package edu.vub.at.actors.natives;

import edu.vub.at.actors.eventloops.Callable;
import edu.vub.at.actors.net.ConnectionListener;
import edu.vub.at.eval.Evaluator;
import edu.vub.at.exceptions.InterpreterException;
import edu.vub.at.objects.ATObject;
import edu.vub.at.objects.ATTable;
import edu.vub.at.objects.mirrors.NativeClosure;
import edu.vub.at.objects.natives.NATNil;
import edu.vub.at.objects.natives.NATObjectClosureTest;
import edu.vub.at.objects.natives.grammar.AGSymbol;
import edu.vub.at.parser.NATParser;

import junit.framework.TestCase;

public class DistributionTest extends TestCase {

	private ELVirtualMachine virtual1_;
	private ELVirtualMachine virtual2_;
	
	/**
	 * the VMs from this unit test join a dedicated test group (not the default group)
	 * to avoid as much interference as possible with other running AmbientTalk interpreters.
	 */
	private static final String _TEST_GROUP_NAME_ = "AmbientTalkTest";
	
	private static final int _TIMEOUT_ = 10000;
	
	private boolean testResult_ = false;
	
	// used to avoid 'final' restriction for nested classes
	protected synchronized void setTestResult(boolean value) {
		testResult_ = value;
		
		// typically, we wait for a given timeout but can resume earlier when this event takes place
		this.notify();
	}
	
	// used to avoid 'final' restriction for nested classes
	protected boolean getTestResult() {
		return testResult_;
	}
	
	public static void main(String[] args) {
		junit.swingui.TestRunner.run(NATObjectClosureTest.class);
	}

	protected void setUp() throws Exception {
		super.setUp();

		virtual1_ = new ELVirtualMachine(NATNil._INSTANCE_, new SharedActorField[] { }, _TEST_GROUP_NAME_);
		virtual2_ = new ELVirtualMachine(NATNil._INSTANCE_, new SharedActorField[] { }, _TEST_GROUP_NAME_);
	}
	
	protected void tearDown() throws Exception {
		if(virtual1_ != null) {
			virtual1_.event_goOffline();
			virtual1_.stopProcessing();
		}
		
		if(virtual2_ != null) {
			virtual2_.event_goOffline();
			virtual2_.stopProcessing();
		}
	}
	
	// Creates an ELActor, hosted on the provided VM.
	private ELActor setUpActor(ELVirtualMachine host) throws InterpreterException {
		return NATActorMirror.createEmptyActor(host, new NATActorMirror(host)).getFarHost();
	}
	
	// installs a closure in a particular actor's scope which allows signalling a return value
	// with the added bonus of waking up the test thread from waiting.
	private void setUpSuccessTrigger(ELActor processor) throws Exception {
		processor.sync_event_performTest(new Callable() {
			public Object call(Object argument)throws InterpreterException {
				return Evaluator.getGlobalLexicalScope().meta_defineField(
						AGSymbol.jAlloc("success"),
						new NativeClosure(NATNil._INSTANCE_) {

							public ATObject base_apply(ATTable arguments) throws InterpreterException {
								setTestResult(true);
								
								return NATNil._INSTANCE_;
							}
						});
			}
		});
	}
	
	// Joint code for the various test suites to test the behaviour of the AT connection observers 
	private void setUpConnectionObservers() throws Exception {
		ELActor subscriber = setUpActor(virtual1_);
		ELActor provider   = setUpActor(virtual2_);
		
		// We define a closure to inform us the test succeeded
		setUpSuccessTrigger(subscriber);
		
		subscriber.sync_event_eval(
				NATParser.parse("DistributionTest#setUpConnectionObservers()",
						"defstripe Service; \n" +
						"when: Service discovered: { | ref |" +
						"  when: ref disconnected: { success(); }; \n" +
						"  when: ref reconnected:  { success(); }; \n" +
						// explicitly triggering success, although we are not testing service discovery
						// allows to minimize the waiting time until we can go offline
						"  success(); " +
						"} \n;"));
		
		provider.sync_event_eval(
				NATParser.parse("DistributionTest#setUpConnectionObservers()",
						"defstripe Service; \n" +
						"export: (object: { nil }) as: Service"));
	}

