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.surefire.testset.TestSetFailedException;
  
  import java.io.DataInputStream;
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.PrintStream;
  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.Thread.State.NEW;
  import static java.lang.Thread.State.RUNNABLE;
  import static java.lang.Thread.State.TERMINATED;
  import static java.lang.StrictMath.max;
  import static org.apache.maven.surefire.booter.Command.toShutdown;
  import static org.apache.maven.surefire.booter.ForkingRunListener.BOOTERCODE_NEXT_TEST;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.NOOP;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.RUN_CLASS;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.SHUTDOWN;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.SKIP_SINCE_NEXT_TEST;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.TEST_SET_FINISHED;
  import static org.apache.maven.surefire.booter.MasterProcessCommand.decode;
  import static org.apache.maven.surefire.util.internal.StringUtils.encodeStringForForkCommunication;
  import static org.apache.maven.surefire.util.internal.StringUtils.isNotBlank;
  import static org.apache.maven.surefire.util.internal.StringUtils.isBlank;
  import static org.apache.maven.surefire.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
  {
      private static final String LAST_TEST_SYMBOL = "";
  
      private static final CommandReader READER = new CommandReader();
  
      private final Queue<BiProperty<MasterProcessCommand, CommandListener>> listeners
          = new ConcurrentLinkedQueue<BiProperty<MasterProcessCommand, CommandListener>>();
  
      private final Thread commandThread = newDaemonThread( new CommandRunnable(), "surefire-forkedjvm-command-thread" );
  
      private final AtomicReference<Thread.State> state = new AtomicReference<Thread.State>( NEW );
  
      private final CountDownLatch startMonitor = new CountDownLatch( 1 );
  
      private final Semaphore nextCommandNotifier = new Semaphore( 0 );
  
      private final CopyOnWriteArrayList<String> testClasses = new CopyOnWriteArrayList<String>();
  
      private volatile Shutdown shutdown;
  
      private int iteratedCount;
  
      public static CommandReader getReader()
      {
          final CommandReader reader = READER;
          if ( reader.state.compareAndSet( NEW, RUNNABLE ) )
          {
              reader.commandThread.start();
          }
          return reader;
      }
  
      public CommandReader setShutdown( Shutdown shutdown )
      {
          this.shutdown = shutdown;
          return this;
      }
  
      public boolean awaitStarted()
         throws TestSetFailedException
     {
         if ( state.get() == RUNNABLE )
         {
             try
             {
                 startMonitor.await();
                 return true;
             }
             catch ( InterruptedException e )
             {
                 throw new TestSetFailedException( e.getLocalizedMessage() );
             }
         }
         else
         {
             return false;
         }
     }
 
     /**
      * @param listener listener called with <em>Any</em> {@link MasterProcessCommand command type}
      */
     public void addListener( CommandListener listener )
     {
         listeners.add( new BiProperty<MasterProcessCommand, CommandListener>( null, listener ) );
     }
 
     public void addTestListener( CommandListener listener )
     {
         addListener( RUN_CLASS, listener );
     }
 
     public void addTestsFinishedListener( CommandListener listener )
     {
         addListener( TEST_SET_FINISHED, listener );
     }
 
     public void addSkipNextTestsListener( CommandListener listener )
     {
         addListener( SKIP_SINCE_NEXT_TEST, listener );
     }
 
     public void addShutdownListener( CommandListener listener )
     {
         addListener( SHUTDOWN, listener );
     }
 
     public void addNoopListener( CommandListener listener )
     {
         addListener( NOOP, listener );
     }
 
     private void addListener( MasterProcessCommand cmd, CommandListener listener )
     {
         listeners.add( new BiProperty<MasterProcessCommand, CommandListener>( cmd, listener ) );
     }
 
     public void removeListener( CommandListener listener )
     {
         for ( Iterator<BiProperty<MasterProcessCommand, CommandListener>> it = listeners.iterator(); it.hasNext(); )
         {
             BiProperty<MasterProcessCommand, CommandListener> listenerWrapper = it.next();
             if ( listener == listenerWrapper.getP2() )
             {
                 it.remove();
             }
         }
     }
 
