RecyclerView with pagination

list_item_loading.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
                                    xmlns:app="http://schemas.android.com/apk/res-auto"
                                    android:layout_width="match_parent"
                                    android:layout_height="64dp"
                                    android:elevation="3dp"
                                    android:orientation="vertical"
                                    app:cardElevation="3dp">

    <ProgressBar
        android:layout_width="36dp"
        android:layout_height="36dp"
        android:layout_gravity="center"/>

</android.support.v7.widget.CardView>

list_item_station.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:custom="http://schemas.android.com/apk/res-auto"
                android:layout_width="match_parent"
                android:layout_height="200dp"
                android:orientation="vertical">

    <ImageView
        android:id="@+id/station_iv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"/>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@drawable/background_news_list_item_details"
        android:padding="16dp">

        <ro.rompetrol.mobileapp.ui.TextView
            android:id="@+id/station_name_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Rompetrol Viilor"
            android:textColor="@android:color/white"
            android:textSize="20sp"
            custom:font="roboto_regular"/>

        <ProgressBar
            android:id="@+id/direction_progressBar"
            style="?android:attr/progressBarStyleHorizontal"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@id/distance_tv"
            android:layout_alignTop="@id/distance_tv"
            android:indeterminate="true"/>

        <ro.rompetrol.mobileapp.ui.TextView
            android:id="@+id/distance_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/station_name_tv"
            android:text="2 KM"
            android:textColor="@android:color/white"
            custom:font="roboto_condensed"
            />

        <ro.rompetrol.mobileapp.ui.TextView
            android:id="@+id/eta_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/station_name_tv"
            android:layout_marginLeft="10dp"
            android:layout_toRightOf="@id/distance_tv"
            android:text="2 ore 33 min"
            android:textColor="@android:color/white"
            custom:font="roboto_condensed"/>
    </RelativeLayout>

</RelativeLayout>

StationListAdapter.java

import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.text.TextUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.akexorcist.googledirection.DirectionCallback;
import com.akexorcist.googledirection.GoogleDirection;
import com.akexorcist.googledirection.constant.RequestResult;
import com.akexorcist.googledirection.constant.TransportMode;
import com.akexorcist.googledirection.constant.Unit;
import com.akexorcist.googledirection.model.Direction;
import com.akexorcist.googledirection.model.Leg;
import com.bumptech.glide.Glide;
import com.google.android.gms.maps.model.LatLng;

import org.greenrobot.eventbus.EventBus;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import butterknife.Bind;
import butterknife.ButterKnife;
import ro.rompetrol.mobileapp.LocationService;
import ro.rompetrol.mobileapp.R;
import ro.rompetrol.mobileapp.models.StationModel;
import ro.rompetrol.mobileapp.utils.DirectionsHelper;
import rx.Observer;

/**
 * Created by Alex Nitu on 4/14/2016.
 */
public class StationListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    public static final String TAG = StationListAdapter.class.getSimpleName();

    public static final int STATION_ITEM_VIEW = 0;
    public static final int LOADING_ITEM_VIEW = 1;

    public static final String LANGUAGE_ROMANIAN = "ro";

    private Context mContext;
    private int mListItemHeight;

    private List<StationModel> mItems = new ArrayList<>();

    private LatLng mMyLastLocation;

    private boolean mIsLoadingFooterAdded;

    private DirectionsHelper mDirectionsHelper = new DirectionsHelper();
    private Map<StationViewHolder, Observer> mRequestMap = new HashMap<>();

    public StationListAdapter(Context context) {
        mContext = context;
        mMyLastLocation = LocationService.mLastLocation;
    }

    public void setItems(List<StationModel> items) {
        mItems = items;
    }

    public void addAll(Collection<StationModel> items) {
        mItems.addAll(items);
    }

    public void animateTo(List<StationModel> models) {
        applyAndAnimateRemovals(models);
        applyAndAnimateAdditions(models);
        applyAndAnimateMovedItems(models);
    }

