FairEmail/app/src/main/java/eu/faircode/email/Helper.java

package eu.faircode.email;

/*
    This file is part of FairEmail.

    FairEmail 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.

    FairEmail 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 FairEmail.  If not, see <http://www.gnu.org/licenses/>.

    Copyright 2018-2020 by Marcel Bokhorst (M66B)
*/

import android.Manifest;
import android.app.Activity;
import android.app.KeyguardManager;
import android.content.ActivityNotFoundException;
import android.content.ComponentName;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.LocaleList;
import android.os.Parcel;
import android.os.PowerManager;
import android.os.StatFs;
import android.provider.DocumentsContract;
import android.security.KeyChain;
import android.security.KeyChainAliasCallback;
import android.security.KeyChainException;
import android.text.Spannable;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.text.format.Time;
import android.util.TypedValue;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.inputmethod.EditorInfo;
import android.webkit.MimeTypeMap;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.RadioButton;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.biometric.BiometricManager;
import androidx.biometric.BiometricPrompt;
import androidx.browser.customtabs.CustomTabsClient;
import androidx.browser.customtabs.CustomTabsIntent;
import androidx.browser.customtabs.CustomTabsServiceConnection;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.core.content.ContextCompat;
import androidx.core.content.FileProvider;
import androidx.core.graphics.ColorUtils;
import androidx.fragment.app.FragmentActivity;
import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleObserver;
import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.OnLifecycleEvent;
import androidx.preference.PreferenceManager;
import androidx.recyclerview.widget.RecyclerView;

import com.google.android.material.bottomnavigation.BottomNavigationView;

import org.jetbrains.annotations.NotNull;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.DateFormat;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Objects;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.regex.Pattern;

import static android.os.Process.THREAD_PRIORITY_BACKGROUND;
import static androidx.browser.customtabs.CustomTabsService.ACTION_CUSTOM_TABS_CONNECTION;

public class Helper {
    static final int NOTIFICATION_SYNCHRONIZE = 1;
    static final int NOTIFICATION_SEND = 2;
    static final int NOTIFICATION_EXTERNAL = 3;
    static final int NOTIFICATION_UPDATE = 4;

    static final float LOW_LIGHT = 0.6f;

    static final int BUFFER_SIZE = 8192; // Same as in Files class

    static final String PGP_BEGIN_MESSAGE = "-----BEGIN PGP MESSAGE-----";
    static final String PGP_END_MESSAGE = "-----END PGP MESSAGE-----";

    static final String FAQ_URI = "https://github.com/M66B/FairEmail/blob/master/FAQ.md";
    static final String XDA_URI = "https://forum.xda-developers.com/showthread.php?t=3824168";
    static final String SUPPORT_URI = "https://contact.faircode.eu/?product=fairemailsupport";
    static final String TEST_URI = "https://play.google.com/apps/testing/" + BuildConfig.APPLICATION_ID;
    static final String CROWDIN_URI = "https://crowdin.com/project/open-source-email";
    static final String GRAVATAR_PRIVACY_URI = "https://meta.stackexchange.com/questions/44717/is-gravatar-a-privacy-risk";

    static final Pattern EMAIL_ADDRESS
            = Pattern.compile(
            "[\\S]{1,256}" +
                    "\\@" +
                    "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
                    "(" +
                    "\\." +
                    "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" +
                    ")+"
    );

    static ExecutorService getBackgroundExecutor(int threads, final String name) {
        ThreadFactory factory = new ThreadFactory() {
            private final AtomicInteger threadId = new AtomicInteger();

            @Override
            public Thread newThread(@NonNull Runnable runnable) {
                Thread thread = new Thread(runnable);
                thread.setName("FairEmail_bg_" + name + "_" + threadId.getAndIncrement());
                thread.setPriority(THREAD_PRIORITY_BACKGROUND);
                return thread;
            }
        };

        if (threads == 0)
            return new ThreadPoolExecutorEx(
                    name,
                    0, Integer.MAX_VALUE,
                    60L, TimeUnit.SECONDS,
                    new SynchronousQueue<Runnable>(),
                    factory);
        else if (threads == 1)
            return new ThreadPoolExecutorEx(
                    name,
                    threads, threads,
                    0L, TimeUnit.MILLISECONDS,
                    new PriorityBlockingQueue<Runnable>(10, new PriorityComparator()),
                    factory) {
                private final AtomicLong sequenceId = new AtomicLong();

