NewPipe/app/src/main/java/org/schabi/newpipe/fragments/subscription/SubscriptionFragment.java

package org.schabi.newpipe.fragments.subscription;

import android.content.Context;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import org.schabi.newpipe.R;
import org.schabi.newpipe.database.subscription.SubscriptionEntity;
import org.schabi.newpipe.extractor.InfoItem;
import org.schabi.newpipe.extractor.channel.ChannelInfoItem;
import org.schabi.newpipe.fragments.BaseStateFragment;
import org.schabi.newpipe.info_list.InfoItemBuilder;
import org.schabi.newpipe.info_list.InfoListAdapter;
import org.schabi.newpipe.report.UserAction;
import org.schabi.newpipe.util.NavigationHelper;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import icepick.State;
import io.reactivex.Observer;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.CompositeDisposable;
import io.reactivex.disposables.Disposable;
import io.reactivex.schedulers.Schedulers;

import static org.schabi.newpipe.util.AnimationUtils.animateView;

public class SubscriptionFragment extends BaseStateFragment<List<SubscriptionEntity>> {
    private View headerRootLayout;

    private InfoListAdapter infoListAdapter;
    private RecyclerView itemsList;

    @State
    protected Parcelable itemsListState;

    /* Used for independent events */
    private CompositeDisposable disposables = new CompositeDisposable();
    private SubscriptionService subscriptionService;

    ///////////////////////////////////////////////////////////////////////////
    // Fragment LifeCycle
    ///////////////////////////////////////////////////////////////////////////

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        infoListAdapter = new InfoListAdapter(activity);
        subscriptionService = SubscriptionService.getInstance();
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_subscription, container, false);
    }

    @Override
    public void onPause() {
        super.onPause();
        itemsListState = itemsList.getLayoutManager().onSaveInstanceState();
    }

    @Override
    public void onDestroyView() {
        if (disposables != null) disposables.clear();

        super.onDestroyView();
    }

    @Override
    public void onDestroy() {
        if (disposables != null) disposables.dispose();
        disposables = null;
        subscriptionService = null;

        super.onDestroy();
    }

    ///////////////////////////////////////////////////////////////////////////
    // Fragment Views
    ///////////////////////////////////////////////////////////////////////////

    @Override
    protected void initViews(View rootView, Bundle savedInstanceState) {
        super.initViews(rootView, savedInstanceState);

        infoListAdapter = new InfoListAdapter(getActivity());
        itemsList = rootView.findViewById(R.id.items_list);
        itemsList.setLayoutManager(new LinearLayoutManager(activity));

        infoListAdapter.setHeader(headerRootLayout = activity.getLayoutInflater().inflate(R.layout.subscription_header, itemsList, false));
        infoListAdapter.useMiniItemVariants(true);

        itemsList.setAdapter(infoListAdapter);
    }

    @Override
    protected void initListeners() {
        super.initListeners();

        infoListAdapter.setOnChannelSelectedListener(new InfoItemBuilder.OnInfoItemSelectedListener<ChannelInfoItem>() {
            @Override
            public void selected(ChannelInfoItem selectedItem) {
                // Requires the parent fragment to find holder for fragment replacement
                NavigationHelper.openChannelFragment(getParentFragment().getFragmentManager(), selectedItem.service_id, selectedItem.url, selectedItem.name);

            }
        });

        headerRootLayout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavigationHelper.openWhatsNewFragment(getParentFragment().getFragmentManager());
            }
        });
    }

    private void resetFragment() {
        if (disposables != null) disposables.clear();
        if (infoListAdapter != null) infoListAdapter.clearStreamItemList();
    }

    ///////////////////////////////////////////////////////////////////////////
    // Subscriptions Loader
    ///////////////////////////////////////////////////////////////////////////

    @Override
    public void startLoading(boolean forceLoad) {
        super.startLoading(forceLoad);
        resetFragment();

        subscriptionService.getSubscription().toObservable()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(getSubscriptionObserver());
    }

    private Observer<List<SubscriptionEntity>> getSubscriptionObserver() {
        return new Observer<List<SubscriptionEntity>>() {
            @Override
            public void onSubscribe(Disposable d) {
                showLoading();
                disposables.add(d);
            }

            @Override
            public void onNext(List<SubscriptionEntity> subscriptions) {
                handleResult(subscriptions);
            }

            @Override
            public void onError(Throwable exception) {
                SubscriptionFragment.this.onError(exception);
            }

            @Override
            public void onComplete() {
            }
        };
    }

    @Override
    public void handleResult(@NonNull List<SubscriptionEntity> result) {
        super.handleResult(result);

        infoListAdapter.clearStreamItemList();

        if (result.isEmpty()) {
            showEmptyState();
        } else {
            infoListAdapter.addInfoItemList(getSubscriptionItems(result));
            if (itemsListState != null) {
                itemsList.getLayoutManager().onRestoreInstanceState(itemsListState);
                itemsListState = null;
            }

            hideLoading();
        }
    }


    private List<InfoItem> getSubscriptionItems(List<SubscriptionEntity> subscriptions) {
        List<InfoItem> items = new ArrayList<>();
        for (final SubscriptionEntity subscription : subscriptions) items.add(subscription.toChannelInfoItem());

        Collections.sort(items, new Comparator<InfoItem>() {
            @Override
            public int compare(InfoItem o1, InfoItem o2) {
                return o1.name.compareToIgnoreCase(o2.name);
            }
        });
        return items;
    }

    /*//////////////////////////////////////////////////////////////////////////
    // Contract
    //////////////////////////////////////////////////////////////////////////*/

    @Override
    public void showLoading() {
        super.showLoading();
        animateView(itemsList, false, 100);
    }

    @Override
    public void hideLoading() {
        super.hideLoading();
        animateView(itemsList, true, 200);
    }

    @Override
    public void showEmptyState() {
        super.showEmptyState();
        animateView(itemsList, false, 200);
    }

    ///////////////////////////////////////////////////////////////////////////
    // Fragment Error Handling
    ///////////////////////////////////////////////////////////////////////////

    @Override
    protected boolean onError(Throwable exception) {
        resetFragment();
        if (super.onError(exception)) return true;

        onUnrecoverableError(exception, UserAction.SOMETHING_ELSE, "none", "Subscriptions", R.string.general_error);
        return true;
    }
}