FeedFragment.java

package org.briarproject.android.blogs;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityOptionsCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;

import org.briarproject.R;
import org.briarproject.android.ActivityComponent;
import org.briarproject.android.blogs.BaseController.OnBlogPostAddedListener;
import org.briarproject.android.blogs.BlogPostAdapter.OnBlogPostClickListener;
import org.briarproject.android.controller.handler.UiResultExceptionHandler;
import org.briarproject.android.fragment.BaseFragment;
import org.briarproject.android.view.BriarRecyclerView;
import org.briarproject.api.blogs.Blog;
import org.briarproject.api.blogs.BlogPostHeader;
import org.briarproject.api.db.DbException;

import java.util.Collection;
import java.util.logging.Logger;

import javax.inject.Inject;

import static android.app.Activity.RESULT_OK;
import static android.support.design.widget.Snackbar.LENGTH_LONG;
import static android.support.v4.app.ActivityOptionsCompat.makeCustomAnimation;
import static org.briarproject.android.BriarActivity.GROUP_ID;
import static org.briarproject.android.blogs.BlogActivity.REQUEST_WRITE_POST;

public class FeedFragment extends BaseFragment implements
		OnBlogPostClickListener, OnBlogPostAddedListener {

	public final static String TAG = FeedFragment.class.getName();
	private static final Logger LOG = Logger.getLogger(TAG);

	@Inject
	FeedController feedController;

	private BlogPostAdapter adapter;
	private LinearLayoutManager layoutManager;
	private BriarRecyclerView list;
	private Blog personalBlog = null;

	public static FeedFragment newInstance() {
		FeedFragment f = new FeedFragment();

		Bundle args = new Bundle();
		f.setArguments(args);

		return f;
	}

	@Nullable
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {

		View v = inflater.inflate(R.layout.fragment_blog, container, false);

		adapter = new BlogPostAdapter(getActivity(), this);

		layoutManager = new LinearLayoutManager(getActivity());
		list = (BriarRecyclerView) v.findViewById(R.id.postList);
		list.setLayoutManager(layoutManager);
		list.setAdapter(adapter);
		list.setEmptyText(R.string.blogs_feed_empty_state);

		return v;
	}

	@Override
	public void injectFragment(ActivityComponent component) {
		component.inject(this);
		feedController.setOnBlogPostAddedListener(this);
	}

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

		// The BlogPostAddedEvent arrives when the controller is not listening
		if (requestCode == REQUEST_WRITE_POST && resultCode == RESULT_OK) {
			showSnackBar(R.string.blogs_blog_post_created);
		}
	}

	@Override
	public void onStart() {
		super.onStart();
		feedController.onStart();
		loadPersonalBlog();
		loadBlogPosts(false);
	}

	@Override
	public void onStop() {
		super.onStop();
		feedController.onStop();
		adapter.clear();
		list.showProgressBar();
		list.stopPeriodicUpdate();
		// TODO save list position in database/preferences?
	}

	private void loadPersonalBlog() {
		feedController.loadPersonalBlog(
				new UiResultExceptionHandler<Blog, DbException>(this) {
					@Override
					public void onResultUi(Blog b) {
						personalBlog = b;
					}

					@Override
					public void onExceptionUi(DbException exception) {
						// TODO: Decide how to handle errors in the UI
					}
				});
	}

	private void loadBlogPosts(final boolean clear) {
		final int revision = adapter.getRevision();
		feedController.loadBlogPosts(
				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
						this) {
					@Override
					public void onResultUi(Collection<BlogPostItem> posts) {
						if (revision == adapter.getRevision()) {
							adapter.incrementRevision();
							if (clear) adapter.setItems(posts);
							else adapter.addAll(posts);
							if (posts.isEmpty()) list.showData();
						} else {
							LOG.info("Concurrent update, reloading");
							loadBlogPosts(clear);
						}
					}

					@Override
					public void onExceptionUi(DbException e) {
						// TODO: Decide how to handle errors in the UI
					}
				});
		list.startPeriodicUpdate();
	}

	@Override
	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
		inflater.inflate(R.menu.blogs_feed_actions, menu);
		super.onCreateOptionsMenu(menu, inflater);
	}

	@Override
	public boolean onOptionsItemSelected(final MenuItem item) {
		if (personalBlog == null) return false;
		ActivityOptionsCompat options =
				makeCustomAnimation(getActivity(), android.R.anim.slide_in_left,
						android.R.anim.slide_out_right);
		switch (item.getItemId()) {
			case R.id.action_write_blog_post:
				Intent i1 =
						new Intent(getActivity(), WriteBlogPostActivity.class);
				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
				startActivityForResult(i1, REQUEST_WRITE_POST,
						options.toBundle());
				return true;
			case R.id.action_rss_feeds_import:
				Intent i2 =
						new Intent(getActivity(), RssFeedImportActivity.class);
				i2.putExtra(GROUP_ID, personalBlog.getId().getBytes());
				startActivity(i2, options.toBundle());
				return true;
			case R.id.action_rss_feeds_manage:
				Intent i3 =
						new Intent(getActivity(), RssFeedManageActivity.class);
				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
				startActivity(i3, options.toBundle());
				return true;
			default:
				return super.onOptionsItemSelected(item);
		}
	}

	@Override
	public void onBlogPostAdded(BlogPostHeader header, final boolean local) {
		feedController.loadBlogPost(header,
				new UiResultExceptionHandler<BlogPostItem, DbException>(
						this) {
					@Override
					public void onResultUi(BlogPostItem post) {
						adapter.incrementRevision();
						adapter.add(post);
						if (local) {
							showSnackBar(R.string.blogs_blog_post_created);
						} else {
							showSnackBar(R.string.blogs_blog_post_received);
						}
					}

					@Override
					public void onExceptionUi(DbException exception) {
						// TODO: Decide how to handle errors in the UI
					}
				}
		);
	}

	@Override
	public void onBlogPostClick(BlogPostItem post) {
		FeedPostPagerFragment f = FeedPostPagerFragment
				.newInstance(post.getId());
		getActivity().getSupportFragmentManager().beginTransaction()
				.replace(R.id.content_fragment, f, f.getUniqueTag())
				.addToBackStack(f.getUniqueTag())
				.commit();
	}

	@Override
	public String getUniqueTag() {
		return TAG;
	}

	private void showSnackBar(int stringRes) {
		int firstVisible =
				layoutManager.findFirstCompletelyVisibleItemPosition();
		int lastVisible = layoutManager.findLastCompletelyVisibleItemPosition();
		int count = adapter.getItemCount();
		boolean scroll = count > (lastVisible - firstVisible + 1);

		Snackbar s = Snackbar.make(list, stringRes, LENGTH_LONG);
		s.getView().setBackgroundResource(R.color.briar_primary);
		if (scroll) {
			OnClickListener onClick = new OnClickListener() {
				@Override
				public void onClick(View v) {
					list.smoothScrollToPosition(0);
				}
			};
			s.setActionTextColor(ContextCompat
					.getColor(getContext(),
							R.color.briar_button_positive));
			s.setAction(R.string.blogs_blog_post_scroll_to, onClick);
		}
		s.show();
	}

	@Override
	public void onBlogRemoved() {
		loadBlogPosts(true);
	}
}