ConcatenatePDFs.java

/*
 * (C) Copyright 2013 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * Licensed 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.
 *
 * Contributors:
 *     Vladimir Pasquier <vpasquier@nuxeo.com>
 */
package org.nuxeo.ecm.automation.core.operations.blob;

import java.io.File;
import java.io.IOException;

import org.apache.pdfbox.exceptions.COSVisitorException;
import org.apache.pdfbox.util.PDFMergerUtility;
import org.nuxeo.ecm.automation.OperationContext;
import org.nuxeo.ecm.automation.OperationException;
import org.nuxeo.ecm.automation.core.Constants;
import org.nuxeo.ecm.automation.core.annotations.Context;
import org.nuxeo.ecm.automation.core.annotations.Operation;
import org.nuxeo.ecm.automation.core.annotations.OperationMethod;
import org.nuxeo.ecm.automation.core.annotations.Param;
import org.nuxeo.ecm.automation.core.util.BlobList;
import org.nuxeo.ecm.core.api.Blob;
import org.nuxeo.ecm.core.api.Blobs;
import org.nuxeo.runtime.api.Framework;

/**
 * Given a File document holding a pdf on the file:content property and 2 pdfs on the files:files property, the
 * following operation will provide a pdf that is the result of the merge of all the pdfs, with the content of the one
 * in file:content property first.
 *
 * @since 5.8
 */
@Operation(id = ConcatenatePDFs.ID, category = Constants.CAT_CONVERSION, label = "Concatenate PDFs", description = "Given a File document holding a pdf on the file:content property and 2 pdfs on the files:files property, the following operation will provide a pdf that is the result of the merge of all the pdfs, with the content of the one in file:content property first.")
public class ConcatenatePDFs {

    public static final String ID = "Blob.ConcatenatePDFs";

    @Context
    protected OperationContext ctx;

    @Param(name = "blob_to_append", required = false, description = "Optional blob reference in context to append in first place.")
    protected String xpathBlobToAppend = "";

    @Param(name = "filename", required = true, description = "The merge pdf result filename.")
    protected String filename;

    @OperationMethod
    public Blob run(Blob blob) throws OperationException, IOException, COSVisitorException {
        PDFMergerUtility ut = new PDFMergerUtility();
        checkPdf(blob);
        if (xpathBlobToAppend.isEmpty()) {
            return blob;
        }
        handleBlobToAppend(ut);
        ut.addSource(blob.getStream());
        return appendPDFs(ut);
    }

    @OperationMethod
    public Blob run(BlobList blobs) throws IOException, OperationException, COSVisitorException {
        PDFMergerUtility ut = new PDFMergerUtility();
        if (!xpathBlobToAppend.isEmpty()) {
            handleBlobToAppend(ut);
        }
        for (Blob blob : blobs) {
            checkPdf(blob);
            ut.addSource(blob.getStream());
        }
        return appendPDFs(ut);
    }

    protected Blob appendPDFs(PDFMergerUtility ut) throws IOException, COSVisitorException {
        File tempFile = Framework.createTempFile(filename, ".pdf");
        ut.setDestinationFileName(tempFile.getAbsolutePath());
        ut.mergeDocuments();
        Blob fb = Blobs.createBlob(tempFile);
        Framework.trackFile(tempFile, fb);
        fb.setFilename(filename);
        return fb;
    }

    /**
     * Check if blob to append is a PDF blob.
     */
    protected void handleBlobToAppend(PDFMergerUtility ut) throws IOException, OperationException {
        try {
            Blob blobToAppend = (Blob) ctx.get(xpathBlobToAppend);
            if (blobToAppend == null) {
                throw new OperationException("The blob to append from variable context: '" + xpathBlobToAppend
                        + "' is null.");
            }
            checkPdf(blobToAppend);
            ut.addSource(blobToAppend.getStream());
        } catch (ClassCastException e) {
            throw new OperationException("The blob to append from variable context: '" + xpathBlobToAppend
                    + "' is not a blob.", e);
        }
    }

    /**
     * Check if blob is a pdf.
     */
    protected void checkPdf(Blob blob) throws OperationException {
        if (!"application/pdf".equals(blob.getMimeType())) {
            throw new OperationException("Blob " + blob.getFilename() + " is not a PDF.");
        }
    }
}