/*********************************************************************
 * Copyright (c) 2009 - 2012 SpringSource, a division of VMware, Inc.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
**********************************************************************/

package org.eclipse.virgo.ide.bundlor.internal.core.maven;

import java.util.Properties;

import org.eclipse.core.resources.IProject;
import org.eclipse.virgo.bundlor.support.properties.PropertiesSource;
import org.eclipse.virgo.ide.facet.core.FacetUtils;

/**
 * Factory implementation to create instances of {@link MavenPropertiesSource}.
 * <p>
 * This implementation will make sure not to depend on M2E until it is actually installed.
 *
 * @author Christian Dupuis
 * @author Leo Dos Santos
 */
public class MavenPropertiesSourceFactory {

    private static final String M2E_CLASS_NAME = "org.eclipse.m2e.core.project.IMavenProjectRegistry"; //$NON-NLS-1$

    private static final String M2E_PROJECT_NATURE = "org.eclipse.m2e.core.maven2Nature"; //$NON-NLS-1$

    private static final boolean IS_M2E_PRESENT = isM2ePresent();

    private static final PropertiesSource EMPTY_PROPERTIES_SOURCE = new NoOpPropertiesSource();

    public static boolean shouldCreate(IProject project) {
        return IS_M2E_PRESENT && FacetUtils.hasNature(project, M2E_PROJECT_NATURE);
    }

    public static PropertiesSource createPropertiesSource(IProject project) {
        if (shouldCreate(project)) {
            return new MavenPropertiesSource(project);
        }
        return EMPTY_PROPERTIES_SOURCE;
    }

    private static boolean isM2ePresent() {
        try {
            MavenPropertiesSourceFactory.class.getClassLoader().loadClass(M2E_CLASS_NAME);
            return true;
        } catch (ClassNotFoundException e) {
            return false;
        }
    }

    private static class NoOpPropertiesSource implements PropertiesSource {

        public int getPriority() {
            return Integer.MIN_VALUE;
        }

        public Properties getProperties() {
            return new Properties();
        }

    }

}