/*
 * 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: PDFStructElem.java 1693102 2015-07-28 14:46:09Z ssteiner $ */

package org.apache.fop.pdf;

import java.io.IOException;
import java.io.OutputStream;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;

import org.apache.fop.accessibility.StructureTreeElement;
import org.apache.fop.pdf.StandardStructureAttributes.Table;
import org.apache.fop.util.LanguageTags;

Class representing a PDF Structure Element.
/**
 * Class representing a PDF Structure Element.
 */
public class PDFStructElem extends StructureHierarchyMember
        implements StructureTreeElement, CompressedObject {

    private StructureType structureType;

    protected PDFStructElem parentElement;

    
Elements to be added to the kids array.
/**
     * Elements to be added to the kids array.
     */
    protected List<PDFObject> kids;

    private List<PDFDictionary> attributes;

    
Creates PDFStructElem with no entries.
/**
     * Creates PDFStructElem with no entries.
     */
    public PDFStructElem() {
    }

    
Creates a new structure element.
Params:
parent – parent of this element
structureType – the structure type of this element/**
     * Creates a new structure element.
     *
     * @param parent parent of this element
     * @param structureType the structure type of this element
     */
    public PDFStructElem(PDFObject parent, StructureType structureType) {
        this(parent);
        this.structureType = structureType;
        put("S", structureType.getName());
        setParent(parent);
    }

    private PDFStructElem(PDFObject parent) {
        if (parent instanceof PDFStructElem) {
            parentElement = (PDFStructElem) parent;
        }
    }

    
Returns the parent of this structure element.
Returns:
the parent, null if the parent is not a structure
element (i.e., is the structure tree root)/**
     * Returns the parent of this structure element.
     *
     * @return the parent, <code>null</code> if the parent is not a structure
     * element (i.e., is the structure tree root)
     */
    public PDFStructElem getParentStructElem() {
        return parentElement;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public void setParent(PDFObject parent) {
        if (parent != null && parent.hasObjectNumber()) {
           put("P", new PDFReference(parent));
        }
    }

    
Adds a kid to this structure element.
Params:
kid – element to be added/**
     * Adds a kid to this structure element.
     *
     * @param kid element to be added
     */
    @Override
    public void addKid(PDFObject kid) {
        if (kids == null) {
            kids = new ArrayList<PDFObject>();
        }
        kids.add(kid);
    }

    
Sets the given mcid as the kid of this structure element. This element
will then add itself to its parent structure element if it has not
already, and so will the parent, and so on.
Params:
mcid – mcid of the marked-content sequence corresponding to this
structure element's kid/**
     * Sets the given mcid as the kid of this structure element. This element
     * will then add itself to its parent structure element if it has not
     * already, and so will the parent, and so on.
     *
     * @param mcid mcid of the marked-content sequence corresponding to this
     * structure element's kid
     */
    public void setMCIDKid(int mcid) {
        put("K", mcid);
    }

    
Sets the page reference of this structure element.
Params:
page – value for the Pg entry/**
     * Sets the page reference of this structure element.
     *
     * @param page value for the Pg entry
     */
    public void setPage(PDFPage page) {
        put("Pg", page);
    }

    
Returns the structure type of this structure element.
Returns:
the value of the S entry/**
     * Returns the structure type of this structure element.
     *
     * @return the value of the S entry
     */
    public StructureType getStructureType() {
        return structureType;
    }

    
Sets the language of this structure element.
Params:
language – the language (as defined in the section about
                         "Natural Language Specification")/**
     * Sets the language of this structure element.
     * @param language the language (as defined in the section about
     *                          "Natural Language Specification")
     */
    private void setLanguage(String language) {
        put("Lang", language);
    }

    
Sets the language of this structure element.
Params:
language – a value for the Lang entry/**
     * Sets the language of this structure element.
     *
     * @param language a value for the Lang entry
     */
    public void setLanguage(Locale language) {
        setLanguage(LanguageTags.toLanguageTag(language));
    }

    
Returns the language of this structure element.
Returns:
the value of the Lang entry (null if no language was specified)/**
     * Returns the language of this structure element.
     *
     * @return the value of the Lang entry (<code>null</code> if no language was specified)
     */
    public String getLanguage() {
        return (String) get("Lang");
    }

