/*
 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * Licensed 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.
 */

package cascading.platform;

import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.WeakHashMap;

import cascading.PlatformTestCase;
import junit.framework.Test;
import org.junit.Ignore;
import org.junit.internal.runners.JUnit38ClassRunner;
import org.junit.runner.Description;
import org.junit.runner.Runner;
import org.junit.runner.manipulation.Filter;
import org.junit.runner.manipulation.Filterable;
import org.junit.runner.manipulation.NoTestsRemainException;
import org.junit.runner.notification.RunNotifier;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.ParentRunner;
import org.junit.runners.model.InitializationError;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Class ParentRunner is a JUnit {@link Runner} sub-class for injecting different platform and planners
 * into the *PlatformTest classes.
 * <p/>
 * It works by loading the {@code platform.classname} property from the {@code cascading/platform/platform.properties}
 * resource. Every new platform should provide this resource.
 * <p/>
 * To test against a specific platform, simply make sure the above resource for the platform in question is in the
 * test CLASSPATH. The simplest way is to add it as a dependency.
 */
public class PlatformRunner extends ParentRunner<Runner>
  {
  public static final String PLATFORM_INCLUDES = "test.platform.includes";
  public static final String PLATFORM_RESOURCE = "cascading/platform/platform.properties";
  public static final String PLATFORM_CLASSNAME = "platform.classname";

  private static final Logger LOG = LoggerFactory.getLogger( PlatformRunner.class );

  private Set<String> includes = new HashSet<String>();
  private List<Runner> runners;

  @Retention(RetentionPolicy.RUNTIME)
  @Inherited
  public @interface Platform
    {
    Class<? extends TestPlatform>[] value();
    }

  public PlatformRunner( Class<PlatformTestCase> testClass ) throws Throwable
    {
    super( testClass );

    setIncludes();
    makeRunners();
    }

  private void setIncludes()
    {
    String includesString = System.getProperty( PLATFORM_INCLUDES );

    if( includesString == null || includesString.isEmpty() )
      return;

    String[] split = includesString.split( "," );

    for( String include : split )
      includes.add( include.trim().toLowerCase() );
    }

  public static TestPlatform makeInstance( Class<? extends TestPlatform> type )
    {
    try
      {
      return type.newInstance();
      }
    catch( NoClassDefFoundError exception )
      {
      return null;
      }
    catch( InstantiationException exception )
      {
      throw new RuntimeException( exception );
      }
    catch( IllegalAccessException exception )
      {
      throw new RuntimeException( exception );
      }
    }

  @Override
  protected List<Runner> getChildren()
    {
    return runners;
    }

  private List<Runner> makeRunners() throws Throwable
    {
    Class<?> javaClass = getTestClass().getJavaClass();

    runners = new ArrayList<Runner>();

    // test for use of annotation
    Set<Class<? extends TestPlatform>> classes = getPlatformClassesFromAnnotation( javaClass );

    // if no platforms declared from the annotation, test classpath
    if( classes.isEmpty() )
      classes = getPlatformClassesFromClasspath( javaClass.getClassLoader() );

    int count = 0;
    Iterator<Class<? extends TestPlatform>> iterator = classes.iterator();
    while( iterator.hasNext() )
      addPlatform( javaClass, iterator.next(), count++, classes.size() );

    return runners;
    }

  private Set<Class<? extends TestPlatform>> getPlatformClassesFromAnnotation( Class<?> javaClass ) throws Throwable
    {
    PlatformRunner.Platform annotation = javaClass.getAnnotation( PlatformRunner.Platform.class );

    if( annotation == null )
      return Collections.EMPTY_SET;

    HashSet<Class<? extends TestPlatform>> classes = new LinkedHashSet<Class<? extends TestPlatform>>( Arrays.asList( annotation.value() ) );

    LOG.info( "found {} test platforms from Platform annotation", classes.size() );

    return classes;
    }

  static Map<ClassLoader, Set<Class<? extends TestPlatform>>> cache = new WeakHashMap<>();

  protected synchronized static Set<Class<? extends TestPlatform>> getPlatformClassesFromClasspath( ClassLoader classLoader ) throws IOException, ClassNotFoundException
    {
    if( cache.containsKey( classLoader ) )
      return cache.get( classLoader );

    Set<Class<? extends TestPlatform>> classes = new LinkedHashSet<>();
    Properties properties = new Properties();

