/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.android.exoplayer2.util;

import static android.content.Context.UI_MODE_SERVICE;

import android.Manifest.permission;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.app.UiModeManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.graphics.Point;
import android.media.AudioFormat;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.os.Parcel;
import android.security.NetworkSecurityPolicy;
import android.telephony.TelephonyManager;
import android.text.TextUtils;
import android.view.Display;
import android.view.WindowManager;
import androidx.annotation.Nullable;
import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.ExoPlayerLibraryInfo;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.ParserException;
import com.google.android.exoplayer2.Renderer;
import com.google.android.exoplayer2.RendererCapabilities;
import com.google.android.exoplayer2.RenderersFactory;
import com.google.android.exoplayer2.SeekParameters;
import com.google.android.exoplayer2.audio.AudioRendererEventListener;
import com.google.android.exoplayer2.drm.DrmSessionManager;
import com.google.android.exoplayer2.drm.FrameworkMediaCrypto;
import com.google.android.exoplayer2.upstream.DataSource;
import com.google.android.exoplayer2.video.VideoRendererEventListener;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collections;
import java.util.Formatter;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.TimeZone;
import java.util.UUID;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.DataFormatException;
import java.util.zip.Inflater;
import org.checkerframework.checker.initialization.qual.UnknownInitialization;
import org.checkerframework.checker.nullness.compatqual.NullableType;
import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
import org.checkerframework.checker.nullness.qual.PolyNull;

/**
 * Miscellaneous utility methods.
 */
public final class Util {

  /**
   * Like {@link Build.VERSION#SDK_INT}, but in a place where it can be conveniently
   * overridden for local testing.
   */
  public static final int SDK_INT = Build.VERSION.SDK_INT;

  /**
   * Like {@link Build#DEVICE}, but in a place where it can be conveniently overridden for local
   * testing.
   */
  public static final String DEVICE = Build.DEVICE;

  /**
   * Like {@link Build#MANUFACTURER}, but in a place where it can be conveniently overridden for
   * local testing.
   */
  public static final String MANUFACTURER = Build.MANUFACTURER;

  /**
   * Like {@link Build#MODEL}, but in a place where it can be conveniently overridden for local
   * testing.
   */
  public static final String MODEL = Build.MODEL;

  /**
   * A concise description of the device that it can be useful to log for debugging purposes.
   */
  public static final String DEVICE_DEBUG_INFO = DEVICE + ", " + MODEL + ", " + MANUFACTURER + ", "
      + SDK_INT;

  /** An empty byte array. */
  public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];

  private static final String TAG = "Util";
  private static final Pattern XS_DATE_TIME_PATTERN = Pattern.compile(
      "(\\d\\d\\d\\d)\\-(\\d\\d)\\-(\\d\\d)[Tt]"
      + "(\\d\\d):(\\d\\d):(\\d\\d)([\\.,](\\d+))?"
      + "([Zz]|((\\+|\\-)(\\d?\\d):?(\\d\\d)))?");
  private static final Pattern XS_DURATION_PATTERN =
      Pattern.compile("^(-)?P(([0-9]*)Y)?(([0-9]*)M)?(([0-9]*)D)?"
          + "(T(([0-9]*)H)?(([0-9]*)M)?(([0-9.]*)S)?)?$");
  private static final Pattern ESCAPED_CHARACTER_PATTERN = Pattern.compile("%([A-Fa-f0-9]{2})");

  // Android standardizes to ISO 639-1 2-letter codes and provides no way to map a 3-letter
  // ISO 639-2 code back to the corresponding 2-letter code.
  @Nullable private static HashMap<String, String> languageTagIso3ToIso2;

  private Util() {}

  /**
   * Converts the entirety of an {@link InputStream} to a byte array.
   *
   * @param inputStream the {@link InputStream} to be read. The input stream is not closed by this
   *     method.
   * @return a byte array containing all of the inputStream's bytes.
   * @throws IOException if an error occurs reading from the stream.
   */
  public static byte[] toByteArray(InputStream inputStream) throws IOException {
    byte[] buffer = new byte[1024 * 4];
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    int bytesRead;
    while ((bytesRead = inputStream.read(buffer)) != -1) {
      outputStream.write(buffer, 0, bytesRead);
    }
    return outputStream.toByteArray();
  }

  /**
   * Calls {@link Context#startForegroundService(Intent)} if {@link #SDK_INT} is 26 or higher, or
   * {@link Context#startService(Intent)} otherwise.
   *
   * @param context The context to call.
   * @param intent The intent to pass to the called method.
   * @return The result of the called method.
   */
  @Nullable
  public static ComponentName startForegroundService(Context context, Intent intent) {
    if (Util.SDK_INT >= 26) {
      return context.startForegroundService(intent);
    } else {
      return context.startService(intent);
    }
  }

  /**
   * Checks whether it's necessary to request the {@link permission#READ_EXTERNAL_STORAGE}
   * permission read the specified {@link Uri}s, requesting the permission if necessary.
   *
   * @param activity The host activity for checking and requesting the permission.
   * @param uris {@link Uri}s that may require {@link permission#READ_EXTERNAL_STORAGE} to read.
   * @return Whether a permission request was made.
   */
  @TargetApi(23)
  public static boolean maybeRequestReadExternalStoragePermission(Activity activity, Uri... uris) {
    if (Util.SDK_INT < 23) {
      return false;
    }
    for (Uri uri : uris) {
      if (isLocalFileUri(uri)) {
        if (activity.checkSelfPermission(permission.READ_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {
          activity.requestPermissions(new String[] {permission.READ_EXTERNAL_STORAGE}, 0);
          return true;
        }
        break;
      }
    }
    return false;
  }

  /**
   * Returns whether it may be possible to load the given URIs based on the network security
   * policy's cleartext traffic permissions.
   *
   * @param uris A list of URIs that will be loaded.
   * @return Whether it may be possible to load the given URIs.
   */
  @TargetApi(24)
  public static boolean checkCleartextTrafficPermitted(Uri... uris) {
    if (Util.SDK_INT < 24) {
      // We assume cleartext traffic is permitted.
      return true;
    }
    for (Uri uri : uris) {
      if ("http".equals(uri.getScheme())
          && !NetworkSecurityPolicy.getInstance()
              .isCleartextTrafficPermitted(Assertions.checkNotNull(uri.getHost()))) {
        // The security policy prevents cleartext traffic.
        return false;
      }
    }
    return true;
  }

  /**
   * Returns true if the URI is a path to a local file or a reference to a local file.
   *
   * @param uri The uri to test.
   */
  public static boolean isLocalFileUri(Uri uri) {
    String scheme = uri.getScheme();
    return TextUtils.isEmpty(scheme) || "file".equals(scheme);
  }

  /**
   * Tests two objects for {@link Object#equals(Object)} equality, handling the case where one or
   * both may be null.
   *
   * @param o1 The first object.
   * @param o2 The second object.
   * @return {@code o1 == null ? o2 == null : o1.equals(o2)}.
   */
  public static boolean areEqual(@Nullable Object o1, @Nullable Object o2) {
    return o1 == null ? o2 == null : o1.equals(o2);
  }

  /**
   * Tests whether an {@code items} array contains an object equal to {@code item}, according to
   * {@link Object#equals(Object)}.
   *
   * <p>If {@code item} is null then true is returned if and only if {@code items} contains null.
   *
   * @param items The array of items to search.
   * @param item The item to search for.
   * @return True if the array contains an object equal to the item being searched for.
   */
  public static boolean contains(@NullableType Object[] items, @Nullable Object item) {
    for (Object arrayItem : items) {
      if (areEqual(arrayItem, item)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Removes an indexed range from a List.
   *
   * <p>Does nothing if the provided range is valid and {@code fromIndex == toIndex}.
   *
   * @param list The List to remove the range from.
   * @param fromIndex The first index to be removed (inclusive).
   * @param toIndex The last index to be removed (exclusive).
   * @throws IllegalArgumentException If {@code fromIndex} &lt; 0, {@code toIndex} &gt; {@code
   *     list.size()}, or {@code fromIndex} &gt; {@code toIndex}.
   */
  public static <T> void removeRange(List<T> list, int fromIndex, int toIndex) {
    if (fromIndex < 0 || toIndex > list.size() || fromIndex > toIndex) {
      throw new IllegalArgumentException();
    } else if (fromIndex != toIndex) {
      // Checking index inequality prevents an unnecessary allocation.
      list.subList(fromIndex, toIndex).clear();
    }
  }

  /**
   * Casts a nullable variable to a non-null variable without runtime null check.
   *
   * <p>Use {@link Assertions#checkNotNull(Object)} to throw if the value is null.
   */
  @SuppressWarnings({"contracts.postcondition.not.satisfied", "return.type.incompatible"})
  @EnsuresNonNull("#1")
  public static <T> T castNonNull(@Nullable T value) {
    return value;
  }

  /** Casts a nullable type array to a non-null type array without runtime null check. */
  @SuppressWarnings({"contracts.postcondition.not.satisfied", "return.type.incompatible"})
  @EnsuresNonNull("#1")
  public static <T> T[] castNonNullTypeArray(@NullableType T[] value) {
    return value;
  }

  /**
   * Copies and optionally truncates an array. Prevents null array elements created by {@link
   * Arrays#copyOf(Object[], int)} by ensuring the new length does not exceed the current length.
   *
   * @param input The input array.
   * @param length The output array length. Must be less or equal to the length of the input array.
   * @return The copied array.
   */
  @SuppressWarnings({"nullness:argument.type.incompatible", "nullness:return.type.incompatible"})
  public static <T> T[] nullSafeArrayCopy(T[] input, int length) {
    Assertions.checkArgument(length <= input.length);
    return Arrays.copyOf(input, length);
  }

  /**
   * Copies a subset of an array.
   *
   * @param input The input array.
   * @param from The start the range to be copied, inclusive
   * @param to The end of the range to be copied, exclusive.
   * @return The copied array.
   */
  @SuppressWarnings({"nullness:argument.type.incompatible", "nullness:return.type.incompatible"})
  public static <T> T[] nullSafeArrayCopyOfRange(T[] input, int from, int to) {
    Assertions.checkArgument(0 <= from);
    Assertions.checkArgument(to <= input.length);
    return Arrays.copyOfRange(input, from, to);
  }

  /**
   * Creates a new array containing {@code original} with {@code newElement} appended.
   *
   * @param original The input array.
   * @param newElement The element to append.
   * @return The new array.
   */
  public static <T> T[] nullSafeArrayAppend(T[] original, T newElement) {
    @NullableType T[] result = Arrays.copyOf(original, original.length + 1);
    result[original.length] = newElement;
    return castNonNullTypeArray(result);
  }

