path: root/app/src/main/java/de/danoeh/antennapod/preferences/PreferenceController.java

package de.danoeh.antennapod.preferences;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.TimePickerDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.content.res.Resources;
import android.net.Uri;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiManager;
import android.os.Build;
import android.preference.CheckBoxPreference;
import android.preference.EditTextPreference;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceManager;
import android.preference.PreferenceScreen;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;
import android.text.Editable;
import android.text.Html;
import android.text.TextWatcher;
import android.text.format.DateFormat;
import android.util.Log;
import android.widget.EditText;
import android.widget.Toast;

import com.afollestad.materialdialogs.MaterialDialog;

import org.apache.commons.lang3.ArrayUtils;

import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.concurrent.TimeUnit;

import de.danoeh.antennapod.CrashReportWriter;
import de.danoeh.antennapod.R;
import de.danoeh.antennapod.activity.AboutActivity;
import de.danoeh.antennapod.activity.DirectoryChooserActivity;
import de.danoeh.antennapod.activity.MainActivity;
import de.danoeh.antennapod.activity.PreferenceActivity;
import de.danoeh.antennapod.activity.PreferenceActivityGingerbread;
import de.danoeh.antennapod.asynctask.OpmlExportWorker;
import de.danoeh.antennapod.core.preferences.GpodnetPreferences;
import de.danoeh.antennapod.core.preferences.UserPreferences;
import de.danoeh.antennapod.core.util.Converter;
import de.danoeh.antennapod.core.util.StorageUtils;
import de.danoeh.antennapod.core.util.flattr.FlattrUtils;
import de.danoeh.antennapod.dialog.AuthenticationDialog;
import de.danoeh.antennapod.dialog.AutoFlattrPreferenceDialog;
import de.danoeh.antennapod.dialog.GpodnetSetHostnameDialog;
import de.danoeh.antennapod.dialog.VariableSpeedDialog;

/**
 * Sets up a preference UI that lets the user change user preferences.
 */

public class PreferenceController implements SharedPreferences.OnSharedPreferenceChangeListener {

    private static final String TAG = "PreferenceController";

    public static final String PREF_FLATTR_SETTINGS = "prefFlattrSettings";
    public static final String PREF_FLATTR_AUTH = "pref_flattr_authenticate";
    public static final String PREF_FLATTR_REVOKE = "prefRevokeAccess";
    public static final String PREF_AUTO_FLATTR_PREFS = "prefAutoFlattrPrefs";
    public static final String PREF_OPML_EXPORT = "prefOpmlExport";
    public static final String PREF_ABOUT = "prefAbout";
    public static final String PREF_CHOOSE_DATA_DIR = "prefChooseDataDir";
    public static final String AUTO_DL_PREF_SCREEN = "prefAutoDownloadSettings";
    public static final String PREF_PLAYBACK_SPEED_LAUNCHER = "prefPlaybackSpeedLauncher";
    public static final String PREF_GPODNET_LOGIN = "pref_gpodnet_authenticate";
    public static final String PREF_GPODNET_SETLOGIN_INFORMATION = "pref_gpodnet_setlogin_information";
    public static final String PREF_GPODNET_LOGOUT = "pref_gpodnet_logout";
    public static final String PREF_GPODNET_HOSTNAME = "pref_gpodnet_hostname";
    public static final String PREF_EXPANDED_NOTIFICATION = "prefExpandNotify";

    private final PreferenceUI ui;

    private CheckBoxPreference[] selectedNetworks;

    private static final String[] EXTERNAL_STORAGE_PERMISSIONS = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE };
    private static final int PERMISSION_REQUEST_EXTERNAL_STORAGE = 41;

    public PreferenceController(PreferenceUI ui) {
        this.ui = ui;
        PreferenceManager.getDefaultSharedPreferences(ui.getActivity().getApplicationContext())
            .registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if(key.equals(UserPreferences.PREF_SONIC)) {
            CheckBoxPreference prefSonic = (CheckBoxPreference) ui.findPreference(UserPreferences.PREF_SONIC);
            if(prefSonic != null) {
                prefSonic.setChecked(sharedPreferences.getBoolean(UserPreferences.PREF_SONIC, false));
            }
        }
    }

