package com.bumptech.glide.util;

import android.annotation.TargetApi;
import android.os.Build;
import android.os.SystemClock;

/**
 * A class for logging elapsed real time in millis.
 */
public final class LogTime {
  private static final double MILLIS_MULTIPLIER =
      Build.VERSION_CODES.JELLY_BEAN_MR1 <= Build.VERSION.SDK_INT ? 1d / Math.pow(10, 6) : 1d;

  private LogTime() {
    // Utility class.
  }

  /**
   * Returns the current time in either millis or nanos depending on the api level to be used with
   * {@link #getElapsedMillis(long)}.
   */
  @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
  public static long getLogTime() {
    if (Build.VERSION_CODES.JELLY_BEAN_MR1 <= Build.VERSION.SDK_INT) {
      return SystemClock.elapsedRealtimeNanos();
    } else {
      return System.currentTimeMillis();
    }
  }

  /**
   * Returns the time elapsed since the given logTime in millis.
   *
   * @param logTime The start time of the event.
   */
  public static double getElapsedMillis(long logTime) {
    return (getLogTime() - logTime) * MILLIS_MULTIPLIER;
  }
}
