MainActivity.java

package uk.co.imallan.tuchongdaily.ui.activity;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.SharedElementCallback;
import android.content.Intent;
import android.database.Cursor;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.view.ViewPager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.transition.Fade;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.crashlytics.android.Crashlytics;

import java.util.List;
import java.util.Map;

import io.fabric.sdk.android.Fabric;
import uk.co.imallan.tuchongdaily.BuildConfig;
import uk.co.imallan.tuchongdaily.R;
import uk.co.imallan.tuchongdaily.provider.PostProvider;
import uk.co.imallan.tuchongdaily.service.PostsService;
import uk.co.imallan.tuchongdaily.service.ServiceReceiver;
import uk.co.imallan.tuchongdaily.ui.adapter.PostImagesRecyclerViewAdapter;
import uk.co.imallan.tuchongdaily.ui.adapter.PostPagerAdapter;
import uk.co.imallan.tuchongdaily.ui.fragment.PostFragment;


public class MainActivity extends AbstractActivity
		implements LoaderManager.LoaderCallbacks<Cursor>, ViewPager.OnPageChangeListener {

	private static final int LOADER_POSTS = 1;

	private ViewPager mPager;

	private PostPagerAdapter mAdapter;

	private long mLastBackClicked = 0;

	private int mImagePosition = 0;

	private boolean isReenterTransition = false;

	private ProgressBar mProgressBar;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		if (!BuildConfig.DEBUG) {
			Fabric.with(this, new Crashlytics());
		}
		setContentView(R.layout.activity_main);
		initElements();
		initTransitions();
		setTitle(R.string.app_name);
		PostsService.requestPosts(this, serviceReceiver, 20, 0);
		getSupportLoaderManager().initLoader(LOADER_POSTS, null, this);
	}

	private void initElements() {
		Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
		setSupportActionBar(toolbar);
		mPager = (ViewPager) findViewById(R.id.pager_main);
		mAdapter = new PostPagerAdapter(getSupportFragmentManager());
		mPager.setAdapter(mAdapter);
		mPager.setOnPageChangeListener(this);
		mProgressBar = (ProgressBar) findViewById(R.id.progress_bar_main);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		MenuInflater inflater = getMenuInflater();
		inflater.inflate(R.menu.menu_share, menu);
		inflater.inflate(R.menu.menu_browser, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		PostFragment postFragment;
		switch (item.getItemId()) {
			case R.id.action_share:
				postFragment = getRegisteredFragment(mPager.getCurrentItem());
				if (postFragment != null) {
					postFragment.share();
				}
				return true;
			case R.id.action_open_in_browser:
				postFragment = getRegisteredFragment(mPager.getCurrentItem());
				if (postFragment != null) {
					postFragment.openInBrowser();
				}
				return true;
		}
		return super.onOptionsItemSelected(item);
	}

	private void initTransitions() {
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
			setExitSharedElementCallback(new SharedElementCallback() {
				@SuppressLint("NewApi")
				@Override
				public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
					super.onMapSharedElements(names, sharedElements);
					if (!isReenterTransition) {
						return;
					}
					isReenterTransition = false;
					names.clear();
					sharedElements.clear();
					final PostFragment postFragment = (PostFragment) mAdapter.getRegisteredFragment(mPager.getCurrentItem());
					final RecyclerView recyclerView = postFragment.mRecyclerView;
					View sharedView =
							((PostImagesRecyclerViewAdapter.ViewHolder) recyclerView.findViewHolderForPosition(mImagePosition)).getImage();
					names.add(sharedView.getTransitionName());
					sharedElements.put(sharedView.getTransitionName(), sharedView);
				}
			});

			Fade fadeExit = new Fade();
			fadeExit.addTarget(R.id.text_post_title);
			fadeExit.addTarget(R.id.button_show_gallery);
			fadeExit.addTarget(R.id.recycler_post_images);
			fadeExit.addTarget(R.id.image_post_author);
			fadeExit.addTarget(R.id.bottom_shadow_post);
			fadeExit.addTarget(R.id.toolbar);
			getWindow().setExitTransition(fadeExit);
		}

	}


	@Override
	boolean prepareServiceReceiver() {
		return true;
	}

	@Override
	public void onReceiveResult(int resultCode, Bundle resultData, Intent originalIntent, Bundle originalBundle) {
		switch (resultCode) {
			case ServiceReceiver.STATUS_DATA:
				break;
			case ServiceReceiver.STATUS_FINISHED:
				getSupportLoaderManager().restartLoader(LOADER_POSTS, null, this);
				break;
		}
	}

	@Override
	public Loader<Cursor> onCreateLoader(int id, Bundle args) {
		switch (id) {
			case LOADER_POSTS:
				return new CursorLoader(this, PostProvider.uriPosts(), null, null, null, null);
			default:
				return null;
		}
	}

	@Override
	public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
		switch (loader.getId()) {
			case LOADER_POSTS:
				mAdapter.swapCursor(data);
				if (data.getCount() > 0) {
					mProgressBar.setVisibility(View.GONE);
				}
				break;
		}
	}

	@Override
	public void onLoaderReset(Loader<Cursor> loader) {

	}


	private PostFragment getRegisteredFragment(int position) {
		return (PostFragment) mAdapter.getRegisteredFragment(position);
	}

	@Override
	public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
		PostFragment fromFragment = getRegisteredFragment(position);
		if (fromFragment != null) {
			fromFragment.onPageScrollFrom(positionOffset, positionOffsetPixels);
		}
		PostFragment toFragment = getRegisteredFragment(position + 1);
		if (toFragment != null) {
			toFragment.onPageScrollto(positionOffset, positionOffsetPixels);
		}
	}

	@Override
	public void onPageSelected(int position) {
		PostFragment fragment = getRegisteredFragment(position);
		if (fragment != null) {
			fragment.onPageSelected();
		}

	}

	@Override
	public void onBackPressed() {
		if (System.currentTimeMillis() - mLastBackClicked < 1000) {
			super.onBackPressed();
		} else {
			Toast.makeText(this, R.string.double_click_to_exit, Toast.LENGTH_SHORT).show();
			mLastBackClicked = System.currentTimeMillis();
		}
	}

	@Override
	public void onPageScrollStateChanged(int state) {

	}

	@Override
	public void onActivityReenter(int resultCode, Intent data) {
		super.onActivityReenter(resultCode, data);
		if (resultCode == Activity.RESULT_OK) {
			isReenterTransition = true;
			mImagePosition = data.getIntExtra(ImagePagerActivity.EXTRA_IMAGE_POSITION, 0);
			final PostFragment postFragment = (PostFragment) mAdapter.getRegisteredFragment(mPager.getCurrentItem());
			postFragment.mRecyclerView.scrollToPosition(mImagePosition);
			if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
				postponeEnterTransition();
				postFragment.mRecyclerView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
					@SuppressLint("NewApi")
					@Override
					public boolean onPreDraw() {
						postFragment.mRecyclerView.getViewTreeObserver().removeOnPreDrawListener(this);
						postFragment.mRecyclerView.requestLayout();
						startPostponedEnterTransition();
						return true;
					}
				});
			}
		}
	}

}