# AcroFormOrphanWidgetsProcessor.java

    /*
     * 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.
     */
    package org.apache.pdfbox.pdmodel.fixup.processor;

    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.fontbox.ttf.TrueTypeFont;
    import org.apache.pdfbox.cos.COSDictionary;
    import org.apache.pdfbox.cos.COSName;
    import org.apache.pdfbox.pdmodel.PDDocument;
    import org.apache.pdfbox.pdmodel.PDPage;
    import org.apache.pdfbox.pdmodel.PDResources;
    import org.apache.pdfbox.pdmodel.font.FontMapper;
    import org.apache.pdfbox.pdmodel.font.FontMappers;
    import org.apache.pdfbox.pdmodel.font.FontMapping;
    import org.apache.pdfbox.pdmodel.font.PDType0Font;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationWidget;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDAppearanceStream;
    import org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;
    import org.apache.pdfbox.pdmodel.interactive.form.PDField;
    import org.apache.pdfbox.pdmodel.interactive.form.PDFieldFactory;
    import org.apache.pdfbox.pdmodel.interactive.form.PDVariableText;

    /**
     *  Generate field entries from page level widget annotations
     *  if there AcroForm /Fields entry is empty.
     *
     */
    public class AcroFormOrphanWidgetsProcessor extends AbstractProcessor
    {

        private static final Log LOG = LogFactory.getLog(AcroFormOrphanWidgetsProcessor.class);

        public AcroFormOrphanWidgetsProcessor(PDDocument document)
        {
            super(document);
        }

        @Override
        public void process()
        {
            /*
             * Get the AcroForm in it's current state.
             *
             * Also note: getAcroForm() applies a default fixup which this processor
             * is part of. So keep the null parameter otherwise this will end
             * in an endless recursive call
             */
            PDAcroForm acroForm = document.getDocumentCatalog().getAcroForm(null);

            if (acroForm != null)
            {
                resolveFieldsFromWidgets(acroForm);
            }
        }

        private void resolveFieldsFromWidgets(PDAcroForm acroForm)
        {
            LOG.debug("rebuilding fields from widgets");

            PDResources resources = acroForm.getDefaultResources();
            if (resources == null)
            {
                // failsafe. Currently resources is never null because defaultfixup is called first.
                LOG.debug("AcroForm default resources is null");
                return;
            }

            List<PDField> fields = new ArrayList<>();
            Map<String, PDField> nonTerminalFieldsMap = new HashMap<>();
            for (PDPage page : document.getPages())
            {
                try
                {
                    handleAnnotations(acroForm, resources, fields, page.getAnnotations(), nonTerminalFieldsMap);
                }
                catch (IOException ioe)
                {
                    LOG.debug("couldn't read annotations for page " + ioe.getMessage());
                }
            }

            acroForm.setFields(fields);

            for (PDField field : acroForm.getFieldTree())
            {
                if (field instanceof PDVariableText)
                {
                    ensureFontResources(resources, (PDVariableText) field);
                }
            }
        }

        private void handleAnnotations(PDAcroForm acroForm, PDResources acroFormResources,
                List<PDField> fields, List<PDAnnotation> annotations,
                Map<String, PDField> nonTerminalFieldsMap)
        {
            for (PDAnnotation annot : annotations)
            {
                if (annot instanceof PDAnnotationWidget)
                {
                    addFontFromWidget(acroFormResources, annot);

                    COSDictionary parent = annot.getCOSObject().getCOSDictionary(COSName.PARENT);
                    if (parent != null)
                    {
                        PDField resolvedField = resolveNonRootField(acroForm, parent, nonTerminalFieldsMap);
                        if (resolvedField != null)
                        {
                            fields.add(resolvedField);
                        }
                    }
                    else
                    {
                        PDField field = PDFieldFactory.createField(acroForm, annot.getCOSObject(), null);
                        if (field != null)
                        {
                            fields.add(field);
                        }
                    }
                }
            }
        }

