/*
 * 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.area;

import java.awt.Rectangle;
import java.awt.geom.Rectangle2D;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.fop.fo.Constants;
import org.apache.fop.fo.extensions.ExtensionAttachment;
import org.apache.fop.fo.pagination.SimplePageMaster;

/**
 * Page viewport that specifies the viewport area and holds the page contents.
 * This is the top level object for a page and remains valid for the life
 * of the document and the area tree.
 * This object may be used as a key to reference a page.
 * This is the level that creates the page.
 * The page (reference area) is then rendered inside the page object
 */
public class PageViewport extends AreaTreeObject implements Resolvable, Cloneable {

    private Page page;
    private Rectangle2D viewArea;
    private String simplePageMasterName;

    /**
     * Unique key to identify the page. pageNumberString and pageIndex are both no option
     * for this.
     */
    private String pageKey;

    private int pageNumber = -1;
    private String pageNumberString = null;
    private int pageIndex = -1; //-1 = undetermined
    private boolean blank;

    private transient PageSequence pageSequence;

    // list of id references and the rectangle on the page
    //private Map idReferences = null;

    // set of IDs that appear first (or exclusively) on this page:
    private Set idFirsts = new java.util.HashSet();

    // this keeps a list of currently unresolved areas or extensions
    // once an idref is resolved it is removed
    // when this is empty the page can be rendered
    private Map unresolvedIDRefs = new java.util.HashMap();

    private Map pendingResolved = null;

    // hashmap of markers for this page
    // start and end are added by the fo that contains the markers
    private Map markerFirstStart = null;
    private Map markerLastStart = null;
    private Map markerFirstAny = null;
    private Map markerLastEnd = null;
    private Map markerLastAny = null;

    //Arbitrary attachments to the page from extensions that need to pass information
    //down to the renderers.
    private List/*<ExtensionAttachment>*/ extensionAttachments = null;

    /**
     * logging instance
     */
    protected static Log log = LogFactory.getLog(PageViewport.class);

    /**
     * Create a page viewport.
     * @param spm SimplePageMaster indicating the page and region dimensions
     * @param pageNumber the page number
     * @param pageStr String representation of the page number
     * @param blank true if this is a blank page
     */
    public PageViewport(SimplePageMaster spm, int pageNumber, String pageStr, boolean blank) {
        this.simplePageMasterName = spm.getMasterName();
        this.extensionAttachments = spm.getExtensionAttachments();
        this.blank = blank;
        int pageWidth = spm.getPageWidth().getValue();
        int pageHeight = spm.getPageHeight().getValue();
        this.pageNumber = pageNumber;
        this.pageNumberString = pageStr;
        this.viewArea = new Rectangle(0, 0, pageWidth, pageHeight);
        this.page = new Page(spm);
        createSpan(false);
    }

    /**
     * Copy constructor.
     * @param original the original PageViewport to copy from
     */
    public PageViewport(PageViewport original) {
        if (original.extensionAttachments != null) {
            this.extensionAttachments
                = new java.util.ArrayList/*<ExtensionAttachment>*/(original.extensionAttachments);
        }
        this.pageIndex = original.pageIndex;
        this.pageNumber = original.pageNumber;
        this.pageNumberString = original.pageNumberString;
        this.page = (Page)original.page.clone();
        this.viewArea = (Rectangle2D)original.viewArea.clone();
        this.simplePageMasterName = original.simplePageMasterName;
        this.blank = original.blank;
    }

    /**
     * Constructor used by the area tree parser.
     * @param viewArea the view area
     * @param pageNumber the page number
     * @param pageStr String representation of the page number
     * @param simplePageMasterName name of the original simple-page-master that generated this page
     * @param blank true if this is a blank page
     */
    public PageViewport(Rectangle2D viewArea, int pageNumber, String pageStr,
            String simplePageMasterName, boolean blank) {
        this.viewArea = viewArea;
        this.pageNumber = pageNumber;
        this.pageNumberString = pageStr;
        this.simplePageMasterName = simplePageMasterName;
        this.blank = blank;
    }

    /**
     * Sets the page sequence this page belongs to
     * @param seq the page sequence
     */
    public void setPageSequence(PageSequence seq) {
        this.pageSequence = seq;
    }

    /** @return the page sequence this page belongs to */
    public PageSequence getPageSequence() {
        return this.pageSequence;
    }

    /**
     * Get the view area rectangle of this viewport.
     * @return the rectangle for this viewport
     */
    public Rectangle2D getViewArea() {
        return viewArea;
    }

    /**
     * Get the page reference area with the contents.
     * @return the page reference area
     */
    public Page getPage() {
        return page;
    }

    /**
     * Sets the page object for this PageViewport.
     * @param page the page
     */
    public void setPage(Page page) {
        this.page = page;
    }