                @Override
                protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
                    RunnableFuture<T> task = super.newTaskFor(runnable, value);
                    if (runnable instanceof PriorityRunnable)
                        return new PriorityFuture<T>(task,
                                ((PriorityRunnable) runnable).getPriority(),
                                ((PriorityRunnable) runnable).getOrder());
                    else
                        return new PriorityFuture<>(task, 0, sequenceId.getAndIncrement());
                }
            };
        else
            return new ThreadPoolExecutorEx(
                    name,
                    threads, threads,
                    0L, TimeUnit.MILLISECONDS,
                    new LinkedBlockingQueue<Runnable>(),
                    factory);
    }

    private static class ThreadPoolExecutorEx extends ThreadPoolExecutor {
        String name;

        public ThreadPoolExecutorEx(
                String name,
                int corePoolSize, int maximumPoolSize,
                long keepAliveTime, TimeUnit unit,
                BlockingQueue<Runnable> workQueue,
                ThreadFactory threadFactory) {
            super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
            this.name = name;
        }

        @Override
        protected void beforeExecute(Thread t, Runnable r) {
            Log.d("Executing " + t.getName());
        }
    }

    private static class PriorityFuture<T> implements RunnableFuture<T> {
        private int priority;
        private long order;
        private RunnableFuture<T> wrapped;

        PriorityFuture(RunnableFuture<T> wrapped, int priority, long order) {
            this.wrapped = wrapped;
            this.priority = priority;
            this.order = order;
        }

        public int getPriority() {
            return this.priority;
        }

        public long getOrder() {
            return this.order;
        }

        @Override
        public void run() {
            wrapped.run();
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return wrapped.cancel(mayInterruptIfRunning);
        }

        @Override
        public boolean isCancelled() {
            return wrapped.isCancelled();
        }

        @Override
        public boolean isDone() {
            return wrapped.isDone();
        }

        @Override
        public T get() throws ExecutionException, InterruptedException {
            return wrapped.get();
        }

        @Override
        public T get(long timeout, @NotNull TimeUnit unit) throws ExecutionException, InterruptedException, TimeoutException {
            return wrapped.get(timeout, unit);
        }
    }

    private static class PriorityComparator implements Comparator<Runnable> {
        @Override
        public int compare(Runnable r1, Runnable r2) {
            if (r1 instanceof PriorityFuture<?> && r2 instanceof PriorityFuture<?>) {
                Integer p1 = ((PriorityFuture<?>) r1).getPriority();
                Integer p2 = ((PriorityFuture<?>) r2).getPriority();
                int p = p1.compareTo(p2);
                if (p == 0) {
                    Long o1 = ((PriorityFuture<?>) r1).getOrder();
                    Long o2 = ((PriorityFuture<?>) r2).getOrder();
                    return o1.compareTo(o2);
                } else
                    return p;
            } else
                return 0;
        }
    }

    static class PriorityRunnable implements Runnable {
        private int priority;
        private long order;

        int getPriority() {
            return this.priority;
        }

        long getOrder() {
            return this.order;
        }

        PriorityRunnable(int priority, long order) {
            this.priority = priority;
            this.order = order;
        }

        @Override
        public void run() {
            Log.i("Run priority=" + priority);
        }
    }

    private static final ExecutorService executor = getBackgroundExecutor(1, "helper");

    // Features

    static boolean hasPermission(Context context, String name) {
        return (ContextCompat.checkSelfPermission(context, name) == PackageManager.PERMISSION_GRANTED);
    }

    static boolean hasPermissions(Context context, String[] permissions) {
        for (String permission : permissions)
            if (!hasPermission(context, permission))
                return false;
        return true;
    }

    static String[] getOAuthPermissions() {
        List<String> permissions = new ArrayList<>();
        permissions.add(Manifest.permission.READ_CONTACTS); // profile
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O)
            permissions.add(Manifest.permission.GET_ACCOUNTS);
        return permissions.toArray(new String[0]);
    }

    static boolean hasCustomTabs(Context context, Uri uri) {
        PackageManager pm = context.getPackageManager();
        Intent view = new Intent(Intent.ACTION_VIEW, uri);

        for (ResolveInfo info : pm.queryIntentActivities(view, 0)) {
            Intent intent = new Intent();
            intent.setAction(ACTION_CUSTOM_TABS_CONNECTION);
            intent.setPackage(info.activityInfo.packageName);
            if (pm.resolveService(intent, 0) != null)
                return true;
        }

        return false;
    }

    static boolean hasWebView(Context context) {
        PackageManager pm = context.getPackageManager();
        if (pm.hasSystemFeature(PackageManager.FEATURE_WEBVIEW))
            try {
                new WebView(context);
                return true;
            } catch (Throwable ex) {
                return false;
            }
        else
            return false;
    }

    static boolean canPrint(Context context) {
        PackageManager pm = context.getPackageManager();
        return pm.hasSystemFeature(PackageManager.FEATURE_PRINTING);
    }

    static Boolean isIgnoringOptimizations(Context context) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
            if (pm == null)
                return null;
            return pm.isIgnoringBatteryOptimizations(BuildConfig.APPLICATION_ID);
        }
        return null;
    }

    static boolean isPlayStoreInstall() {
        return BuildConfig.PLAY_STORE_RELEASE;
    }

    static boolean isSecure(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        boolean biometrics = prefs.getBoolean("biometrics", false);
        String pin = prefs.getString("pin", null);
        return (biometrics || !TextUtils.isEmpty(pin));
    }

