package org.eclipse.aether.internal.impl;
   
   /*
    * 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.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import static java.util.Objects.requireNonNull;
  import java.util.Set;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.spi.connector.transport.Transporter;
  import org.eclipse.aether.spi.connector.transport.TransporterFactory;
  import org.eclipse.aether.spi.connector.transport.TransporterProvider;
  import org.eclipse.aether.spi.locator.Service;
  import org.eclipse.aether.spi.locator.ServiceLocator;
  import org.eclipse.aether.transfer.NoTransporterException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   */
  @Singleton
  @Named
  public final class DefaultTransporterProvider
      implements TransporterProvider, Service
  {
  
      private static final Logger LOGGER = LoggerFactory.getLogger( DefaultTransporterProvider.class );
  
      private Collection<TransporterFactory> factories = new ArrayList<>();
  
      public DefaultTransporterProvider()
      {
          // enables default constructor
      }
  
      @Inject
      DefaultTransporterProvider( Set<TransporterFactory> transporterFactories )
      {
          setTransporterFactories( transporterFactories );
      }
  
      public void initService( ServiceLocator locator )
      {
          setTransporterFactories( locator.getServices( TransporterFactory.class ) );
      }
  
      public DefaultTransporterProvider addTransporterFactory( TransporterFactory factory )
      {
          factories.add( requireNonNull( factory, "transporter factory cannot be null" ) );
          return this;
      }
  
      public DefaultTransporterProvider setTransporterFactories( Collection<TransporterFactory> factories )
      {
          if ( factories == null )
          {
              this.factories = new ArrayList<>();
          }
          else
          {
              this.factories = factories;
          }
          return this;
      }
  
      public Transporter newTransporter( RepositorySystemSession session, RemoteRepository repository )
          throws NoTransporterException
      {
          requireNonNull( "session", "session cannot be null" );
          requireNonNull( "repository", "repository cannot be null" );
  
          PrioritizedComponents<TransporterFactory> factories = new PrioritizedComponents<>( session );
          for ( TransporterFactory factory : this.factories )
          {
              factories.add( factory, factory.getPriority() );
         }
 
         List<NoTransporterException> errors = new ArrayList<>();
         for ( PrioritizedComponent<TransporterFactory> factory : factories.getEnabled() )
         {
             try
             {
                 Transporter transporter = factory.getComponent().newInstance( session, repository );
 
                 if ( LOGGER.isDebugEnabled() )
                 {
                     StringBuilder buffer = new StringBuilder( 256 );
                     buffer.append( "Using transporter " ).append( transporter.getClass().getSimpleName() );
                     Utils.appendClassLoader( buffer, transporter );
                     buffer.append( " with priority " ).append( factory.getPriority() );
                     buffer.append( " for " ).append( repository.getUrl() );
                     LOGGER.debug( buffer.toString() );
                 }
 
                 return transporter;
             }
             catch ( NoTransporterException e )
             {
                 // continue and try next factory
                 errors.add( e );
             }
         }
         if ( LOGGER.isDebugEnabled() && errors.size() > 1 )
         {
             for ( Exception e : errors )
             {
                 LOGGER.debug( "Could not obtain transporter factory for {}", repository, e );
             }
         }
 
         StringBuilder buffer = new StringBuilder( 256 );
         if ( factories.isEmpty() )
         {
             buffer.append( "No transporter factories registered" );
         }
         else
         {
             buffer.append( "Cannot access " ).append( repository.getUrl() );
             buffer.append( " using the registered transporter factories: " );
             factories.list( buffer );
         }
 
         throw new NoTransporterException( repository, buffer.toString(), errors.size() == 1 ? errors.get( 0 ) : null );
     }
 
 }