// Allison Obourn
// CSE 143 - lecture 3
// An ArrayIntList stores an ordered list of integers.
// Today's version:
// * adds the remove method
// * adds error check for index parameters using the private checkIndex method
// * adds a second constructor to specify a size
// * reduces redundancy by having one add method call the other
import java.util.*;

public class ArrayIntList {
   private int size;
   private int[] elementData;
   
   public static final int DEFAULT_CAPACITY = 10;

   // Initializes a new empty list with the default capacity.
   public ArrayIntList() {
      this(DEFAULT_CAPACITY);
   }
   
   // Initializes a new empty list with the specified initial capacity.
   // Pre: capacity > 0, throws IllegalArgumentException otherwise
   public ArrayIntList(int capacity) {
      if (capacity <= 0) {
         throw new IllegalArgumentException("capacity must be positive: " + capacity);
      }
      size = 0; // optional; size is initialized to 0 by default
      elementData = new int[capacity];
   }
   
   // Returns the number of elements in the list.
   public int size() {
      return size;
   }

   // Returns true if the list does not contain any elements.
   public boolean isEmpty() {
      return size == 0; // "boolean zen"
   }
   
   // Adds the given value to the end of the list.
   public void add(int value) {
      add(size, value);
   }
   
   // Inserts the given value into the list at the given index.
   // Pre: 0 <= index <= size, throws IndexOutOfBoundsException otherwise
   public void add(int index, int value) {
      checkIndex(index, 0, size); // ok to add at size (end of list)
      ensureCapacity(size + 1);
      for (int i = size; i > index; i--) {
         elementData[i] = elementData[i - 1];
      }
      elementData[index] = value;
      size++;
   }
   
   // Removes the value at the given index.
   // Pre: 0 <= index < size, throws IndexOutOfBoundsException otherwise
   public void remove(int index) {
      checkIndex(index, 0, size - 1);
      for(int i = index; i < size - 1; i++) {
         elementData[i] = elementData[i + 1];
      }
      size--;
   }
   
   // Returns the value at the given index.
   // Pre: 0 <= index < size, throws IndexOutOfBoundsException otherwise
   public int get(int index) {
      checkIndex(index, 0, size - 1);
      return elementData[index];
   }

   // Sets the given index to store the given value.
   // Pre: 0 <= index < size, throws IndexOutOfBoundsException otherwise
   public void set(int index, int value) {
      checkIndex(index, 0, size - 1);
      elementData[index] = value;
   }
   
   // Returns a String representation of the list consisting of the elements
   // in order, separated by commas and enclosed in square brackets.
   public String toString() {
      if(size == 0) {
         return "[]";
      } else {
         String result = "[" + elementData[0];
         for(int i = 1; i < size; i++) {
            result +=  ", " + elementData[i];
         }
         result += "]";
         return result;
      }
   }
   
   // Increases the capacity if needed to ensure that it can hold at
   // least the number of elements specified.
   // Post: elementData.length >= capacity
   public void ensureCapacity(int capacity) {
      // double in size until large enough
      while (capacity > elementData.length) {
         elementData = Arrays.copyOf(elementData, 2 * elementData.length);
      }
   }
   
   // If the given index is outside of the given bounds, throws an
   // IndexOutOfBoundsException.
   private void checkIndex(int index, int min, int max) {
      if (index < min || index > max) {
         throw new IndexOutOfBoundsException("index: " + index);
      }
   }
 
}