import java.util.List;
import java.util.Random;
import java.util.UUID;

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.FetchOptions;
import com.google.appengine.api.datastore.Query;
import com.google.appengine.api.datastore.Query.FilterOperator;
import com.google.appengine.api.datastore.dev.LocalDatastoreService;
import com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig;
import com.google.appengine.tools.development.testing.LocalServiceTestHelper;




public class Test {

    private static LocalServiceTestHelper helper = null ;

    private static LocalDatastoreService service = null ;

    /**
     *  Initializes the environment for using datastore.
     */

    public static void init()
    {
        /**
         *  Configuration for Datastore.
         */
        LocalDatastoreServiceTestConfig config = new LocalDatastoreServiceTestConfig();
        /**
         *  Set the data file location. The file will be local_db.bin in project's root directory.
         */
        config = config.setBackingStoreLocation("local_db.bin");
        /**
         *  Tell that data will be stored in a file
         */
        config = config.setNoStorage(false);

        /**
         *  Create helper
         */
        helper = new LocalServiceTestHelper(config);


        helper = helper.setUp();
        /**
         *  Get the datastore service.
         */
        service = (LocalDatastoreService)
          helper.getLocalService(LocalDatastoreService.PACKAGE);
        //service.start();
        /**
         *  Crucial Statement, starts the service.
         */
        service.start();
    }

    /**
     *  Call after all works related to datastore.
     */
    public static void finish()
    {
        service.stop();
        helper.tearDown();
    }

    public static void main(String[] args) {
        init();

        DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
        Random random = new Random();


        Entity p1 = new Entity("Person"); // a person entity.
        p1.setProperty("pid", random.nextInt(1000)); // random id
        p1.setProperty("name", UUID.randomUUID().toString()); // random name for person

        System.out.println("Recording \"Person\" with pid= "+p1.getProperty("pid")
                                              +" and name= "+p1.getProperty("name") );

        ds.put(p1);

        /**
         *  Find all the persons in the db.
         */

        List<Entity> list = ds.prepare(new Query("Person")).asList(FetchOptions.Builder.withLimit(1000));

        System.out.println("\n\n======= Stored Entries ========= ");

        for( Entity entity : list )
        {
            System.out.print("pid= "+entity.getProperty("pid"));
            System.out.println(" name= "+ entity.getProperty("name"));
        }

        finish();
    }
}