    /**
     * Get the page number of this page.
     * @return the integer value that represents this page
     */
    public int getPageNumber() {
        return pageNumber;
    }

    /**
     * Get the page number of this page.
     * @return the string that represents this page
     */
    public String getPageNumberString() {
        return pageNumberString;
    }

    /**
     * Sets the page index of the page in this rendering run.
     * (This is not the same as the page number!)
     * @param index the page index (zero-based), -1 if it is undetermined
     */
    public void setPageIndex(int index) {
        this.pageIndex = index;
    }

    /**
     * @return the overall page index of the page in this rendering run (zero-based,
     *         -1 if it is undetermined).
     */
    public int getPageIndex() {
        return this.pageIndex;
    }

    /**
     * Sets the unique key for this PageViewport that will be used to reference this page.
     * @param key the unique key.
     */
    public void setKey(String key) {
        this.pageKey = key;
    }

    /**
     * Get the key for this page viewport.
     * This is used so that a serializable key can be used to
     * lookup the page or some other reference.
     *
     * @return a unique page viewport key for this area tree
     */
    public String getKey() {
        if (this.pageKey == null) {
            throw new IllegalStateException("No page key set on the PageViewport: " + toString());
        }
        return this.pageKey;
    }

    /**
     * Add an "ID-first" to this page.
     * This is typically called by the AreaTreeHandler when associating
     * an ID with a PageViewport.
     *
     * @param id the id to be registered as first appearing on this page
     */
    public void setFirstWithID(String id) {
        if (id != null) {
            idFirsts.add(id);
        }
    }

    /**
     * Check whether a certain id first appears on this page
     *
     * @param id the id to be checked
     * @return true if this page is the first where the id appears
     */
    public boolean isFirstWithID(String id) {
        return idFirsts.contains(id);
    }

    /**
     * Add an idref to this page.
     * All idrefs found for child areas of this PageViewport are added
     * to unresolvedIDRefs, for subsequent resolution by AreaTreeHandler
     * calls to this object's resolveIDRef().
     *
     * @param idref the idref
     * @param res the child element of this page that needs this
     *      idref resolved
     */
    public void addUnresolvedIDRef(String idref, Resolvable res) {
        if (unresolvedIDRefs == null) {
            unresolvedIDRefs = new HashMap();
        }
        List list = (List)unresolvedIDRefs.get(idref);
        if (list == null) {
            list = new ArrayList();
            unresolvedIDRefs.put(idref, list);
        }
        list.add(res);
    }

    /**
     * Check if this page has been fully resolved.
     * @return true if the page is resolved and can be rendered
     */
    public boolean isResolved() {
        return unresolvedIDRefs == null
            || unresolvedIDRefs.size() == 0;
    }

    /**
     * Get the unresolved idrefs for this page.
     * @return String array of idref's that still have not been resolved
     */
    public String[] getIDRefs() {
        return (unresolvedIDRefs == null) ? null
            : (String[]) unresolvedIDRefs.keySet().toArray(new String[] {});
    }

    /**
     * {@inheritDoc}
     */
    public void resolveIDRef(String id, List pages) {
        if (page == null) {
            if (pendingResolved == null) {
                pendingResolved = new HashMap();
            }
            pendingResolved.put(id, pages);
        } else {
            if (unresolvedIDRefs != null) {
                List todo = (List)unresolvedIDRefs.get(id);
                if (todo != null) {
                    for (int count = 0; count < todo.size(); count++) {
                        Resolvable res = (Resolvable)todo.get(count);
                        res.resolveIDRef(id, pages);
                    }
                }
            }
        }
        if (unresolvedIDRefs != null && pages != null) {
            unresolvedIDRefs.remove(id);
            if (unresolvedIDRefs.isEmpty()) {
                unresolvedIDRefs = null;
            }
        }
    }

    /**
     * Add the markers for this page.
     * Only the required markers are kept.
     * For "first-starting-within-page" it adds the markers
     * that are starting only if the marker class name is not
     * already added.
     * For "first-including-carryover" it adds any starting marker
     * if the marker class name is not already added.
     * For "last-starting-within-page" it adds all marks that
     * are starting, replacing earlier markers.
     * For "last-ending-within-page" it adds all markers that
     * are ending, replacing earlier markers.
     *
     * Should this logic be placed in the Page layout manager.
     *
     * @param marks the map of markers to add
     * @param starting if the area being added is starting or ending
     * @param isfirst if the area being added has is-first trait
     * @param islast if the area being added has is-last trait
     */
    public void addMarkers(Map marks, boolean starting,
            boolean isfirst, boolean islast) {

        if (marks == null) {
            return;
        }
        if (log.isDebugEnabled()) {
            log.debug("--" + marks.keySet() + ": "
                    + (starting ? "starting" : "ending")
                    + (isfirst ? ", first" : "")
                    + (islast ? ", last" : ""));
        }

