/*
    * Copyright (C) 2021, Thomas Wolf <thomas.wolf@paranor.ch> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  package org.eclipse.jgit.lib;
  
  import java.util.Iterator;
  import java.util.ServiceConfigurationError;
  import java.util.ServiceLoader;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A {@code GpgSignatureVerifierFactory} creates {@link GpgSignatureVerifier} instances.
   *
   * @since 5.11
   */
  public abstract class GpgSignatureVerifierFactory {
  
  	private static final Logger LOG = LoggerFactory
  			.getLogger(GpgSignatureVerifierFactory.class);
  
  	private static volatile GpgSignatureVerifierFactory defaultFactory = loadDefault();
  
  	private static GpgSignatureVerifierFactory loadDefault() {
  		try {
  			ServiceLoader<GpgSignatureVerifierFactory> loader = ServiceLoader
  					.load(GpgSignatureVerifierFactory.class);
  			Iterator<GpgSignatureVerifierFactory> iter = loader.iterator();
  			if (iter.hasNext()) {
  				return iter.next();
  			}
  		} catch (ServiceConfigurationError e) {
  			LOG.error(e.getMessage(), e);
  		}
  		return null;
  	}
  
  	/**
  	 * Retrieves the default factory.
  	 *
  	 * @return the default factory or {@code null} if none set
  	 */
  	public static GpgSignatureVerifierFactory getDefault() {
  		return defaultFactory;
  	}
  
  	/**
  	 * Sets the default factory.
  	 *
  	 * @param factory
  	 *            the new default factory
  	 */
  	public static void setDefault(GpgSignatureVerifierFactory factory) {
  		defaultFactory = factory;
  	}
  
  	/**
  	 * Creates a new {@link GpgSignatureVerifier}.
  	 *
  	 * @return the new {@link GpgSignatureVerifier}
  	 */
  	public abstract GpgSignatureVerifier getVerifier();
  
  }