meinWald/Code Android/meinWald/app/src/main/java/com/example/meinwald/ui/map/MapsFragment.java

package com.example.meinwald.ui.main.map;

import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.meinwald.BuildConfig;
import com.example.meinwald.R;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;

import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;

import static com.example.meinwald.R.layout.fragment_map;

public class MapsFragment extends Fragment implements OnMapReadyCallback {

    /**
     * ______________________________________________________________________________________________
     * MAPS
     */
    // A default location and default zoom to use when location permission is not granted.
    private static final LatLng M_DEFAULT_LOCATION = new LatLng(49.5, 11.0); //Nuremberg
    private static final int DEFAULT_ZOOM = 1;
    private static final float MAX_ZOOM = (float) 20.0;


    private static final int PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1;
    private static final String TAG = MapsFragment.class.getSimpleName();
    // Keys for storing activity state.
    private static final String KEY_CAMERA_POSITION = "camera_position";
    private static final String KEY_LOCATION = "location";

    private GoogleMap mMap;
    private CameraPosition mCameraPosition;

    /**
     * The entry point to the Fused Location Provider.
     */
    private FusedLocationProviderClient mFusedLocationProviderClient;
    private boolean mLocationPermissionGranted;
    /**
     * The geographical location where the device is currently located.
     * That is the last-known location retrieved by the Fused Location Provider.
     */
    private Location mLastKnownLocation;

    /**
     * Is called when the MapsFragment view is created. Initializes all service connections, the location client and map itself.
     * @param inflater Calling LayoutInflater
     * @param container ViewGroup
     * @param savedInstanceState Applications savedInstanceState
     * @return
     */
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        //get view to inflate
        View root = inflater.inflate(fragment_map, container, false);

        //display map fragment
        SupportMapFragment mapFragment = new SupportMapFragment();
        FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
        transaction.add(R.id.map, mapFragment).commit();

        //construct a FusedLocationProviderClient.
        mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(getActivity());

        //wait for map is ready
        mapFragment.getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap googleMap) {
                //save map instance locally
                mMap = googleMap;
                //set max zoom level
                mMap.setMaxZoomPreference(MAX_ZOOM);

                //retrieve saved instance state
                mCameraPosition  = parseCameraPosition(PreferenceManager.getDefaultSharedPreferences(getContext()).getString(KEY_CAMERA_POSITION, new CameraPosition(new LatLng(45.0,11.0), (float) 1.0, (float) 0.0,(float) 0.0).toString()));
                mLastKnownLocation  = new Location(PreferenceManager.getDefaultSharedPreferences(getContext()).getString(KEY_LOCATION, new LatLng(45.0,11.0).toString()));
                mCameraPosition  = parseCameraPosition(PreferenceManager.getDefaultSharedPreferences(getContext()).getString(KEY_CAMERA_POSITION, new CameraPosition(new LatLng(45.0,11.0), (float) 1.0, (float) 0.0,(float) 0.0).toString()));

                //move camera to last position
                mMap.moveCamera(CameraUpdateFactory.newCameraPosition(mCameraPosition));

                //get permission
                getLocationPermission();

                //turn on the My Location layer and the related control on the map.
                updateLocationUI();

                // Get the current location of the device and set the position of the map.
                getDeviceLocation();
            }
        });

        return root;
    }

    @Override
    public void onPause() {

        //save current location and camera position to shared preferences
        if (mMap.getCameraPosition() != null && mLastKnownLocation != null) {
            PreferenceManager.getDefaultSharedPreferences(getContext()).edit().putString(KEY_CAMERA_POSITION, mMap.getCameraPosition().toString()).commit();
            PreferenceManager.getDefaultSharedPreferences(getContext()).edit().putString(KEY_LOCATION, mLastKnownLocation.toString()).commit();
        }

