/* -*- 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.org 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 nsIDocumentObserver_h___
#define nsIDocumentObserver_h___

#include "nsISupports.h"

class nsIAtom;
class nsIContent;
class nsIPresShell;
class nsIStyleSheet;
class nsIStyleRule;
class nsString;
class nsIDocument;

#define NS_IDOCUMENT_OBSERVER_IID \
{ 0xb3f92460, 0x944c, 0x11d1, {0x93, 0x23, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32}}

// Document observer interface
class nsIDocumentObserver : public nsISupports {
public:
  static const nsIID& GetIID() { static nsIID iid = NS_IDOCUMENT_OBSERVER_IID; return iid; }

  /**
   * Notify that a content model update is beginning. This call can be
   * nested.
   */
  NS_IMETHOD BeginUpdate(nsIDocument *aDocument) = 0;

  /**
   * Notify that a content model update is finished. This call can be
   * nested.
   */
  NS_IMETHOD EndUpdate(nsIDocument *aDocument) = 0;

  /**
   * Notify the observer that a document load is beginning.
   */
  NS_IMETHOD BeginLoad(nsIDocument *aDocument) = 0;

  /**
   * Notify the observer that a document load has finished. Note that
   * the associated reflow of the document will be done <b>before</b>
   * EndLoad is invoked, not after.
   */
  NS_IMETHOD EndLoad(nsIDocument *aDocument) = 0;

  /**
   * Notify the observer that the document is being reflowed in
   * the given presentation shell.
   */
  NS_IMETHOD BeginReflow(nsIDocument *aDocument, nsIPresShell* aShell) = 0;

  /**
   * Notify the observer that the document is done being reflowed in
   * the given presentation shell.
   */
  NS_IMETHOD EndReflow(nsIDocument *aDocument, nsIPresShell* aShell) = 0;

  /**
   * Notification that the content model has changed. This method is
   * called automatically by content objects when their state is changed
   * (therefore there is normally no need to invoke this method
   * directly).  The notification is passed to any
   * IDocumentObservers. The notification is passed on to all of the
   * document observers. <p>
   *
   * This notification is not sent when a piece of content is
   * added/removed from the document (the other notifications are used
   * for that).
   *
   * @param aDocument The document being observed
   * @param aContent the piece of content that changed
   * @param aSubContent subrange information about the piece of content
   *  that changed
   */
  NS_IMETHOD ContentChanged(nsIDocument *aDocument,
                            nsIContent* aContent,
                            nsISupports* aSubContent) = 0;

  /**
   * Notification that the state of a content node has changed. 
   * (ie: gained or lost focus, became active or hovered over)
   * This method is called automatically by content objects 
   * when their state is changed (therefore there is normally 
   * no need to invoke this method directly).  The notification 
   * is passed to any IDocumentObservers. The notification is 
   * passed on to all of the document observers. <p>
   *
   * This notification is not sent when a piece of content is
   * added/removed from the document or the content itself changed 
   * (the other notifications are used for that).
   *
   * The optional second content node is to allow optimization
   * of the case where state moves from one node to another
   * (as is likely for :focus and :hover)
   *
   * Either content node may be nsnull, but not both
   *
   * @param aDocument The document being observed
   * @param aContent1 the piece of content that changed
   * @param aContent2 optional second piece of content that changed
   */
  NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                  nsIContent* aContent1,
                                  nsIContent* aContent2) = 0;

  /**
   * Notification that the content model has changed. This method is called
   * automatically by content objects when an attribute's value has changed
   * (therefore there is normally no need to invoke this method directly). The
   * notification is passed to any IDocumentObservers document observers. <p>
   *
   * @param aDocument The document being observed
   * @param aContent the piece of content whose attribute changed
   * @param aAttribute the atom name of the attribute
   */
  NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                              nsIContent*  aContent,
                              PRInt32      aNameSpaceID,
                              nsIAtom*     aAttribute,
                              PRInt32      aHint) = 0;  // See nsStyleConsts fot hint values

  /**
   * Notifcation that the content model has had data appended to the
   * given content object. This method is called automatically by the
   * content container objects when a new content object is appended to
   * the container (therefore there is normally no need to invoke this
   * method directly). The notification is passed on to all of the
   * document observers.
   *
   * @param aDocument The document being observed
   * @param aContainer the container that had a new child appended
   * @param aNewIndexInContainer the index in the container of the first
   *          new child
   */
  NS_IMETHOD ContentAppended(nsIDocument *aDocument,
                             nsIContent* aContainer,
                             PRInt32     aNewIndexInContainer) = 0;