    /**
     * Returns the preference activity that should be used on this device.
     *
     * @return PreferenceActivity if the API level is greater than 10, PreferenceActivityGingerbread otherwise.
     */
    public static Class getPreferenceActivity() {
        if (Build.VERSION.SDK_INT > 10) {
            return PreferenceActivity.class;
        } else {
            return PreferenceActivityGingerbread.class;
        }
    }

    public void onCreate() {
        final Activity activity = ui.getActivity();

        if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
            // disable expanded notification option on unsupported android versions
            ui.findPreference(PreferenceController.PREF_EXPANDED_NOTIFICATION).setEnabled(false);
            ui.findPreference(PreferenceController.PREF_EXPANDED_NOTIFICATION).setOnPreferenceClickListener(
                    preference -> {
                        Toast toast = Toast.makeText(activity,
                                R.string.pref_expand_notify_unsupport_toast, Toast.LENGTH_SHORT);
                        toast.show();
                        return true;
                    }
            );
        }
        ui.findPreference(PreferenceController.PREF_FLATTR_REVOKE).setOnPreferenceClickListener(
                preference -> {
                    FlattrUtils.revokeAccessToken(activity);
                    checkItemVisibility();
                    return true;
                }
        );
        ui.findPreference(PreferenceController.PREF_ABOUT).setOnPreferenceClickListener(
                preference -> {
                    activity.startActivity(new Intent(activity, AboutActivity.class));
                    return true;
                }
        );
        ui.findPreference(PreferenceController.PREF_OPML_EXPORT).setOnPreferenceClickListener(
                preference -> {
                    new OpmlExportWorker(activity).executeAsync();
                    return true;
                }
        );
        ui.findPreference(PreferenceController.PREF_CHOOSE_DATA_DIR).setOnPreferenceClickListener(
                preference -> {
                    if (Build.VERSION_CODES.KITKAT <= Build.VERSION.SDK_INT &&
                            Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP_MR1) {
                        showChooseDataFolderDialog();
                    } else {
                        int readPermission = ActivityCompat.checkSelfPermission(
                                activity, Manifest.permission.READ_EXTERNAL_STORAGE);
                        int writePermission = ActivityCompat.checkSelfPermission(
                                activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);
                        if (readPermission == PackageManager.PERMISSION_GRANTED &&
                                writePermission == PackageManager.PERMISSION_GRANTED) {
                            openDirectoryChooser();
                        } else {
                            requestPermission();
                        }
                    }
                    return true;
                }
        );
        ui.findPreference(PreferenceController.PREF_CHOOSE_DATA_DIR)
                .setOnPreferenceClickListener(
                        new Preference.OnPreferenceClickListener() {
                            @Override
                            public boolean onPreferenceClick(Preference preference) {
                                if (Build.VERSION.SDK_INT >= 19) {
                                    showChooseDataFolderDialog();
                                } else {
                                    Intent intent = new Intent(activity, DirectoryChooserActivity.class);
                                    activity.startActivityForResult(intent,
                                            DirectoryChooserActivity.RESULT_CODE_DIR_SELECTED);
                                }
                                return true;
                            }
                }
        );
        ui.findPreference(UserPreferences.PREF_THEME)
                .setOnPreferenceChangeListener(
                        (preference, newValue) -> {
                            Intent i = new Intent(activity, MainActivity.class);
                            i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK
                                    | Intent.FLAG_ACTIVITY_NEW_TASK);
                            activity.finish();
                            activity.startActivity(i);
                            return true;
                        }
                );
        ui.findPreference(UserPreferences.PREF_HIDDEN_DRAWER_ITEMS)
                .setOnPreferenceClickListener(preference -> {
                    showDrawerPreferencesDialog();
                    return true;
                });

        ui.findPreference(UserPreferences.PREF_UPDATE_INTERVAL)
                .setOnPreferenceClickListener(preference -> {
                    showUpdateIntervalTimePreferencesDialog();
                    return true;
                });