  /**
   * Creates a new array containing the concatenation of two non-null type arrays.
   *
   * @param first The first array.
   * @param second The second array.
   * @return The concatenated result.
   */
  @SuppressWarnings({"nullness:assignment.type.incompatible"})
  public static <T> T[] nullSafeArrayConcatenation(T[] first, T[] second) {
    T[] concatenation = Arrays.copyOf(first, first.length + second.length);
    System.arraycopy(
        /* src= */ second,
        /* srcPos= */ 0,
        /* dest= */ concatenation,
        /* destPos= */ first.length,
        /* length= */ second.length);
    return concatenation;
  }
  /**
   * Creates a {@link Handler} with the specified {@link Handler.Callback} on the current {@link
   * Looper} thread. The method accepts partially initialized objects as callback under the
   * assumption that the Handler won't be used to send messages until the callback is fully
   * initialized.
   *
   * <p>If the current thread doesn't have a {@link Looper}, the application's main thread {@link
   * Looper} is used.
   *
   * @param callback A {@link Handler.Callback}. May be a partially initialized class.
   * @return A {@link Handler} with the specified callback on the current {@link Looper} thread.
   */
  public static Handler createHandler([email protected] Callback callback) {
    return createHandler(getLooper(), callback);
  }

  /**
   * Creates a {@link Handler} with the specified {@link Handler.Callback} on the specified {@link
   * Looper} thread. The method accepts partially initialized objects as callback under the
   * assumption that the Handler won't be used to send messages until the callback is fully
   * initialized.
   *
   * @param looper A {@link Looper} to run the callback on.
   * @param callback A {@link Handler.Callback}. May be a partially initialized class.
   * @return A {@link Handler} with the specified callback on the current {@link Looper} thread.
   */
  @SuppressWarnings({"nullness:argument.type.incompatible", "nullness:return.type.incompatible"})
  public static Handler createHandler(
      Looper looper, [email protected] Callback callback) {
    return new Handler(looper, callback);
  }

  /**
   * Returns the {@link Looper} associated with the current thread, or the {@link Looper} of the
   * application's main thread if the current thread doesn't have a {@link Looper}.
   */
  public static Looper getLooper() {
    Looper myLooper = Looper.myLooper();
    return myLooper != null ? myLooper : Looper.getMainLooper();
  }

  /**
   * Instantiates a new single threaded executor whose thread has the specified name.
   *
   * @param threadName The name of the thread.
   * @return The executor.
   */
  public static ExecutorService newSingleThreadExecutor(final String threadName) {
    return Executors.newSingleThreadExecutor(runnable -> new Thread(runnable, threadName));
  }

  /**
   * Closes a {@link DataSource}, suppressing any {@link IOException} that may occur.
   *
   * @param dataSource The {@link DataSource} to close.
   */
  public static void closeQuietly(@Nullable DataSource dataSource) {
    try {
      if (dataSource != null) {
        dataSource.close();
      }
    } catch (IOException e) {
      // Ignore.
    }
  }

  /**
   * Closes a {@link Closeable}, suppressing any {@link IOException} that may occur. Both {@link
   * java.io.OutputStream} and {@link InputStream} are {@code Closeable}.
   *
   * @param closeable The {@link Closeable} to close.
   */
  public static void closeQuietly(@Nullable Closeable closeable) {
    try {
      if (closeable != null) {
        closeable.close();
      }
    } catch (IOException e) {
      // Ignore.
    }
  }

  /**
   * Reads an integer from a {@link Parcel} and interprets it as a boolean, with 0 mapping to false
   * and all other values mapping to true.
   *
   * @param parcel The {@link Parcel} to read from.
   * @return The read value.
   */
  public static boolean readBoolean(Parcel parcel) {
    return parcel.readInt() != 0;
  }

  /**
   * Writes a boolean to a {@link Parcel}. The boolean is written as an integer with value 1 (true)
   * or 0 (false).
   *
   * @param parcel The {@link Parcel} to write to.
   * @param value The value to write.
   */
  public static void writeBoolean(Parcel parcel, boolean value) {
    parcel.writeInt(value ? 1 : 0);
  }

  /**
   * Returns the language tag for a {@link Locale}.
   *
   * <p>For API levels &ge; 21, this tag is IETF BCP 47 compliant. Use {@link
   * #normalizeLanguageCode(String)} to retrieve a normalized IETF BCP 47 language tag for all API
   * levels if needed.
   *
   * @param locale A {@link Locale}.
   * @return The language tag.
   */
  public static String getLocaleLanguageTag(Locale locale) {
    return SDK_INT >= 21 ? getLocaleLanguageTagV21(locale) : locale.toString();
  }

  /**
   * Returns a normalized IETF BCP 47 language tag for {@code language}.
   *
   * @param language A case-insensitive language code supported by {@link
   *     Locale#forLanguageTag(String)}.
   * @return The all-lowercase normalized code, or null if the input was null, or {@code
   *     language.toLowerCase()} if the language could not be normalized.
   */
  public static @PolyNull String normalizeLanguageCode(@PolyNull String language) {
    if (language == null) {
      return null;
    }
    // Locale data (especially for API < 21) may produce tags with '_' instead of the
    // standard-conformant '-'.
    String normalizedTag = language.replace('_', '-');
    if (Util.SDK_INT >= 21) {
      // Filters out ill-formed sub-tags, replaces deprecated tags and normalizes all valid tags.
      normalizedTag = normalizeLanguageCodeSyntaxV21(normalizedTag);
    }
    if (normalizedTag.isEmpty() || "und".equals(normalizedTag)) {
      // Tag isn't valid, keep using the original.
      normalizedTag = language;
    }
    normalizedTag = Util.toLowerInvariant(normalizedTag);
    String mainLanguage = Util.splitAtFirst(normalizedTag, "-")[0];
    if (mainLanguage.length() == 3) {
      // 3-letter ISO 639-2/B or ISO 639-2/T language codes will not be converted to 2-letter ISO
      // 639-1 codes automatically.
      if (languageTagIso3ToIso2 == null) {
        languageTagIso3ToIso2 = createIso3ToIso2Map();
      }
      String iso2Language = languageTagIso3ToIso2.get(mainLanguage);
      if (iso2Language != null) {
        normalizedTag = iso2Language + normalizedTag.substring(/* beginIndex= */ 3);
      }
    }
    return normalizedTag;
  }

  /**
   * Returns a new {@link String} constructed by decoding UTF-8 encoded bytes.
   *
   * @param bytes The UTF-8 encoded bytes to decode.
   * @return The string.
   */
  public static String fromUtf8Bytes(byte[] bytes) {
    return new String(bytes, Charset.forName(C.UTF8_NAME));
  }

  /**
   * Returns a new {@link String} constructed by decoding UTF-8 encoded bytes in a subarray.
   *
   * @param bytes The UTF-8 encoded bytes to decode.
   * @param offset The index of the first byte to decode.
   * @param length The number of bytes to decode.
   * @return The string.
   */
  public static String fromUtf8Bytes(byte[] bytes, int offset, int length) {
    return new String(bytes, offset, length, Charset.forName(C.UTF8_NAME));
  }

  /**
   * Returns a new byte array containing the code points of a {@link String} encoded using UTF-8.
   *
   * @param value The {@link String} whose bytes should be obtained.
   * @return The code points encoding using UTF-8.
   */
  public static byte[] getUtf8Bytes(String value) {
    return value.getBytes(Charset.forName(C.UTF8_NAME));
  }

  /**
   * Splits a string using {@code value.split(regex, -1}). Note: this is is similar to {@link
   * String#split(String)} but empty matches at the end of the string will not be omitted from the
   * returned array.
   *
   * @param value The string to split.
   * @param regex A delimiting regular expression.
   * @return The array of strings resulting from splitting the string.
   */
  public static String[] split(String value, String regex) {
    return value.split(regex, /* limit= */ -1);
  }

  /**
   * Splits the string at the first occurrence of the delimiter {@code regex}. If the delimiter does
   * not match, returns an array with one element which is the input string. If the delimiter does
   * match, returns an array with the portion of the string before the delimiter and the rest of the
   * string.
   *
   * @param value The string.
   * @param regex A delimiting regular expression.
   * @return The string split by the first occurrence of the delimiter.
   */
  public static String[] splitAtFirst(String value, String regex) {
    return value.split(regex, /* limit= */ 2);
  }

  /**
   * Returns whether the given character is a carriage return ('\r') or a line feed ('\n').
   *
   * @param c The character.
   * @return Whether the given character is a linebreak.
   */
  public static boolean isLinebreak(int c) {
    return c == '\n' || c == '\r';
  }

  /**
   * Converts text to lower case using {@link Locale#US}.
   *
   * @param text The text to convert.
   * @return The lower case text, or null if {@code text} is null.
   */
  public static @PolyNull String toLowerInvariant(@PolyNull String text) {
    return text == null ? text : text.toLowerCase(Locale.US);
  }

  /**
   * Converts text to upper case using {@link Locale#US}.
   *
   * @param text The text to convert.
   * @return The upper case text, or null if {@code text} is null.
   */
  public static @PolyNull String toUpperInvariant(@PolyNull String text) {
    return text == null ? text : text.toUpperCase(Locale.US);
  }

  /**
   * Formats a string using {@link Locale#US}.
   *
   * @see String#format(String, Object...)
   */
  public static String formatInvariant(String format, Object... args) {
    return String.format(Locale.US, format, args);
  }

  /**
   * Divides a {@code numerator} by a {@code denominator}, returning the ceiled result.
   *
   * @param numerator The numerator to divide.
   * @param denominator The denominator to divide by.
   * @return The ceiled result of the division.
   */
  public static int ceilDivide(int numerator, int denominator) {
    return (numerator + denominator - 1) / denominator;
  }

  /**
   * Divides a {@code numerator} by a {@code denominator}, returning the ceiled result.
   *
   * @param numerator The numerator to divide.
   * @param denominator The denominator to divide by.
   * @return The ceiled result of the division.
   */
  public static long ceilDivide(long numerator, long denominator) {
    return (numerator + denominator - 1) / denominator;
  }

  /**
   * Constrains a value to the specified bounds.
   *
   * @param value The value to constrain.
   * @param min The lower bound.
   * @param max The upper bound.
   * @return The constrained value {@code Math.max(min, Math.min(value, max))}.
   */
  public static int constrainValue(int value, int min, int max) {
    return Math.max(min, Math.min(value, max));
  }

