NewPipe/app/src/main/java/org/schabi/newpipe/about/AboutActivity.java

package org.schabi.newpipe.about;

import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.recyclerview.widget.RecyclerView;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import androidx.viewpager2.widget.ViewPager2;

import com.google.android.material.tabs.TabLayout;
import com.google.android.material.tabs.TabLayoutMediator;

import org.schabi.newpipe.BuildConfig;
import org.schabi.newpipe.R;
import org.schabi.newpipe.util.ThemeHelper;

import static org.schabi.newpipe.util.Localization.assureCorrectAppLanguage;
import static org.schabi.newpipe.util.ShareUtils.openUrlInBrowser;

public class AboutActivity extends AppCompatActivity {
    /**
     * List of all software components.
     */
    private static final SoftwareComponent[] SOFTWARE_COMPONENTS = new SoftwareComponent[]{
            new SoftwareComponent("Giga Get", "2014 - 2015", "Peter Cai",
                    "https://github.com/PaperAirplane-Dev-Team/GigaGet", StandardLicenses.GPL2),
            new SoftwareComponent("NewPipe Extractor", "2017 - 2020", "Christian Schabesberger",
                    "https://github.com/TeamNewPipe/NewPipeExtractor", StandardLicenses.GPL3),
            new SoftwareComponent("Jsoup", "2017", "Jonathan Hedley",
                    "https://github.com/jhy/jsoup", StandardLicenses.MIT),
            new SoftwareComponent("Rhino", "2015", "Mozilla",
                    "https://www.mozilla.org/rhino/", StandardLicenses.MPL2),
            new SoftwareComponent("ACRA", "2013", "Kevin Gaudin",
                    "http://www.acra.ch", StandardLicenses.APACHE2),
            new SoftwareComponent("Universal Image Loader", "2011 - 2015", "Sergey Tarasevich",
                    "https://github.com/nostra13/Android-Universal-Image-Loader",
                    StandardLicenses.APACHE2),
            new SoftwareComponent("CircleImageView", "2014 - 2020", "Henning Dodenhof",
                    "https://github.com/hdodenhof/CircleImageView", StandardLicenses.APACHE2),
            new SoftwareComponent("NoNonsense-FilePicker", "2016", "Jonas Kalderstam",
                    "https://github.com/spacecowboy/NoNonsense-FilePicker", StandardLicenses.MPL2),
            new SoftwareComponent("ExoPlayer", "2014 - 2020", "Google Inc",
                    "https://github.com/google/ExoPlayer", StandardLicenses.APACHE2),
            new SoftwareComponent("RxAndroid", "2015 - 2018", "The RxAndroid authors",
                    "https://github.com/ReactiveX/RxAndroid", StandardLicenses.APACHE2),
            new SoftwareComponent("RxJava", "2016 - 2020", "RxJava Contributors",
                    "https://github.com/ReactiveX/RxJava", StandardLicenses.APACHE2),
            new SoftwareComponent("RxBinding", "2015 - 2018", "Jake Wharton",
                    "https://github.com/JakeWharton/RxBinding", StandardLicenses.APACHE2),
            new SoftwareComponent("PrettyTime", "2012 - 2020", "Lincoln Baxter, III",
                    "https://github.com/ocpsoft/prettytime", StandardLicenses.APACHE2),
            new SoftwareComponent("Markwon", "2017 - 2020", "Noties",
                    "https://github.com/noties/Markwon", StandardLicenses.APACHE2),
            new SoftwareComponent("Groupie", "2016", "Lisa Wray",
                    "https://github.com/lisawray/groupie", StandardLicenses.MIT)
    };

    private static final int POS_ABOUT = 0;
    private static final int POS_LICENSE = 1;
    private static final int TOTAL_COUNT = 2;
    /**
     * The {@link RecyclerView.Adapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentStateAdapter} derivative, which will keep every
     * loaded fragment in memory.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;
    /**
     * The {@link ViewPager2} that will host the section contents.
     */
    private ViewPager2 mViewPager;

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        assureCorrectAppLanguage(this);
        super.onCreate(savedInstanceState);
        ThemeHelper.setTheme(this);
        this.setTitle(getString(R.string.title_activity_about));

        setContentView(R.layout.activity_about);

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

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

        final TabLayout tabLayout = findViewById(R.id.tabs);
        new TabLayoutMediator(tabLayout, mViewPager, (tab, position) -> {
            switch (position) {
                default:
                case POS_ABOUT:
                    tab.setText(R.string.tab_about);
                    break;
                case POS_LICENSE:
                    tab.setText(R.string.tab_licenses);
                    break;
            }
        }).attach();
    }

    @Override
    public boolean onOptionsItemSelected(final MenuItem item) {
        final int id = item.getItemId();

        switch (id) {
            case android.R.id.home:
                finish();
                return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class AboutFragment extends Fragment {
        public AboutFragment() { }

        /**
         * Created a new instance of this fragment for the given section number.
         *
         * @return New instance of {@link AboutFragment}
         */
        public static AboutFragment newInstance() {
            return new AboutFragment();
        }

        @Override
        public View onCreateView(final LayoutInflater inflater, final ViewGroup container,
                                 final Bundle savedInstanceState) {
            final View rootView = inflater.inflate(R.layout.fragment_about, container, false);
            final Context context = this.getContext();

            final TextView version = rootView.findViewById(R.id.app_version);
            version.setText(BuildConfig.VERSION_NAME);

            final View githubLink = rootView.findViewById(R.id.github_link);
            githubLink.setOnClickListener(nv ->
                    openUrlInBrowser(context, context.getString(R.string.github_url)));

            final View donationLink = rootView.findViewById(R.id.donation_link);
            donationLink.setOnClickListener(v ->
                    openUrlInBrowser(context, context.getString(R.string.donation_url)));

            final View websiteLink = rootView.findViewById(R.id.website_link);
            websiteLink.setOnClickListener(nv ->
                    openUrlInBrowser(context, context.getString(R.string.website_url)));

            final View privacyPolicyLink = rootView.findViewById(R.id.privacy_policy_link);
            privacyPolicyLink.setOnClickListener(v ->
                    openUrlInBrowser(context, context.getString(R.string.privacy_policy_url)));

            return rootView;
        }

    }

    /**
     * A {@link FragmentStateAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public static class SectionsPagerAdapter extends FragmentStateAdapter {
        public SectionsPagerAdapter(final FragmentActivity fa) {
            super(fa);
        }

        @NonNull
        @Override
        public Fragment createFragment(final int position) {
            switch (position) {
                default:
                case POS_ABOUT:
                    return AboutFragment.newInstance();
                case POS_LICENSE:
                    return LicenseFragment.newInstance(SOFTWARE_COMPONENTS);
            }
        }

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