MainActivity.java

/**
 * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
 *
 * You are hereby granted a non-exclusive, worldwide, royalty-free license to use,
 * copy, modify, and distribute this software in source code or binary form for use
 * in connection with the web services and APIs provided by Facebook.
 *
 * As with any software that integrates with the Facebook platform, your use of
 * this software is subject to the Facebook Developer Principles and Policies
 * [http://developers.facebook.com/policy/]. This copyright notice shall be
 * included in all copies or substantial portions of the software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.example.scrumptious;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;

import com.facebook.AccessToken;
import com.facebook.AccessTokenTracker;
import com.facebook.appevents.AppEventsLogger;
import com.facebook.CallbackManager;

public class MainActivity extends Activity {

    private static final String USER_SKIPPED_LOGIN_KEY = "user_skipped_login";

    private static final int SPLASH = 0;
    private static final int SELECTION = 1;
    private static final int SETTINGS = 2;
    private static final int FRAGMENT_COUNT = SETTINGS +1;

    private Fragment[] fragments = new Fragment[FRAGMENT_COUNT];
    private boolean isResumed = false;
    private boolean userSkippedLogin = false;
    private AccessTokenTracker accessTokenTracker;
    private CallbackManager callbackManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (savedInstanceState != null) {
            userSkippedLogin = savedInstanceState.getBoolean(USER_SKIPPED_LOGIN_KEY);
        }
        callbackManager = CallbackManager.Factory.create();

        accessTokenTracker = new AccessTokenTracker() {
            @Override
            protected void onCurrentAccessTokenChanged(AccessToken oldAccessToken,
                                                       AccessToken currentAccessToken) {
                if (isResumed) {
                    FragmentManager manager = getFragmentManager();
                    int backStackSize = manager.getBackStackEntryCount();
                    for (int i = 0; i < backStackSize; i++) {
                        manager.popBackStack();
                    }
                    if (currentAccessToken != null) {
                        showFragment(SELECTION, false);
                    } else {
                        showFragment(SPLASH, false);
                    }
                }
            }
        };

        setContentView(R.layout.main);

        FragmentManager fm = getFragmentManager();
        SplashFragment splashFragment = (SplashFragment) fm.findFragmentById(R.id.splashFragment);
        fragments[SPLASH] = splashFragment;
        fragments[SELECTION] = fm.findFragmentById(R.id.selectionFragment);
        fragments[SETTINGS] = fm.findFragmentById(R.id.userSettingsFragment);

        FragmentTransaction transaction = fm.beginTransaction();
        for(int i = 0; i < fragments.length; i++) {
            transaction.hide(fragments[i]);
        }
        transaction.commit();

        splashFragment.setSkipLoginCallback(new SplashFragment.SkipLoginCallback() {
            @Override
            public void onSkipLoginPressed() {
                userSkippedLogin = true;
                showFragment(SELECTION, false);
            }
        });
    }

    @Override
    public void onResume() {
        super.onResume();
        isResumed = true;

        if (AccessToken.getCurrentAccessToken() != null) {
            // if the user already logged in, try to show the selection fragment
            showFragment(SELECTION, false);
            userSkippedLogin = false;
        } else if (userSkippedLogin) {
            showFragment(SELECTION, false);
        } else {
            // otherwise present the splash screen and ask the user to login,
            // unless the user explicitly skipped.
            showFragment(SPLASH, false);
        }
    }

    @Override
    public void onPause() {
        super.onPause();
        isResumed = false;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        callbackManager.onActivityResult(requestCode, resultCode, data);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        accessTokenTracker.stopTracking();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);

        outState.putBoolean(USER_SKIPPED_LOGIN_KEY, userSkippedLogin);
    }

    public void showSettingsFragment() {
        showFragment(SETTINGS, true);
    }

    public void showSplashFragment() {
        showFragment(SPLASH, true);
    }


    private void showFragment(int fragmentIndex, boolean addToBackStack) {
        FragmentManager fm = getFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        for (int i = 0; i < fragments.length; i++) {
            if (i == fragmentIndex) {
                transaction.show(fragments[i]);
            } else {
                transaction.hide(fragments[i]);
            }
        }
        if (addToBackStack) {
            transaction.addToBackStack(null);
        }
        transaction.commit();
    }
}