  /**
   * Constrains a value to the specified bounds.
   *
   * @param value The value to constrain.
   * @param min The lower bound.
   * @param max The upper bound.
   * @return The constrained value {@code Math.max(min, Math.min(value, max))}.
   */
  public static long constrainValue(long value, long min, long max) {
    return Math.max(min, Math.min(value, max));
  }

  /**
   * Constrains a value to the specified bounds.
   *
   * @param value The value to constrain.
   * @param min The lower bound.
   * @param max The upper bound.
   * @return The constrained value {@code Math.max(min, Math.min(value, max))}.
   */
  public static float constrainValue(float value, float min, float max) {
    return Math.max(min, Math.min(value, max));
  }

  /**
   * Returns the sum of two arguments, or a third argument if the result overflows.
   *
   * @param x The first value.
   * @param y The second value.
   * @param overflowResult The return value if {@code x + y} overflows.
   * @return {@code x + y}, or {@code overflowResult} if the result overflows.
   */
  public static long addWithOverflowDefault(long x, long y, long overflowResult) {
    long result = x + y;
    // See Hacker's Delight 2-13 (H. Warren Jr).
    if (((x ^ result) & (y ^ result)) < 0) {
      return overflowResult;
    }
    return result;
  }

  /**
   * Returns the difference between two arguments, or a third argument if the result overflows.
   *
   * @param x The first value.
   * @param y The second value.
   * @param overflowResult The return value if {@code x - y} overflows.
   * @return {@code x - y}, or {@code overflowResult} if the result overflows.
   */
  public static long subtractWithOverflowDefault(long x, long y, long overflowResult) {
    long result = x - y;
    // See Hacker's Delight 2-13 (H. Warren Jr).
    if (((x ^ y) & (x ^ result)) < 0) {
      return overflowResult;
    }
    return result;
  }

  /**
   * Returns the index of the first occurrence of {@code value} in {@code array}, or {@link
   * C#INDEX_UNSET} if {@code value} is not contained in {@code array}.
   *
   * @param array The array to search.
   * @param value The value to search for.
   * @return The index of the first occurrence of value in {@code array}, or {@link C#INDEX_UNSET}
   *     if {@code value} is not contained in {@code array}.
   */
  public static int linearSearch(int[] array, int value) {
    for (int i = 0; i < array.length; i++) {
      if (array[i] == value) {
        return i;
      }
    }
    return C.INDEX_UNSET;
  }

  /**
   * Returns the index of the largest element in {@code array} that is less than (or optionally
   * equal to) a specified {@code value}.
   *
   * <p>The search is performed using a binary search algorithm, so the array must be sorted. If the
   * array contains multiple elements equal to {@code value} and {@code inclusive} is true, the
   * index of the first one will be returned.
   *
   * @param array The array to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the array, whether to return the corresponding
   *     index. If false then the returned index corresponds to the largest element strictly less
   *     than the value.
   * @param stayInBounds If true, then 0 will be returned in the case that the value is smaller than
   *     the smallest element in the array. If false then -1 will be returned.
   * @return The index of the largest element in {@code array} that is less than (or optionally
   *     equal to) {@code value}.
   */
  public static int binarySearchFloor(
      int[] array, int value, boolean inclusive, boolean stayInBounds) {
    int index = Arrays.binarySearch(array, value);
    if (index < 0) {
      index = -(index + 2);
    } else {
      while (--index >= 0 && array[index] == value) {}
      if (inclusive) {
        index++;
      }
    }
    return stayInBounds ? Math.max(0, index) : index;
  }

  /**
   * Returns the index of the largest element in {@code array} that is less than (or optionally
   * equal to) a specified {@code value}.
   * <p>
   * The search is performed using a binary search algorithm, so the array must be sorted. If the
   * array contains multiple elements equal to {@code value} and {@code inclusive} is true, the
   * index of the first one will be returned.
   *
   * @param array The array to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the array, whether to return the corresponding
   *     index. If false then the returned index corresponds to the largest element strictly less
   *     than the value.
   * @param stayInBounds If true, then 0 will be returned in the case that the value is smaller than
   *     the smallest element in the array. If false then -1 will be returned.
   * @return The index of the largest element in {@code array} that is less than (or optionally
   *     equal to) {@code value}.
   */
  public static int binarySearchFloor(long[] array, long value, boolean inclusive,
      boolean stayInBounds) {
    int index = Arrays.binarySearch(array, value);
    if (index < 0) {
      index = -(index + 2);
    } else {
      while (--index >= 0 && array[index] == value) {}
      if (inclusive) {
        index++;
      }
    }
    return stayInBounds ? Math.max(0, index) : index;
  }

  /**
   * Returns the index of the largest element in {@code list} that is less than (or optionally equal
   * to) a specified {@code value}.
   *
   * <p>The search is performed using a binary search algorithm, so the list must be sorted. If the
   * list contains multiple elements equal to {@code value} and {@code inclusive} is true, the index
   * of the first one will be returned.
   *
   * @param <T> The type of values being searched.
   * @param list The list to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the list, whether to return the corresponding
   *     index. If false then the returned index corresponds to the largest element strictly less
   *     than the value.
   * @param stayInBounds If true, then 0 will be returned in the case that the value is smaller than
   *     the smallest element in the list. If false then -1 will be returned.
   * @return The index of the largest element in {@code list} that is less than (or optionally equal
   *     to) {@code value}.
   */
  public static <T extends Comparable<? super T>> int binarySearchFloor(
      List<? extends Comparable<? super T>> list,
      T value,
      boolean inclusive,
      boolean stayInBounds) {
    int index = Collections.binarySearch(list, value);
    if (index < 0) {
      index = -(index + 2);
    } else {
      while (--index >= 0 && list.get(index).compareTo(value) == 0) {}
      if (inclusive) {
        index++;
      }
    }
    return stayInBounds ? Math.max(0, index) : index;
  }

  /**
   * Returns the index of the smallest element in {@code array} that is greater than (or optionally
   * equal to) a specified {@code value}.
   *
   * <p>The search is performed using a binary search algorithm, so the array must be sorted. If the
   * array contains multiple elements equal to {@code value} and {@code inclusive} is true, the
   * index of the last one will be returned.
   *
   * @param array The array to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the array, whether to return the corresponding
   *     index. If false then the returned index corresponds to the smallest element strictly
   *     greater than the value.
   * @param stayInBounds If true, then {@code (a.length - 1)} will be returned in the case that the
   *     value is greater than the largest element in the array. If false then {@code a.length} will
   *     be returned.
   * @return The index of the smallest element in {@code array} that is greater than (or optionally
   *     equal to) {@code value}.
   */
  public static int binarySearchCeil(
      int[] array, int value, boolean inclusive, boolean stayInBounds) {
    int index = Arrays.binarySearch(array, value);
    if (index < 0) {
      index = ~index;
    } else {
      while (++index < array.length && array[index] == value) {}
      if (inclusive) {
        index--;
      }
    }
    return stayInBounds ? Math.min(array.length - 1, index) : index;
  }

  /**
   * Returns the index of the smallest element in {@code array} that is greater than (or optionally
   * equal to) a specified {@code value}.
   *
   * <p>The search is performed using a binary search algorithm, so the array must be sorted. If the
   * array contains multiple elements equal to {@code value} and {@code inclusive} is true, the
   * index of the last one will be returned.
   *
   * @param array The array to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the array, whether to return the corresponding
   *     index. If false then the returned index corresponds to the smallest element strictly
   *     greater than the value.
   * @param stayInBounds If true, then {@code (a.length - 1)} will be returned in the case that the
   *     value is greater than the largest element in the array. If false then {@code a.length} will
   *     be returned.
   * @return The index of the smallest element in {@code array} that is greater than (or optionally
   *     equal to) {@code value}.
   */
  public static int binarySearchCeil(
      long[] array, long value, boolean inclusive, boolean stayInBounds) {
    int index = Arrays.binarySearch(array, value);
    if (index < 0) {
      index = ~index;
    } else {
      while (++index < array.length && array[index] == value) {}
      if (inclusive) {
        index--;
      }
    }
    return stayInBounds ? Math.min(array.length - 1, index) : index;
  }

  /**
   * Returns the index of the smallest element in {@code list} that is greater than (or optionally
   * equal to) a specified value.
   *
   * <p>The search is performed using a binary search algorithm, so the list must be sorted. If the
   * list contains multiple elements equal to {@code value} and {@code inclusive} is true, the index
   * of the last one will be returned.
   *
   * @param <T> The type of values being searched.
   * @param list The list to search.
   * @param value The value being searched for.
   * @param inclusive If the value is present in the list, whether to return the corresponding
   *     index. If false then the returned index corresponds to the smallest element strictly
   *     greater than the value.
   * @param stayInBounds If true, then {@code (list.size() - 1)} will be returned in the case that
   *     the value is greater than the largest element in the list. If false then {@code
   *     list.size()} will be returned.
   * @return The index of the smallest element in {@code list} that is greater than (or optionally
   *     equal to) {@code value}.
   */
  public static <T extends Comparable<? super T>> int binarySearchCeil(
      List<? extends Comparable<? super T>> list,
      T value,
      boolean inclusive,
      boolean stayInBounds) {
    int index = Collections.binarySearch(list, value);
    if (index < 0) {
      index = ~index;
    } else {
      int listSize = list.size();
      while (++index < listSize && list.get(index).compareTo(value) == 0) {}
      if (inclusive) {
        index--;
      }
    }
    return stayInBounds ? Math.min(list.size() - 1, index) : index;
  }

  /**
   * Compares two long values and returns the same value as {@code Long.compare(long, long)}.
   *
   * @param left The left operand.
   * @param right The right operand.
   * @return 0, if left == right, a negative value if left &lt; right, or a positive value if left
   *     &gt; right.
   */
  public static int compareLong(long left, long right) {
    return left < right ? -1 : left == right ? 0 : 1;
  }