        // at the start of the area, register is-first and any areas
        if (starting) {
            if (isfirst) {
                if (markerFirstStart == null) {
                    markerFirstStart = new HashMap();
                }
                if (markerFirstAny == null) {
                    markerFirstAny = new HashMap();
                }
                // first on page: only put in new values, leave current
                for (Iterator iter = marks.keySet().iterator(); iter.hasNext();) {
                    Object key = iter.next();
                    if (!markerFirstStart.containsKey(key)) {
                        markerFirstStart.put(key, marks.get(key));
                        if (log.isTraceEnabled()) {
                            log.trace("page " + pageNumberString + ": "
                                    + "Adding marker " + key + " to FirstStart");
                        }
                    }
                    if (!markerFirstAny.containsKey(key)) {
                        markerFirstAny.put(key, marks.get(key));
                        if (log.isTraceEnabled()) {
                            log.trace("page " + pageNumberString + ": "
                                    + "Adding marker " + key + " to FirstAny");
                        }
                    }
                }
                if (markerLastStart == null) {
                    markerLastStart = new HashMap();
                }
                // last on page: replace all
                markerLastStart.putAll(marks);
                if (log.isTraceEnabled()) {
                    log.trace("page " + pageNumberString + ": "
                            + "Adding all markers to LastStart");
                }
            } else {
                if (markerFirstAny == null) {
                    markerFirstAny = new HashMap();
                }
                // first on page: only put in new values, leave current
                for (Iterator iter = marks.keySet().iterator(); iter.hasNext();) {
                    Object key = iter.next();
                    if (!markerFirstAny.containsKey(key)) {
                        markerFirstAny.put(key, marks.get(key));
                        if (log.isTraceEnabled()) {
                            log.trace("page " + pageNumberString + ": "
                                    + "Adding marker " + key + " to FirstAny");
                        }
                    }
                }
            }
        } else {
            // at the end of the area, register is-last and any areas
            if (islast) {
                if (markerLastEnd == null) {
                    markerLastEnd = new HashMap();
                }
                // last on page: replace all
                markerLastEnd.putAll(marks);
                if (log.isTraceEnabled()) {
                    log.trace("page " + pageNumberString + ": "
                            + "Adding all markers to LastEnd");
                }
            }
            if (markerLastAny == null) {
                markerLastAny = new HashMap();
            }
            // last on page: replace all
            markerLastAny.putAll(marks);
            if (log.isTraceEnabled()) {
                log.trace("page " + pageNumberString + ": "
                        + "Adding all markers to LastAny");
            }
        }
    }

    /**
     * Get a marker from this page.
     * This will retrieve a marker with the class name
     * and position.
     *
     * @param name The class name of the marker to retrieve
     * @param pos the position to retrieve
     * @return Object the marker found or null
     */
    public Object getMarker(String name, int pos) {
        Object mark = null;
        String posName = null;
        switch (pos) {
            case Constants.EN_FSWP:
                if (markerFirstStart != null) {
                    mark = markerFirstStart.get(name);
                    posName = "FSWP";
                }
                if (mark == null && markerFirstAny != null) {
                    mark = markerFirstAny.get(name);
                    posName = "FirstAny after " + posName;
                }
            break;
            case Constants.EN_FIC:
                if (markerFirstAny != null) {
                    mark = markerFirstAny.get(name);
                    posName = "FIC";
                }
            break;
            case Constants.EN_LSWP:
                if (markerLastStart != null) {
                    mark = markerLastStart.get(name);
                    posName = "LSWP";
                }
                if (mark == null && markerLastAny != null) {
                    mark = markerLastAny.get(name);
                    posName = "LastAny after " + posName;
                }
            break;
            case Constants.EN_LEWP:
                if (markerLastEnd != null) {
                    mark = markerLastEnd.get(name);
                    posName = "LEWP";
                }
                if (mark == null && markerLastAny != null) {
                    mark = markerLastAny.get(name);
                    posName = "LastAny after " + posName;
                }
            break;
            default:
                throw new RuntimeException();
        }
        if (log.isTraceEnabled()) {
            log.trace("page " + pageNumberString + ": " + "Retrieving marker " + name
                    + " at position " + posName);
        }
        return mark;
    }

    /** Dumps the current marker data to the logger. */
    public void dumpMarkers() {
        if (log.isTraceEnabled()) {
            log.trace("FirstAny: " + this.markerFirstAny);
            log.trace("FirstStart: " + this.markerFirstStart);
            log.trace("LastAny: " + this.markerLastAny);
            log.trace("LastEnd: " + this.markerLastEnd);
            log.trace("LastStart: " + this.markerLastStart);
        }
    }

