/**
 * Same as super-class, but additionally provides support for using a 
 * dynamic callback-method name for JSONP, as might be provided
 * through a URI query-string parameter.
 */
@Provider
@Getter
@Setter
public class JSONPObjectProviderForDynamicCallbacks extends JSONPObjectProvider
{
	/**  */
	private static final Logger log = Logger.getLogger( JSONPObjectProviderForDynamicCallbacks.class );
	
	/**  */
	public static final String DEFAULT_CALLBACK_PARAMETER_NAME = "callback";
	
	/**  */
	private String callbackParamName = DEFAULT_CALLBACK_PARAMETER_NAME;
	
	/**  */
	private boolean checkForValidCallbackName = true;

	/**  */
	@Context
	private UriInfo uriInfo;
	
	/**
	 * 
	 */
	@Override
	protected String getActualCallbackName()
	{
		final MultivaluedMap<String, String> params = uriInfo.getQueryParameters();
		
		// try to determine the desired callback-name dynamically from query-parameters
		if( getCallbackParamName() != null && params.containsKey( getCallbackParamName() ) )
		{
			final String dynamicCallbackName = params.getFirst( getCallbackParamName() );
			if( ! StringUtils.isBlank( dynamicCallbackName ) )
			{
				// if that feature is configured, check that the dynamically determined callback name is a valid JS identifier
				if ( isCheckForValidCallbackName() && ! JavaScriptUtils.isValidJsIdentifier( dynamicCallbackName ) )
				{
					if ( log.isEnabledFor( Level.WARN ) )
					{
						log.warn( 
								"A JSONP client requested invalid callback-name \"" + dynamicCallbackName + "\" through query-string-parameter \"" + getCallbackParamName() + "\". " +
								"Ignoring it and using pre-configured callback-name \"" + getCallbackName() + "\" instead." 
						);
					}
					return getCallbackName();
				}
				
				// return dynamically determined callback name
				return dynamicCallbackName;
			}
		}

		// if determining the actual callback name dynamically failed, fall back to pre-configured callback name
		return getCallbackName();
	}

}