/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (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.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id$ */

package org.apache.fop.fo;

import java.util.HashSet;
import java.util.Set;

import org.xml.sax.SAXException;

import org.apache.fop.apps.FOUserAgent;
import org.apache.fop.fo.extensions.ExternalDocument;
import org.apache.fop.fo.flow.BasicLink;
import org.apache.fop.fo.flow.Block;
import org.apache.fop.fo.flow.BlockContainer;
import org.apache.fop.fo.flow.Character;
import org.apache.fop.fo.flow.ExternalGraphic;
import org.apache.fop.fo.flow.Footnote;
import org.apache.fop.fo.flow.FootnoteBody;
import org.apache.fop.fo.flow.Inline;
import org.apache.fop.fo.flow.InstreamForeignObject;
import org.apache.fop.fo.flow.Leader;
import org.apache.fop.fo.flow.ListBlock;
import org.apache.fop.fo.flow.ListItem;
import org.apache.fop.fo.flow.PageNumber;
import org.apache.fop.fo.flow.PageNumberCitation;
import org.apache.fop.fo.flow.PageNumberCitationLast;
import org.apache.fop.fo.flow.table.Table;
import org.apache.fop.fo.flow.table.TableBody;
import org.apache.fop.fo.flow.table.TableCell;
import org.apache.fop.fo.flow.table.TableColumn;
import org.apache.fop.fo.flow.table.TableRow;
import org.apache.fop.fo.pagination.Flow;
import org.apache.fop.fo.pagination.PageSequence;
import org.apache.fop.fonts.FontInfo;

/**
 * Abstract class defining what should be done with SAX events that map to
 * XSL-FO input. The events are actually captured by fo/FOTreeBuilder, passed
 * to the various fo Objects, which in turn, if needed, pass them to an instance
 * of FOEventHandler.
 *
 * Sub-classes will generally fall into one of two categories:
 * 1) a handler that actually builds an FO Tree from the events, or 2) a
 * handler that builds a structured (as opposed to formatted) document, such
 * as our MIF and RTF output targets.
 */
public abstract class FOEventHandler {
    
    /** 
     * The FOUserAgent for this process
     */
    protected FOUserAgent foUserAgent;

    /** 
     * The Font information relevant for this document
     */
    protected FontInfo fontInfo;

    /**
     * The current set of id's in the FO tree.
     * This is used so we know if the FO tree contains duplicates.
     */
    private Set idReferences = new HashSet();

    /**
     * The property list maker.
     */
    protected PropertyListMaker propertyListMaker;

    /**
     * The XMLWhitespaceHandler for this tree
     */
    protected XMLWhiteSpaceHandler whiteSpaceHandler = new XMLWhiteSpaceHandler();
    
    /**
     * Indicates whether processing descendants of a marker
     */
    private boolean inMarker = false;
    
    /**
     * Main constructor
     * @param foUserAgent the apps.FOUserAgent instance for this process
     */
    public FOEventHandler(FOUserAgent foUserAgent) {
        this.foUserAgent = foUserAgent;
        this.fontInfo = new FontInfo();
    }

    /**
     * Retuns the set of ID references.
     * @return the ID references
     */
    public Set getIDReferences() {
        return idReferences;
    }

    /**
     * Returns the User Agent object associated with this FOEventHandler.
     * @return the User Agent object
     */
    public FOUserAgent getUserAgent() {
        return foUserAgent;
    }

    /**
     * Retrieve the font information for this document
     * @return the FontInfo instance for this document
     */
    public FontInfo getFontInfo() {
        return this.fontInfo;
    }

    /**
     * Return the propertyListMaker.
    */
    public PropertyListMaker getPropertyListMaker() {
        return propertyListMaker;
    }
     
    /**
     * Set a new propertyListMaker.
     */
    public void setPropertyListMaker(PropertyListMaker propertyListMaker) {
        this.propertyListMaker = propertyListMaker;
    }
    
