.arraycopy(arr, index+1, arr, index, count-index+1);
    count--;
    return index;

}
public static void main(String[] args){

	Scanner scan = new Scanner(System.in);

    CustomArrayList shoppingList = new CustomArrayList();
    shoppingList.add("Milk");
    shoppingList.add("Honey");
    shoppingList.add("Olives");
    shoppingList.add("Beer");
    shoppingList.remove("Olives");
    while(true) {
    	System.out.println("What do you want to do?\n 1.Add Element \n 2.Remove Element \n 3.End Program");
    	String question = scan.nextLine().toLowerCase();

    	if(question.equals("add")){
    		String product = scan.nextLine();
    		if(shoppingList.contains(product)) {
     		   System.out.println("This element is alreadt in");
     	   }else{
     		   System.out.println("add element");
     		   shoppingList.add(product);
        }
      }
    	else if(question.equals("remove")) {
      	  String product  = scan.nextLine();
      	   if(shoppingList.contains(product)) {
      		   System.out.println("remove element");
      		   shoppingList.remove(product);
      	   }else{
      		   System.out.println("This element is missing ");

      	   }
         }
    	else if(question.equals("end")) {
     	   System.out.println("the program is off");
     	   break;
        }else{
         	System.out.println("wrong command");
         }
    	for(int i=0; i<shoppingList.getLength(); i++) {
			System.out.println(shoppingList.elementAt(i));
    	}
    	}

  }
}