/*
 * 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.pagination;

// Java
import java.util.Collections;
import java.util.List;

import org.xml.sax.Locator;

import org.apache.fop.apps.FOPException;
import org.apache.fop.fo.FONode;
import org.apache.fop.fo.FObj;
import org.apache.fop.fo.PropertyList;
import org.apache.fop.fo.ValidationException;
import org.apache.fop.layoutmgr.BlockLevelEventProducer;

/**
 * Class modelling the <a href="http://www.w3.org/TR/xsl/#fo_page-sequence-master">
 * <code>fo:page-sequence-master</code></a> object.
 *
 * This class handles a list of subsequence specifiers
 * which are simple or complex references to page-masters.
 */
public class PageSequenceMaster extends FObj {
    // The value of properties relevant for fo:page-sequence-master.
    private String masterName;
    // End of property values

    private LayoutMasterSet layoutMasterSet;
    private List<SubSequenceSpecifier> subSequenceSpecifiers;
    private SubSequenceSpecifier currentSubSequence;
    private int currentSubSequenceNumber = -1;
    private BlockLevelEventProducer blockLevelEventProducer;
    protected boolean onlyTryInfinite;

    // The terminology may be confusing. A 'page-sequence-master' consists
    // of a sequence of what the XSL spec refers to as
    // 'sub-sequence-specifiers'. These are, in fact, simple or complex
    // references to page-masters. So the methods use the former
    // terminology ('sub-sequence-specifiers', or SSS),
    // but the actual FO's are MasterReferences.

    /**
     * Create a PageSequenceMaster instance that is a child of the
     * given {@link FONode}.
     *
     * @param parent {@link FONode} that is the parent of this object
     * @param blockLevelEventProducer event producer
     */
    public PageSequenceMaster(FONode parent, BlockLevelEventProducer blockLevelEventProducer) {
        super(parent);
        this.blockLevelEventProducer = blockLevelEventProducer;
    }

    /** {@inheritDoc} */
    public void bind(PropertyList pList) throws FOPException {
        masterName = pList.get(PR_MASTER_NAME).getString();

        if (masterName == null || masterName.equals("")) {
            missingPropertyError("master-name");
        }
    }

    /** {@inheritDoc} */
    public void startOfNode() throws FOPException {
        subSequenceSpecifiers = new java.util.ArrayList<SubSequenceSpecifier>();
        layoutMasterSet = parent.getRoot().getLayoutMasterSet();
        layoutMasterSet.addPageSequenceMaster(masterName, this);
    }

    /** {@inheritDoc} */
    public void endOfNode() throws FOPException {
        if (firstChild == null) {
            missingChildElementError("(single-page-master-reference|"
                    + "repeatable-page-master-reference|repeatable-page-master-alternatives)+");
        }
    }

    /**
     * {@inheritDoc}
     * <br>XSL/FOP: (single-page-master-reference|repeatable-page-master-reference|
     *     repeatable-page-master-alternatives)+
     */
    protected void validateChildNode(Locator loc, String nsURI, String localName)
        throws ValidationException {
        if (FO_URI.equals(nsURI)) {
            if (!"single-page-master-reference".equals(localName)
                && !"repeatable-page-master-reference".equals(localName)
                && !"repeatable-page-master-alternatives".equals(localName)) {
                    invalidChildError(loc, nsURI, localName);
            }
        }
    }

    /**
     * Adds a new suqsequence specifier to the page sequence master.
     * @param pageMasterReference the subsequence to add
     */
    protected void addSubsequenceSpecifier(SubSequenceSpecifier pageMasterReference) {
        subSequenceSpecifiers.add(pageMasterReference);
    }

    public LayoutMasterSet getLayoutMasterSet() {
        return layoutMasterSet;
    }

    /**
     * Returns the next subsequence specifier
     * @return a subsequence specifier
     */
    private SubSequenceSpecifier getNextSubSequence() {
        currentSubSequenceNumber++;
        if (currentSubSequenceNumber >= 0
                && currentSubSequenceNumber < subSequenceSpecifiers.size()) {
            return subSequenceSpecifiers.get(currentSubSequenceNumber);
        }
        return null;
    }

    List<SubSequenceSpecifier> getSubSequenceSpecifier() {
        return Collections.unmodifiableList(subSequenceSpecifiers);
    }

    /**
     * Resets the subsequence specifiers subsystem.
     */
    public void reset() {
        currentSubSequenceNumber = -1;
        currentSubSequence = null;
        if (subSequenceSpecifiers != null) {
            for (SubSequenceSpecifier subSequenceSpecifier : subSequenceSpecifiers) {
                subSequenceSpecifier.reset();
            }
        }
    }