    // View

    static Intent getChooser(Context context, Intent intent) {
        PackageManager pm = context.getPackageManager();
        if (pm.queryIntentActivities(intent, 0).size() == 1)
            return intent;
        else
            return Intent.createChooser(intent, context.getString(R.string.title_select_app));
    }

    static void share(Context context, File file, String type, String name) {
        // https://developer.android.com/reference/android/support/v4/content/FileProvider
        Uri uri = FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID, file);
        Log.i("uri=" + uri);

        // Build intent
        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndTypeAndNormalize(uri, type);
        intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        if (!TextUtils.isEmpty(name))
            intent.putExtra(Intent.EXTRA_TITLE, Helper.sanitizeFilename(name));
        Log.i("Intent=" + intent + " type=" + type);

        // Get targets
        PackageManager pm = context.getPackageManager();
        List<ResolveInfo> ris = pm.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
        for (ResolveInfo ri : ris) {
            Log.i("Target=" + ri);
            context.grantUriPermission(ri.activityInfo.packageName, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);
        }

        // Check if viewer available
        if (ris.size() == 0) {
            String message = context.getString(R.string.title_no_viewer,
                    type != null ? type : name != null ? name : file.getName());
            ToastEx.makeText(context, message, Toast.LENGTH_LONG).show();
        } else
            context.startActivity(intent);
    }

    static void view(Context context, Intent intent) {
        Uri uri = intent.getData();
        if ("http".equals(uri.getScheme()) || "https".equals(uri.getScheme()))
            view(context, intent.getData(), false);
        else
            context.startActivity(intent);
    }

    static void view(Context context, Uri uri, boolean browse) {
        Log.i("View=" + uri);

        if (browse || !hasCustomTabs(context, uri)) {
            Intent view = new Intent(Intent.ACTION_VIEW, uri);
            context.startActivity(getChooser(context, view));
        } else {
            // https://developer.chrome.com/multidevice/android/customtabs
            CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();
            builder.setToolbarColor(resolveColor(context, R.attr.colorPrimary));
            builder.setSecondaryToolbarColor(resolveColor(context, R.attr.colorPrimaryDark));
            builder.setColorScheme(Helper.isDarkTheme(context)
                    ? CustomTabsIntent.COLOR_SCHEME_DARK : CustomTabsIntent.COLOR_SCHEME_LIGHT);
            builder.addDefaultShareMenuItem();

            CustomTabsIntent customTabsIntent = builder.build();
            try {
                customTabsIntent.launchUrl(context, uri);
            } catch (ActivityNotFoundException ex) {
                Log.w(ex);
                ToastEx.makeText(context, context.getString(R.string.title_no_viewer, uri.toString()), Toast.LENGTH_LONG).show();
            } catch (Throwable ex) {
                Log.e(ex);
                ToastEx.makeText(context, Log.formatThrowable(ex, false), Toast.LENGTH_LONG).show();
            }
        }
    }

    static void customTabsWarmup(Context context) {
        try {
            CustomTabsClient.bindCustomTabsService(context, "com.android.chrome", new CustomTabsServiceConnection() {
                @Override
                public void onCustomTabsServiceConnected(@NonNull ComponentName name, @NonNull CustomTabsClient client) {
                    Log.i("Warming up custom tabs");
                    try {
                        client.warmup(0);
                    } catch (Throwable ex) {
                        Log.w(ex);
                    }
                }

                @Override
                public void onServiceDisconnected(ComponentName name) {
                    // Do nothing
                }
            });
        } catch (Throwable ex) {
            Log.w(ex);
        }
    }

    static void viewFAQ(Context context, int question) {
        if (question == 0)
            view(context, Uri.parse(FAQ_URI), false);
        else
            view(context, Uri.parse(FAQ_URI + "#user-content-faq" + question), false);
    }

    static Intent getIntentOpenKeychain() {
        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setData(Uri.parse(BuildConfig.OPENKEYCHAIN_URI));
        return intent;
    }

    static String getOpenKeychainPackage(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        return prefs.getString("openpgp_provider", "org.sufficientlysecure.keychain");
    }

    static Intent getIntentIssue(Context context) {
        if (ActivityBilling.isPro(context)) {
            String version = BuildConfig.VERSION_NAME + "/" +
                    (Helper.hasValidFingerprint(context) ? "1" : "3") +
                    (BuildConfig.PLAY_STORE_RELEASE ? "p" : "") +
                    (BuildConfig.DEBUG ? "d" : "") +
                    (ActivityBilling.isPro(context) ? "+" : "");
            Intent intent = new Intent(Intent.ACTION_SEND);
            intent.setPackage(BuildConfig.APPLICATION_ID);
            intent.setType("text/plain");
            try {
                intent.putExtra(Intent.EXTRA_EMAIL, new String[]{Log.myAddress().getAddress()});
            } catch (UnsupportedEncodingException ex) {
                Log.w(ex);
            }
            intent.putExtra(Intent.EXTRA_SUBJECT, context.getString(R.string.title_issue_subject, version));
            return intent;
        } else
            return new Intent(Intent.ACTION_VIEW, Uri.parse(XDA_URI));
    }