  /**
   * Parses an xs:duration attribute value, returning the parsed duration in milliseconds.
   *
   * @param value The attribute value to decode.
   * @return The parsed duration in milliseconds.
   */
  public static long parseXsDuration(String value) {
    Matcher matcher = XS_DURATION_PATTERN.matcher(value);
    if (matcher.matches()) {
      boolean negated = !TextUtils.isEmpty(matcher.group(1));
      // Durations containing years and months aren't completely defined. We assume there are
      // 30.4368 days in a month, and 365.242 days in a year.
      String years = matcher.group(3);
      double durationSeconds = (years != null) ? Double.parseDouble(years) * 31556908 : 0;
      String months = matcher.group(5);
      durationSeconds += (months != null) ? Double.parseDouble(months) * 2629739 : 0;
      String days = matcher.group(7);
      durationSeconds += (days != null) ? Double.parseDouble(days) * 86400 : 0;
      String hours = matcher.group(10);
      durationSeconds += (hours != null) ? Double.parseDouble(hours) * 3600 : 0;
      String minutes = matcher.group(12);
      durationSeconds += (minutes != null) ? Double.parseDouble(minutes) * 60 : 0;
      String seconds = matcher.group(14);
      durationSeconds += (seconds != null) ? Double.parseDouble(seconds) : 0;
      long durationMillis = (long) (durationSeconds * 1000);
      return negated ? -durationMillis : durationMillis;
    } else {
      return (long) (Double.parseDouble(value) * 3600 * 1000);
    }
  }

  /**
   * Parses an xs:dateTime attribute value, returning the parsed timestamp in milliseconds since
   * the epoch.
   *
   * @param value The attribute value to decode.
   * @return The parsed timestamp in milliseconds since the epoch.
   * @throws ParserException if an error occurs parsing the dateTime attribute value.
   */
  public static long parseXsDateTime(String value) throws ParserException {
    Matcher matcher = XS_DATE_TIME_PATTERN.matcher(value);
    if (!matcher.matches()) {
      throw new ParserException("Invalid date/time format: " + value);
    }

    int timezoneShift;
    if (matcher.group(9) == null) {
      // No time zone specified.
      timezoneShift = 0;
    } else if (matcher.group(9).equalsIgnoreCase("Z")) {
      timezoneShift = 0;
    } else {
      timezoneShift = ((Integer.parseInt(matcher.group(12)) * 60
          + Integer.parseInt(matcher.group(13))));
      if ("-".equals(matcher.group(11))) {
        timezoneShift *= -1;
      }
    }

    Calendar dateTime = new GregorianCalendar(TimeZone.getTimeZone("GMT"));

    dateTime.clear();
    // Note: The month value is 0-based, hence the -1 on group(2)
    dateTime.set(Integer.parseInt(matcher.group(1)),
                 Integer.parseInt(matcher.group(2)) - 1,
                 Integer.parseInt(matcher.group(3)),
                 Integer.parseInt(matcher.group(4)),
                 Integer.parseInt(matcher.group(5)),
                 Integer.parseInt(matcher.group(6)));
    if (!TextUtils.isEmpty(matcher.group(8))) {
      final BigDecimal bd = new BigDecimal("0." + matcher.group(8));
      // we care only for milliseconds, so movePointRight(3)
      dateTime.set(Calendar.MILLISECOND, bd.movePointRight(3).intValue());
    }

    long time = dateTime.getTimeInMillis();
    if (timezoneShift != 0) {
      time -= timezoneShift * 60000;
    }

    return time;
  }

  /**
   * Scales a large timestamp.
   * <p>
   * Logically, scaling consists of a multiplication followed by a division. The actual operations
   * performed are designed to minimize the probability of overflow.
   *
   * @param timestamp The timestamp to scale.
   * @param multiplier The multiplier.
   * @param divisor The divisor.
   * @return The scaled timestamp.
   */
  public static long scaleLargeTimestamp(long timestamp, long multiplier, long divisor) {
    if (divisor >= multiplier && (divisor % multiplier) == 0) {
      long divisionFactor = divisor / multiplier;
      return timestamp / divisionFactor;
    } else if (divisor < multiplier && (multiplier % divisor) == 0) {
      long multiplicationFactor = multiplier / divisor;
      return timestamp * multiplicationFactor;
    } else {
      double multiplicationFactor = (double) multiplier / divisor;
      return (long) (timestamp * multiplicationFactor);
    }
  }

  /**
   * Applies {@link #scaleLargeTimestamp(long, long, long)} to a list of unscaled timestamps.
   *
   * @param timestamps The timestamps to scale.
   * @param multiplier The multiplier.
   * @param divisor The divisor.
   * @return The scaled timestamps.
   */
  public static long[] scaleLargeTimestamps(List<Long> timestamps, long multiplier, long divisor) {
    long[] scaledTimestamps = new long[timestamps.size()];
    if (divisor >= multiplier && (divisor % multiplier) == 0) {
      long divisionFactor = divisor / multiplier;
      for (int i = 0; i < scaledTimestamps.length; i++) {
        scaledTimestamps[i] = timestamps.get(i) / divisionFactor;
      }
    } else if (divisor < multiplier && (multiplier % divisor) == 0) {
      long multiplicationFactor = multiplier / divisor;
      for (int i = 0; i < scaledTimestamps.length; i++) {
        scaledTimestamps[i] = timestamps.get(i) * multiplicationFactor;
      }
    } else {
      double multiplicationFactor = (double) multiplier / divisor;
      for (int i = 0; i < scaledTimestamps.length; i++) {
        scaledTimestamps[i] = (long) (timestamps.get(i) * multiplicationFactor);
      }
    }
    return scaledTimestamps;
  }

  /**
   * Applies {@link #scaleLargeTimestamp(long, long, long)} to an array of unscaled timestamps.
   *
   * @param timestamps The timestamps to scale.
   * @param multiplier The multiplier.
   * @param divisor The divisor.
   */
  public static void scaleLargeTimestampsInPlace(long[] timestamps, long multiplier, long divisor) {
    if (divisor >= multiplier && (divisor % multiplier) == 0) {
      long divisionFactor = divisor / multiplier;
      for (int i = 0; i < timestamps.length; i++) {
        timestamps[i] /= divisionFactor;
      }
    } else if (divisor < multiplier && (multiplier % divisor) == 0) {
      long multiplicationFactor = multiplier / divisor;
      for (int i = 0; i < timestamps.length; i++) {
        timestamps[i] *= multiplicationFactor;
      }
    } else {
      double multiplicationFactor = (double) multiplier / divisor;
      for (int i = 0; i < timestamps.length; i++) {
        timestamps[i] = (long) (timestamps[i] * multiplicationFactor);
      }
    }
  }

  /**
   * Returns the duration of media that will elapse in {@code playoutDuration}.
   *
   * @param playoutDuration The duration to scale.
   * @param speed The playback speed.
   * @return The scaled duration, in the same units as {@code playoutDuration}.
   */
  public static long getMediaDurationForPlayoutDuration(long playoutDuration, float speed) {
    if (speed == 1f) {
      return playoutDuration;
    }
    return Math.round((double) playoutDuration * speed);
  }

  /**
   * Returns the playout duration of {@code mediaDuration} of media.
   *
   * @param mediaDuration The duration to scale.
   * @return The scaled duration, in the same units as {@code mediaDuration}.
   */
  public static long getPlayoutDurationForMediaDuration(long mediaDuration, float speed) {
    if (speed == 1f) {
      return mediaDuration;
    }
    return Math.round((double) mediaDuration / speed);
  }

  /**
   * Resolves a seek given the requested seek position, a {@link SeekParameters} and two candidate
   * sync points.
   *
   * @param positionUs The requested seek position, in microseocnds.
   * @param seekParameters The {@link SeekParameters}.
   * @param firstSyncUs The first candidate seek point, in micrseconds.
   * @param secondSyncUs The second candidate seek point, in microseconds. May equal {@code
   *     firstSyncUs} if there's only one candidate.
   * @return The resolved seek position, in microseconds.
   */
  public static long resolveSeekPositionUs(
      long positionUs, SeekParameters seekParameters, long firstSyncUs, long secondSyncUs) {
    if (SeekParameters.EXACT.equals(seekParameters)) {
      return positionUs;
    }
    long minPositionUs =
        subtractWithOverflowDefault(positionUs, seekParameters.toleranceBeforeUs, Long.MIN_VALUE);
    long maxPositionUs =
        addWithOverflowDefault(positionUs, seekParameters.toleranceAfterUs, Long.MAX_VALUE);
    boolean firstSyncPositionValid = minPositionUs <= firstSyncUs && firstSyncUs <= maxPositionUs;
    boolean secondSyncPositionValid =
        minPositionUs <= secondSyncUs && secondSyncUs <= maxPositionUs;
    if (firstSyncPositionValid && secondSyncPositionValid) {
      if (Math.abs(firstSyncUs - positionUs) <= Math.abs(secondSyncUs - positionUs)) {
        return firstSyncUs;
      } else {
        return secondSyncUs;
      }
    } else if (firstSyncPositionValid) {
      return firstSyncUs;
    } else if (secondSyncPositionValid) {
      return secondSyncUs;
    } else {
      return minPositionUs;
    }
  }

  /**
   * Converts a list of integers to a primitive array.
   *
   * @param list A list of integers.
   * @return The list in array form, or null if the input list was null.
   */
  public static int @PolyNull [] toArray(@PolyNull List<Integer> list) {
    if (list == null) {
      return null;
    }
    int length = list.size();
    int[] intArray = new int[length];
    for (int i = 0; i < length; i++) {
      intArray[i] = list.get(i);
    }
    return intArray;
  }

  /**
   * Returns the integer equal to the big-endian concatenation of the characters in {@code string}
   * as bytes. The string must be no more than four characters long.
   *
   * @param string A string no more than four characters long.
   */
  public static int getIntegerCodeForString(String string) {
    int length = string.length();
    Assertions.checkArgument(length <= 4);
    int result = 0;
    for (int i = 0; i < length; i++) {
      result <<= 8;
      result |= string.charAt(i);
    }
    return result;
  }

  /**
   * Converts an integer to a long by unsigned conversion.
   *
   * <p>This method is equivalent to {@link Integer#toUnsignedLong(int)} for API 26+.
   */
  public static long toUnsignedLong(int x) {
    // x is implicitly casted to a long before the bit operation is executed but this does not
    // impact the method correctness.
    return x & 0xFFFFFFFFL;
  }

  /**
   * Returns a byte array containing values parsed from the hex string provided.
   *
   * @param hexString The hex string to convert to bytes.
   * @return A byte array containing values parsed from the hex string provided.
   */
  public static byte[] getBytesFromHexString(String hexString) {
    byte[] data = new byte[hexString.length() / 2];
    for (int i = 0; i < data.length; i++) {
      int stringOffset = i * 2;
      data[i] = (byte) ((Character.digit(hexString.charAt(stringOffset), 16) << 4)
          + Character.digit(hexString.charAt(stringOffset + 1), 16));
    }
    return data;
  }

