package org.apache.maven.lifecycle.internal;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  import java.util.List;
  import java.util.Map;
  
  import org.apache.maven.execution.ExecutionEvent;
  import org.apache.maven.execution.MavenExecutionResult;
  import org.apache.maven.execution.MavenSession;
  import org.apache.maven.lifecycle.DefaultLifecycles;
  import org.apache.maven.lifecycle.MissingProjectException;
  import org.apache.maven.lifecycle.NoGoalSpecifiedException;
  import org.apache.maven.lifecycle.internal.builder.Builder;
  import org.apache.maven.lifecycle.internal.builder.BuilderNotFoundException;
  import org.apache.maven.session.scope.internal.SessionScope;
  import org.codehaus.plexus.component.annotations.Component;
  import org.codehaus.plexus.component.annotations.Requirement;
  import org.codehaus.plexus.logging.Logger;
  
  /**
   * Starts the build life cycle
   *
   * @author Jason van Zyl
   * @author Benjamin Bentmann
   * @author Kristian Rosenvold
   */
  @Component( role = LifecycleStarter.class )
  public class LifecycleStarter
  {
      @Requirement
      private ExecutionEventCatapult eventCatapult;
  
      @Requirement
      private DefaultLifecycles defaultLifeCycles;
  
      @Requirement
      private Logger logger;
  
      @Requirement
      private BuildListCalculator buildListCalculator;
  
      @Requirement
      private LifecycleDebugLogger lifecycleDebugLogger;
  
      @Requirement
      private LifecycleTaskSegmentCalculator lifecycleTaskSegmentCalculator;
  
      @Requirement
      private Map<String, Builder> builders;
      
      @Requirement
      private SessionScope sessionScope;
  
      public void execute( MavenSession session )
      {
          eventCatapult.fire( ExecutionEvent.Type.SessionStarted, session, null );
  
          ReactorContext reactorContext = null;
          ProjectBuildList projectBuilds = null;
          MavenExecutionResult result = session.getResult();
  
          try
          {
              if ( buildExecutionRequiresProject( session ) && projectIsNotPresent( session ) )
              {
                  throw new MissingProjectException( "The goal you specified requires a project to execute"
                      + " but there is no POM in this directory (" + session.getExecutionRootDirectory() + ")."
                      + " Please verify you invoked Maven from the correct directory." );
              }
  
              List<TaskSegment> taskSegments = lifecycleTaskSegmentCalculator.calculateTaskSegments( session );
              projectBuilds = buildListCalculator.calculateProjectBuilds( session, taskSegments );
  
              if ( projectBuilds.isEmpty() )
              {
                  throw new NoGoalSpecifiedException( "No goals have been specified for this build."
                      + " You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or"
                      + " <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>."
                      + " Available lifecycle phases are: " + defaultLifeCycles.getLifecyclePhaseList() + "." );
              }
  
             ProjectIndex projectIndex = new ProjectIndex( session.getProjects() );
 
             if ( logger.isDebugEnabled() )
             {
                 lifecycleDebugLogger.debugReactorPlan( projectBuilds );
             }
 
             ClassLoader oldContextClassLoader = Thread.currentThread().getContextClassLoader();
             ReactorBuildStatus reactorBuildStatus = new ReactorBuildStatus( session.getProjectDependencyGraph() );
             reactorContext =
                 new ReactorContext( result, projectIndex, oldContextClassLoader, reactorBuildStatus,
                                     sessionScope.memento() );
 
             String builderId = session.getRequest().getBuilderId();
             Builder builder = builders.get( builderId );
             if ( builder == null )
             {
                 throw new BuilderNotFoundException( String.format( "The builder requested using id = %s cannot be"
                     + " found", builderId ) );
             }
 
             int degreeOfConcurrency = session.getRequest().getDegreeOfConcurrency();
             if ( degreeOfConcurrency > 1 )
             {
                 logger.info( "" );
                 logger.info( String.format( "Using the %s implementation with a thread count of %d",
                                             builder.getClass().getSimpleName(), degreeOfConcurrency ) );
             }
             builder.build( session, reactorContext, projectBuilds, taskSegments, reactorBuildStatus );
 
         }
         catch ( Exception e )
         {
             result.addException( e );
         }
         finally
         {
             eventCatapult.fire( ExecutionEvent.Type.SessionEnded, session, null );
         }
     }
 
     private boolean buildExecutionRequiresProject( MavenSession session )
     {
         return lifecycleTaskSegmentCalculator.requiresProject( session );
     }
 
     private boolean projectIsNotPresent( MavenSession session )
     {
         return !session.getRequest().isProjectPresent();
     }
 }