NewPipe/app/src/main/java/org/schabi/newpipe/history/HistoryActivity.java

package org.schabi.newpipe.history;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.util.SparseArray;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import com.jakewharton.rxbinding2.view.RxView;

import org.schabi.newpipe.R;
import org.schabi.newpipe.settings.SettingsActivity;
import org.schabi.newpipe.util.ThemeHelper;

import io.reactivex.Observable;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.functions.Consumer;
import io.reactivex.functions.Function;
import io.reactivex.schedulers.Schedulers;

public class HistoryActivity extends AppCompatActivity {

    private static final String TAG = "HistoryActivity";
    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    private ViewPager mViewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ThemeHelper.setTheme(this);
        setContentView(R.layout.activity_history);

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setTitle(R.string.title_activity_history);
        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayout tabLayout = findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        final FloatingActionButton fab = findViewById(R.id.fab);
        RxView.clicks(fab)
                .observeOn(Schedulers.io())
                .flatMap(new Function<Object, Observable<HistoryFragment>>() {
                    @Override
                    public Observable<HistoryFragment> apply(Object o) {
                        int currentItem = mViewPager.getCurrentItem();
                        HistoryFragment fragment = (HistoryFragment) mSectionsPagerAdapter.getFragment(currentItem);
                        if(fragment == null) {
                            Log.w(TAG, "Couldn't find current fragment");
                            return Observable.empty();
                        } else {
                            fragment.onClearHistory();
                            return Observable.just(fragment);
                        }
                    }
                })
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Consumer<HistoryFragment>() {
                    @Override
                    public void accept(HistoryFragment historyFragment) {
                        View view = historyFragment.getView();
                        if(view != null) {
                            Snackbar.make(view, R.string.history_cleared, Snackbar.LENGTH_LONG).show();
                        }
                        historyFragment.onHistoryCleared();
                    }
                });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_history, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
            case R.id.action_settings:
                Intent intent = new Intent(this, SettingsActivity.class);
                startActivity(intent);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        private SparseArray<Fragment> fragments = new SparseArray<>();

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }


        @Override
        public Fragment getItem(int position) {
            Fragment fragment;
            switch (position) {
                case 0:
                    fragment = SearchHistoryFragment.newInstance();
                    break;
                case 1:
                    fragment = WatchedHistoryFragment.newInstance();
                    break;
                default:
                    throw new IllegalArgumentException("position: " + position);
            }
            fragments.put(position, fragment);
            return fragment;
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            super.destroyItem(container, position, object);
            fragments.remove(position);
        }

        @Nullable
        public Fragment getFragment(int position) {
            return fragments.get(position);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return getString(R.string.title_history_search);
                case 1:
                    return getString(R.string.title_history_view);
            }
            throw new IllegalArgumentException("position: " + position);
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 2;
        }
    }
}