/*
 * @(#)AccessibleHyperlink.java	1.9 00/02/02
 *
 * Copyright 1998-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package javax.accessibility;


import java.lang.*;
import java.util.*;
import java.awt.*;
import javax.swing.text.*;


/**
 * Encapsulation of a link, or set of links (e.g. client side imagemap)
 * in a Hypertext document
 *
 * @see Accessible
 * @see Accessible#getAccessibleContext
 * @see AccessibleContext
 * @see AccessibleText
 * @see AccessibleContext#getAccessibleText
 *
 * @version 1.9, 02/02/00
 * @author	Peter Korn
 */
public abstract class AccessibleHyperlink implements AccessibleAction {

	/**
	 * Since the document a link is associated with may have
	 * changed, this method returns whether or not this Link is still valid
	 * (with respect to the document it references).
	 *
	 * @return a flag indicating whether this link is still valid with
	 *         respect to the AccessibleHypertext it belongs to
	 */
	public abstract boolean isValid();

	/**
	 * Returns the number of accessible actions available in this Link
	 * If there are more than one, the first one is NOT considered the
         * "default" action of this LINK object (e.g. in an HTML imagemap).
	 * In general, links will have only one AccessibleAction in them.
	 *
	 * @return the zero-based number of Actions in this object
	 */
	public abstract int getAccessibleActionCount();

	/**
	 * Performs the specified Action on the object
	 *
	 * @param i zero-based index of actions
	 * @return true if the action was performed; otherwise false.
	 * @see #getAccessibleActionCount
	 */
	public abstract boolean doAccessibleAction(int i);

	/**
	 * Returns a String description of this particular
	 * link action.  This should be a text string
	 * associated with anchoring text, this should be the
	 * anchor text.  E.g. from HTML:
	 *   <a HREF="http://www.sun.com/access">Accessibility</a>
	 * this method would return "Accessibility".
	 *
	 * Similarly, from this HTML:
	 *   <a HREF="#top"><img src="top-hat.gif" alt="top hat"></a>
	 * this method would return "top hat"
	 *
         * @param i zero-based index of the actions
         * @return a String description of the action
	 * @see #getAccessibleActionCount
	 */
	public abstract String getAccessibleActionDescription(int i);

	/**
	 * Returns an object that represents the link action,
	 * as appropriate for that link.  E.g. from HTML:
	 *   <a HREF="http://www.sun.com/access">Accessibility</a>
	 * this method would return a
	 * java.net.URL("http://www.sun.com/access.html");
	 *
         * @param i zero-based index of the actions
         * @return an Object representing the hypertext link itself
	 * @see #getAccessibleActionCount
	 */
	public abstract Object getAccessibleActionObject(int i);

	/**
	 * Returns an object that represents the link anchor,
	 * as appropriate for that link.  E.g. from HTML:
	 *   <a href="http://www.sun.com/access">Accessibility</a>
	 * this method would return a String containing the text:
	 * "Accessibility".
	 *
	 * Similarly, from this HTML:
	 *   <a HREF="#top"><img src="top-hat.gif" alt="top hat"></a>
	 * this might return the object ImageIcon("top-hat.gif", "top hat");
	 *
         * @param i zero-based index of the actions
         * @return an Object representing the hypertext anchor
	 * @see #getAccessibleActionCount
	 */
	public abstract Object getAccessibleActionAnchor(int i);

	/**
	 * Gets the index with the hypertext document at which this
	 * link begins
	 *
	 * @return index of start of link
	 */
	public abstract int getStartIndex();

	/**
	 * Gets the index with the hypertext document at which this
	 * link ends
	 *
	 * @return index of end of link
	 */
	public abstract int getEndIndex();
}