    /**
     * Save the page contents to an object stream.
     * The map of unresolved references are set on the page so that
     * the resolvers can be properly serialized and reloaded.
     * @param out the object output stream to write the contents
     * @throws IOException in case of an I/O error while serializing the page
     */
    public void savePage(ObjectOutputStream out) throws IOException {
        // set the unresolved references so they are serialized
        page.setUnresolvedReferences(unresolvedIDRefs);
        out.writeObject(page);
        page = null;
    }

    /**
     * Load the page contents from an object stream.
     * This loads the page contents from the stream and
     * if there are any unresolved references that were resolved
     * while saved they will be resolved on the page contents.
     * @param in the object input stream to read the page from
     * @throws ClassNotFoundException if a class was not found while loading the page
     * @throws IOException if an I/O error occurred while loading the page
     */
    public void loadPage(ObjectInputStream in) throws IOException, ClassNotFoundException {
        page = (Page) in.readObject();
        unresolvedIDRefs = page.getUnresolvedReferences();
        if (unresolvedIDRefs != null && pendingResolved != null) {
            for (Iterator iter = pendingResolved.keySet().iterator();
                         iter.hasNext();) {
                String id = (String) iter.next();
                resolveIDRef(id, (List)pendingResolved.get(id));
            }
            pendingResolved = null;
        }
    }

    /**
     * Clone this page.
     * Used by the page master to create a copy of an original page.
     * @return a copy of this page and associated viewports
     */
    public Object clone() {
        return new PageViewport(this);
    }

    /**
     * Clear the page contents to save memory.
     * This object is kept for the life of the area tree since
     * it holds id and marker information and is used as a key.
     */
    public void clear() {
        page = null;
    }

    /**
     * {@inheritDoc}
     */
    public String toString() {
        StringBuffer sb = new StringBuffer(64);
        sb.append("PageViewport: page=");
        sb.append(getPageNumberString());
        return sb.toString();
    }

    /** @return the name of the simple-page-master that created this page */
    public String getSimplePageMasterName() {
        return this.simplePageMasterName;
    }

    /**
     * Adds a new ExtensionAttachment instance to this page.
     * @param attachment the ExtensionAttachment
     */
    public void addExtensionAttachment(ExtensionAttachment attachment) {
        if (this.extensionAttachments == null) {
            this.extensionAttachments = new java.util.ArrayList/*<ExtensionAttachment>*/();
        }
        extensionAttachments.add(attachment);
    }

    /** @return the list of extension attachments for this page */
    public List getExtensionAttachments() {
        if (this.extensionAttachments == null) {
            return Collections.EMPTY_LIST;
        } else {
            return this.extensionAttachments;
        }
    }

    /** @return True if this is a blank page. */
    public boolean isBlank() {
        return this.blank;
    }

    /**
     * Convenience method to get BodyRegion of this PageViewport
     * @return BodyRegion object
     */
    public BodyRegion getBodyRegion() {
        return (BodyRegion) getPage().getRegionViewport(
                Constants.FO_REGION_BODY).getRegionReference();
    }

    /**
     * Convenience method to create a new Span for this
     * this PageViewport.
     *
     * @param spanAll whether this is a single-column span
     * @return Span object created
     */
    public Span createSpan(boolean spanAll) {
        return getBodyRegion().getMainReference().createSpan(spanAll);
    }

    /**
     * Convenience method to get the span-reference-area currently
     * being processed
     *
     * @return span currently being processed.
     */
    public Span getCurrentSpan() {
        return getBodyRegion().getMainReference().getCurrentSpan();
    }

    /**
     * Convenience method to get the normal-flow-reference-area
     * currently being processed
     *
     * @return span currently being processed.
     */
    public NormalFlow getCurrentFlow() {
        return getCurrentSpan().getCurrentFlow();
    }

    /**
     * Convenience method to increment the Span to the
     * next NormalFlow to be processed, and to return that flow.
     *
     * @return the next NormalFlow in the Span.
     */
    public NormalFlow moveToNextFlow() {
        return getCurrentSpan().moveToNextFlow();
    }

    /**
     * Convenience method to return a given region-reference-area,
     * keyed by the Constants class identifier for the corresponding
     * formatting object (ie. Constants.FO_REGION_BODY, FO_REGION_START,
     * etc.)
     *
     * @param id the Constants class identifier for the region.
     * @return the corresponding region-reference-area for this page.
     */
    public RegionReference getRegionReference(int id) {
        return getPage().getRegionViewport(id).getRegionReference();
    }

    /** @return whether this page viewport has any extension attachments */
    public boolean hasExtensionAttachments() {
        return this.extensionAttachments != null && !this.extensionAttachments.isEmpty();
    }
}