    public StationModel removeItem(int position) {
        final StationModel model = mItems.remove(position);
        notifyItemRemoved(position);
        return model;
    }

    public void addItem(int position, StationModel model) {
        mItems.add(position, model);
        notifyItemInserted(position);
    }

    public void moveItem(int fromPosition, int toPosition) {
        final StationModel model = mItems.remove(fromPosition);
        mItems.add(toPosition, model);
        notifyItemMoved(fromPosition, toPosition);
    }

    public void clear() {
        mItems.clear();
        mIsLoadingFooterAdded = false;
        notifyDataSetChanged();
    }

    public void addLoadingFooter() {
        mIsLoadingFooterAdded = true;
        addItem(mItems.size(), new StationModel());
    }

    public void removeLoadingFooter() {
        if (!mIsLoadingFooterAdded) {
            return;
        }
        mIsLoadingFooterAdded = false;

        int position = mItems.size() - 1;
        mItems.remove(position);
        notifyItemRemoved(position);
    }

    public void setListItemHeight(int listItemHeight) {
        mListItemHeight = listItemHeight;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        switch (viewType) {
            case STATION_ITEM_VIEW:
                View itemView = inflater.inflate(R.layout.list_item_station, parent, false);

                RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) itemView.getLayoutParams();
                lp.height = mListItemHeight;

                return new StationViewHolder(itemView);
            case LOADING_ITEM_VIEW:
                itemView = inflater.inflate(R.layout.list_item_loading, parent, false);
                return new LoadingViewHolder(itemView);
        }
        return null;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        switch (holder.getItemViewType()) {
            case STATION_ITEM_VIEW:
                StationModel item = mItems.get(position);

                StationViewHolder svh = (StationViewHolder) holder;
                svh.mStationNameTv.setText(item.getName());
//                svh.mDistanceTv.setText(item.getDistance());
                //holder.mEtaTv.setText("");
                Glide.with(mContext)
                        .load("")
                        .placeholder(R.drawable.ic_station_placeholder)
                        .centerCrop()
                        .into(svh.mStationIv);

                String distance = item.getDistance();
                if (TextUtils.isEmpty(distance)) {
                    requestDistance(item, svh);

                    svh.mDirectionsPb.setVisibility(View.VISIBLE);
                    svh.mDistanceTv.setVisibility(View.INVISIBLE);
                    svh.mEtaTv.setVisibility(View.INVISIBLE);
                } else {
                    svh.mDirectionsPb.setVisibility(View.INVISIBLE);
                    svh.mDistanceTv.setVisibility(View.VISIBLE);
                    svh.mEtaTv.setVisibility(View.VISIBLE);

                    svh.mDistanceTv.setText(distance);
                    svh.mEtaTv.setText(item.getEta());
                }
                break;
            case LOADING_ITEM_VIEW:
                LoadingViewHolder lvh = (LoadingViewHolder) holder;
                break;
        }
    }

    @Override
    public int getItemViewType(int position) {
        return ((position == (mItems.size() - 1)) && mIsLoadingFooterAdded) ? LOADING_ITEM_VIEW : STATION_ITEM_VIEW;
    }

    @Override
    public int getItemCount() {
        return mItems != null ? mItems.size() : 0;
    }

    private void applyAndAnimateRemovals(List<StationModel> newModels) {
        for (int i = mItems.size() - 1; i >= 0; i--) {
            final StationModel model = mItems.get(i);
            if (!newModels.contains(model)) {
                removeItem(i);
            }
        }
    }

    private void applyAndAnimateAdditions(List<StationModel> newModels) {
        for (int i = 0, count = newModels.size(); i < count; i++) {
            final StationModel model = newModels.get(i);
            if (!mItems.contains(model)) {
                addItem(i, model);
            }
        }
    }

    private void applyAndAnimateMovedItems(List<StationModel> newModels) {
        for (int toPosition = newModels.size() - 1; toPosition >= 0; toPosition--) {
            final StationModel model = newModels.get(toPosition);
            final int fromPosition = mItems.indexOf(model);
            if (fromPosition >= 0 && fromPosition != toPosition) {
                moveItem(fromPosition, toPosition);
            }
        }
    }