    static Intent getIntentRate(Context context) {
        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=" + BuildConfig.APPLICATION_ID));
        if (intent.resolveActivity(context.getPackageManager()) == null)
            intent = new Intent(Intent.ACTION_VIEW, Uri.parse("https://play.google.com/store/apps/details?id=" + BuildConfig.APPLICATION_ID));
        return intent;
    }

    static long getInstallTime(Context context) {
        try {
            PackageManager pm = context.getPackageManager();
            PackageInfo pi = pm.getPackageInfo(BuildConfig.APPLICATION_ID, 0);
            if (pi != null)
                return pi.firstInstallTime;
        } catch (Throwable ex) {
            Log.e(ex);
        }
        return 0;
    }

    // Graphics

    static int dp2pixels(Context context, int dp) {
        float scale = context.getResources().getDisplayMetrics().density;
        return Math.round(dp * scale);
    }

    static int pixels2dp(Context context, float pixels) {
        float scale = context.getResources().getDisplayMetrics().density;
        return Math.round(pixels / scale);
    }

    static float getTextSize(Context context, int zoom) {
        TypedArray ta = null;
        try {
            if (zoom == 0)
                ta = context.obtainStyledAttributes(
                        R.style.TextAppearance_AppCompat_Small, new int[]{android.R.attr.textSize});
            else if (zoom == 2)
                ta = context.obtainStyledAttributes(
                        R.style.TextAppearance_AppCompat_Large, new int[]{android.R.attr.textSize});
            else
                ta = context.obtainStyledAttributes(
                        R.style.TextAppearance_AppCompat_Medium, new int[]{android.R.attr.textSize});
            return ta.getDimension(0, 0);
        } finally {
            if (ta != null)
                ta.recycle();
        }
    }

    static int resolveColor(Context context, int attr) {
        int[] attrs = new int[]{attr};
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs);
        int color = a.getColor(0, 0xFF0000);
        a.recycle();
        return color;
    }

    static void setViewsEnabled(ViewGroup view, boolean enabled) {
        for (int i = 0; i < view.getChildCount(); i++) {
            View child = view.getChildAt(i);
            if (child instanceof Spinner ||
                    child instanceof EditText ||
                    child instanceof CheckBox ||
                    child instanceof ImageView /* =ImageButton */ ||
                    child instanceof RadioButton ||
                    (child instanceof Button && "disable".equals(child.getTag())))
                child.setEnabled(enabled);
            else if (child instanceof BottomNavigationView) {
                Menu menu = ((BottomNavigationView) child).getMenu();
                menu.setGroupEnabled(0, enabled);
            } else if (child instanceof RecyclerView)
                ; // do nothing
            else if (child instanceof ViewGroup)
                setViewsEnabled((ViewGroup) child, enabled);
        }
    }

    static void hide(View view) {
        view.setPadding(0, 0, 0, 0);

        ViewGroup.LayoutParams lparam = view.getLayoutParams();
        lparam.width = 0;
        lparam.height = 0;
        if (lparam instanceof ConstraintLayout.LayoutParams)
            ((ConstraintLayout.LayoutParams) lparam).setMargins(0, 0, 0, 0);
        view.setLayoutParams(lparam);
    }

    static boolean isDarkTheme(Context context) {
        TypedValue tv = new TypedValue();
        context.getTheme().resolveAttribute(R.attr.themeName, tv, true);
        return (tv.string != null && !"light".contentEquals(tv.string));
    }

    static int adjustLuminance(int color, boolean dark, float min) {
        float lum = (float) ColorUtils.calculateLuminance(color);
        if (dark ? lum < min : lum > 1 - min)
            return ColorUtils.blendARGB(color,
                    dark ? Color.WHITE : Color.BLACK,
                    dark ? min - lum : lum - (1 - min));
        return color;
    }

    // Formatting

    private static final DecimalFormat df = new DecimalFormat("@@");

    static String humanReadableByteCount(long bytes, boolean si) {
        int unit = si ? 1000 : 1024;
        if (bytes < unit) return bytes + " B";
        int exp = (int) (Math.log(bytes) / Math.log(unit));
        String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
        return df.format(bytes / Math.pow(unit, exp)) + " " + pre + "B";
    }

    static boolean isPrintableChar(char c) {
        Character.UnicodeBlock block = Character.UnicodeBlock.of(c);
        if (block == null || block == Character.UnicodeBlock.SPECIALS)
            return false;
        return !Character.isISOControl(c);
    }
    // https://issuetracker.google.com/issues/37054851

    static DateFormat getTimeInstance(Context context) {
        return Helper.getTimeInstance(context, SimpleDateFormat.MEDIUM);
    }

