TwitterAuthHelper.java

/*
 * Copyright 2012 Feedlr
 *
 * 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.chalmers.feedlr.client;

import org.scribe.model.Token;
import org.scribe.model.Verifier;
import org.scribe.oauth.OAuthService;

import com.chalmers.feedlr.activity.TwitterWebActivity;
import com.chalmers.feedlr.listener.AuthListener;
import com.chalmers.feedlr.util.ClientStore;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;

/**
 * Class description
 * 
 * @author Olle Werme
 * 
 * 		This class provides help methods for Twitter authorization. 
 */

public class TwitterAuthHelper {

	private Context context;
	private OAuthService twitter;
	private AuthListener authListener;

	public TwitterAuthHelper(Context context) {
		this.context = context;
		twitter = Clients.getTwitter();
	}
	
	/*
	 * Authorizes the session, if is not authorized.
	 * 
	 * @param listener the listener to be used in the authorization request
	 */
	public void authorize(AuthListener listener) {
		authListener = listener;
		new GetTwitterRequestTokenTask().execute();
	}
	
	/*
	 * Verifies the data from the param through the Oauth-verifier.
	 * 
	 * @param Intent data to be verified.
	 */
	public void onAuthCallback(Intent data) {
		String verifier = (String) data.getExtras().get("oauth_verifier");
		new GetTwitterAccessTokenTask().execute(verifier);
	}
	
	/*
	 * Inner class to the get request tokens for Twitter. 
	 */
	private class GetTwitterRequestTokenTask extends
			AsyncTask<Void, Void, Token> {
		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#doInBackground(Params[])
		 */
		protected Token doInBackground(Void... params) {
			return twitter.getRequestToken();
		}
		
		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
		 */
		protected void onPostExecute(Token requestToken) {
			ClientStore.saveTwitterRequestToken(requestToken, context);
			new GetTwitterAuthUriTask().execute();
		}
	}
	
	/*
	 * Inner class to get Twitter Authorized 
	 */
	private class GetTwitterAuthUriTask extends AsyncTask<Void, Void, String> {
		
		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#doInBackground(Params[])
		 */
		protected String doInBackground(Void... params) {
			Token requestToken = ClientStore.getTwitterRequestToken(context);
			return twitter.getAuthorizationUrl(requestToken);
		}

		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
		 */
		protected void onPostExecute(String authURL) {
			// Send to twitter authorization page for user input
			Intent intent = new Intent(context, TwitterWebActivity.class);
			intent.putExtra("URL", authURL);
			((Activity) context).startActivityForResult(intent,
					Clients.TWITTER);
		}
	}
	
	/*
	 * Inner class to get the access token for Twitter
	 */
	private class GetTwitterAccessTokenTask extends
			AsyncTask<String, Void, Token> {
		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#doInBackground(Params[])
		 */
		protected Token doInBackground(String... verifier) {
			Token requestToken = ClientStore.getTwitterRequestToken(context);
			Token result = twitter.getAccessToken(requestToken, new Verifier(
					verifier[0]));
			return result;
		}
		/*
		 * (non-Javadoc)
		 * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
		 */
		protected void onPostExecute(Token accessToken) {
			ClientStore.saveTwitterAccessToken(accessToken, context);
			authListener.onAuthorizationComplete();
		}
	}
}