/**
 * 
 */
package com.topsun.posclient.application;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.Platform;

public class ContributionItemsRegistry {
//	private static final Logger logger = SystemLogFactory.getLogger(ContributionItemsRegistry.class);

	private static ContributionItemsRegistry instance = null;

	public static ContributionItemsRegistry getInstance() {
		if (instance == null) {
			synchronized (ContributionItemsRegistry.class) {
				if (instance == null) {
					instance = new ContributionItemsRegistry();
				}
			}
		}
		return instance;
	}

	private List<ContributionItemDescriptor> descriptorList = new ArrayList<ContributionItemDescriptor>();

	public ContributionItemsRegistry() {
		init();
	}

	private void init() {
		ContributionItemCategoryDescriptor[] categorys = ContributionItemCategorysRegistry.getInstance().getDescriptors();
		for (ContributionItemCategoryDescriptor category : categorys) {
			IExtensionPoint extensionPoint = Platform.getExtensionRegistry().getExtensionPoint(category.getExtensionPointId());
			IExtension[] extensions = extensionPoint.getExtensions();
			for (IExtension extension : extensions) {
				IConfigurationElement[] elements = extension.getConfigurationElements();
				descriptorList.addAll(load(elements, category.getId()));
			}
		}
	}

	private List<ContributionItemDescriptor> load(IConfigurationElement[] children, String category) {
		List<ContributionItemDescriptor> descriptors = new ArrayList<ContributionItemDescriptor>(children.length);
		for (IConfigurationElement element : children) {
			ContributionItemDescriptor descriptor = null;
			if ("actionItem".equals(element.getName())) {
				descriptor = new ContributionItemActionDescriptor();
			} else if ("controlItem".equals(element.getName())) {
				descriptor = new ContributionItemControlDescriptor();
			}

			if (descriptor != null) {
				try {
					descriptor.init(element);
					descriptor.setCategory(category);
					if (descriptors.contains(descriptor)) {
						throw new IllegalArgumentException("Duplicated '" + element.getName() + "' with id '" + descriptor.getId() + "' and category '" + descriptor.getCategory() + "'.");
					}
					descriptors.add(descriptor);
				} catch (Throwable e) {
//					logger.error(e);
				}
			}
		}
		return descriptors;
	}

	public ContributionItemDescriptor[] getDescriptors() {
		sortDescriptorList(descriptorList);
		return descriptorList.toArray(new ContributionItemDescriptor[descriptorList.size()]);
	}

	private void sortDescriptorList(List<ContributionItemDescriptor> descriptorList) {
		Collections.sort(descriptorList, new Comparator<ContributionItemDescriptor>() {
			public int compare(ContributionItemDescriptor o1, ContributionItemDescriptor o2) {
				if (o1 == null) {
					return -1;
				}
				if (o2 == null) {
					return 1;
				}
				return o1.getIndex() - o2.getIndex();
			}
		});
	}
}