    /**
     * Used to set the "cursor position" for the page masters to the previous item.
     * @return true if there is a previous item, false if the current one was the first one.
     */
    public boolean goToPreviousSimplePageMaster() {
        if (currentSubSequence != null) {
            boolean success = currentSubSequence.goToPrevious();
            if (!success) {
                if (currentSubSequenceNumber > 0) {
                    currentSubSequenceNumber--;
                    currentSubSequence = subSequenceSpecifiers
                        .get(currentSubSequenceNumber);
                } else {
                    currentSubSequence = null;
                }
            }
        }
        return (currentSubSequence != null);
    }

    /** @return true if the page-sequence-master has a page-master with page-position="last" */
    public boolean hasPagePositionLast() {
        return (currentSubSequence != null
                && currentSubSequence.hasPagePositionLast());
    }

    /** @return true if the page-sequence-master has a page-master with page-position="only" */
    public boolean hasPagePositionOnly() {
        return (currentSubSequence != null
                && currentSubSequence.hasPagePositionOnly());
    }

    /**
     * Returns the next simple-page-master.
     * @param isOddPage True if the next page number is odd
     * @param isFirstPage True if the next page is the first
     * @param isLastPage True if the next page is the last
     * @param isBlankPage True if the next page is blank
     * @param mainFlowName the name of the main flow of the page sequence
     * @return the requested page master
     * @throws PageProductionException if there's a problem determining the next page master
     */
    public SimplePageMaster getNextSimplePageMaster(boolean isOddPage,
                                                    boolean isFirstPage,
                                                    boolean isLastPage,
                                                    boolean isBlankPage,
                                                    String mainFlowName)
                                                      throws PageProductionException {
        if (onlyTryInfinite && currentSubSequence != null && !currentSubSequence.isInfinite()) {
            throw new PageProductionException("Limited to infinite");
        }
        if (currentSubSequence == null) {
            currentSubSequence = getNextSubSequence();
            if (currentSubSequence == null) {
                blockLevelEventProducer.missingSubsequencesInPageSequenceMaster(this,
                        masterName, getLocator());
            }
            if (currentSubSequence.isInfinite() && !currentSubSequence.canProcess(mainFlowName)) {
                throw new PageProductionException(
                "The current sub-sequence will not terminate whilst processing then main flow");
            }
        }

        SimplePageMaster pageMaster = currentSubSequence
            .getNextPageMaster(isOddPage, isFirstPage, isLastPage, isBlankPage);

        boolean canRecover = true;

        while (pageMaster == null) {
            SubSequenceSpecifier nextSubSequence = getNextSubSequence();

            if (nextSubSequence == null) {
                //Sub-sequence exhausted so attempt to reuse it
                blockLevelEventProducer.pageSequenceMasterExhausted(this,
                        masterName, canRecover & currentSubSequence.isReusable(), getLocator());
                currentSubSequence.reset();
                if (!currentSubSequence.canProcess(mainFlowName)) {
                    throw new PageProductionException(
                    "The last simple-page-master does not reference the main flow");
                }
                canRecover = false;
            } else {
                currentSubSequence = nextSubSequence;
            }

            pageMaster = currentSubSequence
                .getNextPageMaster(isOddPage, isFirstPage, isLastPage, isBlankPage);
        }

        return pageMaster;
    }


    /** {@inheritDoc} */
    public String getLocalName() {
        return "page-sequence-master";
    }

    /**
     * {@inheritDoc}
     * @return {@link org.apache.fop.fo.Constants#FO_PAGE_SEQUENCE_MASTER}
     */
    public int getNameId() {
        return FO_PAGE_SEQUENCE_MASTER;
    }

    public SimplePageMaster getLastSimplePageMaster(boolean isOddPage, boolean isFirstPage, boolean isBlank,
            String flowName) {
        if (currentSubSequence == null) {
            currentSubSequence = getNextSubSequence();
            if (currentSubSequence == null) {
                blockLevelEventProducer.missingSubsequencesInPageSequenceMaster(this, masterName,
                        getLocator());
            }
            if (currentSubSequence.isInfinite() && !currentSubSequence.canProcess(flowName)) {
                throw new PageProductionException(
                        "The current sub-sequence will not terminate whilst processing the main flow");
            }
        }

        SimplePageMaster pageMaster = currentSubSequence.getLastPageMaster(isOddPage, isFirstPage, isBlank,
                blockLevelEventProducer);
        return pageMaster;
    }

}