MainActivity.java

/*
 * Copyright (c) 2013 Google 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.example.authsample;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

import android.accounts.AccountManager;
import android.app.FragmentManager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.gcm.GoogleCloudMessaging;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.cloud.backend.android.CloudBackendActivity;
import com.google.cloud.backend.android.CloudBackendMessaging;
import com.google.cloud.backend.android.CloudCallbackHandler;
import com.google.cloud.backend.android.CloudEntity;
import com.google.cloud.backend.android.Consts;
import com.google.cloud.backend.android.CloudQuery.Order;
import com.google.cloud.backend.android.CloudQuery.Scope;

/**
 * Sample Guestbook app with Mobile Backend Starter.
 * 
 */
public class MainActivity extends CloudBackendActivity {

    private static final int REQUEST_ACCOUNT_PICKER = 2;

    private static final String PREF_KEY_ACCOUNT_NAME = "PREF_KEY_ACCOUNT_NAME";

    private static final String BROADCAST_PROP_DURATION = "duration";
    private static final String BROADCAST_PROP_MESSAGE = "message";

    private GoogleAccountCredential credential;

    // UI components
    private EditText mEditText;
    private View mSendBtn;

    // a list of posts on the UI
    List<CloudEntity> posts = new LinkedList<CloudEntity>();

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

        CloudBackendMessaging cloudBackend = getCloudBackend();

        // create credential
        credential = GoogleAccountCredential.usingAudience(this, Consts.AUTH_AUDIENCE);
        cloudBackend.setCredential(credential);

        // get account name from the shared pref
        String accountName = PreferenceManager.getDefaultSharedPreferences(this).getString(PREF_KEY_ACCOUNT_NAME, null);
        if (accountName == null) {
            // let user pick an account
            startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
            return; // continue init in onActivityResult
        } else {
            credential.setSelectedAccountName(accountName);
        }

        mEditText = (EditText) findViewById(R.id.edit_text);
        mSendBtn = findViewById(R.id.send_btn);
    }

    /**
     * Returns account name selected by user, or null if any account is
     * selected.
     */
    protected String getAccountName() {
        return credential == null ? null : credential.getSelectedAccountName();
    }

    @Override
    protected void onDestroy() {
        GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
        gcm.close();
        super.onDestroy();
    }

    @Override
    protected void onPostCreate() {
        super.onPostCreate();
        listAllPosts();
    }

    /**
     * Handles callback from Intents like authorization request or account
     * picking.
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        switch (requestCode) {
            case REQUEST_ACCOUNT_PICKER:
                if (data != null && data.getExtras() != null) {
                    // set the picked account name to the credential
                    String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
                    credential.setSelectedAccountName(accountName);

                    // save account name to shared pref
                    SharedPreferences.Editor e = PreferenceManager.getDefaultSharedPreferences(this).edit();
                    e.putString(PREF_KEY_ACCOUNT_NAME, accountName);
                    e.commit();
                }

                // post create initialization
                onPostCreate();
                break;
        }
    }

    // execute query "SELECT * FROM Guestbook ORDER BY _createdAt DESC LIMIT 50"
    // this query will be re-executed when matching entity is updated
    private void listAllPosts() {

        // create a response handler that will receive the query result or an
        // error
        CloudCallbackHandler<List<CloudEntity>> handler = new CloudCallbackHandler<List<CloudEntity>>() {
            @Override
            public void onComplete(List<CloudEntity> results) {
                posts = results;
                updateGuestbookUI();
            }

            @Override
            public void onError(IOException exception) {
                handleEndpointException(exception);
            }
        };

        // execute the query with the handler
        getCloudBackend().listByKind("Guestbook", CloudEntity.PROP_CREATED_AT, Order.DESC, 50, Scope.FUTURE_AND_PAST,
                handler);
    }

    private void handleEndpointException(IOException e) {
        Toast.makeText(this, e.toString(), Toast.LENGTH_LONG).show();
        mSendBtn.setEnabled(true);
    }

    // convert posts into string and update UI
    private void updateGuestbookUI() {
        FragmentManager manager = getFragmentManager();
        PostListFragment f = (PostListFragment) manager.findFragmentById(R.id.fragment_list);
        f.setEntities(posts);
    }

    // post a new message to server
    public void onSendButtonPressed(View view) {

        // create a CloudEntity with the new post
        CloudEntity newPost = new CloudEntity("Guestbook");
        newPost.put("message", mEditText.getText().toString());

        // create a response handler that will receive the result or an error
        CloudCallbackHandler<CloudEntity> handler = new CloudCallbackHandler<CloudEntity>() {
            @Override
            public void onComplete(final CloudEntity result) {
                posts.add(0, result);
                updateGuestbookUI();
                mEditText.setText("");
                mSendBtn.setEnabled(true);
            }

            @Override
            public void onError(final IOException exception) {
                handleEndpointException(exception);
            }
        };

        // execute the insertion with the handler
        getCloudBackend().insert(newPost, handler);
        mSendBtn.setEnabled(false);
    }

    // handles broadcast message and show a toast
    @Override
    public void onBroadcastMessageReceived(List<CloudEntity> l) {
        for (CloudEntity e : l) {
            String message = (String) e.get(BROADCAST_PROP_MESSAGE);
            int duration = Integer.parseInt((String) e.get(BROADCAST_PROP_DURATION));
            Toast.makeText(this, message, duration).show();
        }
    }
}