package serie06;

import java.util.Map;
import java.util.TreeMap;

import util.Contract;

public class StdStock<E> implements Stock<E> {

	// ATTRIBUTS

	private final Map<E, Integer> stock;

	// CONSTRUCTEURS

	/**
	 * Un stock vide.
	 * @post <pre>
	 * 		e != null </pre>
	 */
	public StdStock() {
		stock = new TreeMap<E, Integer>();
	}

	// REQUETES

	public int getNumber(E e) {
		Contract.checkCondition(e != null);
		if (stock.get(e) == null) {
			return 0;
		}
		return stock.get(e).intValue();
	}

	public int getTotalNumber() {
		int sum = 0;
		for (E e : stock.keySet()) {
			sum += stock.get(e).intValue();
		}
		return sum;
	}

	// COMMANDES

	public void addElement(E e) {
		Contract.checkCondition(e != null);

		if (!stock.containsKey(e)) {
			stock.put(e, new Integer(1));
		} else {
			changeNumber(e, 1);
		}
	}

	public void addElement(E e, int qty) {
		Contract.checkCondition(e != null);
		Contract.checkCondition(qty > 0);

		if (!stock.containsKey(e)) {
			stock.put(e, new Integer(qty));
		} else {
			changeNumber(e, qty);
		}
	}

	public void removeElement(E e) {
		Contract.checkCondition(e != null);
		Contract.checkCondition(getNumber(e) >= 1);

		changeNumber(e, -1);
	}

	public void removeElement(E e, int qty) {
		Contract.checkCondition(e != null);
		Contract.checkCondition(qty > 0);
		Contract.checkCondition(getNumber(e) >= qty);

		changeNumber(e, -qty);
	}

	public void reset() {
		stock.clear();
	}

	// OUTILS

	private void changeNumber(E e, int qty) {
		stock.put(e, new Integer(stock.get(e).intValue() + qty));
	}
}