/**
 * A priority queue. This priority Queue is built on top of a sorted ArrayList class
 * 
 * @param <K> the Key element. This must implement Comparable.
 * @param <V> The Value element.  This could be anything.
 * 
 * For methods that exactly follow the interface, see the documentation in the interface.
 * 
 * @author gtowell 
 * Created APRIL 6, 2020
 * Modified: Oct 18, 2020
 */
public class PriorityQueueSAL<K extends Comparable<K>, V> extends AbstractPriorityQueue<K,V> {

 
    /** The thing actually holding the data in the priority queue.  Using an ArrayList
     * to get unbounded length.  
     */
    final private SAL<Pair<K,V>> pqStore;

    /**
     * Initialize the priority queue
     */
    public PriorityQueueSAL() {
        this(Ordering.ASCENDING);
    }
    public PriorityQueueSAL(Ordering order) {
        this.order=order;
        pqStore = new SAL<>(SAL.Ordering.DESCENDING);
    }


    @Override
    public int size() {
        return pqStore.size();
    }

    @Override
    public boolean isEmpty() {
        return pqStore.isEmpty();
    }

    @Override
    public boolean offer(K newK, V newV) {
        Pair<K,V> entry = new Pair<>(newK, newV);
        pqStore.add(entry);
        // Note that this always succeeds, so always return true.
        return true;
    }

    @Override
    public V poll() {
        if (isEmpty())
            return null;
        Pair<K,V> p = pqStore.getAndRemove(pqStore.size()-1);
        return p.theV;
    }

    @Override
    public V peek() {
        Pair<K,V> entry = pqStore.get(pqStore.size()-1);
        if (entry==null) return null;
        return entry.theV;
    }

    public String toString() {
        return pqStore.toString();
    }

    public static void main(String[] args) {
        PriorityQueueSAL<Integer, Rabbit> pq = new PriorityQueueSAL<>(Ordering.ASCENDING);
        pq.offer(1, new Rabbit(Rabbit.BreedEnum.DwarfDutch, 1, "flopsy"));
        pq.offer(10, new Rabbit(Rabbit.BreedEnum.DwarfDutch, 10, "mopsy"));
        pq.offer(5, new Rabbit(Rabbit.BreedEnum.DwarfDutch, 5, "peter"));
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println();

        PriorityQueueSAL<Integer, String> pqpq = new PriorityQueueSAL<>(Ordering.DESCENDING);
        pqpq.offer(1,"Jane");
        pqpq.offer(10,"WET");
        pqpq.offer(5, "WAS");
        System.out.println(pqpq.poll());
        System.out.println(pqpq.poll());
        System.out.println(pqpq.poll());
    }

}