DriveTask.java

/**
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * 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.
 */

package com.google.samples.apps.iosched.sync.userdata.http;

import android.util.Log;

import com.google.samples.apps.iosched.sync.userdata.util.UserDataHelper;
import com.google.api.client.http.ByteArrayContent;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpResponse;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.model.File;
import com.google.api.services.drive.model.FileList;
import com.google.api.services.drive.model.ParentReference;

import java.io.IOException;
import java.util.Arrays;

import static com.google.samples.apps.iosched.util.LogUtils.makeLogTag;

/**
 * Provides fundamental base abstractions for handling files in App Data
 *
 */
public abstract class DriveTask {

    private static final String TAG = makeLogTag(DriveTask.class);
    private Drive mDriveService = null;

    final public static String FILE_NAME = "starred_sessions.json";
    final public static String FILE_MIME_TYPE = "application/json";

    /**
     * Constructs an object.
     * @param driveService
     */
    public DriveTask(Drive driveService) {
        mDriveService = driveService;
    }

    /**
     * Getter for the Drive service.
     */
    public Drive getDriveService() {
        return mDriveService;
    }

    /**
     * Inserts preferences file into the appdata folder.
     * @param content The application context.
     * @return Inserted file.
     * @throws IOException
     */
    public File insertPreferencesFile(String content) throws IOException {
        File metadata = new File();
        metadata.setTitle(FILE_NAME);
        metadata.setParents(Arrays.asList(new ParentReference().setId("appdata")));
        ByteArrayContent c =
                ByteArrayContent.fromString(FILE_MIME_TYPE, content);
        return mDriveService.files().insert(metadata, c).execute();
    }

    /**
     * Updates the preferences file with content.
     * @param file File metadata.
     * @param content File content in JSON.
     * @return Updated file.
     * @throws IOException
     */
    public File updatePreferencesFile(File file, String content)
            throws IOException {
        Log.d(TAG, "Saving content to remote drive "+file.getId()+" : [" + content + "]");
        ByteArrayContent c =
                ByteArrayContent.fromString(FILE_MIME_TYPE, content);
        return mDriveService.files().update(file.getId(), file, c).execute();
    }

    /**
     * Retrieves the preferences file from the appdata folder.
     * @return Retrieved preferences file or {@code null}.
     * @throws IOException
     */
    public File getOrCreateFile() throws IOException {
        // TODO: fix the contains query once title querying bug is being resolved.
        String query =
                "title contains '" + FILE_NAME + "' and 'appdata' in parents";
        FileList list = mDriveService.files().list().setQ(query).execute();
        if (list != null && list.getItems().size() > 0) {
            return list.getItems().get(0);
        } else {
            // create a new preferences file
            return insertPreferencesFile("{\"starred_sessions\": []}");
        }
    }

    /**
     * Downloads the file contents.
     * @param file File to download.
     * @return The file content.l
     * @throws IOException
     */
    public String downloadFile(File file) throws IOException {
        HttpResponse res = mDriveService.getRequestFactory()
                .buildGetRequest(new GenericUrl(file.getDownloadUrl())).execute();
        return UserDataHelper.fromStreamToString(res.getContent());
    }

}