MainActivity.java

package course.labs.notificationslab;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends Activity implements SelectionListener {

	public static final String TWEET_FILENAME = "tweets.txt";
	public static final String[] FRIENDS = { "taylorswift13", "msrebeccablack",
			"ladygaga" };
	public static final String DATA_REFRESHED_ACTION = "course.labs.notificationslab.DATA_REFRESHED";
	
	private static final int NUM_FRIENDS = 3;
	private static final String URL_LGAGA = "https://d396qusza40orc.cloudfront.net/android%2FLabs%2FUserNotifications%2Fladygaga.txt";
	private static final String URL_RBLACK = "https://d396qusza40orc.cloudfront.net/android%2FLabs%2FUserNotifications%2Frebeccablack.txt";
	private static final String URL_TSWIFT = "https://d396qusza40orc.cloudfront.net/android%2FLabs%2FUserNotifications%2Ftaylorswift.txt";
	private static final String TAG = "Lab-Notifications";
	private static final long TWO_MIN = 2 * 60 * 1000;
	private static final int UNSELECTED = -1;

	private FragmentManager mFragmentManager;
	private FriendsFragment mFriendsFragment;
	private boolean mIsFresh;
	private BroadcastReceiver mRefreshReceiver;
	private int mFeedSelected = UNSELECTED;
	private FeedFragment mFeedFragment;
	private String[] mRawFeeds = new String[3];
	private String[] mProcessedFeeds = new String[3];

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		mFragmentManager = getFragmentManager();
		addFriendsFragment();

		// The feed is fresh if it was downloaded less than 2 minutes ago
		mIsFresh = (System.currentTimeMillis() - getFileStreamPath(
				TWEET_FILENAME).lastModified()) < TWO_MIN;

		ensureData();

	}

	// Add Friends Fragment to Activity
	private void addFriendsFragment() {

		mFriendsFragment = new FriendsFragment();
		mFriendsFragment.setArguments(getIntent().getExtras());

		FragmentTransaction transaction = mFragmentManager.beginTransaction();
		transaction.add(R.id.fragment_container, mFriendsFragment);

		transaction.commit();
	}

	// If stored Tweets are not fresh, reload them from network
	// Otherwise, load them from file
	private void ensureData() {

		log("In ensureData(), mIsFresh:" + mIsFresh);

		if (!mIsFresh) {

			// TODO:
			// Show a Toast Notification to inform user that 
			// the app is "Downloading Tweets from Network"
			log ("Issuing Toast Message");
			Toast.makeText(getApplicationContext(), "Downloading Tweets from Network", Toast.LENGTH_SHORT).show();

			
			
			// TODO:
			// Start new AsyncTask to download Tweets from network
			DownloaderTask downloaderTask = new DownloaderTask(this);
			downloaderTask.execute(URL_TSWIFT, URL_RBLACK, URL_LGAGA);
			


			
			// Set up a BroadcastReceiver to receive an Intent when download
			// finishes. 
			mRefreshReceiver = new BroadcastReceiver() {
				@Override
				public void onReceive(Context context, Intent intent) {

					log("BroadcastIntent received in MainActivity");

					// TODO:				
					// Check to make sure this is an ordered broadcast
					// Let sender know that the Intent was received
					// by setting result code to RESULT_OK
					if (isOrderedBroadcast()) {
						mRefreshReceiver.setResultCode(RESULT_OK);
					}


				}
			};

		} else {

			loadTweetsFromFile();
			parseJSON();
			updateFeed();

		}
	}

	// Called when new Tweets have been downloaded 
	public void setRefreshed(String[] feeds) {

		mRawFeeds[0] = feeds[0];
		mRawFeeds[1] = feeds[1];
		mRawFeeds[2] = feeds[2];

		parseJSON();
		updateFeed();
		mIsFresh = true;

	};

	// Called when a Friend is clicked on
	@Override
	public void onItemSelected(int position) {

		mFeedSelected = position;
		mFeedFragment = addFeedFragment();

		if (mIsFresh) {
			updateFeed();
		}
	}

	// Calls FeedFragement.update, passing in the 
	// the tweets for the currently selected friend
 
	void updateFeed() {

		if (null != mFeedFragment)

			mFeedFragment.update(mProcessedFeeds[mFeedSelected]);

	}

	// Add FeedFragment to Activity
	private FeedFragment addFeedFragment() {
		FeedFragment feedFragment;
		feedFragment = new FeedFragment();

		FragmentTransaction transaction = mFragmentManager.beginTransaction();

		transaction.replace(R.id.fragment_container, feedFragment);
		transaction.addToBackStack(null);

		transaction.commit();
		mFragmentManager.executePendingTransactions();
		return feedFragment;

	}

	// Register the BroadcastReceiver
	@Override
	protected void onResume() {
		super.onResume();

		// TODO:
		// Register the BroadcastReceiver to receive a 
		// DATA_REFRESHED_ACTION broadcast
		IntentFilter filter = new IntentFilter();
		filter.addAction(DATA_REFRESHED_ACTION);
		registerReceiver(mRefreshReceiver, filter);

		
	}

	@Override
	protected void onPause() {

		// TODO:
		// Unregister the BroadcastReceiver
		if (mRefreshReceiver != null) {
			unregisterReceiver(mRefreshReceiver);
		}

		
		
		super.onPause();

	}

	// Convert raw Tweet data (in JSON format) into text for display

	public void parseJSON() {

		JSONArray[] JSONFeeds = new JSONArray[NUM_FRIENDS];

		for (int i = 0; i < NUM_FRIENDS; i++) {
			try {
				JSONFeeds[i] = new JSONArray(mRawFeeds[i]);
			} catch (JSONException e) {
				e.printStackTrace();
			}

			String name = "";
			String tweet = "";

			JSONArray tmp = JSONFeeds[i];

			// string buffer for twitter feeds
			StringBuffer tweetRec = new StringBuffer("");

			for (int j = 0; j < tmp.length(); j++) {
				try {
					tweet = tmp.getJSONObject(j).getString("text");
					JSONObject user = (JSONObject) tmp.getJSONObject(j).get(
							"user");
					name = user.getString("name");

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

				tweetRec.append(name + " - " + tweet + "\n\n");
			}

			mProcessedFeeds[i] = tweetRec.toString();

		}
	}

	// Retrieve feeds text from a file
	// Store them in mRawTextFeed[]

	private void loadTweetsFromFile() {
		BufferedReader reader = null;

		try {
			FileInputStream fis = openFileInput(TWEET_FILENAME);
			reader = new BufferedReader(new InputStreamReader(fis));
			String s = null;
			int i = 0;
			while (null != (s = reader.readLine()) && i < NUM_FRIENDS) {
				mRawFeeds[i] = s;
				i++;
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (null != reader) {
				try {
					reader.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

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