  /**
   * Notification that content has been inserted. This method is called
   * automatically by the content container objects when a new content
   * object is inserted in the container (therefore there is normally no
   * need to invoke this method directly). The notification is passed on
   * to all of the document observers.
   *
   * @param aDocument The document being observed
   * @param aContainer the container that now contains aChild
   * @param aChild the child that was inserted
   * @param aIndexInContainer the index of the child in the container
   */
  NS_IMETHOD ContentInserted(nsIDocument *aDocument,
                             nsIContent* aContainer,
                             nsIContent* aChild,
                             PRInt32 aIndexInContainer) = 0;

  /**
   * Notification that content has been replaced. This method is called
   * automatically by the content container objects when a content object
   * is replaced in the container (therefore there is normally no need to
   * invoke this method directly). The notification is passed on to all
   * of the document observers.
   *
   * @param aDocument The document being observed
   * @param aContainer the container that now contains aChild
   * @param aOldChild the child that was replaced
   * @param aNewChild the child that replaced aOldChild
   * @param aIndexInContainer the index of the old and new child in the
   *  container
   */
  NS_IMETHOD ContentReplaced(nsIDocument *aDocument,
                             nsIContent* aContainer,
                             nsIContent* aOldChild,
                             nsIContent* aNewChild,
                             PRInt32 aIndexInContainer) = 0;

  /**
   * Content has just been removed. This method is called automatically
   * by content container objects when a content object has just been
   * removed from the container (therefore there is normally no need to
   * invoke this method directly). The notification is passed on to all
   * of the document observers.
   *
   * @param aDocument The document being observed
   * @param aContainer the container that had a child removed
   * @param aChild the child that was just removed
   * @param aIndexInContainer the index of the child in the container
   *  before it was removed
   */
  NS_IMETHOD ContentRemoved(nsIDocument *aDocument,
                            nsIContent* aContainer,
                            nsIContent* aChild,
                            PRInt32 aIndexInContainer) = 0;

  /**
   * A StyleSheet has just been added to the document.
   * This method is called automatically when a StyleSheet gets added
   * to the document. The notification is passed on to all of the 
   * document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that has been added
   */
  NS_IMETHOD StyleSheetAdded(nsIDocument *aDocument,
                             nsIStyleSheet* aStyleSheet) = 0;

  /**
   * A StyleSheet has just been removed from the document.
   * This method is called automatically when a StyleSheet gets removed
   * from the document. The notification is passed on to all of the 
   * document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that has been removed
   */
  NS_IMETHOD StyleSheetRemoved(nsIDocument *aDocument,
                               nsIStyleSheet* aStyleSheet) = 0;

  /**
   * A StyleSheet has just disabled or enabled.
   * This method is called automatically when the disabled state
   * of a StyleSheet gets changed. The style sheet passes this
   * notification to the document. The notification is passed on 
   * to all of the document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that has been added
   * @param aDisabled PR_TRUE if the sheet is disabled, PR_FALSE if
   *        it is enabled
   */
  NS_IMETHOD StyleSheetDisabledStateChanged(nsIDocument *aDocument,
                                            nsIStyleSheet* aStyleSheet,
                                            PRBool aDisabled) = 0;

  /**
   * A StyleRule has just been modified within a style sheet.
   * This method is called automatically when the rule gets
   * modified. The style sheet passes this notification to 
   * the document. The notification is passed on to all of 
   * the document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that contians the rule
   * @param aStyleRule the rule that was modified
   * @param aHint some possible info about the nature of the change
   */
  NS_IMETHOD StyleRuleChanged(nsIDocument *aDocument,
                              nsIStyleSheet* aStyleSheet,
                              nsIStyleRule* aStyleRule,
                              PRInt32 aHint) = 0; // See nsStyleConsts fot hint values

  /**
   * A StyleRule has just been added to a style sheet.
   * This method is called automatically when the rule gets
   * added to the sheet. The style sheet passes this
   * notification to the document. The notification is passed on 
   * to all of the document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that has been modified
   * @param aStyleRule the rule that was added
   */
  NS_IMETHOD StyleRuleAdded(nsIDocument *aDocument,
                            nsIStyleSheet* aStyleSheet,
                            nsIStyleRule* aStyleRule) = 0;

  /**
   * A StyleRule has just been removed from a style sheet.
   * This method is called automatically when the rule gets
   * removed from the sheet. The style sheet passes this
   * notification to the document. The notification is passed on 
   * to all of the document observers.
   *
   * @param aDocument The document being observed
   * @param aStyleSheet the StyleSheet that has been modified
   * @param aStyleRule the rule that was removed
   */
  NS_IMETHOD StyleRuleRemoved(nsIDocument *aDocument,
                              nsIStyleSheet* aStyleSheet,
                              nsIStyleRule* aStyleRule) = 0;

 /**
   * The document is in the process of being destroyed.
   * This method is called automatically during document
   * destruction.
   * 
   * @param aDocument The document being observed
   */
  NS_IMETHOD DocumentWillBeDestroyed(nsIDocument *aDocument) = 0;
};

#endif /* nsIDocumentObserver_h___ */