    private void requestDistance(final StationModel stationModel, final StationViewHolder svh) {
        if (TextUtils.isEmpty(stationModel.getLng()) || TextUtils.isEmpty(stationModel.getLat())) {
            svh.mDistanceTv.setText("-");
            svh.mEtaTv.setText("");
            return;
        }

        final Observer<Direction> observer = new Observer<Direction>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {
                Log.d(TAG, "getDirections error");
                svh.mDistanceTv.setText("-");
                svh.mEtaTv.setText("-");
            }

            @Override
            public void onNext(Direction direction) {
                Log.d(TAG, "getDirections success");
                String status = direction.getStatus();
                String distance = "";
                String eta = "";
                if (status.equals(RequestResult.OK)) {
                    Leg mainLeg = direction.getRouteList().get(0).getLegList().get(0);
                    eta = mainLeg.getDuration().getText();
                    distance = mainLeg.getDistance().getText();
                }
                stationModel.setDistance(distance);
                stationModel.setEta(eta);

                boolean isViewStillVisible = mRequestMap.get(svh) == this;
                if (isViewStillVisible) {
                    svh.mEtaTv.setVisibility(View.VISIBLE);
                    svh.mDistanceTv.setVisibility(View.VISIBLE);
                    svh.mDirectionsPb.setVisibility(View.INVISIBLE);

                    svh.mDistanceTv.setText(!TextUtils.isEmpty(distance) ? distance : "-");
                    svh.mEtaTv.setText(!TextUtils.isEmpty(eta) ? eta : "");
                }
                mRequestMap.remove(svh);
            }
        };

        mRequestMap.put(svh, observer);

        mDirectionsHelper.calculateDistance(new LatLng(44.426767, 26.102538),
                new LatLng(Double.parseDouble(stationModel.getLat()), Double.parseDouble(stationModel.getLng())),
                observer);
    }

    class StationViewHolder extends RecyclerView.ViewHolder {

        UUID mUUID = UUID.randomUUID();

        @Bind(R.id.station_iv) ImageView mStationIv;
        @Bind(R.id.station_name_tv) TextView mStationNameTv;
        @Bind(R.id.direction_progressBar) ProgressBar mDirectionsPb;
        @Bind(R.id.distance_tv) TextView mDistanceTv;
        @Bind(R.id.eta_tv) TextView mEtaTv;

        public StationViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);

            itemView.setOnClickListener(mOnClickListener);
        }

        View.OnClickListener mOnClickListener = new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                EventBus.getDefault().postSticky(mItems.get(getAdapterPosition()));
                mContext.startActivity(new Intent(mContext, StationDetailsActivity.class));
            }
        };

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            StationViewHolder that = (StationViewHolder) o;

            return mUUID != null ? mUUID.equals(that.mUUID) : that.mUUID == null;

        }

        @Override
        public int hashCode() {
            return mUUID != null ? mUUID.hashCode() : 0;
        }
    }

    class LoadingViewHolder extends RecyclerView.ViewHolder {

        View mItemView;

        public LoadingViewHolder(View itemView) {
            super(itemView);
            mItemView = itemView;
        }
    }
}

StationListFragment.java

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.widget.SwipeRefreshLayout;
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 android.widget.ProgressBar;

import java.util.ArrayList;
import java.util.List;

import butterknife.Bind;
import butterknife.ButterKnife;
import ro.rompetrol.mobileapp.BaseFragment;
import ro.rompetrol.mobileapp.R;
import ro.rompetrol.mobileapp.models.StationModel;
import ro.rompetrol.mobileapp.utils.UIUtil;
import rx.functions.Action1;

/**
 * Created by Alex Nitu on 5/13/2016.
 */
public class StationListFragment extends BaseFragment {

    public static final String TAG = StationListFragment.class.getSimpleName();

    public static final String EXTRA_STATION_TYPE_ID = "station_type_id";

