code: /*
   * Copyright 2015 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 org.physical_web.physicalweb;
  
  import org.physical_web.collection.UrlDevice;
  
  import android.os.SystemClock;
  
  abstract class UrlDeviceDiscoverer {
    private UrlDeviceDiscoveryCallback mUrlDeviceDiscoveryCallback;
    private long mScanStartTime;
  
    public abstract void startScanImpl();
    public abstract void stopScanImpl();
  
    public void startScan() {
      mScanStartTime = SystemClock.elapsedRealtime();
      startScanImpl();
    }
  
    public void stopScan() {
      stopScanImpl();
    }
  
    public void restartScan() {
      stopScan();
      startScan();
    }
  
    public void setCallback(UrlDeviceDiscoveryCallback urlDeviceDiscoveryCallback) {
      mUrlDeviceDiscoveryCallback = urlDeviceDiscoveryCallback;
    }
  
    protected Utils.UrlDeviceBuilder createUrlDeviceBuilder(String id, String url) {
      return new Utils.UrlDeviceBuilder(id, url)
          .setScanTimeMillis(SystemClock.elapsedRealtime() - mScanStartTime);
    }
  
    protected void reportUrlDevice(UrlDevice urlDevice) {
      mUrlDeviceDiscoveryCallback.onUrlDeviceDiscovered(urlDevice);
    }
  
    public interface UrlDeviceDiscoveryCallback {
      public void onUrlDeviceDiscovered(UrlDevice urlDevice);
    }
  }
  