package org.apache.maven.surefire.booter;
   
   /*
    * 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.apache.maven.plugin.surefire.log.api.ConsoleLogger;
  import org.apache.maven.surefire.api.booter.BiProperty;
  import org.apache.maven.surefire.api.booter.Command;
  import org.apache.maven.surefire.api.booter.DumpErrorSingleton;
  import org.apache.maven.surefire.api.booter.MasterProcessChannelDecoder;
  import org.apache.maven.surefire.api.booter.MasterProcessChannelEncoder;
  import org.apache.maven.surefire.api.booter.MasterProcessCommand;
  import org.apache.maven.surefire.api.booter.Shutdown;
  import org.apache.maven.surefire.api.provider.CommandChainReader;
  import org.apache.maven.surefire.api.provider.CommandListener;
  import org.apache.maven.surefire.api.testset.TestSetFailedException;
  
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.nio.channels.ClosedChannelException;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.Semaphore;
  import java.util.concurrent.atomic.AtomicReference;
  
  import static java.lang.StrictMath.max;
  import static java.lang.Thread.State.NEW;
  import static java.lang.Thread.State.RUNNABLE;
  import static java.lang.Thread.State.TERMINATED;
  import static java.util.Objects.requireNonNull;
  import static org.apache.maven.surefire.api.booter.Command.toShutdown;
  import static org.apache.maven.surefire.api.booter.MasterProcessCommand.BYE_ACK;
  import static org.apache.maven.surefire.api.booter.MasterProcessCommand.NOOP;
  import static org.apache.maven.surefire.api.booter.MasterProcessCommand.SHUTDOWN;
  import static org.apache.maven.surefire.api.booter.MasterProcessCommand.SKIP_SINCE_NEXT_TEST;
  import static org.apache.maven.surefire.shared.utils.StringUtils.isBlank;
  import static org.apache.maven.surefire.shared.utils.StringUtils.isNotBlank;
  import static org.apache.maven.surefire.api.util.internal.DaemonThreadFactory.newDaemonThread;
  
  /**
   * Reader of commands coming from plugin(master) process.
   *
   * @author <a href="mailto:tibordigana@apache.org">Tibor Digana (tibor17)</a>
   * @since 2.19
   */
  public final class CommandReader implements CommandChainReader
  {
      private static final String LAST_TEST_SYMBOL = "";
  
      private final Queue<BiProperty<MasterProcessCommand, CommandListener>> listeners = new ConcurrentLinkedQueue<>();
  
      private final Thread commandThread = newDaemonThread( new CommandRunnable(), "surefire-forkedjvm-command-thread" );
  
      private final AtomicReference<Thread.State> state = new AtomicReference<>( NEW );
  
      private final CountDownLatch startMonitor = new CountDownLatch( 1 );
  
      private final Semaphore nextCommandNotifier = new Semaphore( 0 );
  
      private final CopyOnWriteArrayList<String> testClasses = new CopyOnWriteArrayList<>();
  
      private final MasterProcessChannelDecoder decoder;
  
      private final Shutdown shutdown;
  
      private final ConsoleLogger logger;
  
      private int iteratedCount;
  
      public CommandReader( MasterProcessChannelDecoder decoder, Shutdown shutdown, ConsoleLogger logger )
      {
          this.decoder = requireNonNull( decoder, "null decoder" );
          this.shutdown = requireNonNull( shutdown, "null Shutdown config" );
          this.logger = requireNonNull( logger, "null logger" );
          state.set( RUNNABLE );
          commandThread.start();
      }
  
     @Override
     public boolean awaitStarted()
         throws TestSetFailedException
     {
         if ( state.get() == RUNNABLE )
         {
             try
             {
                 startMonitor.await();
                 return true;
             }
             catch ( InterruptedException e )
             {
                 DumpErrorSingleton.getSingleton().dumpException( e );
                 throw new TestSetFailedException( e.getLocalizedMessage() );
             }
         }
         else
         {
             return false;
         }
     }
 
     @Override
     public void addSkipNextTestsListener( CommandListener listener )
     {
         addListener( SKIP_SINCE_NEXT_TEST, listener );
     }
 