  /**
   * Returns a string with comma delimited simple names of each object's class.
   *
   * @param objects The objects whose simple class names should be comma delimited and returned.
   * @return A string with comma delimited simple names of each object's class.
   */
  public static String getCommaDelimitedSimpleClassNames(Object[] objects) {
    StringBuilder stringBuilder = new StringBuilder();
    for (int i = 0; i < objects.length; i++) {
      stringBuilder.append(objects[i].getClass().getSimpleName());
      if (i < objects.length - 1) {
        stringBuilder.append(", ");
      }
    }
    return stringBuilder.toString();
  }

  /**
   * Returns a user agent string based on the given application name and the library version.
   *
   * @param context A valid context of the calling application.
   * @param applicationName String that will be prefix'ed to the generated user agent.
   * @return A user agent string generated using the applicationName and the library version.
   */
  public static String getUserAgent(Context context, String applicationName) {
    String versionName;
    try {
      String packageName = context.getPackageName();
      PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);
      versionName = info.versionName;
    } catch (NameNotFoundException e) {
      versionName = "?";
    }
    return applicationName + "/" + versionName + " (Linux;Android " + Build.VERSION.RELEASE
        + ") " + ExoPlayerLibraryInfo.VERSION_SLASHY;
  }

  /**
   * Returns a copy of {@code codecs} without the codecs whose track type doesn't match {@code
   * trackType}.
   *
   * @param codecs A codec sequence string, as defined in RFC 6381.
   * @param trackType One of {@link C}{@code .TRACK_TYPE_*}.
   * @return A copy of {@code codecs} without the codecs whose track type doesn't match {@code
   *     trackType}. If this ends up empty, or {@code codecs} is null, return null.
   */
  public static @Nullable String getCodecsOfType(@Nullable String codecs, int trackType) {
    String[] codecArray = splitCodecs(codecs);
    if (codecArray.length == 0) {
      return null;
    }
    StringBuilder builder = new StringBuilder();
    for (String codec : codecArray) {
      if (trackType == MimeTypes.getTrackTypeOfCodec(codec)) {
        if (builder.length() > 0) {
          builder.append(",");
        }
        builder.append(codec);
      }
    }
    return builder.length() > 0 ? builder.toString() : null;
  }

  /**
   * Splits a codecs sequence string, as defined in RFC 6381, into individual codec strings.
   *
   * @param codecs A codec sequence string, as defined in RFC 6381.
   * @return The split codecs, or an array of length zero if the input was empty or null.
   */
  public static String[] splitCodecs(@Nullable String codecs) {
    if (TextUtils.isEmpty(codecs)) {
      return new String[0];
    }
    return split(codecs.trim(), "(\\s*,\\s*)");
  }

  /**
   * Converts a sample bit depth to a corresponding PCM encoding constant.
   *
   * @param bitDepth The bit depth. Supported values are 8, 16, 24 and 32.
   * @return The corresponding encoding. One of {@link C#ENCODING_PCM_8BIT},
   *     {@link C#ENCODING_PCM_16BIT}, {@link C#ENCODING_PCM_24BIT} and
   *     {@link C#ENCODING_PCM_32BIT}. If the bit depth is unsupported then
   *     {@link C#ENCODING_INVALID} is returned.
   */
  @C.PcmEncoding
  public static int getPcmEncoding(int bitDepth) {
    switch (bitDepth) {
      case 8:
        return C.ENCODING_PCM_8BIT;
      case 16:
        return C.ENCODING_PCM_16BIT;
      case 24:
        return C.ENCODING_PCM_24BIT;
      case 32:
        return C.ENCODING_PCM_32BIT;
      default:
        return C.ENCODING_INVALID;
    }
  }

  /**
   * Returns whether {@code encoding} is one of the linear PCM encodings.
   *
   * @param encoding The encoding of the audio data.
   * @return Whether the encoding is one of the PCM encodings.
   */
  public static boolean isEncodingLinearPcm(@C.Encoding int encoding) {
    return encoding == C.ENCODING_PCM_8BIT
        || encoding == C.ENCODING_PCM_16BIT
        || encoding == C.ENCODING_PCM_24BIT
        || encoding == C.ENCODING_PCM_32BIT
        || encoding == C.ENCODING_PCM_FLOAT;
  }

  /**
   * Returns whether {@code encoding} is high resolution (&gt; 16-bit) integer PCM.
   *
   * @param encoding The encoding of the audio data.
   * @return Whether the encoding is high resolution integer PCM.
   */
  public static boolean isEncodingHighResolutionIntegerPcm(@C.PcmEncoding int encoding) {
    return encoding == C.ENCODING_PCM_24BIT || encoding == C.ENCODING_PCM_32BIT;
  }

  /**
   * Returns the audio track channel configuration for the given channel count, or {@link
   * AudioFormat#CHANNEL_INVALID} if output is not poossible.
   *
   * @param channelCount The number of channels in the input audio.
   * @return The channel configuration or {@link AudioFormat#CHANNEL_INVALID} if output is not
   *     possible.
   */
  public static int getAudioTrackChannelConfig(int channelCount) {
    switch (channelCount) {
      case 1:
        return AudioFormat.CHANNEL_OUT_MONO;
      case 2:
        return AudioFormat.CHANNEL_OUT_STEREO;
      case 3:
        return AudioFormat.CHANNEL_OUT_STEREO | AudioFormat.CHANNEL_OUT_FRONT_CENTER;
      case 4:
        return AudioFormat.CHANNEL_OUT_QUAD;
      case 5:
        return AudioFormat.CHANNEL_OUT_QUAD | AudioFormat.CHANNEL_OUT_FRONT_CENTER;
      case 6:
        return AudioFormat.CHANNEL_OUT_5POINT1;
      case 7:
        return AudioFormat.CHANNEL_OUT_5POINT1 | AudioFormat.CHANNEL_OUT_BACK_CENTER;
      case 8:
        if (Util.SDK_INT >= 23) {
          return AudioFormat.CHANNEL_OUT_7POINT1_SURROUND;
        } else if (Util.SDK_INT >= 21) {
          // Equal to AudioFormat.CHANNEL_OUT_7POINT1_SURROUND, which is hidden before Android M.
          return AudioFormat.CHANNEL_OUT_5POINT1
              | AudioFormat.CHANNEL_OUT_SIDE_LEFT
              | AudioFormat.CHANNEL_OUT_SIDE_RIGHT;
        } else {
          // 8 ch output is not supported before Android L.
          return AudioFormat.CHANNEL_INVALID;
        }
      default:
        return AudioFormat.CHANNEL_INVALID;
    }
  }

  /**
   * Returns the frame size for audio with {@code channelCount} channels in the specified encoding.
   *
   * @param pcmEncoding The encoding of the audio data.
   * @param channelCount The channel count.
   * @return The size of one audio frame in bytes.
   */
  public static int getPcmFrameSize(@C.PcmEncoding int pcmEncoding, int channelCount) {
    switch (pcmEncoding) {
      case C.ENCODING_PCM_8BIT:
        return channelCount;
      case C.ENCODING_PCM_16BIT:
        return channelCount * 2;
      case C.ENCODING_PCM_24BIT:
        return channelCount * 3;
      case C.ENCODING_PCM_32BIT:
      case C.ENCODING_PCM_FLOAT:
        return channelCount * 4;
      case C.ENCODING_PCM_A_LAW:
      case C.ENCODING_PCM_MU_LAW:
      case C.ENCODING_INVALID:
      case Format.NO_VALUE:
      default:
        throw new IllegalArgumentException();
    }
  }

  /**
   * Returns the {@link C.AudioUsage} corresponding to the specified {@link C.StreamType}.
   */
  @C.AudioUsage
  public static int getAudioUsageForStreamType(@C.StreamType int streamType) {
    switch (streamType) {
      case C.STREAM_TYPE_ALARM:
        return C.USAGE_ALARM;
      case C.STREAM_TYPE_DTMF:
        return C.USAGE_VOICE_COMMUNICATION_SIGNALLING;
      case C.STREAM_TYPE_NOTIFICATION:
        return C.USAGE_NOTIFICATION;
      case C.STREAM_TYPE_RING:
        return C.USAGE_NOTIFICATION_RINGTONE;
      case C.STREAM_TYPE_SYSTEM:
        return C.USAGE_ASSISTANCE_SONIFICATION;
      case C.STREAM_TYPE_VOICE_CALL:
        return C.USAGE_VOICE_COMMUNICATION;
      case C.STREAM_TYPE_USE_DEFAULT:
      case C.STREAM_TYPE_MUSIC:
      default:
        return C.USAGE_MEDIA;
    }
  }

  /**
   * Returns the {@link C.AudioContentType} corresponding to the specified {@link C.StreamType}.
   */
  @C.AudioContentType
  public static int getAudioContentTypeForStreamType(@C.StreamType int streamType) {
    switch (streamType) {
      case C.STREAM_TYPE_ALARM:
      case C.STREAM_TYPE_DTMF:
      case C.STREAM_TYPE_NOTIFICATION:
      case C.STREAM_TYPE_RING:
      case C.STREAM_TYPE_SYSTEM:
        return C.CONTENT_TYPE_SONIFICATION;
      case C.STREAM_TYPE_VOICE_CALL:
        return C.CONTENT_TYPE_SPEECH;
      case C.STREAM_TYPE_USE_DEFAULT:
      case C.STREAM_TYPE_MUSIC:
      default:
        return C.CONTENT_TYPE_MUSIC;
    }
  }

  /**
   * Returns the {@link C.StreamType} corresponding to the specified {@link C.AudioUsage}.
   */
  @C.StreamType
  public static int getStreamTypeForAudioUsage(@C.AudioUsage int usage) {
    switch (usage) {
      case C.USAGE_MEDIA:
      case C.USAGE_GAME:
      case C.USAGE_ASSISTANCE_NAVIGATION_GUIDANCE:
        return C.STREAM_TYPE_MUSIC;
      case C.USAGE_ASSISTANCE_SONIFICATION:
        return C.STREAM_TYPE_SYSTEM;
      case C.USAGE_VOICE_COMMUNICATION:
        return C.STREAM_TYPE_VOICE_CALL;
      case C.USAGE_VOICE_COMMUNICATION_SIGNALLING:
        return C.STREAM_TYPE_DTMF;
      case C.USAGE_ALARM:
        return C.STREAM_TYPE_ALARM;
      case C.USAGE_NOTIFICATION_RINGTONE:
        return C.STREAM_TYPE_RING;
      case C.USAGE_NOTIFICATION:
      case C.USAGE_NOTIFICATION_COMMUNICATION_REQUEST:
      case C.USAGE_NOTIFICATION_COMMUNICATION_INSTANT:
      case C.USAGE_NOTIFICATION_COMMUNICATION_DELAYED:
      case C.USAGE_NOTIFICATION_EVENT:
        return C.STREAM_TYPE_NOTIFICATION;
      case C.USAGE_ASSISTANCE_ACCESSIBILITY:
      case C.USAGE_ASSISTANT:
      case C.USAGE_UNKNOWN:
      default:
        return C.STREAM_TYPE_DEFAULT;
    }
  }

