jobhunter.persistence.Persistence.java Source code

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Here is the source code for jobhunter.persistence.Persistence.java

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/*
 * Copyright (C) 2014 Alejandro Ayuso
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package jobhunter.persistence;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.ConcurrentModificationException;
import java.util.List;
import java.util.Optional;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

import jobhunter.models.Profile;
import jobhunter.models.Subscription;
import jobhunter.utils.ApplicationState;

import org.apache.commons.codec.digest.DigestUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.thoughtworks.xstream.XStream;

/**
 * Singleton for persistence operations.
 */
public enum Persistence {

    _INSTANCE;

    private static final Logger l = LoggerFactory.getLogger(Persistence.class);
    private final XStream xstream = new XStream();

    private Long lastModification;
    private byte[] md5sum;

    private Persistence() {
        xstream.registerConverter(new LocalDateTimeConverter());
        xstream.registerConverter(new ObjectIdConverter());
        xstream.registerConverter(new LocalDateConverter());
    }

    private static Persistence self() {
        return _INSTANCE;
    }

    @SuppressWarnings("unchecked")
    static <T> List<T> cast(Object obj) {
        return (List<T>) obj;
    }

    private void _save(final File file, final Boolean rewrite) {
        if (wasModified(file) && !rewrite)
            throw new ConcurrentModificationException("File has been modified");

        ApplicationState.changesPending(false);
        zip(file);
    }

    private Optional<Profile> _readProfile(final File file) {

        try (ZipFile zfile = new ZipFile(file)) {
            l.debug("Reading profile from JHF File");
            final InputStream in = zfile.getInputStream(new ZipEntry("profile.xml"));

            MessageDigest md = MessageDigest.getInstance("MD5");
            DigestInputStream dis = new DigestInputStream(in, md);

            final Object obj = xstream.fromXML(dis);

            updateLastMod(file, md);

            return Optional.of((Profile) obj);
        } catch (Exception e) {
            l.error("Failed to read file: {}", e.getMessage());
        }

        return Optional.empty();
    }

    private Optional<List<Subscription>> _readSubscriptions(final File file) {

        try (ZipFile zfile = new ZipFile(file)) {
            l.debug("Reading subscriptions from JHF File");
            final InputStream in = zfile.getInputStream(new ZipEntry("subscriptions.xml"));

            MessageDigest md = MessageDigest.getInstance("MD5");
            DigestInputStream dis = new DigestInputStream(in, md);

            final Object obj = xstream.fromXML(dis);

            updateLastMod(file, md);

            return Optional.of(cast(obj));
        } catch (Exception e) {
            l.error("Failed to read file: {}", e.getMessage());
        }

        return Optional.empty();
    }

    private void zip(final File file) {

        try (ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(file))) {
            l.debug("Generating JHF file");
            zout.setMethod(ZipOutputStream.DEFLATED);
            zout.setLevel(9);

            l.debug("Inserting profile XML");
            zout.putNextEntry(new ZipEntry("profile.xml"));
            xstream.toXML(ProfileRepository.getProfile(), zout);

            l.debug("Inserting subscriptions XML");
            zout.putNextEntry(new ZipEntry("subscriptions.xml"));
            xstream.toXML(SubscriptionRepository.getSubscriptions(), zout);

            updateLastMod(file);
        } catch (IOException e) {
            l.error("Failed to generate file", e);
        }

    }

    private void updateLastMod(final File file) {
        this.lastModification = file.lastModified();
        try (InputStream in = new FileInputStream(file)) {
            this.md5sum = DigestUtils.md5(in);
        } catch (IOException e) {
            l.error("Failed to read MD5 checksum from {}", file.toString(), e);
        }
        l.debug("File was last modified on {} with MD5 {}", lastModification, this.md5sum.toString());
    }

    @SuppressWarnings("unused")
    private void updateLastMod(final File file, final InputStream in) throws IOException {
        this.lastModification = file.lastModified();
        this.md5sum = DigestUtils.md5(in);
    }

    private void updateLastMod(final File file, final MessageDigest md) throws IOException {
        this.lastModification = file.lastModified();
        this.md5sum = md.digest();
        l.debug("File was last modified on {} with MD5 {}", lastModification, this.md5sum.toString());
    }

    private Boolean wasModified(final File file) {
        if (this.lastModification != file.lastModified())
            return true;

        try (InputStream in = new FileInputStream(file)) {
            return Arrays.equals(this.md5sum, DigestUtils.md5(in));
        } catch (IOException e) {
            l.error("Failed to read MD5 checksum from {}", file.toString(), e);
        }

        return false;
    }

    public static void save(final File file) {
        self()._save(file, false);
    }

    public static void rewrite(final File file) {
        self()._save(file, true);
    }

    public static Optional<Profile> readProfile(final File file) {
        return self()._readProfile(file);
    }

    public static Optional<List<Subscription>> readSubscriptions(final File file) {
        return self()._readSubscriptions(file);
    }

    public static String debugProfile() {
        return self().xstream.toXML(ProfileRepository.getProfile());
    }

    public static String debugSubscriptions() {
        return self().xstream.toXML(SubscriptionRepository.getSubscriptions());
    }

}