        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL).setOnPreferenceChangeListener(
                (preference, newValue) -> {
                    if (newValue instanceof Boolean) {
                        boolean enabled = (Boolean) newValue;
                        ui.findPreference(UserPreferences.PREF_EPISODE_CACHE_SIZE).setEnabled(enabled);
                        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL_ON_BATTERY).setEnabled(enabled);
                        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL_WIFI_FILTER).setEnabled(enabled);
                        setSelectedNetworksEnabled(enabled && UserPreferences.isEnableAutodownloadWifiFilter());
                    }
                    return true;
                });
        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL_WIFI_FILTER)
                .setOnPreferenceChangeListener(
                        (preference, newValue) -> {
                            if (newValue instanceof Boolean) {
                                setSelectedNetworksEnabled((Boolean) newValue);
                                return true;
                            } else {
                                return false;
                            }
                        }
                );
        ui.findPreference(UserPreferences.PREF_PARALLEL_DOWNLOADS)
                .setOnPreferenceChangeListener(
                        (preference, o) -> {
                            if (o instanceof String) {
                                try {
                                    int value = Integer.valueOf((String) o);
                                    if (1 <= value && value <= 50) {
                                        setParallelDownloadsText(value);
                                        return true;
                                    }
                                } catch (NumberFormatException e) {
                                    return false;
                                }
                            }
                            return false;
                        }
                );
        // validate and set correct value: number of downloads between 1 and 50 (inclusive)
        final EditText ev = ((EditTextPreference) ui.findPreference(UserPreferences.PREF_PARALLEL_DOWNLOADS)).getEditText();
        ev.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
            }

            @Override
            public void afterTextChanged(Editable s) {
                if (s.length() > 0) {
                    try {
                        int value = Integer.valueOf(s.toString());
                        if (value <= 0) {
                            ev.setText("1");
                        } else if (value > 50) {
                            ev.setText("50");
                        }
                    } catch (NumberFormatException e) {
                        ev.setText("6");
                    }
                    ev.setSelection(ev.getText().length());
                }
            }
        });
        ui.findPreference(UserPreferences.PREF_EPISODE_CACHE_SIZE)
                .setOnPreferenceChangeListener(
                        (preference, o) -> {
                            if (o instanceof String) {
                                setEpisodeCacheSizeText(UserPreferences.readEpisodeCacheSize((String) o));
                            }
                            return true;
                        }
                );
        ui.findPreference(PreferenceController.PREF_PLAYBACK_SPEED_LAUNCHER)
                .setOnPreferenceClickListener(preference -> {
                    VariableSpeedDialog.showDialog(activity);
                    return true;
                });
        ui.findPreference(PreferenceController.PREF_GPODNET_SETLOGIN_INFORMATION)
                .setOnPreferenceClickListener(preference -> {
                    AuthenticationDialog dialog = new AuthenticationDialog(activity,
                            R.string.pref_gpodnet_setlogin_information_title, false, false, GpodnetPreferences.getUsername(),
                            null) {

                        @Override
                        protected void onConfirmed(String username, String password, boolean saveUsernamePassword) {
                            GpodnetPreferences.setPassword(password);
                        }
                    };
                    dialog.show();
                    return true;
                });
        ui.findPreference(PreferenceController.PREF_GPODNET_LOGOUT).setOnPreferenceClickListener(
                preference -> {
                    GpodnetPreferences.logout();
                    Toast toast = Toast.makeText(activity, R.string.pref_gpodnet_logout_toast, Toast.LENGTH_SHORT);
                    toast.show();
                    updateGpodnetPreferenceScreen();
                    return true;
                });
        ui.findPreference(PreferenceController.PREF_GPODNET_HOSTNAME).setOnPreferenceClickListener(
                preference -> {
                    GpodnetSetHostnameDialog.createDialog(activity).setOnDismissListener(dialog -> updateGpodnetPreferenceScreen());
                    return true;
                });

        ui.findPreference(PreferenceController.PREF_AUTO_FLATTR_PREFS)
                .setOnPreferenceClickListener(preference -> {
                    AutoFlattrPreferenceDialog.newAutoFlattrPreferenceDialog(activity,
                            new AutoFlattrPreferenceDialog.AutoFlattrPreferenceDialogInterface() {
                                @Override
                                public void onCancelled() {

