/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package gov.nist.secauto.metaschema.cli.processor.command;
   
   import java.util.List;
   import java.util.ServiceLoader;
  import java.util.ServiceLoader.Provider;
  import java.util.stream.Collectors;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import nl.talsmasoftware.lazy4j.Lazy;
  
  public final class CommandService {
    private static final Lazy<CommandService> INSTANCE = Lazy.lazy(() -> new CommandService());
    @NonNull
    private final ServiceLoader<ICommand> loader;
  
    /**
     * Get the singleton instance of the function service.
     *
     * @return the service instance
     */
    public static CommandService getInstance() {
      return INSTANCE.get();
    }
  
    public CommandService() {
      ServiceLoader<ICommand> loader = ServiceLoader.load(ICommand.class);
      assert loader != null;
      this.loader = loader;
    }
  
    /**
     * Get the function service loader instance.
     *
     * @return the service loader instance.
     */
    @NonNull
    private ServiceLoader<ICommand> getLoader() {
      return loader;
    }
  
    @SuppressWarnings("null")
    @NonNull
    public List<ICommand> getCommands() {
      return getLoader().stream()
          .map(Provider<ICommand>::get)
          .collect(Collectors.toUnmodifiableList());
    }
  }