/*
 * #%L
 * ImageJ software for multidimensional image processing and analysis.
 * %%
 * Copyright (C) 2009 - 2013 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
 * Institute of Molecular Cell Biology and Genetics.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * The views and conclusions contained in the software and documentation are
 * those of the authors and should not be interpreted as representing official
 * policies, either expressed or implied, of any organization.
 * #L%
 */

package imagej.plugin;

import java.util.Collections;
import java.util.List;

import org.scijava.log.LogService;
import org.scijava.plugin.Parameter;

/**
 * Abstract base class for {@link SingletonService}s.
 * 
 * @author Curtis Rueden
 * @param <PT> Plugin type of the {@link ImageJPlugin}s being managed.
 */
public abstract class AbstractSingletonService<PT extends SingletonPlugin>
	extends AbstractPTService<PT> implements SingletonService<PT>
{

	@Parameter
	private LogService log;

	// TODO: Listen for PluginsAddedEvent and PluginsRemovedEvent
	// and update the list of singletons accordingly.

	/** List of singleton plugin instances. */
	private List<PT> instances;

	// -- SingletonService methods --

	@Override
	public List<PT> getInstances() {
		return instances;
	}

	// -- Service methods --

	@Override
	public void initialize() {
		createInstances();
	}

	// -- Helper methods --

	private void createInstances() {
		instances =
			Collections.unmodifiableList(getPluginService().createInstancesOfType(
				getPluginType()));

		log.info("Found " + instances.size() + " " +
			getPluginType().getSimpleName() + " plugins.");
	}

}

/*
 * #%L
 * ImageJ software for multidimensional image processing and analysis.
 * %%
 * Copyright (C) 2009 - 2013 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
 * Institute of Molecular Cell Biology and Genetics.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * The views and conclusions contained in the software and documentation are
 * those of the authors and should not be interpreted as representing official
 * policies, either expressed or implied, of any organization.
 * #L%
 */

package imagej.plugin;

import java.util.Collections;
import java.util.List;

import org.scijava.log.LogService;
import org.scijava.plugin.Parameter;

/**
 * Abstract base class for {@link SingletonService}s.
 * 
 * @author Curtis Rueden
 * @param <PT> Plugin type of the {@link ImageJPlugin}s being managed.
 */
public abstract class AbstractSingletonService<PT extends SingletonPlugin>
	extends AbstractPTService<PT> implements SingletonService<PT>
{

	@Parameter
	private LogService log;

	// TODO: Listen for PluginsAddedEvent and PluginsRemovedEvent
	// and update the list of singletons accordingly.

	/** List of singleton plugin instances. */
	private List<PT> instances;

	// -- SingletonService methods --

	@Override
	public List<PT> getInstances() {
		if (instances == null) {
			createInstances();
		}
		return instances;
	}

	// -- Helper methods --

	private void createInstances() {
		instances =
			Collections.unmodifiableList(getPluginService().createInstancesOfType(
				getPluginType()));

		log.info("Found " + instances.size() + " " +
			getPluginType().getSimpleName() + " plugins.");
	}

}

create instances lazily