// Adam Blank
/** The ArrayIntList class stores an ordered list of integers. */

import java.util.Arrays;

public class ArrayIntList implements IntList {
    private int size;
    private int[] data;

    public static final int DEFAULT_CAPACITY = 10;

    /** Initializes a new array list with initial capacity of initialCapacity integers. <br><br>
     *  pre: initialCapacity >= 0 otherwise throws an IllegalArgumentException */
    public ArrayIntList(int initialCapacity) {
        if (initialCapacity < 0) {
            throw new IllegalArgumentException();
        }
        this.data = new int[initialCapacity];
        this.size = 0;
    }

    /** Initializes a new empty list with initial capacity of DEFAULT_CAPACITY integers. */
    public ArrayIntList() {
        this(DEFAULT_CAPACITY);
    }

    /** Adds value to the end of the list. <br><br>
     *  post: value is appended to the ArrayList */
    public void add(int value) {
        this.add(size, value);      
    }

    /** Inserts value into the list at index. <br><br>
     *  pre:  0 <= index <= size otherwise throws IndexOutOfBoundsException <br>
     *  post: value is inserted at index; all later values are shifted right by 1 element */
    public void add(int index, int value) {
        // Increment the size early; so that we can access the element
        // at this.size
        this.size++;

        // Ensure the array as capacity for our new size
        this.grow(this.size);

        checkIndex(index);
        for (int i = this.size - 1; i > index; i--) {
            this.set(i, this.get(i-1));
        }

        this.set(index, value);
    }

    /** Returns the value at index. <br><br>
     *  pre: 0 <= index <= size otherwise throws IndexOutOfBoundsException */ 
    public int get(int index) {
        checkIndex(index);
        return this.data[index];
    }

    /** Stores value in index. <br><br>
     *  pre: 0 <= index <= size otherwise throws IndexOutOfBoundsException */
    public void set(int index, int value) {
        checkIndex(index);
        this.data[index] = value;
    }

    /** Removes the value at the given index, shifting later values over. <br>
     *  pre: 0 <= index < size otherwise throws IndexOutOfBoundsException */
    public void remove(int index) {
        checkIndex(index);
        for (int i = index; i < size - 1; i++) {
            this.set(i, this.get(i+1));
        }
        size--;
    }

    /** Returns the number of elements in the list. */
    public int size() {
        return size;
    }

    /** Returns true if list is empty, false otherwise. */
    public boolean isEmpty() {
        return size == 0;
    }

    /** Returns a String representation of the list consisting of the elements
     *  in order, separated by commas and enclosed in square brackets. */
    public String toString() {
        String result = "";
        if (this.size > 0) {
            result = "" + this.data[0];
            for (int i = 1; i < this.size; i++) {
                result += ", " + this.data[i];
            }
        }
        return "[" + result + "]";
    }

    /** Grows the ArrayIntList to have room for *at least* requiredCapacity elements. <br>
     *  pre: 0 <= requiredCapacity otherwise throws IllegalArgumentException */
    private void grow(int requiredCapacity) {
        if (requiredCapacity < 0) {
            throw new IllegalArgumentException();
        }

        if (requiredCapacity > this.data.length) {
            this.data = Arrays.copyOf(this.data, this.data.length * 2);
        }
    }

    /** Checks if index is a valid index into this ArrayIntList. <br>
     *  post: throws IndexOutOfBoundsException if index < 0 or index >= max*/
    private void checkIndex(int index) {
        if (0 > index || index >= this.size) {
            throw new IndexOutOfBoundsException();
        }
    }
}