/*
    * This file is a part of CAST project.
    * (c) Copyright 2007, AGH University of Science & Technology
    * https://caribou.iisg.agh.edu.pl/trac/cast
    *
    * Licensed under the Eclipse Public License, Version 1.0 (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.eclipse.org/legal/epl-v10.html
   */
  /*
   * File: ResourceRegistry.java
   * Created: 2009-07-22
   * Author: kpietak
   * $Id$
   */
  
  package pl.edu.agh.cast.resource;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.log4j.Logger;
  
  import pl.edu.agh.cast.Activator;
  
  /**
   * Default implementation of {@link IResourceRegistry}.
   *
   * @author AGH CAST Team
   */
  public class ResourceRegistry implements IResourceRegistry {
  
  	private static Logger log = Activator.getLogger();
  
  	private Map<String, IVisualResource> idToResourceMap;
  
  	private Map<String, List<IVisualResource>> tagToResourcesMap;
  
  	private IVisualResourcesProvidersReader providersReader;
  
  	/**
  	 * Constructor.
  	 */
  	public ResourceRegistry() {
  		idToResourceMap = new HashMap<String, IVisualResource>();
  		tagToResourcesMap = new HashMap<String, List<IVisualResource>>();
  		providersReader = new RCPVisualResourcesProvidersReader();
  	}
  
  	/**
  	 * {@inheritDoc}
  	 *
  	 * @see pl.edu.agh.cast.resource.IResourceRegistry#getResource(java.lang.String)
  	 */
  	@Override
  	public IVisualResource getResource(String id) {
  		if (id == null) {
  			throw new IllegalArgumentException("Cannot get resource with null id"); //$NON-NLS-1$
  		}
  		return idToResourceMap.get(id);
  	}
  
  	/**
  	 * {@inheritDoc}
  	 *
  	 * @see pl.edu.agh.cast.resource.IResourceRegistry#getResource(java.lang.String, java.lang.String)
  	 */
  	@Override
  	public IVisualResource getResource(String id, String defaultId) {
  		IVisualResource resource = getResource(id);
  		if (resource == null) {
  			resource = getResource(defaultId);
  		}
  		return resource;
  	}
  
  	/**
  	 * {@inheritDoc}
  	 *
  	 * @see pl.edu.agh.cast.resource.IResourceRegistry#getResources(java.lang.String)
  	 */
  	@SuppressWarnings("unchecked")
  	@Override
  	public List<IVisualResource> getResources(String tag) {
  		if (tag == null) {
  			throw new IllegalArgumentException("Cannot get resources by null tag"); //$NON-NLS-1$
  		}
  		return tagToResourcesMap.containsKey(tag) ? tagToResourcesMap.get(tag) : Collections.EMPTY_LIST;
  	}
  
  	/**
  	 * {@inheritDoc}
  	 *
  	 * @see pl.edu.agh.cast.resource.IResourceRegistry#initalize()
  	 */
 	@Override
 	public void initalize() throws ResourceException {
 		log.info("Initializing resource registry..."); //$NON-NLS-1$
 		List<IVisualResourcesProvider> providers = providersReader.getVisualResourcesProviders();
 		for (IVisualResourcesProvider provider : providers) {
 			for (IVisualResource resource : provider.getVisualResources()) {
 				register(resource);
 			}
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 *
 	 * @see pl.edu.agh.cast.resource.IResourceRegistry#dispose()
 	 */
 	@Override
 	public void dispose() {
 		for (IVisualResource resource : idToResourceMap.values()) {
 			resource.dispose();
 		}
 		idToResourceMap.clear();
 		tagToResourcesMap.clear();
 		log.info("Resource registry disposed"); //$NON-NLS-1$
 
 	}
 
 	/**
 	 * {@inheritDoc}
 	 *
 	 * @see pl.edu.agh.cast.resource.IResourceRegistry#register(pl.edu.agh.cast.resource.VisualResourceEntry)
 	 */
 	@Override
 	public void register(IVisualResource resource) throws ResourceException {
 		if (resource == null) {
 			throw new IllegalArgumentException("Cannot register null resource"); //$NON-NLS-1$
 		}
 		String id = resource.getId();
 		if (id == null || id.isEmpty()) {
 			throw new IllegalArgumentException("Cannot register resource with null or empty id"); //$NON-NLS-1$
 		}
 		// register resource by id
 		if (idToResourceMap.containsKey(id)) {
 			throw new ResourceException(String.format("Resource with id %1$ already exists", id)); //$NON-NLS-1$
 		}
 		idToResourceMap.put(id, resource);
 
 		// register resource by all it's tags
 		List<String> tags = resource.getTags();
 		if (tags != null) {
 			for (String tag : tags) {
 				if (!tagToResourcesMap.containsKey(tag)) {
 					tagToResourcesMap.put(tag, new LinkedList<IVisualResource>());
 				}
 				List<IVisualResource> values = tagToResourcesMap.get(tag);
 				values.add(resource);
 			}
 		}
 		log.info(String.format("Resource with id %1$s added to resource registry", id)); //$NON-NLS-1$
 	}
 
 	/**
 	 * {@inheritDoc}
 	 *
 	 * @see pl.edu.agh.cast.resource.IResourceRegistry#unregister(java.lang.String)
 	 */
 	@SuppressWarnings("nls")
 	@Override
 	public boolean unregister(String id) throws ResourceException {
 		if (id == null) {
 			throw new IllegalArgumentException("Cannot unregister resource with null id");
 		}
 		if (idToResourceMap.containsKey(id)) {
 			IVisualResource resource = idToResourceMap.remove(id);
 			List<String> tags = resource.getTags();
 			if (tags != null) {
 				for (String tag : tags) {
 					List<IVisualResource> values = tagToResourcesMap.get(tag);
 					values.remove(resource);
 				}
 			}
 			resource.dispose();
 			log.info(String.format("Resource with id %1$s disposed and removed from resource registry", id));
 			return true;
 		} else {
 			// resource does not exists
 			log.warn(String.format("Cannot unregister resource: Resource with id %1$s does not exists"));
 			return false;
 		}
 
 	}
 
 	protected void setResourcesProvidersReader(IVisualResourcesProvidersReader reader) {
 		this.providersReader = reader;
 	}
 
 	/**
 	 * Interface for objects which reads available resources providers.
 	 *
 	 * @author AGH CAST Team
 	 */
 	interface IVisualResourcesProvidersReader {
 
 		/**
 		 * Gets visual resources providers
 		 *
 		 * @return list of resources providers
 		 */
 		List<IVisualResourcesProvider> getVisualResourcesProviders();
 	}
 
 	/**
 	 * Default implementation of {@link IVisualResourcesProvidersReader} which reads resources providers from
 	 * <code>pl.edu.agh.cast.resource.provider</code> extension point.
 	 *
 	 * @author AGH CAST Team
 	 */
 	class RCPVisualResourcesProvidersReader implements IVisualResourcesProvidersReader {
 
 		/**
 		 * {@inheritDoc}
 		 *
 		 * @see pl.edu.agh.cast.resource.ResourceRegistry.IVisualResourcesProvidersReader#getVisualResourcesProviders()
 		 */
 		@Override
 		public List<IVisualResourcesProvider> getVisualResourcesProviders() {
 			return Activator.getResourcesProviders();
 		}
 
 	}
 
 }