package org.csstudio.sds.internal.eventhandling;

import java.util.ArrayList;
import java.util.List;

import org.csstudio.sds.SdsPlugin;
import org.csstudio.sds.eventhandling.AbstractWidgetPropertyPostProcessor;
import org.csstudio.sds.eventhandling.EventType;
import org.csstudio.sds.model.AbstractWidgetModel;
import org.csstudio.sds.model.WidgetProperty;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.gef.commands.CompoundCommand;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@SuppressWarnings("unchecked")
public class WidgetPropertyPostProcessingService implements IWidgetPropertyPostProcessingService {
	private List<AbstractWidgetPropertyPostProcessor> processors;
    private static final Logger LOG = LoggerFactory.getLogger(WidgetPropertyPostProcessingService.class);

	public WidgetPropertyPostProcessingService() {
		processors = lookup();
	}

	/**
	 *{@inheritDoc}
	 */
	@Override
	public void applyForAllProperties(AbstractWidgetModel widget, EventType eventType) {
		for (WidgetProperty property : widget.getProperties()) {
			CompoundCommand chain = new CompoundCommand();
			applyForSingleProperty(widget, property, chain, EventType.ON_DISPLAY_MODEL_LOADED);

			if (!chain.isEmpty()) {
				chain.execute();
			}
		}
	}

	/**
	 *{@inheritDoc}
	 */
	@Override
	public void applyForSingleProperty(AbstractWidgetModel widget, WidgetProperty widgetProperty, CompoundCommand chain, EventType eventType) {
		for (AbstractWidgetPropertyPostProcessor processor : processors) {
			processor.applyAfterPropertyChangeCommands(widget, widgetProperty, chain, eventType);
		}
	}

	private List<AbstractWidgetPropertyPostProcessor> lookup() {
		List<AbstractWidgetPropertyPostProcessor> processors = new ArrayList<AbstractWidgetPropertyPostProcessor>();

		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
		IConfigurationElement[] elements = extensionRegistry.getConfigurationElementsFor(SdsPlugin.EXTPOINT_WIDGET_PROPERTY_POSTPROCESSORS);

		for (IConfigurationElement element : elements) {
			try {
				AbstractWidgetPropertyPostProcessor processor = (AbstractWidgetPropertyPostProcessor) element.createExecutableExtension("class"); //$NON-NLS-1$
				assert processor != null;
				processors.add(processor);
			} catch (CoreException e) {
				LOG.warn("Cannot instantiate extension class [" + element.getAttribute("class") + "] for extension point ["
								+ SdsPlugin.EXTPOINT_WIDGET_PROPERTY_POSTPROCESSORS + "]");
			}
		}

		return processors;
	}

}