     @Override
     public void addShutdownListener( CommandListener listener )
     {
         addListener( SHUTDOWN, listener );
     }
 
     public void addNoopListener( CommandListener listener )
     {
         addListener( NOOP, listener );
     }
 
     public void addByeAckListener( CommandListener listener )
     {
         addListener( BYE_ACK, listener );
     }
 
     private void addListener( MasterProcessCommand cmd, CommandListener listener )
     {
         listeners.add( new BiProperty<>( cmd, listener ) );
     }
 
     /**
      * @return test classes which have been retrieved by
      * {@link CommandReader#getIterableClasses(MasterProcessChannelEncoder)}.
      */
     Iterator<String> iterated()
     {
         return testClasses.subList( 0, iteratedCount ).iterator();
     }
 
     /**
      * The iterator can be used only in one Thread.
      * Two simultaneous instances are not allowed for sake of only one {@link #nextCommandNotifier}.
      *
      * @param eventChannel original stream in current JVM process
      * @return Iterator with test classes lazily loaded as commands from the main process
      */
     Iterable<String> getIterableClasses( MasterProcessChannelEncoder eventChannel )
     {
         return new ClassesIterable( eventChannel );
     }
 
     public void stop()
     {
         if ( !isStopped() )
         {
             state.set( TERMINATED );
             makeQueueFull();
             listeners.clear();
             commandThread.interrupt();
         }
     }
 
     private boolean isStopped()
     {
         return state.get() == TERMINATED;
     }
 
     /**
      * @return {@code true} if {@link #LAST_TEST_SYMBOL} found at the last index in {@link #testClasses}.
      */
     private boolean isQueueFull()
     {
         // The problem with COWAL is that such collection doe not have operation getLast, however it has get(int)
         // and we need both atomic.
         //
         // Both lines can be Java Concurrent, but the last operation is atomic with optimized search.
         // Searching index of LAST_TEST_SYMBOL in the only last few (concurrently) inserted strings.
         // The insert operation is concurrent with this method.
         // Prerequisite: The strings are added but never removed and the method insertToQueue() does not
         // allow adding a string after LAST_TEST_SYMBOL.
         int searchFrom = max( 0, testClasses.size() - 1 );
         return testClasses.indexOf( LAST_TEST_SYMBOL, searchFrom ) != -1;
     }
 
     private void makeQueueFull()
     {
         testClasses.addIfAbsent( LAST_TEST_SYMBOL );
     }
 
     private boolean insertToQueue( String test )
     {
         return isNotBlank( test ) && !isQueueFull() && testClasses.add( test );
     }
 
     private final class ClassesIterable
         implements Iterable<String>
     {
         private final MasterProcessChannelEncoder eventChannel;
 
         ClassesIterable( MasterProcessChannelEncoder eventChannel )
         {
             this.eventChannel = eventChannel;
         }
 
         @Override
         public Iterator<String> iterator()
         {
             return new ClassesIterator( eventChannel );
         }
     }
 
     private final class ClassesIterator
         implements Iterator<String>
     {
         private final MasterProcessChannelEncoder eventChannel;
 
         private String clazz;
 
         private int nextQueueIndex;
 
         private ClassesIterator( MasterProcessChannelEncoder eventChannel )
         {
             this.eventChannel = eventChannel;
         }
 
         @Override
         public boolean hasNext()
         {
             popUnread();
             return isNotBlank( clazz );
         }
 
         @Override
         public String next()
         {
             popUnread();
             try
             {
                 if ( isBlank( clazz ) )
                 {
                     throw new NoSuchElementException( CommandReader.this.isStopped() ? "stream was stopped" : "" );
                 }
                 else
                 {
                     return clazz;
                 }
             }
             finally
             {
                 clazz = null;
             }
         }
 
         @Override
         public void remove()
         {
             throw new UnsupportedOperationException();
         }
 
         private void popUnread()
         {
             if ( shouldFinish() )
             {
                 clazz = null;
                 return;
             }
 
             if ( isBlank( clazz ) )
             {
                 requestNextTest();
                 CommandReader.this.awaitNextTest();
                 if ( shouldFinish() )
                 {
                     clazz = null;
                     return;
                 }
                 clazz = CommandReader.this.testClasses.get( nextQueueIndex++ );
                 CommandReader.this.iteratedCount = nextQueueIndex;
             }
 
             if ( CommandReader.this.isStopped() )
             {
                 clazz = null;
             }
         }
 
