package ch.qos.logback.classic.stopwatch;

import java.text.DecimalFormat;

class Util {

  static final long NANOS_IN_ONE_MICROSECOND = 1000;
  static final long NANOS_IN_ONE_MILLISECOND = NANOS_IN_ONE_MICROSECOND * 1000;
  static final long NANOS_IN_ONE_SECOND =NANOS_IN_ONE_MILLISECOND * 1000;
  private static final DecimalFormat DECIMAL_FORMAT = new DecimalFormat("0.000");
  
  static DurationUnit selectDurationUnitForDisplay(StopWatch sw) {
    return selectDurationUnitForDisplay(sw.getResultInNanos());
  }
  
  static DurationUnit selectDurationUnitForDisplay(long durationInNanos) {
    if (durationInNanos < 10*NANOS_IN_ONE_MICROSECOND) {
      return DurationUnit.NANOSECOND;
    } else if (durationInNanos < 10*NANOS_IN_ONE_MILLISECOND) {
      return DurationUnit.MICROSECOND;
    } else if (durationInNanos < NANOS_IN_ONE_SECOND) {
      return DurationUnit.MILLISSECOND;
    } else {
      return DurationUnit.SECOND;
    }
  }
  
  static public long convertToMicros(long nanos) {
    return nanos / NANOS_IN_ONE_MICROSECOND;
  }

  static public long convertToMillis(long nanos) {
    return nanos / NANOS_IN_ONE_MILLISECOND;
  }

  static public double convertToSeconds(long nanos) {
    return ((double) nanos / NANOS_IN_ONE_SECOND);
  }
  
  static String durationInDunrationUnitsAsStr(StringBuffer buf, StopWatch sw) {
    DurationUnit du = selectDurationUnitForDisplay(sw);
    return durationInDunrationUnitsAsStr(sw.getResultInNanos(), du);
  }
  
  static String durationInDunrationUnitsAsStr(long nanos, DurationUnit durationUnit) {
    StringBuffer buf = new StringBuffer();
    switch (durationUnit) {
    case NANOSECOND:
      buf.append(nanos);
      break;
    case MICROSECOND:
      buf.append(convertToMicros(nanos));
      break;
    case MILLISSECOND:
      buf.append(convertToMillis(nanos));
      break;
    case SECOND:
      double seconds = convertToSeconds(nanos);
      buf.append(DECIMAL_FORMAT.format(seconds));
      break;
    }
    return buf.toString();
  }
  
  static void appendDurationUnitAsStr(StringBuffer buf, DurationUnit durationUnit) {
    switch (durationUnit) {
    case NANOSECOND:
      buf.append("nanoseconds.");
      break;
    case MICROSECOND:
      buf.append("microseconds.");
      break;
    case MILLISSECOND:
      buf.append("milliseconds.");
      break;
    case SECOND:
      buf.append(" seconds.");
      break;
    }
  }
}