    static DateFormat getDateInstance(Context context) {
        return SimpleDateFormat.getDateInstance(SimpleDateFormat.MEDIUM);
    }

    static DateFormat getTimeInstance(Context context, int style) {
        if (context != null &&
                (style == SimpleDateFormat.SHORT || style == SimpleDateFormat.MEDIUM)) {
            Locale locale = Locale.getDefault();
            boolean is24Hour = android.text.format.DateFormat.is24HourFormat(context);
            String skeleton = (is24Hour ? "Hm" : "hm");
            if (style == SimpleDateFormat.MEDIUM)
                skeleton += "s";
            String pattern = android.text.format.DateFormat.getBestDateTimePattern(locale, skeleton);
            return new SimpleDateFormat(pattern, locale);
        } else
            return SimpleDateFormat.getTimeInstance(style);
    }

    static DateFormat getDateTimeInstance(Context context) {
        return Helper.getDateTimeInstance(context, SimpleDateFormat.MEDIUM, SimpleDateFormat.MEDIUM);
    }

    static DateFormat getDateTimeInstance(Context context, int dateStyle, int timeStyle) {
        // TODO fix time format
        return SimpleDateFormat.getDateTimeInstance(dateStyle, timeStyle);
    }

    static CharSequence getRelativeTimeSpanString(Context context, long millis) {
        long now = System.currentTimeMillis();
        long span = Math.abs(now - millis);
        Time nowTime = new Time();
        Time thenTime = new Time();
        nowTime.set(now);
        thenTime.set(millis);
        if (span < DateUtils.DAY_IN_MILLIS && nowTime.weekDay == thenTime.weekDay)
            return getTimeInstance(context, SimpleDateFormat.SHORT).format(millis);
        else
            return DateUtils.getRelativeTimeSpanString(context, millis);
    }

    static String ellipsize(String text, int maxLen) {
        if (text == null || text.length() < maxLen) {
            return text;
        }
        return text.substring(0, maxLen) + "...";
    }

    static void clearComposingText(Spannable text) {
        Object[] spans = text.getSpans(0, text.length(), Object.class);
        for (Object span : spans)
            if ((text.getSpanFlags(span) & Spanned.SPAN_COMPOSING) != 0)
                text.removeSpan(span);
    }

    static String localizeFolderType(Context context, String type) {
        int resid = context.getResources().getIdentifier(
                "title_folder_" + type.toLowerCase(Locale.ROOT),
                "string",
                context.getPackageName());
        return (resid > 0 ? context.getString(resid) : type);
    }

    static String localizeFolderName(Context context, String name) {
        if (name != null && "INBOX".equals(name.toUpperCase(Locale.ROOT)))
            return context.getString(R.string.title_folder_inbox);
        else if ("OUTBOX".equals(name))
            return context.getString(R.string.title_folder_outbox);
        else
            return name;
    }

    static void linkPro(final TextView tv) {
        if (ActivityBilling.isPro(tv.getContext()) && !BuildConfig.DEBUG)
            hide(tv);
        else {
            tv.getPaint().setUnderlineText(true);
            tv.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    tv.getContext().startActivity(new Intent(tv.getContext(), ActivityBilling.class));
                }
            });
        }
    }

    static String[] getStrings(Context context, int resid, Object... formatArgs) {
        List<String> result = new ArrayList<>();

        Configuration configuration = new Configuration(context.getResources().getConfiguration());
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
            result.add(context.getString(resid, formatArgs));
            if (!Locale.getDefault().getLanguage().equals("en")) {
                configuration.setLocale(new Locale("en"));
                Resources res = context.createConfigurationContext(configuration).getResources();
                result.add(res.getString(resid, formatArgs));
            }
        } else {
            LocaleList ll = context.getResources().getConfiguration().getLocales();
            for (int i = 0; i < ll.size(); i++) {
                configuration.setLocale(ll.get(i));
                Resources res = context.createConfigurationContext(configuration).getResources();
                result.add(res.getString(resid, formatArgs));
            }
        }

        return result.toArray(new String[0]);
    }

    static boolean containsWhiteSpace(String text) {
        return text.matches(".*\\s+.*");
    }

    static boolean containsControlChars(String text) {
        for (int offset = 0; offset < text.length(); ) {
            int codePoint = text.codePointAt(offset);
            offset += Character.charCount(codePoint);
            switch (Character.getType(codePoint)) {
                case Character.CONTROL:     // \p{Cc}
                case Character.FORMAT:      // \p{Cf}
                case Character.PRIVATE_USE: // \p{Co}
                case Character.SURROGATE:   // \p{Cs}
                case Character.UNASSIGNED:  // \p{Cn}
                    return true;
            }
        }
        return false;
    }

    static boolean isUTF8(String text) {
        // Get extended ASCII characters
        byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);

