/*
 * $Id$
 *
 * Copyright (C) 2003-2015 JNode.org
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public 
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; If not, write to the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package org.jnode.driver;

import java.util.Collection;
import java.util.Collections;
import javax.naming.NameNotFoundException;
import org.jnode.naming.InitialNaming;

/**
 * Class with utility methods for the device framework.
 * 
 * @author Ewout Prangsma (epr@users.sourceforge.net)
 */
public class DeviceUtils {

    /**
     * Cached device manager reference
     */
    private static DeviceManager deviceManager;

    /**
     * Gets the device manager
     * 
     * @return The device manager
     * @throws NameNotFoundException
     */
    public static DeviceManager getDeviceManager() throws NameNotFoundException {
        if (deviceManager == null) {
            deviceManager = InitialNaming.lookup(DeviceManager.NAME);
        }
        return deviceManager;
    }

    /**
     * Gets a device by name
     * 
     * @param deviceID
     * @return The device
     * @throws DeviceNotFoundException
     */
    public static Device getDevice(final String deviceID) throws DeviceNotFoundException {
        try {
            return getDeviceManager().getDevice(deviceID);
        } catch (NameNotFoundException ex) {
            throw new DeviceNotFoundException("DeviceManager not found", ex);
        }
    }

    /**
     * Gets a specific API from a device.
     * 
     * @param deviceID the ame of the requested device
     * @param api the API class to use
     * @return The api implementation
     * @throws DeviceNotFoundException
     * @throws ApiNotFoundException
     */
    public static <T extends DeviceAPI> T getAPI(final String deviceID, final Class<T> api)
        throws DeviceNotFoundException, ApiNotFoundException {
        try {
            return getDeviceManager().getDevice(deviceID).getAPI(api);
        } catch (NameNotFoundException ex) {
            throw new DeviceNotFoundException("DeviceManager not found", ex);
        }
    }

    /**
     * Returns a collection of all known devices that implement the given api..
     * The collection is not modifiable, but the underlying collection can
     * change, so be aware of exceptions in iterators.
     * 
     * @param apiClass
     * @return All known devices the implement the given api.
     */
    public static Collection<Device> getDevicesByAPI(final Class<? extends DeviceAPI> apiClass) {
        Collection<Device> deviceList;
        try {
            deviceList = getDeviceManager().getDevicesByAPI(apiClass);
        } catch (NameNotFoundException ex) {
            deviceList = Collections.emptyList();
        }
        return deviceList;
    }
}