bundles/core/org.eclipse.apogy.core.ui/src/org/eclipse/apogy/core/ui/composites/ApogySystemApiAdapterBasedComposite.java

/*******************************************************************************
 * Copyright (c) 2018 Agence spatiale canadienne / Canadian Space Agency 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Pierre Allard,
 *     Regent L'Archeveque - initial API and implementation
 *  
 * SPDX-License-Identifier: EPL-1.0
 *******************************************************************************/
package org.eclipse.apogy.core.ui.composites;

import org.eclipse.apogy.core.ApogySystemApiAdapter;
import org.eclipse.apogy.core.invocator.ApogyCoreInvocatorFacade;
import org.eclipse.apogy.core.invocator.ApogyCoreInvocatorPackage;
import org.eclipse.apogy.core.invocator.Context;
import org.eclipse.apogy.core.invocator.Environment;
import org.eclipse.apogy.core.invocator.InvocatorSession;
import org.eclipse.apogy.core.invocator.TypeApiAdapter;
import org.eclipse.apogy.core.invocator.VariableFeatureReference;
import org.eclipse.emf.common.notify.Adapter;
import org.eclipse.emf.common.notify.Notification;
import org.eclipse.emf.common.notify.impl.AdapterImpl;
import org.eclipse.emf.ecore.util.EContentAdapter;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;

public abstract class ApogySystemApiAdapterBasedComposite extends Composite {
	private VariableFeatureReference variableFeatureReference;
	private ApogySystemApiAdapter apogySystemApiAdapter;

	private Adapter variableFeatureReferenceAdapter;
	private ApiInstanceAdapter instancesAdapter;

	public ApogySystemApiAdapterBasedComposite(Composite parent, int style) {
		super(parent, style);

		getInstanceAdapter().registerToAll();

		addDisposeListener(new DisposeListener() {

			@Override
			public void widgetDisposed(DisposeEvent e) {
				// Unregister adapter.
				getInstanceAdapter().unregisterFromAll();
			}
		});
	}

	public VariableFeatureReference getVariableFeatureReference() {
		return this.variableFeatureReference;
	}

	public void setVariableFeatureReference(VariableFeatureReference newVariableFeatureReference) {
		if (this.variableFeatureReference != null) {
			this.variableFeatureReference.eAdapters().remove(getVariableFeatureReferenceAdapter());
		}

		this.variableFeatureReference = newVariableFeatureReference;

		if (newVariableFeatureReference != null) {
			newVariableFeatureReference.eAdapters().add(getVariableFeatureReferenceAdapter());
		}

		ApogySystemApiAdapter oldApogySystemApiAdapter = this.apogySystemApiAdapter;

		// Attempts to resolve the ApogySystemApiAdapter associated with the new
		// variable.
		this.apogySystemApiAdapter = resolveApogySystemApiAdapter(newVariableFeatureReference);

		// Notify of the change of the ApogySystemApiAdapter.
		apogySystemApiAdapterChanged(oldApogySystemApiAdapter, this.apogySystemApiAdapter);
	}

	/**
	 * Return the ApogySystemApiAdapter associated with the variable.
	 * 
	 * @return The ApogySystemApiAdapter, can be null.
	 */
	public ApogySystemApiAdapter getApogySystemApiAdapter() {
		return this.apogySystemApiAdapter;
	}

	public ApogySystemApiAdapter resolveApogySystemApiAdapter(VariableFeatureReference variableFeatureReference) {
		ApogySystemApiAdapter apogySystemApiAdapter = null;
		if (variableFeatureReference != null && variableFeatureReference.getVariable() != null) {
			if (ApogyCoreInvocatorFacade.INSTANCE.getActiveInvocatorSession() != null) {
				// Attempts to resolve the ApogySystem associated with the variable.
				TypeApiAdapter typeApiAdapter = ApogyCoreInvocatorFacade.INSTANCE
						.getTypeApiAdapter(variableFeatureReference);
				if (typeApiAdapter instanceof ApogySystemApiAdapter) {
					apogySystemApiAdapter = (ApogySystemApiAdapter) typeApiAdapter;
				}
			}
		}

		return apogySystemApiAdapter;
	}

	/**
	 * Method called whenever the apogySystemApiAdapter associated with the variable
	 * changes.
	 * 
	 * @param apogySystemApiAdapter The new ApogySystemApiAdapter associated with
	 *                              the variable.
	 */
	abstract protected void apogySystemApiAdapterChanged(final ApogySystemApiAdapter oldApogySystemApiAdapter,
			final ApogySystemApiAdapter newApogySystemApiAdapter);

	private Adapter getVariableFeatureReferenceAdapter() {
		if (this.variableFeatureReferenceAdapter == null) {
			this.variableFeatureReferenceAdapter = new EContentAdapter() {
				@Override
				public void notifyChanged(Notification msg) {
					Display.getDefault().asyncExec(new Runnable() {
						@Override
						public void run() {
							ApogySystemApiAdapter oldApogySystemApiAdapter = getApogySystemApiAdapter();
							ApogySystemApiAdapterBasedComposite.this.apogySystemApiAdapter = resolveApogySystemApiAdapter(
									ApogySystemApiAdapterBasedComposite.this.variableFeatureReference);
							apogySystemApiAdapterChanged(oldApogySystemApiAdapter,
									ApogySystemApiAdapterBasedComposite.this.apogySystemApiAdapter);
						}
					});

					super.notifyChanged(msg);
				}
			};
		}

		return this.variableFeatureReferenceAdapter;
	}

	/**
	 * Return the adapter used to monitor changes on the instantiation of the
	 * variables.
	 * 
	 * @return The adapter, never null.
	 */
	private ApiInstanceAdapter getInstanceAdapter() {
		if (this.instancesAdapter == null) {
			this.instancesAdapter = new ApiInstanceAdapter();
		}

		return this.instancesAdapter;
	}

	class ApiInstanceAdapter extends AdapterImpl {
		private InvocatorSession invocatorSession;
		private Environment environment;
		private Context context;

		public void registerToAll() {
			// Register adapter to listen for variable instantiation.
			ApogyCoreInvocatorFacade.INSTANCE.eAdapters().add(this);