	
	/**
	 * When a virtual machine joins the AmbientTalk overlay network, all virtual machines are 
	 * notified of this fact by the underlying distribution layer. Messages are sent to the 
	 * DiscoveryManager to notify it of a new vm which may host required services and to all
	 * (far reference) listeners waiting for the appearance of that VM.
	 * 
	 * This test registers a dedicated listener to test the dispatching of connected and 
	 * disconnected messages to such listeners when appropriate.
	 */
	public synchronized void testVirtualMachineDiscovery() {
		
		// We prevent any race conditions between the going online and offline, forcing both
		// handlers to be called. Therefore the test fails unless the disconnected handler
		// determines it was successful
		setTestResult(false);
		
		virtual1_.connectionManager_.addConnectionListener(
				virtual2_.getGUID(),
				new ConnectionListener() {
					public void connected() {
						setTestResult(true);
					}
					public void disconnected() { }
				});
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("DiscoveryBus notification of the VM has failed to arrive within " + _TIMEOUT_ /1000 + " sec.");
	}
	
	/**
	 * When a virtual machine leaves the AmbientTalk overlay network, all virtual machines are 
	 * notified of this fact by the underlying distribution layer. Messages are sent to the 
	 * DiscoveryManager and to all (far reference) listeners connected to that VM.
	 * 
	 * This test registers a dedicated listener to test the dispatching of disconnected 
	 * messages to such listeners when appropriate.
	 */
	public synchronized void testVirtualMachineDisconnection() {
		
		setTestResult(false);
		
		virtual2_.connectionManager_.addConnectionListener(
				virtual1_.getGUID(),
				new ConnectionListener() {
					public void connected() { }
					public void disconnected() { 
						setTestResult(true);
					}
				});
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();

		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		
		virtual1_.event_goOffline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Disconnection notification of the VM has failed to arrive within " + _TIMEOUT_ /1000 + " sec.");
	}
	
	/**
	 * This test registers a dedicated listener to test the dispatching of disconnected 
	 * messages. When the time lapse betwen connection and disconnection is too small,
	 * the test may be subject to race conditions, hence we provide a version where
	 * no wait is performed, to provoke them.
	 */
	public synchronized void testVirtualMachineDisconnectionRace() {
		
		// If the race occurs and neither the connected, nor the disconnected event listener
		// are triggered, the test should succeed, unless exceptions were raised.
		setTestResult(true);
		
		virtual2_.connectionManager_.addConnectionListener(
				virtual1_.getGUID(),
				new ConnectionListener() {
					public void connected() { 
						setTestResult(false);
					}
					public void disconnected() { 
						setTestResult(true);
					}
				});
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		virtual1_.event_goOffline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Disconnection notification of the VM has failed to arrive within " + _TIMEOUT_ /1000 + " sec.");
	}
	
	/**
	 * Uses the when: discovered: and export: as: constructs to make an object on one virtual
	 * machine accessible to another virtual machine. 
	 * @throws Exception
	 */
	public synchronized void testServiceDiscovery() throws Exception {
		
		setTestResult(false);
		
		setUpConnectionObservers();
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Service DiscoveryBus notification has failed to arrive within " + _TIMEOUT_ /1000 + " sec.");
	}
		
	/**
	 * This test uses the when: disconnected: to detect when a far reference has become
	 * disconnected. We distinguish between two tests, depending on the role of the device
	 * that falls away. If the provider disconnects, the subscriber hosting the far reference
	 * is notified of this event through by the distribution layer.
	 * 
	 * @throws Exception
	 */
	public synchronized void testProviderDisconnection() throws Exception {
		
		setUpConnectionObservers();
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		// reset the test condition
		setTestResult(false);
		
		virtual2_.event_goOffline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Disconnection observer has failed to trigger within " + _TIMEOUT_ /1000 + " sec.");

		// reset the test condition
		setTestResult(false);

		virtual2_.event_goOnline();
		
		try {
			this.wait(  );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Reconnection observer has failed to trigger within " + _TIMEOUT_ /1000 + " sec.");
	
