package freenet.client.filter;

import freenet.client.filter.HTMLFilter.ParsedTag;


/**
 * Callback to be provided to a content filter.
 */
public interface FilterCallback {

	/**
	 * Process a URI.
	 * If it cannot be turned into something sufficiently safe, then return null.
	 * @param overrideType Force the return type.
	 * @throws CommentException If the URI is nvalid or unacceptable in some way.
	 */
	public String processURI(String uri, String overrideType) throws CommentException;

	/**
	 * Process a URI.
	 * If it cannot be turned into something sufficiently safe, then return null.
	 * @param overrideType Force the return type.
	 * @throws CommentException If the URI is nvalid or unacceptable in some way.
	 */
	public String processURI(String uri, String overrideType, boolean noRelative, boolean inline) throws CommentException;

	/**
	 * Process a base URI in the page. Not only is this filtered, it affects all
	 * relative uri's on the page.
	 */
	public String onBaseHref(String baseHref);
	
	/**
	 * Process plain-text. Notification only; can't modify.
	 * Type can be null, or can correspond, for example to HTML tag name around text
	 * (for example: "title").
	 *    
	 * Note that the string will have been fed through the relevant decoder if 
	 * necessary (e.g. HTMLDecoder). It must be re-encoded if it is sent out as
	 * text to a browser.
	 */
	public void onText(String s, String type);

	/**
	 * Process a form on the page.
	 * @param method The form sending method. Normally GET or POST.
	 * @param action The URI to send the form to.
	 * @return The new action URI, or null if the form is not allowed.
	 * @throws CommentException 
	 */
	public String processForm(String method, String action) throws CommentException;
	
	/**
	 * Process a tag. If it needs changing, then return the changed
	 * HTML, if not, then return null;
	 * @param pt - The tag to be replaced
	 * @return The new tag, or null, if it doesn't need changing
	 * */
	public String processTag(ParsedTag pt);
	
	public void onFinished();
	
}
