LoginHandler.java

/*
 * Copyright 2010 Facebook, Inc.
 *
 * 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.facebook.stream;

import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import com.facebook.android.AsyncFacebookRunner;
import com.facebook.android.DialogError;
import com.facebook.android.Facebook;
import com.facebook.android.FacebookError;
import com.facebook.android.Facebook.DialogListener;

/**
 * A handler for the login page.
 * 
 * @author yariv
 */
public class LoginHandler extends Handler {

    // The permissions that the app should request from the user
    // when the user authorizes the app.
    private static String[] PERMISSIONS = 
        new String[] { "offline_access", "read_stream", "publish_stream" };

    /**
     * Render the Login page.
     */
    public void go() {
        dispatcher.getWebView().addJavascriptInterface(
                new JsHandler(), "app");
        dispatcher.loadFile("login.html");
    }

    /**
     * Contains functions that are exported to the Javascript context
     * in Login.html
     * 
     * @author yariv
     */
    private class JsHandler {

        /**
         * Opens the Facebook login dialog.
         */
        public void login() {
            final Activity activity = LoginHandler.this.getActivity();
            activity.runOnUiThread(new Runnable() {
                public void run() {
                    // We need to temporarily remove the app's WebView
                    // instance because Android apparently doesn't support
                    // multiple WebView instances in the same app.
                    dispatcher.hideWebView();
                    final Facebook fb = new Facebook(App.FB_APP_ID);
                    Session.waitForAuthCallback(fb);
                    fb.authorize(getActivity(), PERMISSIONS,
                                 new AppLoginListener(fb));
                }
            });
        }

        private class AppLoginListener implements DialogListener {

            private Facebook fb;

            public AppLoginListener(Facebook fb) {
                this.fb = fb;
            }

            public void onCancel() {
                Log.d("app", "login canceled");
            }

            public void onComplete(Bundle values) {
                /**
                 * We request the user's info so we can cache it locally and
                 * use it to render the new html snippets
                 * when the user updates her status or comments on a post. 
                 */
                new AsyncFacebookRunner(fb).request("/me", 
                        new AsyncRequestListener() {
                    public void onComplete(JSONObject obj, final Object state) {
                        // save the session data
                        String uid = obj.optString("id");
                        String name = obj.optString("name");
                        new Session(fb, uid, name).save(getActivity());

                        // render the Stream page in the UI thread
                        getActivity().runOnUiThread(new Runnable() {
                            public void run() {
                                dispatcher.showWebView();
                                dispatcher.runHandler("stream");
                            }
                        });
                    }
                }, null);
            }

            public void onError(DialogError e) {
                Log.d("app", "dialog error: " + e);               
            }

            public void onFacebookError(FacebookError e) {
                Log.d("app", "facebook error: " + e);
            }
        }
    }

}