			// Register to active session.
			registerToInvocatorSession(ApogyCoreInvocatorFacade.INSTANCE.getActiveInvocatorSession());
		}

		public void unregisterFromAll() {
			if (this.invocatorSession != null)
				this.invocatorSession.eAdapters().remove(this);
			if (this.environment != null)
				this.environment.eAdapters().remove(this);
			if (this.context != null)
				this.context.eAdapters().remove(this);

			// Unregister from Facade.
			ApogyCoreInvocatorFacade.INSTANCE.eAdapters().remove(this);
		}

		@Override
		public void notifyChanged(Notification msg) {
			if (msg.getNotifier() instanceof ApogyCoreInvocatorFacade) {
				int featureID = msg.getFeatureID(ApogyCoreInvocatorFacade.class);
				switch (featureID) {
				case ApogyCoreInvocatorPackage.APOGY_CORE_INVOCATOR_FACADE__INIT_VARIABLE_INSTANCES_DATE:

					// Updates ApogySystemApiAdapter.
					updateApogySystemApiAdapter();
					break;

				// If the Active Invocator Session changes.
				case ApogyCoreInvocatorPackage.APOGY_CORE_INVOCATOR_FACADE__ACTIVE_INVOCATOR_SESSION:

					unregisterFromInvocatorSession((InvocatorSession) msg.getOldValue());
					registerToInvocatorSession((InvocatorSession) msg.getNewValue());

					// Updates ApogySystemApiAdapter.
					updateApogySystemApiAdapter();

					break;

				default:
					break;
				}
			} else if (msg.getNotifier() instanceof InvocatorSession) {
				int featureID = msg.getFeatureID(InvocatorSession.class);
				switch (featureID) {
				case ApogyCoreInvocatorPackage.INVOCATOR_SESSION__ENVIRONMENT:

					unregisterFromEnvironment((Environment) msg.getOldValue());
					registerToEnvironment((Environment) msg.getNewValue());

					// Updates ApogySystemApiAdapter.
					updateApogySystemApiAdapter();
					break;

				default:
					break;
				}
			} else if (msg.getNotifier() instanceof Environment) {
				int featureID = msg.getFeatureID(Environment.class);
				switch (featureID) {
				case ApogyCoreInvocatorPackage.ENVIRONMENT__ACTIVE_CONTEXT:

					unregisterFromContext((Context) msg.getOldValue());
					registerToContext((Context) msg.getNewValue());

					// Updates ApogySystemApiAdapter.
					updateApogySystemApiAdapter();
					break;

				default:
					break;
				}
			} else if (msg.getNotifier() instanceof Context) {
				int featureID = msg.getFeatureID(Context.class);
				switch (featureID) {
				case ApogyCoreInvocatorPackage.CONTEXT__INSTANCES_DISPOSAL_DATE:

					// Updates ApogySystemApiAdapter.
					updateApogySystemApiAdapter();
					break;

				default:
					break;
				}
			}
		}

		private void registerToInvocatorSession(InvocatorSession invocatorSession) {
			if (invocatorSession != null) {
				invocatorSession.eAdapters().add(this);
				registerToEnvironment(invocatorSession.getEnvironment());
			}

			this.invocatorSession = null;
		}

		private void unregisterFromInvocatorSession(InvocatorSession invocatorSession) {
			if (invocatorSession != null) {
				invocatorSession.eAdapters().remove(this);
				unregisterFromEnvironment(invocatorSession.getEnvironment());
			}

			this.invocatorSession = invocatorSession;
		}

		private void registerToEnvironment(Environment environment) {
			if (environment != null) {
				environment.eAdapters().add(this);

				if (environment.getActiveContext() != null) {
					environment.getActiveContext().eAdapters().add(this);
				}
			}

			this.environment = environment;
		}

		private void unregisterFromEnvironment(Environment environment) {
			if (environment != null) {
				environment.eAdapters().remove(this);

				if (environment.getActiveContext() != null) {
					environment.getActiveContext().eAdapters().remove(this);
				}
			}

			this.environment = null;
		}

		private void registerToContext(Context context) {
			if (context != null) {
				context.eAdapters().add(this);
			}

			this.context = context;
		}

		private void unregisterFromContext(Context context) {
			if (context != null) {
				context.eAdapters().remove(this);
			}

			this.context = null;
		}

		private void updateApogySystemApiAdapter() {
			Display.getDefault().asyncExec(new Runnable() {
				@Override
				public void run() {
					ApogySystemApiAdapter oldApogySystemApiAdapter = getApogySystemApiAdapter();
					ApogySystemApiAdapterBasedComposite.this.apogySystemApiAdapter = resolveApogySystemApiAdapter(
							ApogySystemApiAdapterBasedComposite.this.variableFeatureReference);
					apogySystemApiAdapterChanged(oldApogySystemApiAdapter,
							ApogySystemApiAdapterBasedComposite.this.apogySystemApiAdapter);
				}
			});
		}
	}

}