/*
 * This file is part of the Illarion project.
 *
 * Copyright © 2015 - Illarion e.V.
 *
 * Illarion is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Illarion is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
package org.illarion.engine.backend.shared;

import org.illarion.engine.MouseCursor;
import org.illarion.engine.assets.CursorManager;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.HashMap;
import java.util.Map;

/**
 * This is the shared cursor manager implementation that can be used by the different backend implementations in the
 * same way.
 *
 * @author Martin Karing <nitram@illarion.org>
 */
public abstract class AbstractCursorManager implements CursorManager {
    /**
     * This map stores the cursors that were already load.
     */
    @Nonnull
    private final Map<String, MouseCursor> loadedCursors;

    /**
     * Create a new instance of this manager.
     */
    protected AbstractCursorManager() {
        loadedCursors = new HashMap<>();
    }

    @Nullable
    @Override
    public final MouseCursor getCursor(@Nonnull String ref, int hotspotX, int hotspotY) {
        @Nullable MouseCursor bufferedCursor = loadedCursors.get(ref);
        if (bufferedCursor == null) {
            @Nullable MouseCursor newCursor = loadCursor(ref, hotspotX, hotspotY);
            if (newCursor != null) {
                loadedCursors.put(ref, newCursor);
            }
            return newCursor;
        }
        return bufferedCursor;
    }

    /**
     * Load the cursor that is referred to with the reference.
     *
     * @param ref the reference to the cursor
     * @param hotSpotX the x coordinate of the hot spot
     * @param hotSpotY the y coordinate of the hot spot
     * @return the newly load cursor
     */
    @Nullable
    protected abstract MouseCursor loadCursor(@Nonnull String ref, int hotSpotX, int hotSpotY);
}