	}
	
	/**
	 * This test uses the when: disconnected: to detect when a far reference has become
	 * disconnected. We distinguish between two tests, depending on the role of the device
	 * that goes offline.
	 * 
	 * @throws Exception
	 */
	public synchronized void testSubscriberDisconnection() throws Exception {
		
		setUpConnectionObservers();
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		// reset the test condition
		setTestResult(false);
		
		virtual1_.event_goOffline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Disconnection observer has failed to trigger within " + _TIMEOUT_ /1000 + " sec.");
		
		// reset the test condition
		setTestResult(false);

		virtual1_.event_goOnline();
		
		try {
			this.wait(  );
		} catch (InterruptedException e) {};
		
		if(! getTestResult())
			fail("Reconnection observer has failed to trigger within " + _TIMEOUT_ /1000 + " sec.");
	
	}

	public synchronized void testRetract() throws Exception {
		
		final ELActor provider = setUpActor(virtual1_);
		final ELActor subscriber = setUpActor(virtual2_);
		
		// We define a closure to inform us the test succeeded
		setUpSuccessTrigger(subscriber);
		
		subscriber.sync_event_eval(
				NATParser.parse("DistributionTest#testRetract()",
						"def messages := nil;" +
						"def far := nil;" +
						"defstripe Service; \n" +
						"when: Service discovered: { | ref | \n" +
						"  far := ref; \n" +
						"  when: ref disconnected: { \n" +
						"    messages := retract: ref; \n" +
						"    success(); \n" +
						"  }; \n" +
						"  success(); " +
						"} \n;"));
		
		provider.sync_event_eval(
				NATParser.parse("DistributionTest#testRetract()",
						"defstripe Service; \n" +
						"export: (object: { def inc(num) { num + 1; }; }) as: Service"));
		
		virtual1_.event_goOnline();
		virtual2_.event_goOnline();
		
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		// reset the test condition
		setTestResult(false);
		
		// Spawn a new thread to allow the disconnection of the provider to be in 
		// parallel with the sending of messages by the subscriber
		Thread sender = new Thread() {
			public void run() {
				try {
					subscriber.sync_event_eval(
							NATParser.parse("DistributionTest#testRetract()",
									"1.to: 5 do: { | i | \n" +
									"  far<-inc(i); \n" +
									"}; \n" +
									// Stop waiting after five messages were scheduled to ensure
									// some messages may still be in the outbox
									"success(); \n"+
									"6.to: 10 do: { | i | \n" +
									"  far<-inc(i); \n" +
									"}; \n"));
				} catch (InterpreterException e) {
					e.printStackTrace();
					fail("exception: " + e);
				}
			};
		};

		sender.start();
		
		// wait till some messages were sent
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		virtual1_.event_goOffline();
		
		// wait till disconnection event was processed
		try {
			this.wait( _TIMEOUT_ );
		} catch (InterruptedException e) {};
		
		// ELActor must not be busy while retracting the messages
		sender.join();
		
		ATObject messages = subscriber.sync_event_eval(
				NATParser.parse("DistributionTest#testRetract()",
						"messages"));
		
		
	}
	
	public void notestSimple() {
		try {
			ELActor alice = setUpActor(virtual1_);
			ELActor bob = setUpActor(virtual2_);
			
			alice.sync_event_eval(
					NATParser.parse("CrossVMCommunicationTest#testSimple()", 
							"defstripe HelloWorld; \n" +
							"whenever: HelloWorld discovered: { | ref | \n" +
							"  ref <- hello(\"alice\"); \n" +
							"}; \n"));
			
			bob.sync_event_eval(
					NATParser.parse("CrossVMCommunicationTest#testSimple()", 
							"defstripe HelloWorld; \n" +
							"def english := object: { \n" +
							"  def hello( name ) { \"hello \" + name }; \n" +
							"}; \n" +
							"def spanish := object: { \n" +
							"  def hello( name ) { \"hola \" + name }; \n" +
							"}; \n" +
							"export: english as: HelloWorld; \n" +
							"export: spanish as: HelloWorld; \n"));
			
			alice.host_.event_goOnline();
			bob.host_.event_goOnline();
			
			synchronized (this) {
				try {
					this.wait(10000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
			
		} catch (InterpreterException e) {
			e.printStackTrace();
		}	
	}

}