        for (int i = 0; i < octets.length; i++) {
            int bytes;
            if ((octets[i] & 0b10000000) == 0b00000000)
                bytes = 1;
            else if ((octets[i] & 0b11100000) == 0b11000000)
                bytes = 2;
            else if ((octets[i] & 0b11110000) == 0b11100000)
                bytes = 3;
            else if ((octets[i] & 0b11111000) == 0b11110000)
                bytes = 4;
            else if ((octets[i] & 0b11111100) == 0b11111000)
                bytes = 5;
            else if ((octets[i] & 0b11111110) == 0b11111100)
                bytes = 6;
            else
                return false;

            if (i + bytes > octets.length)
                return false;

            while (--bytes > 0)
                if ((octets[++i] & 0b11000000) != 0b10000000)
                    return false;
        }

        return true;
    }

    // Files

    static String sanitizeFilename(String name) {
        if (name == null)
            return null;

        return name.replaceAll("[?:\"*|/\\\\<>]", "_");
    }

    static String getExtension(String filename) {
        if (filename == null)
            return null;
        int index = filename.lastIndexOf(".");
        if (index < 0)
            return null;
        return filename.substring(index + 1);
    }

    static String guessMimeType(String filename) {
        String type = null;

        String extension = Helper.getExtension(filename);
        if (extension != null)
            type = MimeTypeMap.getSingleton()
                    .getMimeTypeFromExtension(extension.toLowerCase(Locale.ROOT));

        if (TextUtils.isEmpty(type))
            type = "application/octet-stream";

        return type;
    }

    static void writeText(File file, String content) throws IOException {
        try (FileOutputStream out = new FileOutputStream(file)) {
            if (content != null)
                out.write(content.getBytes());
        }
    }

    static String readStream(InputStream is, String charset) throws IOException {
        ByteArrayOutputStream os = new ByteArrayOutputStream(Math.max(BUFFER_SIZE, is.available()));
        byte[] buffer = new byte[BUFFER_SIZE];
        for (int len = is.read(buffer); len != -1; len = is.read(buffer))
            os.write(buffer, 0, len);
        return new String(os.toByteArray(), charset);
    }

    static String readText(File file) throws IOException {
        try (FileInputStream in = new FileInputStream(file)) {
            return readStream(in, StandardCharsets.UTF_8.name());
        }
    }

    static void copy(File src, File dst) throws IOException {
        try (InputStream in = new FileInputStream(src)) {
            try (FileOutputStream out = new FileOutputStream(dst)) {
                copy(in, out);
            }
        }
    }

    static void copy(InputStream in, OutputStream out) throws IOException {
        byte[] buf = new byte[BUFFER_SIZE];
        int len;
        while ((len = in.read(buf)) > 0)
            out.write(buf, 0, len);
    }

    static long copy(Context context, Uri uri, File file) throws IOException {
        long size = 0;
        InputStream is = null;
        OutputStream os = null;
        try {
            is = context.getContentResolver().openInputStream(uri);
            os = new FileOutputStream(file);

            byte[] buffer = new byte[Helper.BUFFER_SIZE];
            for (int len = is.read(buffer); len != -1; len = is.read(buffer)) {
                size += len;
                os.write(buffer, 0, len);
            }
        } finally {
            try {
                if (is != null)
                    is.close();
            } finally {
                if (os != null)
                    os.close();
            }
        }
        return size;
    }

    static long getAvailableStorageSpace() {
        StatFs stats = new StatFs(Environment.getDataDirectory().getAbsolutePath());
        return stats.getAvailableBlocksLong() * stats.getBlockSizeLong();
    }

    static long getTotalStorageSpace() {
        StatFs stats = new StatFs(Environment.getDataDirectory().getAbsolutePath());
        return stats.getTotalBytes();
    }

    static void openAdvanced(Intent intent) {
        // https://issuetracker.google.com/issues/72053350
        intent.putExtra("android.content.extra.SHOW_ADVANCED", true);
        intent.putExtra("android.content.extra.FANCY", true);
        intent.putExtra("android.content.extra.SHOW_FILESIZE", true);
        intent.putExtra("android.provider.extra.SHOW_ADVANCED", true);
        File initial = Environment.getExternalStorageDirectory();
        intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Uri.fromFile(initial));
    }