        /**
         * Add font resources from the widget to the AcroForm to make sure embedded fonts are being used
         * and not added by ensureFontResources potentially using a fallback font.
         *
         * @param acroFormResources AcroForm default resources, should not be null.
         * @param annotation annotation, should not be null.
         */
        private void addFontFromWidget(PDResources acroFormResources, PDAnnotation annotation)
        {
            PDAppearanceStream normalAppearanceStream = annotation.getNormalAppearanceStream();
            if (normalAppearanceStream == null)
            {
                return;
            }
            PDResources widgetResources = normalAppearanceStream.getResources();
            if (widgetResources == null)
            {
                return;
            }
            widgetResources.getFontNames().forEach(fontName ->
            {
                if (!fontName.getName().startsWith("+"))
                {
                    try
                    {
                        if (acroFormResources.getFont(fontName) == null)
                        {
                            acroFormResources.put(fontName, widgetResources.getFont(fontName));
                            LOG.debug("added font resource to AcroForm from widget for font name " + fontName.getName());
                        }
                    }
                    catch (IOException ioe)
                    {
                        LOG.debug("unable to add font to AcroForm for font name " + fontName.getName());
                    }
                }
                else
                {
                    LOG.debug("font resource for widget was a subsetted font - ignored: " + fontName.getName());
                }
            });
        }

        /*
         *  Widgets having a /Parent entry are non root fields. Go up until the root node is found
         *  and handle from there.
         */
        private PDField resolveNonRootField(PDAcroForm acroForm, COSDictionary parent, Map<String, PDField> nonTerminalFieldsMap)
        {
            while (parent.containsKey(COSName.PARENT))
            {
                parent = parent.getCOSDictionary(COSName.PARENT);
                if (parent == null)
                {
                    return null;
                }
            }

            if (nonTerminalFieldsMap.get(parent.getString(COSName.T)) == null)
            {
                PDField field = PDFieldFactory.createField(acroForm, parent, null);
                if (field != null)
                {
                    nonTerminalFieldsMap.put(field.getFullyQualifiedName(), field);
                }
                return field;
            }

            // this should not happen, likely broken PDF
            return null;
        }

        /*
         *  Lookup the font used in the default appearance and if this is
         *  not available try to find a suitable font and use that.
         *  This may not be the original font but a similar font replacement
         *
         *  TODO: implement a font lookup similar as discussed in PDFBOX-2661 so that already existing
         *        font resources might be accepatble.
         *        In such case this must be implemented in PDDefaultAppearanceString too!
         */
        private void ensureFontResources(PDResources defaultResources, PDVariableText field)
        {
            String daString = field.getDefaultAppearance();
            if (daString.startsWith("/") && daString.length() > 1)
            {
                COSName fontName = COSName.getPDFName(daString.substring(1, daString.indexOf(" ")));
                try
                {
                    if (defaultResources.getFont(fontName) == null)
                    {
                        LOG.debug("trying to add missing font resource for field " + field.getFullyQualifiedName());
                        FontMapper mapper = FontMappers.instance();
                        FontMapping<TrueTypeFont> fontMapping = mapper.getTrueTypeFont(fontName.getName() , null);
                        if (fontMapping != null)
                        {
                            PDType0Font pdFont = PDType0Font.load(document, fontMapping.getFont(), false);
                            LOG.debug("looked up font for " + fontName.getName() + " - found " + fontMapping.getFont().getName());
                            defaultResources.put(fontName, pdFont);
                        }
                        else
                        {
                            LOG.debug("no suitable font found for field " + field.getFullyQualifiedName() + " for font name " + fontName.getName());
                        }
                    }
                }
                catch (IOException ioe)
                {
                    LOG.debug("unable to handle font resources for field " + field.getFullyQualifiedName() + ": " + ioe.getMessage());
                }
            }
        }
    }