NewPipe/app/src/main/java/org/schabi/newpipe/fragments/local/bookmark/BaseLocalListFragment.java

package org.schabi.newpipe.fragments.local.bookmark;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBar;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;

import org.schabi.newpipe.R;
import org.schabi.newpipe.fragments.BaseStateFragment;
import org.schabi.newpipe.fragments.list.ListViewContract;
import org.schabi.newpipe.fragments.local.LocalItemListAdapter;

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

/**
 * This fragment is design to be used with persistent data such as
 * {@link org.schabi.newpipe.database.LocalItem}, and does not cache the data contained
 * in the list adapter to avoid extra writes when the it exits or re-enters its lifecycle.
 *
 * This fragment destroys its adapter and views when {@link Fragment#onDestroyView()} is
 * called and is memory efficient when in backstack.
 * */
public abstract class BaseLocalListFragment<I, N> extends BaseStateFragment<I>
        implements ListViewContract<I, N> {

    /*//////////////////////////////////////////////////////////////////////////
    // Views
    //////////////////////////////////////////////////////////////////////////*/

    protected View headerRootView;
    protected View footerRootView;

    protected LocalItemListAdapter itemListAdapter;
    protected RecyclerView itemsList;

    /*//////////////////////////////////////////////////////////////////////////
    // Lifecycle - Creation
    //////////////////////////////////////////////////////////////////////////*/

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    /*//////////////////////////////////////////////////////////////////////////
    // Lifecycle - View
    //////////////////////////////////////////////////////////////////////////*/

    protected View getListHeader() {
        return null;
    }

    protected View getListFooter() {
        return activity.getLayoutInflater().inflate(R.layout.pignate_footer, itemsList, false);
    }

    protected RecyclerView.LayoutManager getListLayoutManager() {
        return new LinearLayoutManager(activity);
    }

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

        itemsList = rootView.findViewById(R.id.items_list);
        itemsList.setLayoutManager(getListLayoutManager());

        itemListAdapter = new LocalItemListAdapter(activity);
        itemListAdapter.setHeader(headerRootView = getListHeader());
        itemListAdapter.setFooter(footerRootView = getListFooter());

        itemsList.setAdapter(itemListAdapter);
    }

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

    /*//////////////////////////////////////////////////////////////////////////
    // Lifecycle - Menu
    //////////////////////////////////////////////////////////////////////////*/

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        if (DEBUG) Log.d(TAG, "onCreateOptionsMenu() called with: menu = [" + menu +
                "], inflater = [" + inflater + "]");

        final ActionBar supportActionBar = activity.getSupportActionBar();
        if (supportActionBar == null) return;

        supportActionBar.setDisplayShowTitleEnabled(true);
    }

    /*//////////////////////////////////////////////////////////////////////////
    // Lifecycle - Destruction
    //////////////////////////////////////////////////////////////////////////*/

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        itemsList = null;
        itemListAdapter = null;
    }

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

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

    @Override
    public void showLoading() {
        super.showLoading();
        if (itemsList != null) animateView(itemsList, false, 200);
        if (headerRootView != null) animateView(headerRootView, false, 200);
    }

    @Override
    public void hideLoading() {
        super.hideLoading();
        if (itemsList != null) animateView(itemsList, true, 200);
        if (headerRootView != null) animateView(headerRootView, true, 200);
    }

    @Override
    public void showError(String message, boolean showRetryButton) {
        super.showError(message, showRetryButton);
        showListFooter(false);

        if (itemsList != null) animateView(itemsList, false, 200);
        if (headerRootView != null) animateView(headerRootView, false, 200);
    }

    @Override
    public void showEmptyState() {
        super.showEmptyState();
        showListFooter(false);
    }

    @Override
    public void showListFooter(final boolean show) {
        if (itemsList == null) return;
        itemsList.post(() -> {
            if (itemListAdapter != null) itemListAdapter.showFooter(show);
        });
    }

    @Override
    public void handleNextItems(N result) {
        isLoading.set(false);
    }

    /*//////////////////////////////////////////////////////////////////////////
    // Error handling
    //////////////////////////////////////////////////////////////////////////*/

    protected void resetFragment() {
        if (itemListAdapter != null) itemListAdapter.clearStreamItemList();
    }

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