        super.onPause();
    }

    @Override
    public void onResume() {
        super.onResume();
    }

    /**
     * Parses a string and creates a new CameraPosition from it.
     * Use CameraPosition.toString() to get corresponding string.
     * @param posString String which includes a camera position.
     * @return The parsed position of type CameraPosition.
     */
    private CameraPosition parseCameraPosition(String posString) {
        //parse string from shared preferences (CameraPosition.toString())
        String[] stringsplit = posString.split(" ");
        float lat = Float.parseFloat(stringsplit[1].split(",")[0].substring(1));
        float lng = Float.parseFloat(stringsplit[1].split(",")[1].substring(0,stringsplit[1].split(",")[1].length()-1));
        float zoom = Float.parseFloat(stringsplit[2].split("=")[1].substring(0,stringsplit[2].split("=")[1].length()-1));
        float tilt = Float.parseFloat(stringsplit[3].split("=")[1].substring(0,stringsplit[3].split("=")[1].length()-1));
        float bearing = Float.parseFloat(stringsplit[4].split("=")[1].substring(0,stringsplit[4].split("=")[1].length()-1));

        return new CameraPosition(new LatLng(lat,lng),zoom,tilt,bearing);
    }

    /**
     * Request location permission, so that we can get the location of the device.
     * The result of the permission request is handled by a callback,
     * onRequestPermissionsResult.
     *
     */
    private void getLocationPermission() {
        if (ContextCompat.checkSelfPermission(getActivity().getApplicationContext(),
                android.Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            mLocationPermissionGranted = true;
        } else {
            ActivityCompat.requestPermissions(getActivity(),
                    new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
                    PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
        }
    }

    /**
     * DOCU ME!
     * TOOD: What are grant results etc for?
     * @param requestCode
     * @param permissions
     * @param grantResults
     */
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
    {
        mLocationPermissionGranted = false;
        switch (requestCode) {
            case PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                {
                    updateLocationUI();
                    mLocationPermissionGranted = true;
                }
            }
        }
    }

    /**
     * Get the best and most recent location of the device, which may be null in rare
     * cases when a location is not available.
     *
     */
    private void getDeviceLocation() {
        try {
            if (mLocationPermissionGranted) {
                Task<Location> locationResult = mFusedLocationProviderClient.getLastLocation();
                locationResult.addOnCompleteListener(getActivity(), new OnCompleteListener<Location>() {
                    @Override
                    public void onComplete(@NonNull Task<Location> task) {
                        if (task.isSuccessful()) {
                            // Set the last known position to the current location of the device.
                            mLastKnownLocation = task.getResult();
                            if (BuildConfig.DEBUG) {

                                if (task.getResult() != null)
                                {
                                    Log.d(TAG, "getDeviceLocation " + task.getResult().toString());

                                }
                            }
                        } else {
                            if (BuildConfig.DEBUG) {
                                Log.d(TAG, "Current location is null. Using defaults.");
                                Log.e(TAG, "Exception: %s", task.getException());
                            }
                            mMap.moveCamera(CameraUpdateFactory
                                    .newLatLngZoom(M_DEFAULT_LOCATION, DEFAULT_ZOOM));
                            //mMap.getUiSettings().setMyLocationButtonEnabled(false);
                            if (BuildConfig.DEBUG) {
                                Log.d(TAG, "getDeviceLocation: task not successful");
                            }
                        }
                    }
                });
            }
        } catch (SecurityException e)  {
            if (BuildConfig.DEBUG) {
                Log.e(TAG, "Exception occurred: ");
                e.printStackTrace();
            }
        }
    }

    private void updateLocationUI() {
        if (mMap == null) {
            if (BuildConfig.DEBUG) {
                Log.d(TAG, "Permission: Map not ready!");
            }
            return;
        }
        try {
            if (mLocationPermissionGranted) {
                mMap.setMyLocationEnabled(true);
                mMap.getUiSettings().setMapToolbarEnabled(true);
                mMap.getUiSettings().setMyLocationButtonEnabled(true);
                mMap.getUiSettings().setCompassEnabled(true);
                mMap.getUiSettings().setZoomControlsEnabled(true);

                if (BuildConfig.DEBUG) {
                    Log.d(TAG, "Permission: Granted!");
                }
            } else {
                mMap.setMyLocationEnabled(false);
                mMap.getUiSettings().setMyLocationButtonEnabled(false);
                mMap.getUiSettings().setZoomControlsEnabled(false);
                mMap.getUiSettings().setCompassEnabled(false);
                mMap.getUiSettings().setMapToolbarEnabled(false);
                mLastKnownLocation = null;

                if (BuildConfig.DEBUG) {
                    Log.d(TAG, "Permission: Denied!");
                }

                getLocationPermission();
            }
        } catch (SecurityException e)  {
            if (BuildConfig.DEBUG) {
                Log.e(TAG, "Exception occurred: ");
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) { }
}