package org.eclipse.aether.internal.impl.synccontext.named;
   
   /*
    * 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 org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.SyncContext;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.named.NamedLock;
  import org.eclipse.aether.named.NamedLockFactory;
  import org.eclipse.aether.named.support.FileSystemFriendly;
  import org.eclipse.aether.util.ConfigUtils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayDeque;
  import java.util.Collection;
  import java.util.Deque;
  import java.util.Objects;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Adapter to adapt {@link NamedLockFactory} and {@link NamedLock} to {@link SyncContext}.
   */
  public final class NamedLockFactoryAdapter
  {
      public static final String TIME_KEY = "aether.syncContext.named.time";
  
      public static final long DEFAULT_TIME = 30L;
  
      public static final String TIME_UNIT_KEY = "aether.syncContext.named.time.unit";
  
      public static final TimeUnit DEFAULT_TIME_UNIT = TimeUnit.SECONDS;
  
      private final NameMapper nameMapper;
  
      private final NamedLockFactory namedLockFactory;
  
      public NamedLockFactoryAdapter( final NameMapper nameMapper, final NamedLockFactory namedLockFactory )
      {
          this.nameMapper = Objects.requireNonNull( nameMapper );
          this.namedLockFactory = Objects.requireNonNull( namedLockFactory );
          // TODO: this is ad-hoc "validation", experimental and likely to change
          if ( this.namedLockFactory instanceof FileSystemFriendly
                  && !( this.nameMapper instanceof FileSystemFriendly ) )
          {
              throw new IllegalArgumentException(
                      "Misconfiguration: FS friendly lock factory requires FS friendly name mapper"
              );
          }
      }
  
      public SyncContext newInstance( final RepositorySystemSession session, final boolean shared )
      {
          return new AdaptedLockSyncContext( session, shared, nameMapper, namedLockFactory );
      }
  
      public void shutdown()
      {
          namedLockFactory.shutdown();
      }
  
      private static class AdaptedLockSyncContext implements SyncContext
      {
          private static final Logger LOGGER = LoggerFactory.getLogger( AdaptedLockSyncContext.class );
  
          private final RepositorySystemSession session;
  
          private final boolean shared;
  
          private final NameMapper lockNaming;
  
          private final NamedLockFactory namedLockFactory;
  
          private final long time;
  
          private final TimeUnit timeUnit;
  
          private final Deque<NamedLock> locks;
  
          private AdaptedLockSyncContext( final RepositorySystemSession session, final boolean shared,
                                         final NameMapper lockNaming, final NamedLockFactory namedLockFactory )
         {
             this.session = session;
             this.shared = shared;
             this.lockNaming = lockNaming;
             this.namedLockFactory = namedLockFactory;
             this.time = getTime( session );
             this.timeUnit = getTimeUnit( session );
             this.locks = new ArrayDeque<>();
 
             if ( time < 0L )
             {
                 throw new IllegalArgumentException( "time cannot be negative" );
             }
         }
 
         private long getTime( final RepositorySystemSession session )
         {
             return ConfigUtils.getLong( session, DEFAULT_TIME, TIME_KEY );
         }
 
         private TimeUnit getTimeUnit( final RepositorySystemSession session )
         {
             return TimeUnit.valueOf( ConfigUtils.getString(
                 session, DEFAULT_TIME_UNIT.name(), TIME_UNIT_KEY
             ) );
         }
 
         @Override
         public void acquire( Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas )
         {
             Collection<String> keys = lockNaming.nameLocks( session, artifacts, metadatas );
             if ( keys.isEmpty() )
             {
                 return;
             }
 
             LOGGER.trace( "Need {} {} lock(s) for {}", keys.size(), shared ? "read" : "write", keys );
             int acquiredLockCount = 0;
             for ( String key : keys )
             {
                 NamedLock namedLock = namedLockFactory.getLock( key );
                 try
                 {
                      LOGGER.trace( "Acquiring {} lock for '{}'",
                              shared ? "read" : "write", key );
 
                     boolean locked;
                     if ( shared )
                     {
                         locked = namedLock.lockShared( time, timeUnit );
                     }
                     else
                     {
                         locked = namedLock.lockExclusively( time, timeUnit );
                     }
 
                     if ( !locked )
                     {
                         LOGGER.trace( "Failed to acquire {} lock for '{}'",
                                 shared ? "read" : "write", key );
 
                         namedLock.close();
                         throw new IllegalStateException(
                                 "Could not acquire " + ( shared ? "read" : "write" )
                                 + " lock for '" + namedLock.name() + "'" );
                     }
 
                     locks.push( namedLock );
                     acquiredLockCount++;
                 }
                 catch ( InterruptedException e )
                 {
                     Thread.currentThread().interrupt();
                     throw new RuntimeException( e );
                 }
             }
             LOGGER.trace( "Total locks acquired: {}", acquiredLockCount );
         }
 
         @Override
         public void close()
         {
             if ( locks.isEmpty() )
             {
                 return;
             }
 
             // Release locks in reverse insertion order
             int released = 0;
             while ( !locks.isEmpty() )
             {
                 try ( NamedLock namedLock = locks.pop() )
                 {
                     LOGGER.trace( "Releasing {} lock for '{}'",
                             shared ? "read" : "write", namedLock.name() );
                     namedLock.unlock();
                     released++;
                 }
             }
             LOGGER.trace( "Total locks released: {}", released );
         }
     }
 }