JavaAdventureRepo/src/main/java/cz/davza/studentadventure/objects/PlayerInventory.java

package cz.davza.studentadventure.objects;

import cz.davza.studentadventure.base.ItemCollectionBase;
import cz.davza.studentadventure.enums.CommandState;
import cz.davza.studentadventure.interfaces.IItem;
import cz.davza.studentadventure.interfaces.IObservable;
import cz.davza.studentadventure.interfaces.IObserver;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
 * The player's personal item inventory, with Observer support for change notifications.
 *
 * <p>Extends {@link ItemCollectionBase} with the full slot-based stacking logic,
 * and additionally implements {@link IObservable} so that external listeners
 * (such as a GUI panel) can react whenever the inventory contents change.</p>
 *
 * <p>Every call to {@link #Add} or {@link #Remove} automatically fires a
 * {@link CommandState#INVENTORY_CHANGE} notification to all registered observers
 * after delegating the operation to the superclass.</p>
 *
 * @see cz.davza.studentadventure.base.ItemCollectionBase
 * @see IObservable
 * @see IObserver
 */
public class PlayerInventory extends ItemCollectionBase<IItem> implements IObservable {
    private final Map<CommandState, Set<IObserver>> observers = new HashMap<>();
    /**
     * Creates a new inventory with the given number of bulk-unit capacity.
     *
     * @param size the total bulk capacity of this inventory
     */
    public PlayerInventory(int size) {
        super(size);
    }
    /**
     * {@inheritDoc}
     *
     * <p>After the item is added (or partially added) by the superclass,
     * all observers registered for {@link CommandState#INVENTORY_CHANGE} are notified.</p>
     */
    @Override
    public int Add(IItem item, int count){
        int result = super.Add(item, count);
        notifyObservers(CommandState.INVENTORY_CHANGE);
        return result;
    }
    /**
     * {@inheritDoc}
     *
     * <p>After the item is removed by the superclass,
     * all observers registered for {@link CommandState#INVENTORY_CHANGE} are notified.</p>
     */
    @Override
    public void Remove(String itemCode, int count) {
        super.Remove(itemCode, count);
        notifyObservers(CommandState.INVENTORY_CHANGE);
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public void addObserver(CommandState observedstate, IObserver o) {
        if  (!observers.containsKey(observedstate)) observers.put(observedstate, new HashSet<>());
        observers.get(observedstate).add(o);
    }


    /**
     * {@inheritDoc}
     */
    @Override
    public void notifyObservers(CommandState notifiedState) {
        if   (!observers.containsKey(notifiedState)) return;

        for (IObserver observer : observers.get(notifiedState)) {
            observer.update();
        }
    }
}