    LOG.debug( "classloader: {}", classLoader );

    Enumeration<URL> urls = classLoader.getResources( PLATFORM_RESOURCE );

    while( urls.hasMoreElements() )
      {
      InputStream stream = urls.nextElement().openStream();
      classes.add( (Class<? extends TestPlatform>) getPlatformClass( classLoader, properties, stream ) );
      }

    if( classes.isEmpty() )
      {
      LOG.warn( "no platform tests will be run" );
      LOG.warn( "did not find {} in the classpath, no {} instances found", PLATFORM_RESOURCE, TestPlatform.class.getCanonicalName() );
      LOG.warn( "add cascading-local, cascading-hadoop, and/or external planner library to the test classpath" );
      }
    else
      {
      LOG.info( "found {} test platforms from classpath", classes.size() );
      }

    cache.put( classLoader, classes );
    return classes;
    }

  private static Class<?> getPlatformClass( ClassLoader classLoader, Properties properties, InputStream stream ) throws IOException, ClassNotFoundException
    {
    if( stream == null )
      throw new IllegalStateException( "platform provider resource not found: " + PLATFORM_RESOURCE );

    properties.load( stream );

    String classname = properties.getProperty( PLATFORM_CLASSNAME );

    if( classname == null )
      throw new IllegalStateException( "platform provider value not found: " + PLATFORM_CLASSNAME );

    Class<?> type = classLoader.loadClass( classname );

    if( type == null )
      throw new IllegalStateException( "platform provider class not found: " + classname );

    return type;
    }

  private void addPlatform( final Class<?> javaClass, Class<? extends TestPlatform> type, int ordinal, int size ) throws Throwable
    {
    if( javaClass.getAnnotation( Ignore.class ) != null ) // ignore this class
      {
      LOG.info( "ignoring test class: {}", javaClass.getCanonicalName() );
      return;
      }

    final TestPlatform testPlatform = makeInstance( type );

    // test platform dependencies not installed, so skip
    if( testPlatform == null )
      return;

    final String platformName = testPlatform.getName();

    if( !includes.isEmpty() && !includes.contains( platformName.toLowerCase() ) )
      {
      LOG.info( "ignoring platform: {}", platformName );
      return;
      }

    LOG.info( "adding test: {}, with platform: {}", javaClass.getName(), platformName );

    PlatformSuite suiteAnnotation = javaClass.getAnnotation( PlatformSuite.class );

    if( suiteAnnotation != null )
      runners.add( makeSuiteRunner( javaClass, suiteAnnotation.method(), testPlatform ) );
    else
      runners.add( makeClassRunner( javaClass, testPlatform, platformName, size != 1 ) );
    }

  private JUnit38ClassRunner makeSuiteRunner( Class<?> javaClass, String suiteMethod, final TestPlatform testPlatform ) throws Throwable
    {
    Method method = javaClass.getMethod( suiteMethod, TestPlatform.class );

    return new JUnit38ClassRunner( (Test) method.invoke( null, testPlatform ) );
    }

  private BlockJUnit4ClassRunner makeClassRunner( final Class<?> javaClass, final TestPlatform testPlatform, final String platformName, final boolean useName ) throws InitializationError
    {
    return new BlockJUnit4ClassRunner( javaClass )
    {
    @Override
    protected String getName() // the runner name
    {
    if( useName )
      return String.format( "%s[%s]", super.getName(), platformName );
    else
      return super.getName();
    }

//        @Override
//        protected String testName( FrameworkMethod method )
//          {
//          return String.format( "%s[%s]", super.testName( method ), platformName );
//          }

    @Override
    protected Object createTest() throws Exception
      {
      PlatformTestCase testCase = (PlatformTestCase) super.createTest();

      testCase.installPlatform( testPlatform );

      return testCase;
      }
    };
    }

  @Override
  protected Description describeChild( Runner runner )
    {
    return runner.getDescription();
    }

  @Override
  protected void runChild( Runner runner, RunNotifier runNotifier )
    {
    runner.run( runNotifier );
    }

  @Override
  public void filter( Filter filter ) throws NoTestsRemainException
    {
    for( Runner runner : getChildren() )
      {
      if( runner instanceof Filterable )
        ( (Filterable) runner ).filter( filter );
      }
    }
  }