         private void requestNextTest()
         {
             eventChannel.acquireNextTest();
         }
 
         private boolean shouldFinish()
         {
             boolean wasLastTestRead = isEndSymbolAt( nextQueueIndex );
             return CommandReader.this.isStopped() || wasLastTestRead;
         }
 
         private boolean isEndSymbolAt( int index )
         {
             return CommandReader.this.isQueueFull() && 1 + index == CommandReader.this.testClasses.size();
         }
     }
 
     private void awaitNextTest()
     {
         nextCommandNotifier.acquireUninterruptibly();
     }
 
     private void wakeupIterator()
     {
         nextCommandNotifier.release();
     }
 
     private final class CommandRunnable
         implements Runnable
     {
         @Override
         public void run()
         {
             CommandReader.this.startMonitor.countDown();
             boolean isTestSetFinished = false;
             try ( MasterProcessChannelDecoder commandReader = CommandReader.this.decoder )
             {
                 while ( CommandReader.this.state.get() == RUNNABLE )
                 {
                     Command command = commandReader.decode();
                     switch ( command.getCommandType() )
                     {
                         case RUN_CLASS:
                             String test = command.getData();
                             boolean inserted = CommandReader.this.insertToQueue( test );
                             if ( inserted )
                             {
                                 CommandReader.this.wakeupIterator();
                                 callListeners( command );
                             }
                             break;
                         case TEST_SET_FINISHED:
                             CommandReader.this.makeQueueFull();
                             isTestSetFinished = true;
                             CommandReader.this.wakeupIterator();
                             callListeners( command );
                             break;
                         case SHUTDOWN:
                             CommandReader.this.makeQueueFull();
                             CommandReader.this.wakeupIterator();
                             callListeners( command );
                                 break;
                         case BYE_ACK:
                             callListeners( command );
                             // After SHUTDOWN no more commands can come.
                             // Hence, do NOT go back to blocking in I/O.
                             CommandReader.this.state.set( TERMINATED );
                             break;
                         default:
                             callListeners( command );
                             break;
                     }
                 }
             }
             catch ( EOFException | ClosedChannelException e )
             {
                 CommandReader.this.state.set( TERMINATED );
                 if ( !isTestSetFinished )
                 {
                     String msg = "TestSet has not finished before stream error has appeared >> "
                                          + "initializing exit by non-null configuration: "
                                          + CommandReader.this.shutdown;
                     DumpErrorSingleton.getSingleton().dumpStreamException( e, msg );
 
                     exitByConfiguration();
                     // does not go to finally for non-default config: Shutdown.EXIT or Shutdown.KILL
                 }
             }
             catch ( IOException e )
             {
                 CommandReader.this.state.set( TERMINATED );
                 // If #stop() method is called, reader thread is interrupted
                 // and exception is InterruptedIOException or its cause is InterruptedException.
                 if ( !( e instanceof InterruptedIOException || e.getCause() instanceof InterruptedException ) )
                 {
                     String msg = "[SUREFIRE] std/in stream corrupted";
                     DumpErrorSingleton.getSingleton().dumpStreamException( e, msg );
                     CommandReader.this.logger.error( msg, e );
                 }
             }
             finally
             {
                 // ensure fail-safe iterator as well as safe to finish in for-each loop using ClassesIterator
                 if ( !isTestSetFinished )
                 {
                     CommandReader.this.makeQueueFull();
                 }
                 CommandReader.this.wakeupIterator();
             }
         }
 
         private void callListeners( Command cmd )
         {
             MasterProcessCommand expectedCommandType = cmd.getCommandType();
             for ( BiProperty<MasterProcessCommand, CommandListener> listenerWrapper : CommandReader.this.listeners )
             {
                 MasterProcessCommand commandType = listenerWrapper.getP1();
                 CommandListener listener = listenerWrapper.getP2();
                 if ( commandType == null || commandType == expectedCommandType )
                 {
                     listener.update( cmd );
                 }
             }
         }
 
         private void exitByConfiguration()
         {
             Shutdown shutdown = CommandReader.this.shutdown; // won't read inconsistent changes through the stack
             if ( shutdown != null )
             {
                 CommandReader.this.makeQueueFull();
                 CommandReader.this.wakeupIterator();
                 callListeners( toShutdown( shutdown ) );
             }
         }
     }
 }