    // Cryptography

    static String sha256(String data) throws NoSuchAlgorithmException {
        return sha256(data.getBytes());
    }

    static String sha1(byte[] data) throws NoSuchAlgorithmException {
        return sha("SHA-1", data);
    }

    static String sha256(byte[] data) throws NoSuchAlgorithmException {
        return sha("SHA-256", data);
    }

    static String md5(byte[] data) throws NoSuchAlgorithmException {
        return sha("MD5", data);
    }

    static String sha(String digest, byte[] data) throws NoSuchAlgorithmException {
        byte[] bytes = MessageDigest.getInstance(digest).digest(data);
        return hex(bytes);
    }

    static String hex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes)
            sb.append(String.format("%02x", b));
        return sb.toString();
    }

    static String getFingerprint(Context context) {
        try {
            PackageManager pm = context.getPackageManager();
            String pkg = context.getPackageName();
            PackageInfo info = pm.getPackageInfo(pkg, PackageManager.GET_SIGNATURES);
            byte[] cert = info.signatures[0].toByteArray();
            MessageDigest digest = MessageDigest.getInstance("SHA1");
            byte[] bytes = digest.digest(cert);
            StringBuilder sb = new StringBuilder();
            for (byte b : bytes)
                sb.append(Integer.toString(b & 0xff, 16).toUpperCase(Locale.ROOT));
            return sb.toString();
        } catch (Throwable ex) {
            Log.e(ex);
            return null;
        }
    }

    static boolean hasValidFingerprint(Context context) {
        String signed = getFingerprint(context);
        String expected = context.getString(R.string.fingerprint);
        return Objects.equals(signed, expected);
    }

    static boolean canAuthenticate(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        String pin = prefs.getString("pin", null);
        if (!TextUtils.isEmpty(pin))
            return true;

        BiometricManager bm = BiometricManager.from(context);
        return (bm.canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS);
    }

    static boolean shouldAuthenticate(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        boolean biometrics = prefs.getBoolean("biometrics", false);
        String pin = prefs.getString("pin", null);

        if (biometrics || !TextUtils.isEmpty(pin)) {
            long now = new Date().getTime();
            long last_authentication = prefs.getLong("last_authentication", 0);
            long biometrics_timeout = prefs.getInt("biometrics_timeout", 2) * 60 * 1000L;
            Log.i("Authentication valid until=" + new Date(last_authentication + biometrics_timeout));

            if (last_authentication + biometrics_timeout < now)
                return true;

            prefs.edit().putLong("last_authentication", now).apply();
        }

        return false;
    }

    static void authenticate(final FragmentActivity activity,
                             Boolean enabled, final
                             Runnable authenticated, final Runnable cancelled) {
        final Handler handler = new Handler();

        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
        String pin = prefs.getString("pin", null);

        if (enabled != null || TextUtils.isEmpty(pin)) {
            BiometricPrompt.PromptInfo.Builder info = new BiometricPrompt.PromptInfo.Builder()
                    .setTitle(activity.getString(enabled == null ? R.string.app_name : R.string.title_setup_biometrics));

            KeyguardManager kgm = (KeyguardManager) activity.getSystemService(Context.KEYGUARD_SERVICE);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && kgm != null && kgm.isDeviceSecure())
                info.setDeviceCredentialAllowed(true);
            else
                info.setNegativeButtonText(activity.getString(android.R.string.cancel));

            info.setConfirmationRequired(false);

            info.setSubtitle(activity.getString(enabled == null ? R.string.title_setup_biometrics_unlock
                    : enabled
                    ? R.string.title_setup_biometrics_disable
                    : R.string.title_setup_biometrics_enable));

            BiometricPrompt prompt = new BiometricPrompt(activity, executor,
                    new BiometricPrompt.AuthenticationCallback() {
                        @Override
                        public void onAuthenticationError(final int errorCode, @NonNull final CharSequence errString) {
                            Log.w("Biometric error " + errorCode + ": " + errString);

                            if (errorCode != BiometricPrompt.ERROR_NEGATIVE_BUTTON &&
                                    errorCode != BiometricPrompt.ERROR_CANCELED &&
                                    errorCode != BiometricPrompt.ERROR_USER_CANCELED)
                                handler.post(new Runnable() {
                                    @Override
                                    public void run() {
                                        ToastEx.makeText(activity,
                                                "Error " + errorCode + ": " + errString,
                                                Toast.LENGTH_LONG).show();
                                    }
                                });

                            handler.post(cancelled);
                        }

                        @Override
                        public void onAuthenticationSucceeded(@NonNull BiometricPrompt.AuthenticationResult result) {
                            Log.i("Biometric succeeded");
                            setAuthenticated(activity);
                            handler.post(authenticated);
                        }

                        @Override
                        public void onAuthenticationFailed() {
                            Log.w("Biometric failed");
                            handler.post(cancelled);
                        }
                    });

            prompt.authenticate(info.build());
        } else {
            final View dview = LayoutInflater.from(activity).inflate(R.layout.dialog_pin_ask, null);
            final EditText etPin = dview.findViewById(R.id.etPin);

            final AlertDialog dialog = new AlertDialog.Builder(activity)
                    .setView(dview)
                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
                            String pin = prefs.getString("pin", "");
                            String entered = etPin.getText().toString();

