/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.gv.egiz.pdfas.utils;

import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.BooleanUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.pdmodel.PDDocument;

import at.gv.egiz.pdfas.api.io.DataSource;
import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.knowcenter.wag.egov.egiz.cfg.SettingsReader;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;

import com.lowagie.text.Document;
import com.lowagie.text.pdf.BadPasswordException;
import com.lowagie.text.pdf.PdfReader;

/**
 * Collection of useful utilities.
 */
public class PDFASUtils {

	private static Log log = LogFactory.getLog(PDFASUtils.class);

	/**
	 * The configuration key for PDF/A support.
	 */
	public static final String CFG_KEY_PDFA = "SIG_PDFA1B_VALID";

	private PDFASUtils() {
	}

	/**
	 * Verifies that a document could be opened with full permissions.
	 *
	 * @param pdfReader
	 *            The PdfReader.
	 * @throws PDFDocumentException
	 *             Thrown if document has not been opened with full permissions.
	 */
	private static void checkReaderPermissions(PdfReader pdfReader) throws PDFDocumentException {
		if (pdfReader.isEncrypted()) {
			throw new PDFDocumentException(ErrorCode.DOCUMENT_IS_PROTECTED, "Document is encrypted.");
		}
		if (!pdfReader.isOpenedWithFullPermissions()) {
			throw new PDFDocumentException(ErrorCode.DOCUMENT_IS_PROTECTED, "Document is protected.");
		}
	}

	/**
	 * Verifies that the document is not encrypted and/or protected. In case no restrictions have been applied to the
	 * document a pdf reader is returned.
	 *
	 * @param dataSource
	 *            The document data source.
	 * @throws PDFDocumentException
	 *             Thrown if the document could not be opened with full permissions.
	 */
	public static PdfReader createPdfReaderCheckingPermissions(DataSource dataSource) throws PDFDocumentException {
		return createPdfReaderCheckingPermissions(dataSource.createInputStream());
	}

	/**
	 * Verifies that the document is not encrypted and/or protected. In case no restrictions have been applied to the
	 * document a pdf reader is returned.
	 *
	 * @param dataSource
	 *            The document data source.
	 * @throws PDFDocumentException
	 *             Thrown if the document could not be opened with full permissions.
	 */
	public static PdfReader createPdfReaderCheckingPermissions(at.gv.egiz.pdfas.framework.input.DataSource dataSource)
			throws PDFDocumentException {
		return createPdfReaderCheckingPermissions(dataSource.createInputStream());
	}

	/**
	 * Verifies that the document is not encrypted and/or protected. In case no restrictions have been applied to the
	 * document a pdf reader is returned.
	 *
	 * @param inputStream
	 *            The document data input stream.
	 * @throws PDFDocumentException
	 *             Thrown if the document could not be opened with full permissions.
	 */
	public static PdfReader createPdfReaderCheckingPermissions(InputStream inputStream) throws PDFDocumentException {
		PdfReader reader = null;
		try {
			// try to parse document
			// If fully encrypted, PdfReader will fail;
			// It should throw a BadPasswordException, but unfortunately does not (throws an IOException instead,
			// internally catching BadPAsswordException; see comments below).
			reader = new PdfReader(inputStream);
			checkReaderPermissions(reader);
			return reader;
		} catch (BadPasswordException e) {
			// will never be reached with itext-2.1.5-rev3628-pdfas:v1.1
			// just added for later versions... (see comments below)
			// itext-2.1.5-rev3628-pdfas:v1.2 correctly throws BadPasswordException
			throw new PDFDocumentException(ErrorCode.DOCUMENT_IS_PROTECTED, "Document is protected.");
		} catch (PDFDocumentException e) {
			throw e;
		} catch (Exception e) {
			final String EX_MSG_FOR_ENCRYPTED_DOCUMENT = "Bad user Password";
			// Inspecting the exception message seems to be the only way when using itext-2.1.5-rev3628-pdfas:v1.1:
			// itext neither externally throws a BadPasswordException nor passed the cause...,
			// later versions do!
			// String "Bad user Password" is set in com.lowagie.text.pdf.BadPasswordException so this approach will
			// work as long as the underlying itext library is not beeing updated.
			if (StringUtils.containsIgnoreCase(e.getMessage(), EX_MSG_FOR_ENCRYPTED_DOCUMENT)) {
				throw new PDFDocumentException(ErrorCode.DOCUMENT_IS_PROTECTED, "Document is protected.");
			}
			throw new PDFDocumentException(ErrorCode.DOCUMENT_CANNOT_BE_READ, "Unable to parse document.");
		} finally {
			IOUtils.closeQuietly(inputStream);
			closeQuietly(reader);
		}
	}

	/**
	 * Quietly closes a pdf reader.
	 *
	 * @param reader
	 *            The reader.
	 */
	public static void closeQuietly(PdfReader reader) {
		if (reader != null) {
			try {
				reader.close();
			} catch (Throwable e) {
				// ignore
			}
		}
	}

	/**
	 * Quietly closes a pdf document.
	 *
	 * @param pdDocument
	 *            The pdf document.
	 */
	public static void closeQuietly(PDDocument pdDocument) {
		if (pdDocument != null) {
			try {
				pdDocument.close();
			} catch (Throwable e) {
				// ignore
			}
		}
	}

	/**
	 * Quietly closes a pdf document.
	 *
	 * @param pdDocument
	 *            The pdf document.
	 */
	public static void closeQuietly(org.pdfbox.pdmodel.PDDocument pdDocument) {
		if (pdDocument != null) {
			try {
				pdDocument.close();
			} catch (Throwable e) {
				// ignore
			}
		}
	}

	/**
	 * Quietly closes a pdf document.
	 *
	 * @param pdDocument
	 *            The pdf document.
	 */
	public static void closeQuietly(Document doc) {
		if (doc != null) {
			try {
				doc.close();
			} catch (Throwable e) {
				// ignore
			}
		}
	}

	public static boolean toFile(byte[] data, File file) throws IOException {
		return PDFASUtils.toFile(new ByteArrayInputStream(data), file);
	}

	public static boolean toFile(InputStream inputStream, File file) throws IOException {
		boolean result = false;
		BufferedOutputStream bufferedOutputStream = null;
		try {
			bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(file));
			ConfigUtils.writeInputStreamToOutputStream(inputStream, bufferedOutputStream);
		} finally {
			if (bufferedOutputStream != null) {
				try {
					bufferedOutputStream.close();
					result = true;
				} catch (IOException e) {
					result = false;
				}
			}
		}
		return result;
	}

	/**
	 * Returns {@code true} if the given {@code profileId} is PDF/A-1b enabled, {@code false} if not.
	 *
	 * @param profileId
	 *            The signature profile.
	 * @return {@code true} if the given {@code profileId} is PDF/A-1b enabled, {@code false} if not.
	 */
	public static boolean isPdfAEnabled(String profileId) {
		if (profileId == null) {
			throw new NullPointerException("Profile identifier must not be null.");
		}
		if (StringUtils.isEmpty(profileId)) {
			throw new IllegalArgumentException("Profile identifier must not be empty.");
		}
		try {
			String pdfa = SettingsReader.getInstance().getSetting("sig_obj." + profileId + ".key." + CFG_KEY_PDFA,
					"default." + CFG_KEY_PDFA, "false");
			return BooleanUtils.toBoolean(pdfa);
		} catch (Exception e) {
			log.error("Unable to read settings for PDF/A functionality.", e);
			return false;
		}
	}

}