package net.abhinavsarkar.algorist;


public class GrowableArray<T>
{

    private Object[] store;

    public GrowableArray(int initialCapacity) {
        if (initialCapacity <= 0) {
            throw new IllegalArgumentException("capacity too small");
        }
        this.store = new Object[initialCapacity];
    }

    public T get(int index) {
        if (index < 0) {
            throw new IllegalArgumentException("index too small");
        }
        if (index >= store.length) {
            throw new IllegalArgumentException("index too large");
        }

        return (T) this.store[index];
    }

    public void set(int index, T val) {
        if (index < 0) {
            throw new IllegalArgumentException("index too small");
        }
        if (index >= store.length) {
            int factor = (int) Math.pow(2, Math.ceil(Math.log(index * 1.0 /store.length)/Math.log(2)));
            Object[] nStore = new Object[store.length * factor];
            System.arraycopy(store, 0, nStore, 0, store.length);
            this.store = nStore;
        }
        this.store[index] = val;
    }

    @Override
    public String toString()
    {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < store.length; i++) {
            T val = (T) this.store[i];
            if (val == null)
            {
                sb.append("<NULL>, ");
            } else {
                sb.append(val + ", ");
            }
        }

        sb.delete(sb.length()-2, sb.length());

        return "[" + sb.toString() + "]";
    }

    public static void main(String[] arg) {
        GrowableArray<String> array = new GrowableArray<>(2);
        array.set(0, "a");
        array.set(6, "b");
        array.set(9, "c");
        array.set(7, "x");
        System.out.println(array);
        System.out.println(array.get(0));
        System.out.println(array.get(1));
    }

}