                            if (pin.equals(entered)) {
                                setAuthenticated(activity);
                                handler.post(authenticated);
                            } else
                                handler.post(cancelled);
                        }
                    })
                    .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            handler.post(cancelled);
                        }
                    })
                    .setOnDismissListener(new DialogInterface.OnDismissListener() {
                        @Override
                        public void onDismiss(DialogInterface dialog) {
                            handler.post(cancelled);
                        }
                    })
                    .create();

            etPin.setOnEditorActionListener(new TextView.OnEditorActionListener() {
                @Override
                public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                    if (actionId == EditorInfo.IME_ACTION_DONE) {
                        dialog.getButton(DialogInterface.BUTTON_POSITIVE).performClick();
                        return true;
                    } else
                        return false;
                }
            });

            etPin.setOnFocusChangeListener(new View.OnFocusChangeListener() {
                @Override
                public void onFocusChange(View v, boolean hasFocus) {
                    if (hasFocus)
                        dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
                }
            });

            new Handler().post(new Runnable() {
                @Override
                public void run() {
                    etPin.requestFocus();
                }
            });

            dialog.show();
        }
    }

    static void setAuthenticated(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        prefs.edit().putLong("last_authentication", new Date().getTime()).apply();
    }

    static void clearAuthentication(Context context) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        prefs.edit().remove("last_authentication").apply();
    }

    static void selectKeyAlias(final Activity activity, final LifecycleOwner owner, final String alias, final IKeyAlias intf) {
        final Context context = activity.getApplicationContext();
        final Handler handler = new Handler();

        new Thread(new Runnable() {
            @Override
            public void run() {
                if (alias != null)
                    try {
                        if (KeyChain.getPrivateKey(context, alias) != null) {
                            Log.i("Private key available alias=" + alias);
                            handler.post(new Runnable() {
                                @Override
                                public void run() {
                                    if (owner.getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.STARTED))
                                        intf.onSelected(alias);
                                }
                            });
                            return;
                        }
                    } catch (KeyChainException ex) {
                        Log.w(ex);
                    } catch (Throwable ex) {
                        Log.e(ex);
                    }

                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        KeyChain.choosePrivateKeyAlias(activity, new KeyChainAliasCallback() {
                                    @Override
                                    public void alias(@Nullable final String alias) {
                                        Log.i("Selected key alias=" + alias);
                                        handler.post(new Runnable() {
                                            @Override
                                            public void run() {
                                                if (owner.getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.STARTED)) {
                                                    if (alias == null)
                                                        intf.onNothingSelected();
                                                    else
                                                        intf.onSelected(alias);
                                                } else {
                                                    owner.getLifecycle().addObserver(new LifecycleObserver() {
                                                        @OnLifecycleEvent(Lifecycle.Event.ON_START)
                                                        public void onStart() {
                                                            owner.getLifecycle().removeObserver(this);
                                                            if (alias == null)
                                                                intf.onNothingSelected();
                                                            else
                                                                intf.onSelected(alias);
                                                        }
                                                    });
                                                }
                                            }
                                        });
                                    }
                                },
                                null, null, null, -1, alias);
                    }
                });
            }
        }).start();
    }

    interface IKeyAlias {
        void onSelected(String alias);

        void onNothingSelected();
    }

    public static String HMAC(String algo, int blocksize, byte[] key, byte[] text) throws NoSuchAlgorithmException {
        MessageDigest md = MessageDigest.getInstance(algo);

        if (key.length > blocksize)
            key = md.digest(key);

        byte[] ipad = new byte[blocksize];
        byte[] opad = new byte[blocksize];

        for (int i = 0; i < key.length; i++) {
            ipad[i] = key[i];
            opad[i] = key[i];
        }

        for (int i = 0; i < blocksize; i++) {
            ipad[i] ^= 0x36;
            opad[i] ^= 0x5c;
        }

        byte[] digest;

        md.update(ipad);
        md.update(text);
        digest = md.digest();

        md.update(opad);
        md.update(digest);
        digest = md.digest();

        StringBuilder sb = new StringBuilder();
        for (byte b : digest)
            sb.append(String.format("%02x", b));
        return sb.toString();
    }

    // Miscellaneous

    static <T> List<List<T>> chunkList(List<T> list, int size) {
        List<List<T>> result = new ArrayList<>(list.size() / size);
        for (int i = 0; i < list.size(); i += size)
            result.add(list.subList(i, i + size < list.size() ? i + size : list.size()));
        return result;
    }

    static long[] toLongArray(List<Long> list) {
        long[] result = new long[list.size()];
        for (int i = 0; i < list.size(); i++)
            result[i] = list.get(i);
        return result;
    }

    static List<Long> fromLongArray(long[] array) {
        List<Long> result = new ArrayList<>();
        for (int i = 0; i < array.length; i++)
            result.add(array[i]);
        return result;
    }

    static boolean equal(String[] a1, String[] a2) {
        if (a1.length != a2.length)
            return false;

        for (int i = 0; i < a1.length; i++)
            if (!a1[i].equals(a2[i]))
                return false;

        return true;
    }

    static int getSize(Bundle bundle) {
        Parcel p = Parcel.obtain();
        bundle.writeToParcel(p, 0);
        return p.dataSize();
    }
}