org.pharmgkb.common.io.google.GoogleApiHelper.java Source code

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Here is the source code for org.pharmgkb.common.io.google.GoogleApiHelper.java

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/*
 ----- BEGIN LICENSE BLOCK -----
 This Source Code Form is subject to the terms of the Mozilla Public License, v.2.0.
 If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 ----- END LICENSE BLOCK -----
 */
package org.pharmgkb.common.io.google;

import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.ThreadSafe;
import javax.xml.bind.DatatypeConverter;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.gson.GsonFactory;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.slf4j.LoggerFactory;

/**
 * This helper class handles the prep for using Google API.
 *
 * @author Mark Woon
 */
@ThreadSafe
public class GoogleApiHelper implements AutoCloseable {
    private static final Pattern sf_privateKeyPattern = Pattern
            .compile("-----BEGIN .*?PRIVATE KEY-----(.*)-----END .*?PRIVATE KEY-----");
    private HttpTransport m_httpTransport;
    private JsonFactory m_jsonFactory;
    private GoogleCredential m_credential;

    /**
     * Constructs a {@link GoogleCredential}.
     */
    public GoogleApiHelper(@Nonnull String userId, @Nonnull String privateKey, String... scopes)
            throws IOException, GeneralSecurityException {

        Preconditions.checkNotNull(userId);
        Preconditions.checkNotNull(privateKey);
        m_jsonFactory = GsonFactory.getDefaultInstance();
        m_httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        m_credential = new GoogleCredential.Builder().setTransport(m_httpTransport).setJsonFactory(m_jsonFactory)
                .setServiceAccountId(userId).setServiceAccountPrivateKey(getPrivateKey(privateKey))
                .setServiceAccountScopes(Lists.newArrayList(scopes)).build();
    }

    @Override
    public void close() {
        try {
            m_httpTransport.shutdown();
        } catch (IOException ex) {
            LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()).error("Problem shutting down", ex);
        }
    }

    public JsonFactory getJsonFactory() {
        return m_jsonFactory;
    }

    public HttpTransport getHttpTransport() {
        return m_httpTransport;
    }

    public GoogleCredential getCredential() {
        return m_credential;
    }

    /**
     * This class converts a private key in PEM/PKCS#8 formatted String into a {@link PrivateKey}.
     */
    private static PrivateKey getPrivateKey(String key) throws GeneralSecurityException {

        key = stripKey(key);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(DatatypeConverter.parseBase64Binary(key));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePrivate(keySpec);
    }

    /**
     * Strips header and footer from key and concatenates it to a single line.
     */
    static String stripKey(String key) {
        key = key.replaceAll("[\\r\\n]", "");
        Matcher m = sf_privateKeyPattern.matcher(key);
        if (m.find()) {
            return m.group(1);
        }
        return key;
    }
}