    /**
     * Return the XMLWhiteSpaceHandler
     * @return the whiteSpaceHandler
     */
    public XMLWhiteSpaceHandler getXMLWhiteSpaceHandler() {
        return whiteSpaceHandler;
    }

    /**
     * Switch to or from marker context
     * (used by FOTreeBuilder when processing
     *  a marker)
     *
     */
    protected void switchMarkerContext(boolean inMarker) {
        this.inMarker = inMarker;
    }
    
    /**
     * Check whether in marker context
     */
    protected boolean inMarker() {
        return this.inMarker;
    }
    
    /**
     * This method is called to indicate the start of a new document run.
     * @throws SAXException In case of a problem
     */
    public void startDocument() throws SAXException {
    }

    /**
     * This method is called to indicate the end of a document run.
     * @throws SAXException In case of a problem
     */
    public void endDocument() throws SAXException {
    }

    /**
     *
     * @param pageSeq PageSequence that is starting.
     */
    public void startPageSequence(PageSequence pageSeq) {
    }

    /**
     * @param pageSeq PageSequence that is ending.
     */
    public void endPageSequence(PageSequence pageSeq) {
    }

    /**
     *
     * @param pagenum PageNumber that is starting.
     */
    public void startPageNumber(PageNumber pagenum) {
    }

    /**
     *
     * @param pagenum PageNumber that is ending.
     */
    public void endPageNumber(PageNumber pagenum) {
    }

    /**
     * 
     * @param pageCite PageNumberCitation that is starting.
     */
    public void startPageNumberCitation(PageNumberCitation pageCite) {
    }

    /**
     * 
     * @param pageCite PageNumberCitation that is ending.
     */
    public void endPageNumberCitation(PageNumberCitation pageCite) {
    }

    /**
     * 
     * @param pageLast PageNumberCitationLast that is starting.
     */
    public void startPageNumberCitationLast(PageNumberCitationLast pageLast) {
    }

    /**
     * 
     * @param pageLast PageNumberCitationLast that is ending.
     */
    public void endPageNumberCitationLast(PageNumberCitationLast pageLast) {
    }

    /**
     * This method is called to indicate the start of a new fo:flow 
     * or fo:static-content.
     * This method also handles fo:static-content tags, because the 
     * StaticContent class is derived from the Flow class.
     *
     * @param fl Flow that is starting.
     */
    public void startFlow(Flow fl) {
    }

    /**
     *
     * @param fl Flow that is ending.
     */
    public void endFlow(Flow fl) {
    }

    /**
     *
     * @param bl Block that is starting.
     */
    public void startBlock(Block bl) {
    }

    /**
     *
     * @param bl Block that is ending.
     */
    public void endBlock(Block bl) {
    }

    /**
    *
    * @param blc BlockContainer that is starting.
    */
    public void startBlockContainer(BlockContainer blc) {
    }

    /**
    *
    * @param blc BlockContainer that is ending.
    */
    public void endBlockContainer(BlockContainer blc) {
    }

    /**
     *
     * @param inl Inline that is starting.
     */
    public void startInline(Inline inl) {
    }

    /**
     *
     * @param inl Inline that is ending.
     */
    public void endInline(Inline inl) {
    }

    // Tables
    /**
     *
     * @param tbl Table that is starting.
     */
    public void startTable(Table tbl) {
    }

    /**
     *
     * @param tbl Table that is ending.
     */
    public void endTable(Table tbl) {
    }

    /**
     *
     * @param tc TableColumn that is starting;
     */
    public void startColumn(TableColumn tc) {
    }

    /**
     *
     * @param tc TableColumn that is ending;
     */
    public void endColumn(TableColumn tc) {
    }

    /**
     *
     * @param th TableBody that is starting;
     */
    public void startHeader(TableBody th) {
    }

    /**
     *
     * @param th TableBody that is ending.
     */
    public void endHeader(TableBody th) {
    }

    /**
     *
     * @param tf TableFooter that is starting.
     */
    public void startFooter(TableBody tf) {
    }