  /**
   * Derives a DRM {@link UUID} from {@code drmScheme}.
   *
   * @param drmScheme A UUID string, or {@code "widevine"}, {@code "playready"} or {@code
   *     "clearkey"}.
   * @return The derived {@link UUID}, or {@code null} if one could not be derived.
   */
  public static @Nullable UUID getDrmUuid(String drmScheme) {
    switch (toLowerInvariant(drmScheme)) {
      case "widevine":
        return C.WIDEVINE_UUID;
      case "playready":
        return C.PLAYREADY_UUID;
      case "clearkey":
        return C.CLEARKEY_UUID;
      default:
        try {
          return UUID.fromString(drmScheme);
        } catch (RuntimeException e) {
          return null;
        }
    }
  }

  /**
   * Makes a best guess to infer the type from a {@link Uri}.
   *
   * @param uri The {@link Uri}.
   * @param overrideExtension If not null, used to infer the type.
   * @return The content type.
   */
  @C.ContentType
  public static int inferContentType(Uri uri, @Nullable String overrideExtension) {
    return TextUtils.isEmpty(overrideExtension)
        ? inferContentType(uri)
        : inferContentType("." + overrideExtension);
  }

  /**
   * Makes a best guess to infer the type from a {@link Uri}.
   *
   * @param uri The {@link Uri}.
   * @return The content type.
   */
  @C.ContentType
  public static int inferContentType(Uri uri) {
    String path = uri.getPath();
    return path == null ? C.TYPE_OTHER : inferContentType(path);
  }

  /**
   * Makes a best guess to infer the type from a file name.
   *
   * @param fileName Name of the file. It can include the path of the file.
   * @return The content type.
   */
  @C.ContentType
  public static int inferContentType(String fileName) {
    fileName = toLowerInvariant(fileName);
    if (fileName.endsWith(".mpd")) {
      return C.TYPE_DASH;
    } else if (fileName.endsWith(".m3u8")) {
      return C.TYPE_HLS;
    } else if (fileName.matches(".*\\.ism(l)?(/manifest(\\(.+\\))?)?")) {
      return C.TYPE_SS;
    } else {
      return C.TYPE_OTHER;
    }
  }

  /**
   * Returns the specified millisecond time formatted as a string.
   *
   * @param builder The builder that {@code formatter} will write to.
   * @param formatter The formatter.
   * @param timeMs The time to format as a string, in milliseconds.
   * @return The time formatted as a string.
   */
  public static String getStringForTime(StringBuilder builder, Formatter formatter, long timeMs) {
    if (timeMs == C.TIME_UNSET) {
      timeMs = 0;
    }
    long totalSeconds = (timeMs + 500) / 1000;
    long seconds = totalSeconds % 60;
    long minutes = (totalSeconds / 60) % 60;
    long hours = totalSeconds / 3600;
    builder.setLength(0);
    return hours > 0 ? formatter.format("%d:%02d:%02d", hours, minutes, seconds).toString()
        : formatter.format("%02d:%02d", minutes, seconds).toString();
  }

  /**
   * Escapes a string so that it's safe for use as a file or directory name on at least FAT32
   * filesystems. FAT32 is the most restrictive of all filesystems still commonly used today.
   *
   * <p>For simplicity, this only handles common characters known to be illegal on FAT32:
   * &lt;, &gt;, :, ", /, \, |, ?, and *. % is also escaped since it is used as the escape
   * character. Escaping is performed in a consistent way so that no collisions occur and
   * {@link #unescapeFileName(String)} can be used to retrieve the original file name.
   *
   * @param fileName File name to be escaped.
   * @return An escaped file name which will be safe for use on at least FAT32 filesystems.
   */
  public static String escapeFileName(String fileName) {
    int length = fileName.length();
    int charactersToEscapeCount = 0;
    for (int i = 0; i < length; i++) {
      if (shouldEscapeCharacter(fileName.charAt(i))) {
        charactersToEscapeCount++;
      }
    }
    if (charactersToEscapeCount == 0) {
      return fileName;
    }

    int i = 0;
    StringBuilder builder = new StringBuilder(length + charactersToEscapeCount * 2);
    while (charactersToEscapeCount > 0) {
      char c = fileName.charAt(i++);
      if (shouldEscapeCharacter(c)) {
        builder.append('%').append(Integer.toHexString(c));
        charactersToEscapeCount--;
      } else {
        builder.append(c);
      }
    }
    if (i < length) {
      builder.append(fileName, i, length);
    }
    return builder.toString();
  }

  private static boolean shouldEscapeCharacter(char c) {
    switch (c) {
      case '<':
      case '>':
      case ':':
      case '"':
      case '/':
      case '\\':
      case '|':
      case '?':
      case '*':
      case '%':
        return true;
      default:
        return false;
    }
  }

  /**
   * Unescapes an escaped file or directory name back to its original value.
   *
   * <p>See {@link #escapeFileName(String)} for more information.
   *
   * @param fileName File name to be unescaped.
   * @return The original value of the file name before it was escaped, or null if the escaped
   *     fileName seems invalid.
   */
  public static @Nullable String unescapeFileName(String fileName) {
    int length = fileName.length();
    int percentCharacterCount = 0;
    for (int i = 0; i < length; i++) {
      if (fileName.charAt(i) == '%') {
        percentCharacterCount++;
      }
    }
    if (percentCharacterCount == 0) {
      return fileName;
    }

    int expectedLength = length - percentCharacterCount * 2;
    StringBuilder builder = new StringBuilder(expectedLength);
    Matcher matcher = ESCAPED_CHARACTER_PATTERN.matcher(fileName);
    int startOfNotEscaped = 0;
    while (percentCharacterCount > 0 && matcher.find()) {
      char unescapedCharacter = (char) Integer.parseInt(matcher.group(1), 16);
      builder.append(fileName, startOfNotEscaped, matcher.start()).append(unescapedCharacter);
      startOfNotEscaped = matcher.end();
      percentCharacterCount--;
    }
    if (startOfNotEscaped < length) {
      builder.append(fileName, startOfNotEscaped, length);
    }
    if (builder.length() != expectedLength) {
      return null;
    }
    return builder.toString();
  }

  /**
   * A hacky method that always throws {@code t} even if {@code t} is a checked exception,
   * and is not declared to be thrown.
   */
  public static void sneakyThrow(Throwable t) {
    sneakyThrowInternal(t);
  }

  @SuppressWarnings("unchecked")
  private static <T extends Throwable> void sneakyThrowInternal(Throwable t) throws T {
    throw (T) t;
  }

  /** Recursively deletes a directory and its content. */
  public static void recursiveDelete(File fileOrDirectory) {
    File[] directoryFiles = fileOrDirectory.listFiles();
    if (directoryFiles != null) {
      for (File child : directoryFiles) {
        recursiveDelete(child);
      }
    }
    fileOrDirectory.delete();
  }

  /** Creates an empty directory in the directory returned by {@link Context#getCacheDir()}. */
  public static File createTempDirectory(Context context, String prefix) throws IOException {
    File tempFile = createTempFile(context, prefix);
    tempFile.delete(); // Delete the temp file.
    tempFile.mkdir(); // Create a directory with the same name.
    return tempFile;
  }

  /** Creates a new empty file in the directory returned by {@link Context#getCacheDir()}. */
  public static File createTempFile(Context context, String prefix) throws IOException {
    return File.createTempFile(prefix, null, context.getCacheDir());
  }

  /**
   * Returns the result of updating a CRC-32 with the specified bytes in a "most significant bit
   * first" order.
   *
   * @param bytes Array containing the bytes to update the crc value with.
   * @param start The index to the first byte in the byte range to update the crc with.
   * @param end The index after the last byte in the byte range to update the crc with.
   * @param initialValue The initial value for the crc calculation.
   * @return The result of updating the initial value with the specified bytes.
   */
  public static int crc32(byte[] bytes, int start, int end, int initialValue) {
    for (int i = start; i < end; i++) {
      initialValue = (initialValue << 8)
          ^ CRC32_BYTES_MSBF[((initialValue >>> 24) ^ (bytes[i] & 0xFF)) & 0xFF];
    }
    return initialValue;
  }

  /**
   * Returns the result of updating a CRC-8 with the specified bytes in a "most significant bit
   * first" order.
   *
   * @param bytes Array containing the bytes to update the crc value with.
   * @param start The index to the first byte in the byte range to update the crc with.
   * @param end The index after the last byte in the byte range to update the crc with.
   * @param initialValue The initial value for the crc calculation.
   * @return The result of updating the initial value with the specified bytes.
   */
  public static int crc8(byte[] bytes, int start, int end, int initialValue) {
    for (int i = start; i < end; i++) {
      initialValue = CRC8_BYTES_MSBF[initialValue ^ (bytes[i] & 0xFF)];
    }
    return initialValue;
  }

  /**
   * Returns the {@link C.NetworkType} of the current network connection.
   *
   * @param context A context to access the connectivity manager.
   * @return The {@link C.NetworkType} of the current network connection.
   */
  @C.NetworkType
  public static int getNetworkType(Context context) {
    if (context == null) {
      // Note: This is for backward compatibility only (context used to be @Nullable).
      return C.NETWORK_TYPE_UNKNOWN;
    }
    NetworkInfo networkInfo;
    ConnectivityManager connectivityManager =
        (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivityManager == null) {
      return C.NETWORK_TYPE_UNKNOWN;
    }
    try {
      networkInfo = connectivityManager.getActiveNetworkInfo();
    } catch (SecurityException e) {
      // Expected if permission was revoked.
      return C.NETWORK_TYPE_UNKNOWN;
    }
    if (networkInfo == null || !networkInfo.isConnected()) {
      return C.NETWORK_TYPE_OFFLINE;
    }
    switch (networkInfo.getType()) {
      case ConnectivityManager.TYPE_WIFI:
        return C.NETWORK_TYPE_WIFI;
      case ConnectivityManager.TYPE_WIMAX:
        return C.NETWORK_TYPE_4G;
      case ConnectivityManager.TYPE_MOBILE:
      case ConnectivityManager.TYPE_MOBILE_DUN:
      case ConnectivityManager.TYPE_MOBILE_HIPRI:
        return getMobileNetworkType(networkInfo);
      case ConnectivityManager.TYPE_ETHERNET:
        return C.NETWORK_TYPE_ETHERNET;
      default: // VPN, Bluetooth, Dummy.
        return C.NETWORK_TYPE_OTHER;
    }
  }

