package org.apache.maven.surefire.util;
   
   /*
    * 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.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintStream;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import org.apache.maven.surefire.booter.ForkingRunListener;
  
  /**
   * A variant of TestsToRun that is provided with test class names
   * from an {@link InputStream} (e.g. {@code System.in}). The method
   * {@link #iterator()} returns an Iterator that blocks on calls to
   * {@link Iterator#hasNext()} until new classes are available, or no more
   * classes will be available.
   *
   * @author Andreas Gudian
   */
  public class LazyTestsToRun
      extends TestsToRun
  {
      private List workQueue = new ArrayList();
  
      private BufferedReader inputReader;
  
      private boolean streamClosed = false;
  
      private ClassLoader testClassLoader;
  
      private PrintStream originalOutStream;
  
      /**
       * C'tor
       *
       * @param testSource        source to read the tests from
       * @param testClassLoader   class loader to load the test classes
       * @param originalOutStream the output stream to use when requesting new new tests
       */
      public LazyTestsToRun( InputStream testSource, ClassLoader testClassLoader, PrintStream originalOutStream )
      {
          super( Collections.emptyList() );
  
          this.testClassLoader = testClassLoader;
          this.originalOutStream = originalOutStream;
  
          inputReader = new BufferedReader( new InputStreamReader( testSource ) );
      }
  
      protected void addWorkItem( String className )
      {
          synchronized ( workQueue )
          {
              workQueue.add( ReflectionUtils.loadClass( testClassLoader, className ) );
          }
      }
  
      protected void requestNextTest()
      {
          StringBuffer sb = new StringBuffer();
          sb.append( (char) ForkingRunListener.BOOTERCODE_NEXT_TEST ).append( ",0,want more!\n" );
          originalOutStream.print( sb.toString() );
      }
  
      private class BlockingIterator
          implements Iterator
      {
          private int lastPos = -1;
  
          public boolean hasNext()
          {
              int nextPos = lastPos + 1;
              synchronized ( workQueue )
              {
                  if ( workQueue.size() > nextPos )
                  {
                      return true;
                 }
                 else
                 {
                     if ( needsToWaitForInput( nextPos ) )
                     {
                         requestNextTest();
 
                         String nextClassName;
                         try
                         {
                             nextClassName = inputReader.readLine();
                         }
                         catch ( IOException e )
                         {
                             streamClosed = true;
                             return false;
                         }
 
                         if ( null == nextClassName )
                         {
                             streamClosed = true;
                         }
                         else
                         {
                             addWorkItem( nextClassName );
                         }
                     }
 
                     return ( workQueue.size() > nextPos );
                 }
             }
         }
 
         private boolean needsToWaitForInput( int nextPos )
         {
             return workQueue.size() == nextPos && !streamClosed;
         }
 
         public Object next()
         {
             synchronized ( workQueue )
             {
                 return workQueue.get( ++lastPos );
             }
         }
 
         public void remove()
         {
             throw new UnsupportedOperationException();
         }
 
     }
 
     /* (non-Javadoc)
       * @see org.apache.maven.surefire.util.TestsToRun#iterator()
       */
     public Iterator iterator()
     {
         return new BlockingIterator();
     }
 
     /* (non-Javadoc)
       * @see org.apache.maven.surefire.util.TestsToRun#toString()
       */
     public String toString()
     {
         StringBuffer sb = new StringBuffer( "LazyTestsToRun " );
         synchronized ( workQueue )
         {
             sb.append( "(more items expected: " ).append( !streamClosed ).append( "): " );
             sb.append( workQueue );
         }
 
         return sb.toString();
     }
 
     /* (non-Javadoc)
      * @see org.apache.maven.surefire.util.TestsToRun#allowEagerReading()
      */
     public boolean allowEagerReading() {
         return false;
     }
 
 }