/**
 * Copyright (c) 2021 LEAP Encryption Access Project and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package se.leap.bitmaskclient.base.fragments;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.widget.AppCompatButton;
import androidx.appcompat.widget.AppCompatTextView;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.lang.ref.WeakReference;
import java.util.List;
import java.util.Observable;
import java.util.Observer;

import de.blinkt.openvpn.core.VpnStatus;
import se.leap.bitmaskclient.R;
import se.leap.bitmaskclient.base.MainActivity;
import se.leap.bitmaskclient.base.models.Location;
import se.leap.bitmaskclient.base.utils.PreferenceHelper;
import se.leap.bitmaskclient.base.views.LocationIndicator;
import se.leap.bitmaskclient.eip.EipCommand;
import se.leap.bitmaskclient.eip.EipStatus;
import se.leap.bitmaskclient.eip.GatewaysManager;

import static android.content.Context.MODE_PRIVATE;
import static android.view.View.INVISIBLE;
import static android.view.View.VISIBLE;
import static se.leap.bitmaskclient.base.MainActivity.ACTION_SHOW_VPN_FRAGMENT;
import static se.leap.bitmaskclient.base.models.Constants.SHARED_PREFERENCES;
import static se.leap.bitmaskclient.base.models.Constants.USE_BRIDGES;

interface LocationListSelectionListener {
    void onLocationSelected(String name);
}

public class GatewaySelectionFragment extends Fragment implements SharedPreferences.OnSharedPreferenceChangeListener, Observer, LocationListSelectionListener {

    private static final String TAG = GatewaySelectionFragment.class.getSimpleName();


    private RecyclerView recyclerView;
    private LocationListAdapter locationListAdapter;
    private AppCompatTextView currentLocationDescription;
    private AppCompatTextView currentLocation;
    private AppCompatButton autoSelectionButton;
    private GatewaysManager gatewaysManager;
    private SharedPreferences preferences;
    private EipStatus eipStatus;

    public GatewaySelectionFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        gatewaysManager = new GatewaysManager(getContext());
        preferences = getContext().getSharedPreferences(SHARED_PREFERENCES, MODE_PRIVATE);
        eipStatus = EipStatus.getInstance();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.f_gateway_selection, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        initRecyclerView();
        initAutoSelectionButton();
        initCurrentLocationInfoPanel();
        eipStatus.addObserver(this);
        preferences.registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        preferences.unregisterOnSharedPreferenceChangeListener(this);
        eipStatus.deleteObserver(this);
    }



    private void initRecyclerView() {
        recyclerView = getActivity().findViewById(R.id.gatewaySelection_list);
        recyclerView.setHasFixedSize(true);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this.getContext());
        recyclerView.setLayoutManager(layoutManager);
        locationListAdapter = new LocationListAdapter(gatewaysManager.getGatewayLocations(), this);
        recyclerView.setAdapter(locationListAdapter);
        recyclerView.setVisibility(VISIBLE);
    }

    private void initAutoSelectionButton() {
        autoSelectionButton = getActivity().findViewById(R.id.automatic_gateway_selection_btn);
        autoSelectionButton.setOnClickListener(v -> {
            startEipService(null);
        });
    }

    private void initCurrentLocationInfoPanel() {
        currentLocationDescription = getActivity().findViewById(R.id.current_location_description);
        currentLocation = getActivity().findViewById(R.id.current_location);
        setLocationDescription(EipStatus.getInstance(), PreferenceHelper.getPreferredCity(getContext()));
    }

    private void setLocationDescription(EipStatus eipStatus, String preferredCity) {
        if (eipStatus.isConnected()) {
            currentLocationDescription.setText(preferredCity == null ?
                    R.string.gateway_selection_automatic_location :
                    R.string.gateway_selection_manual_location);
            currentLocation.setText(VpnStatus.getLastConnectedVpnName());
            currentLocation.setVisibility(VISIBLE);
        } else if (preferredCity == null) {
            currentLocationDescription.setText(R.string.gateway_selection_automatic_not_connected);
            currentLocation.setVisibility(INVISIBLE);
        } else {
            currentLocationDescription.setText(R.string.gateway_selection_manual_not_connected);
            currentLocation.setText(preferredCity);
            currentLocation.setVisibility(VISIBLE);
        }
    }

    protected void startEipService(String preferredCity) {
        new Thread(() -> {
            PreferenceHelper.setPreferredCity(getContext(), preferredCity);
            EipCommand.startVPN(getContext(), false);
            Intent intent = new Intent(getContext(), MainActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);
            intent.setAction(ACTION_SHOW_VPN_FRAGMENT);
            startActivity(intent);
        }).start();
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if (USE_BRIDGES.equals(key)) {
            locationListAdapter.updateData(gatewaysManager.getGatewayLocations());
        }
    }

    @Override
    public void onLocationSelected(String name) {
        startEipService(name);
    }

    @Override
    public void update(Observable o, Object arg) {
        if (o instanceof EipStatus) {
            Activity activity = getActivity();
            if (activity != null) {
                activity.runOnUiThread(() -> setLocationDescription((EipStatus) o, PreferenceHelper.getPreferredCity(getContext())));
            }
        }
    }


    static class LocationListAdapter extends RecyclerView.Adapter<LocationListAdapter.ViewHolder> {
        private static final String TAG = LocationListAdapter.class.getSimpleName();
        private List<Location> values;
        private final WeakReference<LocationListSelectionListener> callback;

        static class ViewHolder extends RecyclerView.ViewHolder {
            public AppCompatTextView locationLabel;
            public LocationIndicator locationIndicator;
            public View layout;

            public ViewHolder(View v) {
                super(v);
                layout = v;
                locationLabel = v.findViewById(R.id.location);
                locationIndicator = v.findViewById(R.id.quality);
            }
        }

        public void add(int position, Location item) {
            values.add(position, item);
            notifyItemInserted(position);
        }

        public void remove(int position) {
            values.remove(position);
            notifyItemRemoved(position);
        }

        public void updateData(List<Location> data) {
            values = data;
            notifyDataSetChanged();
        }

        public LocationListAdapter(List<Location> data, LocationListSelectionListener selectionListener) {
            values = data;
            callback = new WeakReference<>(selectionListener);
        }

        @NonNull
        @Override
        public LocationListAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
                                                                 int viewType) {
            LayoutInflater inflater = LayoutInflater.from(
                    parent.getContext());
            View v = inflater.inflate(R.layout.v_select_text_list_item, parent, false);
            return new ViewHolder(v);
        }

        // Replace the contents of a view (invoked by the layout manager)
        @Override
        public void onBindViewHolder(ViewHolder holder, final int position) {
            final Location location = values.get(position);
            holder.locationLabel.setText(location.name);
            holder.layout.setOnClickListener(v -> {
                Log.d(TAG, "view at position clicked: " + position);
                LocationListSelectionListener listener = callback.get();
                if (listener != null) {
                    listener.onLocationSelected(location.name);
                }
            });
            holder.locationIndicator.setLoad(GatewaysManager.Load.getLoadByValue(location.averageLoad));
        }


        @Override
        public int getItemCount() {
            return values.size();
        }
    }

}