  /**
   * Returns the upper-case ISO 3166-1 alpha-2 country code of the current registered operator's MCC
   * (Mobile Country Code), or the country code of the default Locale if not available.
   *
   * @param context A context to access the telephony service. If null, only the Locale can be used.
   * @return The upper-case ISO 3166-1 alpha-2 country code, or an empty String if unavailable.
   */
  public static String getCountryCode(@Nullable Context context) {
    if (context != null) {
      TelephonyManager telephonyManager =
          (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
      if (telephonyManager != null) {
        String countryCode = telephonyManager.getNetworkCountryIso();
        if (!TextUtils.isEmpty(countryCode)) {
          return toUpperInvariant(countryCode);
        }
      }
    }
    return toUpperInvariant(Locale.getDefault().getCountry());
  }

  /**
   * Returns a non-empty array of normalized IETF BCP 47 language tags for the system languages
   * ordered by preference.
   */
  public static String[] getSystemLanguageCodes() {
    String[] systemLocales = getSystemLocales();
    for (int i = 0; i < systemLocales.length; i++) {
      systemLocales[i] = normalizeLanguageCode(systemLocales[i]);
    }
    return systemLocales;
  }

  /**
   * Uncompresses the data in {@code input}.
   *
   * @param input Wraps the compressed input data.
   * @param output Wraps an output buffer to be used to store the uncompressed data. If {@code
   *     output.data} isn't big enough to hold the uncompressed data, a new array is created. If
   *     {@code true} is returned then the output's position will be set to 0 and its limit will be
   *     set to the length of the uncompressed data.
   * @param inflater If not null, used to uncompressed the input. Otherwise a new {@link Inflater}
   *     is created.
   * @return Whether the input is uncompressed successfully.
   */
  public static boolean inflate(
      ParsableByteArray input, ParsableByteArray output, @Nullable Inflater inflater) {
    if (input.bytesLeft() <= 0) {
      return false;
    }
    byte[] outputData = output.data;
    if (outputData.length < input.bytesLeft()) {
      outputData = new byte[2 * input.bytesLeft()];
    }
    if (inflater == null) {
      inflater = new Inflater();
    }
    inflater.setInput(input.data, input.getPosition(), input.bytesLeft());
    try {
      int outputSize = 0;
      while (true) {
        outputSize += inflater.inflate(outputData, outputSize, outputData.length - outputSize);
        if (inflater.finished()) {
          output.reset(outputData, outputSize);
          return true;
        }
        if (inflater.needsDictionary() || inflater.needsInput()) {
          return false;
        }
        if (outputSize == outputData.length) {
          outputData = Arrays.copyOf(outputData, outputData.length * 2);
        }
      }
    } catch (DataFormatException e) {
      return false;
    } finally {
      inflater.reset();
    }
  }

  /**
   * Returns whether the app is running on a TV device.
   *
   * @param context Any context.
   * @return Whether the app is running on a TV device.
   */
  public static boolean isTv(Context context) {
    // See https://developer.android.com/training/tv/start/hardware.html#runtime-check.
    UiModeManager uiModeManager =
        (UiModeManager) context.getApplicationContext().getSystemService(UI_MODE_SERVICE);
    return uiModeManager != null
        && uiModeManager.getCurrentModeType() == Configuration.UI_MODE_TYPE_TELEVISION;
  }

  /**
   * Gets the physical size of the default display, in pixels.
   *
   * @param context Any context.
   * @return The physical display size, in pixels.
   */
  public static Point getPhysicalDisplaySize(Context context) {
    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    return getPhysicalDisplaySize(context, windowManager.getDefaultDisplay());
  }

  /**
   * Gets the physical size of the specified display, in pixels.
   *
   * @param context Any context.
   * @param display The display whose size is to be returned.
   * @return The physical display size, in pixels.
   */
  public static Point getPhysicalDisplaySize(Context context, Display display) {
    if (Util.SDK_INT <= 29 && display.getDisplayId() == Display.DEFAULT_DISPLAY && isTv(context)) {
      // On Android TVs it is common for the UI to be configured for a lower resolution than
      // SurfaceViews can output. Before API 26 the Display object does not provide a way to
      // identify this case, and up to and including API 28 many devices still do not correctly set
      // their hardware compositor output size.

      // Sony Android TVs advertise support for 4k output via a system feature.
      if ("Sony".equals(Util.MANUFACTURER)
          && Util.MODEL.startsWith("BRAVIA")
          && context.getPackageManager().hasSystemFeature("com.sony.dtv.hardware.panel.qfhd")) {
        return new Point(3840, 2160);
      }

      // Otherwise check the system property for display size. From API 28 treble may prevent the
      // system from writing sys.display-size so we check vendor.display-size instead.
      String displaySize =
          Util.SDK_INT < 28
              ? getSystemProperty("sys.display-size")
              : getSystemProperty("vendor.display-size");
      // If we managed to read the display size, attempt to parse it.
      if (!TextUtils.isEmpty(displaySize)) {
        try {
          String[] displaySizeParts = split(displaySize.trim(), "x");
          if (displaySizeParts.length == 2) {
            int width = Integer.parseInt(displaySizeParts[0]);
            int height = Integer.parseInt(displaySizeParts[1]);
            if (width > 0 && height > 0) {
              return new Point(width, height);
            }
          }
        } catch (NumberFormatException e) {
          // Do nothing.
        }
        Log.e(TAG, "Invalid display size: " + displaySize);
      }
    }

    Point displaySize = new Point();
    if (Util.SDK_INT >= 23) {
      getDisplaySizeV23(display, displaySize);
    } else if (Util.SDK_INT >= 17) {
      getDisplaySizeV17(display, displaySize);
    } else {
      getDisplaySizeV16(display, displaySize);
    }
    return displaySize;
  }

  /**
   * Extract renderer capabilities for the renderers created by the provided renderers factory.
   *
   * @param renderersFactory A {@link RenderersFactory}.
   * @param drmSessionManager An optional {@link DrmSessionManager} used by the renderers.
   * @return The {@link RendererCapabilities} for each renderer created by the {@code
   *     renderersFactory}.
   */
  public static RendererCapabilities[] getRendererCapabilities(
      RenderersFactory renderersFactory,
      @Nullable DrmSessionManager<FrameworkMediaCrypto> drmSessionManager) {
    Renderer[] renderers =
        renderersFactory.createRenderers(
            new Handler(),
            new VideoRendererEventListener() {},
            new AudioRendererEventListener() {},
            (cues) -> {},
            (metadata) -> {},
            drmSessionManager);
    RendererCapabilities[] capabilities = new RendererCapabilities[renderers.length];
    for (int i = 0; i < renderers.length; i++) {
      capabilities[i] = renderers[i].getCapabilities();
    }
    return capabilities;
  }

  /**
   * Returns a string representation of a {@code TRACK_TYPE_*} constant defined in {@link C}.
   *
   * @param trackType A {@code TRACK_TYPE_*} constant,
   * @return A string representation of this constant.
   */
  public static String getTrackTypeString(int trackType) {
    switch (trackType) {
      case C.TRACK_TYPE_AUDIO:
        return "audio";
      case C.TRACK_TYPE_DEFAULT:
        return "default";
      case C.TRACK_TYPE_METADATA:
        return "metadata";
      case C.TRACK_TYPE_CAMERA_MOTION:
        return "camera motion";
      case C.TRACK_TYPE_NONE:
        return "none";
      case C.TRACK_TYPE_TEXT:
        return "text";
      case C.TRACK_TYPE_VIDEO:
        return "video";
      default:
        return trackType >= C.TRACK_TYPE_CUSTOM_BASE ? "custom (" + trackType + ")" : "?";
    }
  }

  @Nullable
  private static String getSystemProperty(String name) {
    try {
      @SuppressLint("PrivateApi")
      Class<?> systemProperties = Class.forName("android.os.SystemProperties");
      Method getMethod = systemProperties.getMethod("get", String.class);
      return (String) getMethod.invoke(systemProperties, name);
    } catch (Exception e) {
      Log.e(TAG, "Failed to read system property " + name, e);
      return null;
    }
  }

  @TargetApi(23)
  private static void getDisplaySizeV23(Display display, Point outSize) {
    Display.Mode mode = display.getMode();
    outSize.x = mode.getPhysicalWidth();
    outSize.y = mode.getPhysicalHeight();
  }

  @TargetApi(17)
  private static void getDisplaySizeV17(Display display, Point outSize) {
    display.getRealSize(outSize);
  }

  private static void getDisplaySizeV16(Display display, Point outSize) {
    display.getSize(outSize);
  }

  private static String[] getSystemLocales() {
    Configuration config = Resources.getSystem().getConfiguration();
    return SDK_INT >= 24
        ? getSystemLocalesV24(config)
        : new String[] {getLocaleLanguageTag(config.locale)};
  }

  @TargetApi(24)
  private static String[] getSystemLocalesV24(Configuration config) {
    return Util.split(config.getLocales().toLanguageTags(), ",");
  }

  @TargetApi(21)
  private static String getLocaleLanguageTagV21(Locale locale) {
    return locale.toLanguageTag();
  }