    @Bind(R.id.progressBar) ProgressBar mProgressBar;
    @Bind(R.id.swipeRefreshLayout) SwipeRefreshLayout mSwipeRefreshLayout;
    @Bind(R.id.stations_rv) RecyclerView mStationsRv;

    private LinearLayoutManager mLayoutManager;

    private StationListAdapter mAdapter;

    private StationPagerAdapter mVpAdapter;

    private String mStationTypeId;

    private List<StationModel> mItems = new ArrayList<>();


    public static StationListFragment newInstance() {
        StationListFragment fragment = new StationListFragment();
        return fragment;
    }

    public static StationListFragment newInstance(String typeId) {
        Bundle args = new Bundle();
        args.putString(EXTRA_STATION_TYPE_ID, typeId);

        StationListFragment fragment = new StationListFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Bundle args = getArguments();
        if (args != null) {
            mStationTypeId = args.getString(EXTRA_STATION_TYPE_ID);
        }
    }

    //TODO handle no internet loading stuck

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

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        ButterKnife.bind(this, view);

        mLayoutManager = new LinearLayoutManager(getActivity());
        mLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

        mAdapter = new StationListAdapter(getActivity());
        mAdapter.setListItemHeight(getListItemHeight());

        mStationsRv.setHasFixedSize(true);
        mStationsRv.setLayoutManager(mLayoutManager);
        mStationsRv.addOnScrollListener(mRecyclerViewOnScrollListener);
        mStationsRv.setAdapter(mAdapter);

        mSwipeRefreshLayout.setOnRefreshListener(mOnRefreshListener);

        mProgressBar.setVisibility(View.VISIBLE);

        getStations();
    }

    private void getStations() {
        mStationHelper.stations(mStationTypeId, null, new Action1<List<StationModel>>() {
            @Override
            public void call(List<StationModel> stationModels) {
                mProgressBar.setVisibility(View.GONE);
                mSwipeRefreshLayout.setRefreshing(false);
                mItems.addAll(stationModels);
                mAdapter.animateTo(mItems);
            }
        }, new Action1<Throwable>() {
            @Override
            public void call(Throwable throwable) {
                mProgressBar.setVisibility(View.GONE);
                mSwipeRefreshLayout.setRefreshing(false);
            }
        });
    }

    private void loadMoreItems() {
        mAdapter.addLoadingFooter();
        mStationHelper.stations(mStationTypeId, null, new Action1<List<StationModel>>() {
            @Override
            public void call(List<StationModel> stationModels) {
                mAdapter.removeLoadingFooter();
                mItems.addAll(stationModels);
                mAdapter.animateTo(mItems);
            }
        }, new Action1<Throwable>() {
            @Override
            public void call(Throwable throwable) {
                mAdapter.removeLoadingFooter();
                //TODO
            }
        });
    }

    private int getListItemHeight() {
        //Height has to be 1/3 of available space
        //(Total height - (StatusBar height + ActionBar height)) / 3
        return (int) ((UIUtil.getDisplayHeight(getActivity()) - UIUtil.convertDpToPixel(56 + 24)) / 3);
    }

    private RecyclerView.OnScrollListener mRecyclerViewOnScrollListener = new RecyclerView.OnScrollListener() {

        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
        }

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            int visibleItemCount = mLayoutManager.getChildCount();
            int totalItemCount = mLayoutManager.getItemCount();
            int firstVisibleItemPosition = mLayoutManager.findFirstVisibleItemPosition();

            if (mStationHelper.isLoading()) {
                return;
            }
            if (((visibleItemCount + firstVisibleItemPosition) >= totalItemCount)
                    && (firstVisibleItemPosition >= 0)
                    && (totalItemCount >= StationHelper.PAGE_SIZE)) {
                loadMoreItems();
            }
        }
    };

    private SwipeRefreshLayout.OnRefreshListener mOnRefreshListener = new SwipeRefreshLayout.OnRefreshListener() {
        @Override
        public void onRefresh() {
            mItems.clear();
            mAdapter.clear();
            getStations();
        }
    };
}