    /**
     *
     * @param tf TableFooter that is ending.
     */
    public void endFooter(TableBody tf) {
    }

    /**
     *
     * @param tb TableBody that is starting.
     */
    public void startBody(TableBody tb) {
    }

    /**
     *
     * @param tb TableBody that is ending.
     */
    public void endBody(TableBody tb) {
    }

    /**
     *
     * @param tr TableRow that is starting.
     */
    public void startRow(TableRow tr) {
    }

    /**
     *
     * @param tr TableRow that is ending.
     */
    public void endRow(TableRow tr) {
    }

    /**
     *
     * @param tc TableCell that is starting.
     */
    public void startCell(TableCell tc) {
    }

    /**
     *
     * @param tc TableCell that is ending.
     */
    public void endCell(TableCell tc) {
    }


    // Lists
    /**
     *
     * @param lb ListBlock that is starting.
     */
    public void startList(ListBlock lb) {
    }

    /**
     *
     * @param lb ListBlock that is ending.
     */
    public void endList(ListBlock lb) {
    }

    /**
     *
     * @param li ListItem that is starting.
     */
    public void startListItem(ListItem li) {
    }

    /**
     *
     * @param li ListItem that is ending.
     */
    public void endListItem(ListItem li) {
    }

    /**
     * Process start of a ListLabel.
     */
    public void startListLabel() {
    }

    /**
     * Process end of a ListLabel.
     */
    public void endListLabel() {
    }

    /**
     * Process start of a ListBody.
     */
    public void startListBody() {
    }

    /**
     * Process end of a ListBody.
     */
    public void endListBody() {
    }

    // Static Regions
    /**
     * Process start of a Static.
     */
    public void startStatic() {
    }

    /**
     * Process end of a Static.
     */
    public void endStatic() {
    }


    /**
     * Process start of a Markup.
     */
    public void startMarkup() {
    }

    /**
     * Process end of a Markup.
     */
    public void endMarkup() {
    }

    /**
     * Process start of a Link.
     * @param basicLink BasicLink that is ending
     */
    public void startLink(BasicLink basicLink) {
    }

    /**
     * Process end of a Link.
     */
    public void endLink() {
    }

    /**
     * Process an ExternalGraphic.
     * @param eg ExternalGraphic to process.
     */
    public void image(ExternalGraphic eg) {
    }

    /**
     * Process a pageRef.
     */
    public void pageRef() {
    }

    /**
     * Process an InstreamForeignObject.
     * @param ifo InstreamForeignObject to process.
     */
    public void foreignObject(InstreamForeignObject ifo) {
    }

    /**
     * Process the start of a footnote.
     * @param footnote Footnote that is starting
     */
    public void startFootnote(Footnote footnote) {
    }
    
    /**
     * Process the ending of a footnote.
     * @param footnote Footnote that is ending
     */
    public void endFootnote(Footnote footnote) {
    }

    /**
     * Process the start of a footnote body.
     * @param body FootnoteBody that is starting
     */
    public void startFootnoteBody(FootnoteBody body) {
    }
    
    /**
     * Process the ending of a footnote body.
     * @param body FootnoteBody that is ending
     */
    public void endFootnoteBody(FootnoteBody body) {
    }

    /**
     * Process a Leader.
     * @param l Leader to process.
     */
    public void leader(Leader l) {
    }

    /**
     * Process a Character.
     * @param c Character to process.
     */
    public void character(Character c) {
    }

    /**
     * Process character data.
     * @param data Array of characters to process.
     * @param start Offset for characters to process.
     * @param length Portion of array to process.
     */
    public void characters(char data[], int start, int length) {
    }

    /**
     * Process the start of the external-document extension.
     * @param document the external-document node
     */
    public void startExternalDocument(ExternalDocument document) {
    }

    /**
     * Process the end of the external-document extension.
     * @param document the external-document node
     */
    public void endExternalDocument(ExternalDocument document) {
    }

}