                                }

                                @Override
                                public void onConfirmed(boolean autoFlattrEnabled, float autoFlattrValue) {
                                    UserPreferences.setAutoFlattrSettings(autoFlattrEnabled, autoFlattrValue);
                                    checkItemVisibility();
                                }
                            });
                    return true;
                });
        ui.findPreference(UserPreferences.PREF_IMAGE_CACHE_SIZE).setOnPreferenceChangeListener(
                (preference, o) -> {
                    if (o instanceof String) {
                        int newValue = Integer.valueOf((String) o) * 1024 * 1024;
                        if (newValue != UserPreferences.getImageCacheSize()) {
                            AlertDialog.Builder dialog = new AlertDialog.Builder(ui.getActivity());
                            dialog.setTitle(android.R.string.dialog_alert_title);
                            dialog.setMessage(R.string.pref_restart_required);
                            dialog.setPositiveButton(android.R.string.ok, null);
                            dialog.show();
                        }
                        return true;
                    }
                    return false;
                }
        );
        ui.findPreference("prefSendCrashReport").setOnPreferenceClickListener(preference -> {
            Intent emailIntent = new Intent(Intent.ACTION_SEND);
            emailIntent.setType("text/plain");
            emailIntent.putExtra(Intent.EXTRA_EMAIL, new String[]{"Martin.Fietz@gmail.com"});
            emailIntent.putExtra(Intent.EXTRA_SUBJECT, "AntennaPod Crash Report");
            emailIntent.putExtra(Intent.EXTRA_TEXT, "Please describe what you were doing when the app crashed");
            // the attachment
            emailIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(CrashReportWriter.getFile()));
            String intentTitle = ui.getActivity().getString(R.string.send_email);
            ui.getActivity().startActivity(Intent.createChooser(emailIntent, intentTitle));
            return true;
        });
        buildEpisodeCleanupPreference();
        buildSmartMarkAsPlayedPreference();
        buildAutodownloadSelectedNetworsPreference();
        setSelectedNetworksEnabled(UserPreferences.isEnableAutodownloadWifiFilter());
    }

    public void onResume() {
        checkItemVisibility();
        setUpdateIntervalText();
        setParallelDownloadsText(UserPreferences.getParallelDownloads());
        setEpisodeCacheSizeText(UserPreferences.getEpisodeCacheSize());
        setDataFolderText();
        updateGpodnetPreferenceScreen();
    }

    @SuppressLint("NewApi")
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == Activity.RESULT_OK &&
                requestCode == DirectoryChooserActivity.RESULT_CODE_DIR_SELECTED) {
            String dir = data.getStringExtra(DirectoryChooserActivity.RESULT_SELECTED_DIR);

            File path = new File(dir);
            String message = null;
            final Context context= ui.getActivity().getApplicationContext();
            if(!path.exists()) {
                message = String.format(context.getString(R.string.folder_does_not_exist_error), dir);
            } else if(!path.canRead()) {
                message = String.format(context.getString(R.string.folder_not_readable_error), dir);
            } else if(!path.canWrite()) {
                message = String.format(context.getString(R.string.folder_not_writable_error), dir);
            }

            if(message == null) {
                Log.d(TAG, "Setting data folder: " + dir);
                UserPreferences.setDataFolder(dir);
                setDataFolderText();
            } else {
                AlertDialog.Builder ab = new AlertDialog.Builder(ui.getActivity());
                ab.setMessage(message);
                ab.setPositiveButton(android.R.string.ok, null);
                ab.show();
            }
        }
    }


    private void updateGpodnetPreferenceScreen() {
        final boolean loggedIn = GpodnetPreferences.loggedIn();
        ui.findPreference(PreferenceController.PREF_GPODNET_LOGIN).setEnabled(!loggedIn);
        ui.findPreference(PreferenceController.PREF_GPODNET_SETLOGIN_INFORMATION).setEnabled(loggedIn);
        ui.findPreference(PreferenceController.PREF_GPODNET_LOGOUT).setEnabled(loggedIn);
        ui.findPreference(PreferenceController.PREF_GPODNET_HOSTNAME).setSummary(GpodnetPreferences.getHostname());
    }

    private String[] getUpdateIntervalEntries(final String[] values) {
        final Resources res = ui.getActivity().getResources();
        String[] entries = new String[values.length];
        for (int x = 0; x < values.length; x++) {
            Integer v = Integer.parseInt(values[x]);
            switch (v) {
                case 0:
                    entries[x] = res.getString(R.string.pref_update_interval_hours_manual);
                    break;
                case 1:
                    entries[x] = v + " " + res.getString(R.string.pref_update_interval_hours_singular);
                    break;
                default:
                    entries[x] = v + " " + res.getString(R.string.pref_update_interval_hours_plural);
                    break;

