/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (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.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 */
#ifndef nsILinkHandler_h___
#define nsILinkHandler_h___

#include "nsweb.h"
#include "nsISupports.h"

class nsIInputStream;
class nsIContent;
class nsString;
struct nsGUIEvent;

// Interface ID for nsILinkHandler
#define NS_ILINKHANDLER_IID \
 { 0xa6cf905b, 0x15b3, 0x11d2,{0x93, 0x2e, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32}}

enum nsLinkState {
  eLinkState_Unvisited  = 0,
  eLinkState_Visited    = 1, 
  eLinkState_OutOfDate  = 2   // visited, but the cache is stale
};

// XXX Verb to use for link actuation. These are the verbs specified
// in the current XLink draft. We may actually want to support more
// (especially for extended links).
enum nsLinkVerb {
  eLinkVerb_Replace = 0,
  eLinkVerb_New     = 1,
  eLinkVerb_Embed   = 2,
  eLinkVerb_Undefined = 3
};

/**
 * Interface used for handling clicks on links
 */
class nsILinkHandler : public nsISupports {
public:
  NS_DEFINE_STATIC_IID_ACCESSOR(NS_ILINKHANDLER_IID)

  /**
   * Process a click on a link. aContent is the content for the frame 
   * that generated the trigger. aURLSpec is an absolute url spec that 
   * defines the destination for the link. aTargetSpec indicates where 
   * the link is targeted (it may be an empty string). aVerb indicates
   * the verb to use when the link is triggered.
   */
  NS_IMETHOD OnLinkClick(nsIContent* aContent, 
                         nsLinkVerb aVerb,
                         const PRUnichar* aURLSpec,
                         const PRUnichar* aTargetSpec,
                         nsIInputStream* aPostDataStream = 0) = 0;

  /**
   * Process a mouse-over a link. aContent is the 
   * linked content. aURLSpec is an absolute url spec that defines the
   * destination for the link. aTargetSpec indicates where the link is
   * targeted (it may be an empty string).
   */
  NS_IMETHOD OnOverLink(nsIContent* aContent, 
                        const PRUnichar* aURLSpec,
                        const PRUnichar* aTargetSpec) = 0;

  /**
   * Get the state of a link to a given absolute URL
   */
  NS_IMETHOD GetLinkState(const nsString& aLinkURI, nsLinkState& aState) = 0;
};

#endif /* nsILinkHandler_h___ */