  @TargetApi(21)
  private static String normalizeLanguageCodeSyntaxV21(String languageTag) {
    return Locale.forLanguageTag(languageTag).toLanguageTag();
  }

  private static @C.NetworkType int getMobileNetworkType(NetworkInfo networkInfo) {
    switch (networkInfo.getSubtype()) {
      case TelephonyManager.NETWORK_TYPE_EDGE:
      case TelephonyManager.NETWORK_TYPE_GPRS:
        return C.NETWORK_TYPE_2G;
      case TelephonyManager.NETWORK_TYPE_1xRTT:
      case TelephonyManager.NETWORK_TYPE_CDMA:
      case TelephonyManager.NETWORK_TYPE_EVDO_0:
      case TelephonyManager.NETWORK_TYPE_EVDO_A:
      case TelephonyManager.NETWORK_TYPE_EVDO_B:
      case TelephonyManager.NETWORK_TYPE_HSDPA:
      case TelephonyManager.NETWORK_TYPE_HSPA:
      case TelephonyManager.NETWORK_TYPE_HSUPA:
      case TelephonyManager.NETWORK_TYPE_IDEN:
      case TelephonyManager.NETWORK_TYPE_UMTS:
      case TelephonyManager.NETWORK_TYPE_EHRPD:
      case TelephonyManager.NETWORK_TYPE_HSPAP:
      case TelephonyManager.NETWORK_TYPE_TD_SCDMA:
        return C.NETWORK_TYPE_3G;
      case TelephonyManager.NETWORK_TYPE_LTE:
        return C.NETWORK_TYPE_4G;
      case TelephonyManager.NETWORK_TYPE_IWLAN:
        return C.NETWORK_TYPE_WIFI;
      case TelephonyManager.NETWORK_TYPE_GSM:
      case TelephonyManager.NETWORK_TYPE_UNKNOWN:
      default: // Future mobile network types.
        return C.NETWORK_TYPE_CELLULAR_UNKNOWN;
    }
  }

  private static HashMap<String, String> createIso3ToIso2Map() {
    String[] iso2Languages = Locale.getISOLanguages();
    HashMap<String, String> iso3ToIso2 =
        new HashMap<>(
            /* initialCapacity= */ iso2Languages.length + iso3BibliographicalToIso2.length);
    for (String iso2 : iso2Languages) {
      try {
        // This returns the ISO 639-2/T code for the language.
        String iso3 = new Locale(iso2).getISO3Language();
        if (!TextUtils.isEmpty(iso3)) {
          iso3ToIso2.put(iso3, iso2);
        }
      } catch (MissingResourceException e) {
        // Shouldn't happen for list of known languages, but we don't want to throw either.
      }
    }
    // Add additional ISO 639-2/B codes to mapping.
    for (int i = 0; i < iso3BibliographicalToIso2.length; i += 2) {
      iso3ToIso2.put(iso3BibliographicalToIso2[i], iso3BibliographicalToIso2[i + 1]);
    }
    return iso3ToIso2;
  }

  // See https://en.wikipedia.org/wiki/List_of_ISO_639-2_codes.
  private static final String[] iso3BibliographicalToIso2 =
      new String[] {
        "alb", "sq",
        "arm", "hy",
        "baq", "eu",
        "bur", "my",
        "tib", "bo",
        "chi", "zh",
        "cze", "cs",
        "dut", "nl",
        "ger", "de",
        "gre", "el",
        "fre", "fr",
        "geo", "ka",
        "ice", "is",
        "mac", "mk",
        "mao", "mi",
        "may", "ms",
        "per", "fa",
        "rum", "ro",
        "slo", "sk",
        "wel", "cy"
      };

  /**
   * Allows the CRC-32 calculation to be done byte by byte instead of bit per bit in the order "most
   * significant bit first".
   */
  private static final int[] CRC32_BYTES_MSBF = {
    0X00000000, 0X04C11DB7, 0X09823B6E, 0X0D4326D9, 0X130476DC, 0X17C56B6B, 0X1A864DB2,
    0X1E475005, 0X2608EDB8, 0X22C9F00F, 0X2F8AD6D6, 0X2B4BCB61, 0X350C9B64, 0X31CD86D3,
    0X3C8EA00A, 0X384FBDBD, 0X4C11DB70, 0X48D0C6C7, 0X4593E01E, 0X4152FDA9, 0X5F15ADAC,
    0X5BD4B01B, 0X569796C2, 0X52568B75, 0X6A1936C8, 0X6ED82B7F, 0X639B0DA6, 0X675A1011,
    0X791D4014, 0X7DDC5DA3, 0X709F7B7A, 0X745E66CD, 0X9823B6E0, 0X9CE2AB57, 0X91A18D8E,
    0X95609039, 0X8B27C03C, 0X8FE6DD8B, 0X82A5FB52, 0X8664E6E5, 0XBE2B5B58, 0XBAEA46EF,
    0XB7A96036, 0XB3687D81, 0XAD2F2D84, 0XA9EE3033, 0XA4AD16EA, 0XA06C0B5D, 0XD4326D90,
    0XD0F37027, 0XDDB056FE, 0XD9714B49, 0XC7361B4C, 0XC3F706FB, 0XCEB42022, 0XCA753D95,
    0XF23A8028, 0XF6FB9D9F, 0XFBB8BB46, 0XFF79A6F1, 0XE13EF6F4, 0XE5FFEB43, 0XE8BCCD9A,
    0XEC7DD02D, 0X34867077, 0X30476DC0, 0X3D044B19, 0X39C556AE, 0X278206AB, 0X23431B1C,
    0X2E003DC5, 0X2AC12072, 0X128E9DCF, 0X164F8078, 0X1B0CA6A1, 0X1FCDBB16, 0X018AEB13,
    0X054BF6A4, 0X0808D07D, 0X0CC9CDCA, 0X7897AB07, 0X7C56B6B0, 0X71159069, 0X75D48DDE,
    0X6B93DDDB, 0X6F52C06C, 0X6211E6B5, 0X66D0FB02, 0X5E9F46BF, 0X5A5E5B08, 0X571D7DD1,
    0X53DC6066, 0X4D9B3063, 0X495A2DD4, 0X44190B0D, 0X40D816BA, 0XACA5C697, 0XA864DB20,
    0XA527FDF9, 0XA1E6E04E, 0XBFA1B04B, 0XBB60ADFC, 0XB6238B25, 0XB2E29692, 0X8AAD2B2F,
    0X8E6C3698, 0X832F1041, 0X87EE0DF6, 0X99A95DF3, 0X9D684044, 0X902B669D, 0X94EA7B2A,
    0XE0B41DE7, 0XE4750050, 0XE9362689, 0XEDF73B3E, 0XF3B06B3B, 0XF771768C, 0XFA325055,
    0XFEF34DE2, 0XC6BCF05F, 0XC27DEDE8, 0XCF3ECB31, 0XCBFFD686, 0XD5B88683, 0XD1799B34,
    0XDC3ABDED, 0XD8FBA05A, 0X690CE0EE, 0X6DCDFD59, 0X608EDB80, 0X644FC637, 0X7A089632,
    0X7EC98B85, 0X738AAD5C, 0X774BB0EB, 0X4F040D56, 0X4BC510E1, 0X46863638, 0X42472B8F,
    0X5C007B8A, 0X58C1663D, 0X558240E4, 0X51435D53, 0X251D3B9E, 0X21DC2629, 0X2C9F00F0,
    0X285E1D47, 0X36194D42, 0X32D850F5, 0X3F9B762C, 0X3B5A6B9B, 0X0315D626, 0X07D4CB91,
    0X0A97ED48, 0X0E56F0FF, 0X1011A0FA, 0X14D0BD4D, 0X19939B94, 0X1D528623, 0XF12F560E,
    0XF5EE4BB9, 0XF8AD6D60, 0XFC6C70D7, 0XE22B20D2, 0XE6EA3D65, 0XEBA91BBC, 0XEF68060B,
    0XD727BBB6, 0XD3E6A601, 0XDEA580D8, 0XDA649D6F, 0XC423CD6A, 0XC0E2D0DD, 0XCDA1F604,
    0XC960EBB3, 0XBD3E8D7E, 0XB9FF90C9, 0XB4BCB610, 0XB07DABA7, 0XAE3AFBA2, 0XAAFBE615,
    0XA7B8C0CC, 0XA379DD7B, 0X9B3660C6, 0X9FF77D71, 0X92B45BA8, 0X9675461F, 0X8832161A,
    0X8CF30BAD, 0X81B02D74, 0X857130C3, 0X5D8A9099, 0X594B8D2E, 0X5408ABF7, 0X50C9B640,
    0X4E8EE645, 0X4A4FFBF2, 0X470CDD2B, 0X43CDC09C, 0X7B827D21, 0X7F436096, 0X7200464F,
    0X76C15BF8, 0X68860BFD, 0X6C47164A, 0X61043093, 0X65C52D24, 0X119B4BE9, 0X155A565E,
    0X18197087, 0X1CD86D30, 0X029F3D35, 0X065E2082, 0X0B1D065B, 0X0FDC1BEC, 0X3793A651,
    0X3352BBE6, 0X3E119D3F, 0X3AD08088, 0X2497D08D, 0X2056CD3A, 0X2D15EBE3, 0X29D4F654,
    0XC5A92679, 0XC1683BCE, 0XCC2B1D17, 0XC8EA00A0, 0XD6AD50A5, 0XD26C4D12, 0XDF2F6BCB,
    0XDBEE767C, 0XE3A1CBC1, 0XE760D676, 0XEA23F0AF, 0XEEE2ED18, 0XF0A5BD1D, 0XF464A0AA,
    0XF9278673, 0XFDE69BC4, 0X89B8FD09, 0X8D79E0BE, 0X803AC667, 0X84FBDBD0, 0X9ABC8BD5,
    0X9E7D9662, 0X933EB0BB, 0X97FFAD0C, 0XAFB010B1, 0XAB710D06, 0XA6322BDF, 0XA2F33668,
    0XBCB4666D, 0XB8757BDA, 0XB5365D03, 0XB1F740B4
  };

  /**
   * Allows the CRC-8 calculation to be done byte by byte instead of bit per bit in the order "most
   * significant bit first".
   */
  private static final int[] CRC8_BYTES_MSBF = {
    0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15, 0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A,
    0x2D, 0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65, 0x48, 0x4F, 0x46, 0x41, 0x54, 0x53,
    0x5A, 0x5D, 0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5, 0xD8, 0xDF, 0xD6, 0xD1, 0xC4,
    0xC3, 0xCA, 0xCD, 0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85, 0xA8, 0xAF, 0xA6, 0xA1,
    0xB4, 0xB3, 0xBA, 0xBD, 0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2, 0xFF, 0xF8, 0xF1,
    0xF6, 0xE3, 0xE4, 0xED, 0xEA, 0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2, 0x8F, 0x88,
    0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A, 0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32, 0x1F,
    0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A, 0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,
    0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A, 0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B,
    0x9C, 0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4, 0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2,
    0xEB, 0xEC, 0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4, 0x69, 0x6E, 0x67, 0x60, 0x75,
    0x72, 0x7B, 0x7C, 0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44, 0x19, 0x1E, 0x17, 0x10,
    0x05, 0x02, 0x0B, 0x0C, 0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34, 0x4E, 0x49, 0x40,
    0x47, 0x52, 0x55, 0x5C, 0x5B, 0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63, 0x3E, 0x39,
    0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B, 0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13, 0xAE,
    0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB, 0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
    0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB, 0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4,
    0xF3
  };
}