            }
        }
        return entries;
    }

    private void buildEpisodeCleanupPreference() {
        final Resources res = ui.getActivity().getResources();

        ListPreference pref = (ListPreference) ui.findPreference(UserPreferences.PREF_EPISODE_CLEANUP);
        String[] values = res.getStringArray(
                R.array.episode_cleanup_values);
        String[] entries = new String[values.length];
        for (int x = 0; x < values.length; x++) {
            int v = Integer.parseInt(values[x]);
            if (v == UserPreferences.EPISODE_CLEANUP_QUEUE) {
                entries[x] = res.getString(R.string.episode_cleanup_queue_removal);
            } else if (v == UserPreferences.EPISODE_CLEANUP_NULL){
                entries[x] = res.getString(R.string.episode_cleanup_never);
            } else if (v == 0) {
                entries[x] = res.getString(R.string.episode_cleanup_after_listening);
            } else {
                entries[x] = res.getQuantityString(R.plurals.episode_cleanup_days_after_listening, v, v);
            }
        }
        pref.setEntries(entries);
    }

    private void buildSmartMarkAsPlayedPreference() {
        final Resources res = ui.getActivity().getResources();

        ListPreference pref = (ListPreference) ui.findPreference(UserPreferences.PREF_SMART_MARK_AS_PLAYED_SECS);
        String[] values = res.getStringArray(R.array.smart_mark_as_played_values);
        String[] entries = new String[values.length];
        for (int x = 0; x < values.length; x++) {
            if(x == 0) {
                entries[x] = res.getString(R.string.pref_smart_mark_as_played_disabled);
            } else {
                Integer v = Integer.parseInt(values[x]);
                if(v < 60) {
                    entries[x] = res.getQuantityString(R.plurals.time_seconds_quantified, v, v);
                } else {
                    v /= 60;
                    entries[x] = res.getQuantityString(R.plurals.time_minutes_quantified, v, v);
                }
            }
        }
        pref.setEntries(entries);
    }

    private void setSelectedNetworksEnabled(boolean b) {
        if (selectedNetworks != null) {
            for (Preference p : selectedNetworks) {
                p.setEnabled(b);
            }
        }
    }

    @SuppressWarnings("deprecation")
    private void checkItemVisibility() {
        boolean hasFlattrToken = FlattrUtils.hasToken();
        ui.findPreference(PreferenceController.PREF_FLATTR_SETTINGS).setEnabled(FlattrUtils.hasAPICredentials());
        ui.findPreference(PreferenceController.PREF_FLATTR_AUTH).setEnabled(!hasFlattrToken);
        ui.findPreference(PreferenceController.PREF_FLATTR_REVOKE).setEnabled(hasFlattrToken);
        ui.findPreference(PreferenceController.PREF_AUTO_FLATTR_PREFS).setEnabled(hasFlattrToken);

        boolean autoDownload = UserPreferences.isEnableAutodownload();
        ui.findPreference(UserPreferences.PREF_EPISODE_CACHE_SIZE).setEnabled(autoDownload);
        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL_ON_BATTERY).setEnabled(autoDownload);
        ui.findPreference(UserPreferences.PREF_ENABLE_AUTODL_WIFI_FILTER).setEnabled(autoDownload);
        setSelectedNetworksEnabled(autoDownload && UserPreferences.isEnableAutodownloadWifiFilter());

        ui.findPreference("prefSendCrashReport").setEnabled(CrashReportWriter.getFile().exists());

        if (Build.VERSION.SDK_INT >= 16) {
            ui.findPreference(UserPreferences.PREF_SONIC).setEnabled(true);
        } else {
            Preference prefSonic = ui.findPreference(UserPreferences.PREF_SONIC);
            prefSonic.setSummary("[Android 4.1+]\n" + prefSonic.getSummary());
        }
    }

