/*
 * MIT License
 *
 * Copyright (c) 2020-present Cloudogu GmbH and Contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
    
package sonia.scm;

//~--- non-JDK imports --------------------------------------------------------

import sonia.scm.user.User;
import sonia.scm.util.ServiceUtil;

/**
 * The SCMContext searches a implementation of {@link SCMContextProvider} and
 * holds a singleton instance of this implementation.
 *
 * @author Sebastian Sdorra
 */
public final class SCMContext
{

  /** Default java package for finding extensions */
  public static final String DEFAULT_PACKAGE = "sonia.scm";

  /** Name of the anonymous user */
  public static final String USER_ANONYMOUS = "_anonymous";

  /**
   * the anonymous user
   * @since 1.21
   */
  public static final User ANONYMOUS = new User(USER_ANONYMOUS,
                                         "SCM Anonymous",
                                         "scm-anonymous@scm-manager.org");

  /** Singleton instance of {@link SCMContextProvider} */
  private static volatile SCMContextProvider provider;

  //~--- constructors ---------------------------------------------------------

  /**
   * Constructs ...
   *
   */
  private SCMContext() {}

  //~--- get methods ----------------------------------------------------------

  /**
   * Returns the singleton instance of {@link SCMContextProvider}
   *
   *
   * @return singleton instance of {@link SCMContextProvider}
   */
  public static SCMContextProvider getContext()
  {
    if (provider == null)
    {
      synchronized (SCMContext.class)
      {
        if (provider == null)
        {
          provider = ServiceUtil.getService(SCMContextProvider.class);

          if (provider == null)
          {
            provider = new BasicContextProvider();
          }
        }
      }
    }

    return provider;
  }
}
