DownloaderTask.java

package course.labs.notificationslab;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.URL;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.RemoteViews;

public class DownloaderTask extends AsyncTask<String, Void, String[]> {

	private static final int SIM_NETWORK_DELAY = 5000;
	private static final String TAG = "Lab-Notifications";
	private final int MY_NOTIFICATION_ID = 11151990;
	private String mFeeds[] = new String[3];
	private MainActivity mParentActivity;
	private Context mApplicationContext;

	// Change this variable to false if you do not have a stable network
	// connection
	private static final boolean HAS_NETWORK_CONNECTION = true;

	// Raw feed file IDs used if you do not have a stable connection
	public static final int txtFeeds[] = { R.raw.tswift, R.raw.rblack,
			R.raw.lgaga };

	// Constructor
	public DownloaderTask(MainActivity parentActivity) {
		super();

		mParentActivity = parentActivity;
		mApplicationContext = parentActivity.getApplicationContext();

	}

	@Override
	protected String[] doInBackground(String... urlParameters) {
		log("Entered doInBackground()");

		return download(urlParameters);

	}

	private String[] download(String urlParameters[]) {

		boolean downloadCompleted = false;

		try {

			for (int idx = 0; idx < urlParameters.length; idx++) {

				URL url = new URL(urlParameters[idx]);
				try {
					Thread.sleep(SIM_NETWORK_DELAY);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}

				InputStream inputStream;
				BufferedReader in;

				// Alternative for students without
				// a network connection
				if (HAS_NETWORK_CONNECTION) {
					inputStream = url.openStream();
					in = new BufferedReader(new InputStreamReader(inputStream));
				} else {
					inputStream = mApplicationContext.getResources()
							.openRawResource(txtFeeds[idx]);
					in = new BufferedReader(new InputStreamReader(inputStream));
				}

				String readLine;
				StringBuffer buf = new StringBuffer();

				while ((readLine = in.readLine()) != null) {
					buf.append(readLine);
				}

				mFeeds[idx] = buf.toString();

				if (null != in) {
					in.close();
				}
			}

			downloadCompleted = true;

		} catch (IOException e) {
			e.printStackTrace();
		}

		log("Tweet Download Completed:" + downloadCompleted);

		notify(downloadCompleted);
		
		return mFeeds;

	}

	// Call back to the MainActivity to update the feed display

	@Override
	protected void onPostExecute(String[] result) {
		super.onPostExecute(result);

		if (mParentActivity != null) {
			mParentActivity.setRefreshed(result);
		}

	}

	// If necessary, notifies the user that the tweet downloads are complete.
	// Sends an ordered broadcast back to the BroadcastReceiver in MainActivity
	// to determine whether the notification is necessary.

	private void notify(final boolean success) {
		log("Entered notify()");

		final Intent restartMainActivtyIntent = new Intent(mApplicationContext,
				MainActivity.class);
		restartMainActivtyIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

		if (success) {

			// Save tweets to a file
			saveTweetsToFile();

		}

		// Sends an ordered broadcast to determine whether MainActivity is
		// active and in the foreground. Creates a new BroadcastReceiver
		// to receive a result indicating the state of MainActivity

		// The Action for this broadcast Intent is MainActivity.DATA_REFRESHED_ACTION
		// The result Activity.RESULT_OK, indicates that MainActivity is active and
		// in the foreground.

		mApplicationContext.sendOrderedBroadcast(
				new Intent(MainActivity.DATA_REFRESHED_ACTION), 
				null,
				new BroadcastReceiver() {

					final String failMsg = "Download has failed. Please retry Later.";
					final String successMsg = "Download completed successfully.";

					@Override
					public void onReceive(Context context, Intent intent) {

						log("Entered result receiver's onReceive() method");

						// TODO: Check whether the result code is RESULT_OK

						if (getResultCode() != Activity.RESULT_OK) {

							// TODO:  If so, create a PendingIntent using the
							// restartMainActivityIntent and set its flags
							// to FLAG_UPDATE_CURRENT
							
							final PendingIntent pendingIntent = PendingIntent.getActivity(mApplicationContext, 
									0, restartMainActivtyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
							


							// Uses R.layout.custom_notification for the
							// layout of the notification View. The xml 
							// file is in res/layout/custom_notification.xml

							RemoteViews mContentView = new RemoteViews(
									mApplicationContext.getPackageName(),
									R.layout.custom_notification);

							// TODO: Set the notification View's text to
							// reflect whether or the download completed
							// successfully
							if (mFeeds.length > 0) {
								mContentView.setTextViewText(R.id.text, successMsg);
							}  
							else {
							        mContentView.setTextViewText(R.id.text, failMsg);
							}

							
							// TODO: Use the Notification.Builder class to
							// create the Notification. You will have to set
							// several pieces of information. You can use
							// android.R.drawable.stat_sys_warning
							// for the small icon. You should also setAutoCancel(true). 

							Notification.Builder notificationBuilder = new Notification.Builder(mApplicationContext)
									.setContentIntent(pendingIntent)
									.setContent(mContentView)
									.setSmallIcon(android.R.drawable.stat_sys_warning)
									.setAutoCancel(true);		

							// TODO: Send the notification
							NotificationManager mNotificationManager = (NotificationManager) mParentActivity.getSystemService(Context.NOTIFICATION_SERVICE);
							mNotificationManager.notify(MY_NOTIFICATION_ID, notificationBuilder.build());
							
							
							log("Notification Area Notification sent");
						}
					}
				}, 
				null, 
				0, 
				null, 
				null);
	}

	// Saves the tweets to a file
	private void saveTweetsToFile() {
		PrintWriter writer = null;
		try {
			FileOutputStream fos = mApplicationContext.openFileOutput(
					MainActivity.TWEET_FILENAME, Context.MODE_PRIVATE);
			writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
					fos)));

			for (String s : mFeeds) {
				writer.println(s);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (null != writer) {
				writer.close();
			}
		}
	}

	// Simplified log output method
	private void log(String msg) {
		try {
			Thread.sleep(500);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		Log.i(TAG, msg);
	}

}