    private void setUpdateIntervalText() {
        Context context = ui.getActivity().getApplicationContext();
        String val;
        long interval = UserPreferences.getUpdateInterval();
        if(interval > 0) {
            int hours = (int) TimeUnit.MILLISECONDS.toHours(interval);
            String hoursStr = context.getResources().getQuantityString(R.plurals.time_hours_quantified, hours, hours);
            val = String.format(context.getString(R.string.pref_autoUpdateIntervallOrTime_every), hoursStr);
        } else {
            int[] timeOfDay = UserPreferences.getUpdateTimeOfDay();
            if(timeOfDay.length == 2) {
                Calendar cal = new GregorianCalendar();
                cal.set(Calendar.HOUR_OF_DAY, timeOfDay[0]);
                cal.set(Calendar.MINUTE, timeOfDay[1]);
                String timeOfDayStr = DateFormat.getTimeFormat(context).format(cal.getTime());
                val = String.format(context.getString(R.string.pref_autoUpdateIntervallOrTime_at),
                        timeOfDayStr);
            } else {
                val = context.getString(R.string.pref_smart_mark_as_played_disabled);
            }
        }
        String summary = context.getString(R.string.pref_autoUpdateIntervallOrTime_sum) + "\n"
                + String.format(context.getString(R.string.pref_current_value), val);
        ui.findPreference(UserPreferences.PREF_UPDATE_INTERVAL).setSummary(summary);
    }

    private void setParallelDownloadsText(int downloads) {
        final Resources res = ui.getActivity().getResources();

        String s = Integer.toString(downloads)
                    + res.getString(R.string.parallel_downloads_suffix);
        ui.findPreference(UserPreferences.PREF_PARALLEL_DOWNLOADS).setSummary(s);
    }

    private void setEpisodeCacheSizeText(int cacheSize) {
        final Resources res = ui.getActivity().getResources();

        String s;
        if (cacheSize == res.getInteger(
                R.integer.episode_cache_size_unlimited)) {
            s = res.getString(R.string.pref_episode_cache_unlimited);
        } else {
            s = Integer.toString(cacheSize)
                    + res.getString(R.string.episodes_suffix);
        }
        ui.findPreference(UserPreferences.PREF_EPISODE_CACHE_SIZE).setSummary(s);
    }

    private void setDataFolderText() {
        File f = UserPreferences.getDataFolder(null);
        if (f != null) {
            ui.findPreference(PreferenceController.PREF_CHOOSE_DATA_DIR)
                    .setSummary(f.getAbsolutePath());
        }
    }

    private void buildAutodownloadSelectedNetworsPreference() {
        final Activity activity = ui.getActivity();

        if (selectedNetworks != null) {
            clearAutodownloadSelectedNetworsPreference();
        }
        // get configured networks
        WifiManager wifiservice = (WifiManager) activity.getSystemService(Context.WIFI_SERVICE);
        List<WifiConfiguration> networks = wifiservice.getConfiguredNetworks();

        if (networks != null) {
            selectedNetworks = new CheckBoxPreference[networks.size()];
            List<String> prefValues = Arrays.asList(UserPreferences
                    .getAutodownloadSelectedNetworks());
            PreferenceScreen prefScreen = (PreferenceScreen) ui.findPreference(PreferenceController.AUTO_DL_PREF_SCREEN);
            Preference.OnPreferenceClickListener clickListener = preference -> {
                if (preference instanceof CheckBoxPreference) {
                    String key = preference.getKey();
                    ArrayList<String> prefValuesList = new ArrayList<String>(
                            Arrays.asList(UserPreferences
                                    .getAutodownloadSelectedNetworks())
                    );
                    boolean newValue = ((CheckBoxPreference) preference)
                            .isChecked();
                    Log.d(TAG, "Selected network " + key + ". New state: " + newValue);

                    int index = prefValuesList.indexOf(key);
                    if (index >= 0 && newValue == false) {
                        // remove network
                        prefValuesList.remove(index);
                    } else if (index < 0 && newValue == true) {
                        prefValuesList.add(key);
                    }