     /**
      * @return test classes which have been retrieved by {@link CommandReader#getIterableClasses(PrintStream)}.
      */
     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 originalOutStream original stream in current JVM process
      * @return Iterator with test classes lazily loaded as commands from the main process
      */
     Iterable<String> getIterableClasses( PrintStream originalOutStream )
     {
         return new ClassesIterable( originalOutStream );
     }
 
     public void stop()
     {
         if ( state.compareAndSet( NEW, TERMINATED ) || state.compareAndSet( RUNNABLE, TERMINATED ) )
         {
             makeQueueFull();
             listeners.clear();
             commandThread.interrupt();
         }
     }
 
     private boolean isStopped()
     {
         return state.get() == TERMINATED;
     }
 
     /**
      * @return <tt>true</tt> 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 PrintStream originalOutStream;
 
         ClassesIterable( PrintStream originalOutStream )
         {
             this.originalOutStream = originalOutStream;
         }
 
         public Iterator<String> iterator()
         {
             return new ClassesIterator( originalOutStream );
         }
     }
 
     private final class ClassesIterator
         implements Iterator<String>
     {
         private final PrintStream originalOutStream;
 
         private String clazz;
 
         private int nextQueueIndex;
 
         private ClassesIterator( PrintStream originalOutStream )
         {
             this.originalOutStream = originalOutStream;
         }
 
         public boolean hasNext()
         {
             popUnread();
             return isNotBlank( clazz );
         }
 
         public String next()
         {
             popUnread();
             try
             {
                 if ( isBlank( clazz ) )
                 {
                     throw new NoSuchElementException( CommandReader.this.isStopped() ? "stream was stopped" : "" );
                 }
                 else
                 {
                     return clazz;
                 }
             }
             finally
             {
                 clazz = null;
             }
         }
 
         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()
         {
             byte[] encoded = encodeStringForForkCommunication( ( (char) BOOTERCODE_NEXT_TEST ) + ",0,want more!\n" );
             originalOutStream.write( encoded, 0, encoded.length );
         }
 
         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
     {
         public void run()
         {
             CommandReader.this.startMonitor.countDown();
             DataInputStream stdIn = new DataInputStream( System.in );
             boolean isTestSetFinished = false;
             try
             {
                 while ( CommandReader.this.state.get() == RUNNABLE )
                 {
                     Command command = decode( stdIn );
                     if ( command == null )
                     {
                         System.err.println( "[SUREFIRE] std/in stream corrupted: first sequence not recognized" );
                         break;
                     }
                     else
                     {
                         switch ( command.getCommandType() )
                         {
                             case RUN_CLASS:
                                 String test = command.getData();
                                 boolean inserted = CommandReader.this.insertToQueue( test );
                                 if ( inserted )
                                 {
                                     CommandReader.this.wakeupIterator();
                                     insertToListeners( command );
                                 }
                                 break;
                             case TEST_SET_FINISHED:
                                 CommandReader.this.makeQueueFull();
                                 isTestSetFinished = true;
                                 CommandReader.this.wakeupIterator();
                                 insertToListeners( command );
                                 break;
                             case SHUTDOWN:
                                 CommandReader.this.makeQueueFull();
                                 CommandReader.this.wakeupIterator();
                                 insertToListeners( command );
                                 break;
                             default:
                                 insertToListeners( command );
                                 break;
                         }
                     }
                 }
             }
             catch ( EOFException e )
             {
                 CommandReader.this.state.set( TERMINATED );
                 if ( !isTestSetFinished )
                 {
                     exitByConfiguration();
                     // does not go to finally
                 }
             }
             catch ( IOException e )
             {
                 CommandReader.this.state.set( TERMINATED );
                 // If #stop() method is called, reader thread is interrupted and cause is InterruptedException.
                 if ( !( e.getCause() instanceof InterruptedException ) )
                 {
                     System.err.println( "[SUREFIRE] std/in stream corrupted" );
                     e.printStackTrace();
                 }
             }
             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 insertToListeners( 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();
                 insertToListeners( toShutdown( shutdown ) );
                 switch ( shutdown )
                 {
                     case EXIT:
                         System.exit( 1 );
                     case KILL:
                         Runtime.getRuntime().halt( 1 );
                     case DEFAULT:
                     default:
                         // should not happen; otherwise you missed enum case
                         break;
                 }
             }
         }
     }
 
 }