package org.daisy.pipeline.css;
   
   import java.net.URL;
   import java.util.ArrayList;
   import java.util.Collection;
   
   import static com.google.common.collect.Iterables.any;
   
   import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.osgi.service.component.annotations.ReferenceCardinality;
  import org.osgi.service.component.annotations.ReferencePolicy;
  
  @Component(
  	name = "UserAgentStylesheetRegistry",
  	service = { UserAgentStylesheetRegistry.class }
  )
  public class UserAgentStylesheetRegistry {
  
  	/**
  	 * Return the user agent style sheet(s) for the given stylesheet types, content type
  	 * and medium. If there are multiple style sheets, their order is undetermined.
  	 */
  	public Collection<URL> get(Collection<String> types, Collection<String> contentTypes, Collection<Medium> media) {
  		Collection<URL> filtered = new ArrayList<>();
  		for (UserAgentStylesheet s : stylesheets)
  			if (types.contains(s.getType()))
  				if (any(contentTypes, s::matchesContentType))
  					if (any(media, s::matchesMedium))
  						filtered.add(s.getURL());
  		return filtered;
  	}
  
  	private Collection<UserAgentStylesheet> stylesheets = new ArrayList<>();
  
  	@Reference(
  		name = "UserAgentStylesheet",
  		unbind = "-",
  		service = UserAgentStylesheet.class,
  		cardinality = ReferenceCardinality.MULTIPLE,
  		policy = ReferencePolicy.STATIC
  	)
  	protected void addStylesheet(UserAgentStylesheet stylesheet) {
  		stylesheets.add(stylesheet);
  	}
  }