                    UserPreferences.setAutodownloadSelectedNetworks(
                            prefValuesList.toArray(new String[prefValuesList.size()])
                    );
                    return true;
                } else {
                    return false;
                }
            };
            // create preference for each known network. attach listener and set
            // value
            for (int i = 0; i < networks.size(); i++) {
                WifiConfiguration config = networks.get(i);

                CheckBoxPreference pref = new CheckBoxPreference(activity);
                String key = Integer.toString(config.networkId);
                pref.setTitle(config.SSID);
                pref.setKey(key);
                pref.setOnPreferenceClickListener(clickListener);
                pref.setPersistent(false);
                pref.setChecked(prefValues.contains(key));
                selectedNetworks[i] = pref;
                prefScreen.addPreference(pref);
            }
        } else {
            Log.e(TAG, "Couldn't get list of configure Wi-Fi networks");
        }
    }

    private void clearAutodownloadSelectedNetworsPreference() {
        if (selectedNetworks != null) {
            PreferenceScreen prefScreen = (PreferenceScreen) ui.findPreference(PreferenceController.AUTO_DL_PREF_SCREEN);

            for (int i = 0; i < selectedNetworks.length; i++) {
                if (selectedNetworks[i] != null) {
                    prefScreen.removePreference(selectedNetworks[i]);
                }
            }
        }
    }

    private void showDrawerPreferencesDialog() {
        final Context context = ui.getActivity();
        final List<String> hiddenDrawerItems = UserPreferences.getHiddenDrawerItems();
        final String[] navTitles = context.getResources().getStringArray(R.array.nav_drawer_titles);
        final String[] NAV_DRAWER_TAGS = MainActivity.NAV_DRAWER_TAGS;
        boolean[] checked = new boolean[MainActivity.NAV_DRAWER_TAGS.length];
        for(int i=0; i < NAV_DRAWER_TAGS.length; i++) {
            String tag = NAV_DRAWER_TAGS[i];
            if(!hiddenDrawerItems.contains(tag)) {
                checked[i] = true;
            }
        }
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setTitle(R.string.drawer_preferences);
        builder.setMultiChoiceItems(navTitles, checked, (dialog, which, isChecked) -> {
            if (isChecked) {
                hiddenDrawerItems.remove(NAV_DRAWER_TAGS[which]);
            } else {
                hiddenDrawerItems.add(NAV_DRAWER_TAGS[which]);
            }
        });
        builder.setPositiveButton(R.string.confirm_label, (dialog, which) -> {
            UserPreferences.setHiddenDrawerItems(hiddenDrawerItems);
        });
        builder.setNegativeButton(R.string.cancel_label, null);
        builder.create().show();
    }

    // CHOOSE DATA FOLDER

    private void requestPermission() {
        ActivityCompat.requestPermissions(ui.getActivity(), EXTERNAL_STORAGE_PERMISSIONS,
                PERMISSION_REQUEST_EXTERNAL_STORAGE);
    }

    private void openDirectoryChooser() {
        Activity activity = ui.getActivity();
        Intent intent = new Intent(activity, DirectoryChooserActivity.class);
        activity.startActivityForResult(intent, DirectoryChooserActivity.RESULT_CODE_DIR_SELECTED);
    }