    @Override
    protected void writeDictionary(OutputStream out, StringBuilder textBuffer) throws IOException {
        attachKids();
        attachAttributes();
        super.writeDictionary(out, textBuffer);
    }

    private void attachAttributes() {
        if (attributes != null) {
            if (attributes.size() == 1) {
                put("A", attributes.get(0));
            } else {
                PDFArray array = new PDFArray(attributes);
                put("A", array);
            }
        }
    }

    public void addKidInSpecificOrder(int position, PDFStructElem kid) {
        if (kids == null) {
            addKid(kid);
        } else {
            if ((kids.size() - 1) < position) {
                kids.add(kid);
            } else if (kids.get(position) == null) {
                kids.set(position, kid);
            } else {
                if (!kids.contains(kid)) {
                    kids.add(position, kid);
                }
            }
        }
    }

    
Attaches all valid kids to the kids array.
Returns:
true iff 1+ kids were added to the kids array/**
     * Attaches all valid kids to the kids array.
     *
     * @return true iff 1+ kids were added to the kids array
     */
    protected boolean attachKids() {
        List<PDFObject> validKids = new ArrayList<PDFObject>();
        if (kids != null) {
            for (PDFObject kid : kids) {
                if (kid instanceof Placeholder)  {
                    if (((Placeholder) kid).attachKids()) {
                        validKids.add(kid);
                    }
                } else {
                    validKids.add(kid);
                }
            }
        }
        boolean kidsAttached = !validKids.isEmpty();
        if (kidsAttached) {
            PDFArray array = new PDFArray();
            for (PDFObject ob : validKids) {
                array.add(ob);
            }
            put("K", array);
        }
        return kidsAttached;
    }

    public void setTableAttributeColSpan(int colSpan) {
        setTableAttributeRowColumnSpan("ColSpan", colSpan);
    }

    public void setTableAttributeRowSpan(int rowSpan) {
        setTableAttributeRowColumnSpan("RowSpan", rowSpan);
    }

    private void setTableAttributeRowColumnSpan(String typeSpan, int span) {
        PDFDictionary attribute = new PDFDictionary();
        attribute.put("O", Table.NAME);
        attribute.put(typeSpan, span);
        if (attributes == null) {
            attributes = new ArrayList<PDFDictionary>(2);
        }
        attributes.add(attribute);
    }

    public List<PDFObject> getKids() {
        return this.kids;
    }

    public int output(OutputStream stream) throws IOException {
        if (getDocument().getProfile().getPDFUAMode().isEnabled()) {
            if (entries.containsKey("Alt") && "".equals(get("Alt"))) {
                put("Alt", "No alternate text specified");
            } else if (kids != null) {
                for (PDFObject kid : kids) {
                    if (kid instanceof PDFStructElem
                            && !(kid instanceof Placeholder)
                            && structureType.toString().equals("P")
                            && isBSLE(((PDFStructElem) kid).getStructureType().toString())) {
                        structureType = StandardStructureTypes.Grouping.DIV;
                        put("S", StandardStructureTypes.Grouping.DIV.getName());
                        break;
                    }
                }
            }
        }
        return super.output(stream);
    }

    private boolean isBSLE(String type) {
        String[] blseValues = {"Table", "L", "P"};
        return Arrays.asList(blseValues).contains(type);
    }

    
Class representing a placeholder for a PDF Structure Element.
/**
     * Class representing a placeholder for a PDF Structure Element.
     */
    public static class Placeholder extends PDFStructElem {

        @Override
        public void outputInline(OutputStream out, StringBuilder textBuffer) throws IOException {
            if (kids != null) {
                assert kids.size() > 0;
                for (int i = 0; i < kids.size(); i++) {
                    if (i > 0) {
                        textBuffer.append(' ');
                    }
                    Object obj = kids.get(i);
                    if (obj instanceof PDFStructElem) {
                        ((PDFStructElem) obj).setParent(parentElement);
                    }
                    formatObject(obj, out, textBuffer);
                }
            }
        }

        public Placeholder(PDFObject parent) {
            super(parent);
        }
    }

}