    private void showChooseDataFolderDialog() {
        Context context = ui.getActivity();
        File dataFolder =  UserPreferences.getDataFolder(null);
        if(dataFolder == null) {
            new MaterialDialog.Builder(ui.getActivity())
                    .title(R.string.error_label)
                    .content(R.string.external_storage_error_msg)
                    .neutralText(android.R.string.ok)
                    .show();
            return;
        }
        String dataFolderPath = dataFolder.getAbsolutePath();
        int selectedIndex = -1;
        File[] mediaDirs = ContextCompat.getExternalFilesDirs(context, null);
        List<String> folders = new ArrayList<>(mediaDirs.length);
        List<CharSequence> choices = new ArrayList<>(mediaDirs.length);
        for(int i=0; i < mediaDirs.length; i++) {
            if(mediaDirs[i] == null) {
                continue;
            }
            String path = mediaDirs[i].getAbsolutePath();
            folders.add(path);
            if(dataFolderPath.equals(path)) {
                selectedIndex = i;
            }
            int index = path.indexOf("Android");
            String choice;
            if(index >= 0) {
                choice = path.substring(0, index);
            } else {
                choice = path;
            }
            long bytes = StorageUtils.getFreeSpaceAvailable(path);
            String freeSpace = String.format(context.getString(R.string.free_space_label),
                    Converter.byteToString(bytes));
            choices.add(Html.fromHtml("<html><small>" + choice
                    + " [" + freeSpace + "]" + "</small></html>"));
        }
        if(choices.size() == 0) {
            new MaterialDialog.Builder(ui.getActivity())
                    .title(R.string.error_label)
                    .content(R.string.external_storage_error_msg)
                    .neutralText(android.R.string.ok)
                    .show();
            return;
        }
        MaterialDialog dialog = new MaterialDialog.Builder(ui.getActivity())
                .title(R.string.choose_data_directory)
                .content(R.string.choose_data_directory_message)
                .items(choices.toArray(new CharSequence[choices.size()]))
                .itemsCallbackSingleChoice(selectedIndex, (dialog1, itemView, which, text) -> {
                    String folder = folders.get(which);
                    Log.d(TAG, "data folder: " + folder);
                    UserPreferences.setDataFolder(folder);
                    setDataFolderText();
                    return true;
                })
                .negativeText(R.string.cancel_label)
                .cancelable(true)
                .build();
        dialog.show();
    }

    // UPDATE TIME/INTERVAL DIALOG

    private void showUpdateIntervalTimePreferencesDialog() {
        final Context context = ui.getActivity();

        MaterialDialog.Builder builder = new MaterialDialog.Builder(context);
        builder.title(R.string.pref_autoUpdateIntervallOrTime_title);
        builder.content(R.string.pref_autoUpdateIntervallOrTime_message);
        builder.positiveText(R.string.pref_autoUpdateIntervallOrTime_Interval);
        builder.negativeText(R.string.pref_autoUpdateIntervallOrTime_TimeOfDay);
        builder.neutralText(R.string.pref_autoUpdateIntervallOrTime_Disable);
        builder.onPositive((dialog, which) -> {
            AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
            builder1.setTitle(context.getString(R.string.pref_autoUpdateIntervallOrTime_Interval));
            final String[] values = context.getResources().getStringArray(R.array.update_intervall_values);
            final String[] entries = getUpdateIntervalEntries(values);
            long currInterval = UserPreferences.getUpdateInterval();
            int checkedItem = -1;
            if(currInterval > 0) {
                String currIntervalStr = String.valueOf(TimeUnit.MILLISECONDS.toHours(currInterval));
                checkedItem = ArrayUtils.indexOf(values, currIntervalStr);
            }
            builder1.setSingleChoiceItems(entries, checkedItem, (dialog1, which1) -> {
                int hours = Integer.valueOf(values[which1]);
                UserPreferences.setUpdateInterval(hours);
                dialog1.dismiss();
                setUpdateIntervalText();
            });
            builder1.setNegativeButton(context.getString(R.string.cancel_label), null);
            builder1.show();
        });
        builder.onNegative((dialog, which) -> {
            int hourOfDay = 7, minute = 0;
            int[] updateTime = UserPreferences.getUpdateTimeOfDay();
            if (updateTime.length == 2) {
                hourOfDay = updateTime[0];
                minute = updateTime[1];
            }
            TimePickerDialog timePickerDialog = new TimePickerDialog(context,
                    (view, selectedHourOfDay, selectedMinute) -> {
                        if (view.getTag() == null) { // onTimeSet() may get called twice!
                            view.setTag("TAGGED");
                            UserPreferences.setUpdateTimeOfDay(selectedHourOfDay, selectedMinute);
                            setUpdateIntervalText();
                        }
                    }, hourOfDay, minute, DateFormat.is24HourFormat(context));
            timePickerDialog.setTitle(context.getString(R.string.pref_autoUpdateIntervallOrTime_TimeOfDay));
            timePickerDialog.show();
        });
        builder.onNeutral((dialog, which) -> {
            UserPreferences.setUpdateInterval(0);
            setUpdateIntervalText();
        });
        builder.show();
    }


    public interface PreferenceUI {

        /**
         * Finds a preference based on its key.
         */
        Preference findPreference(CharSequence key);

        Activity getActivity();
    }
}