/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.core.util;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Duration instances represent a lapse of time. Internally, the duration is
   * stored in milliseconds. However, whenever a parameter of type Duration is
   * expected, Joran (logback's configuration system) will automatically convert
   * strings such as "20 seconds" "3.5 minutes" or "5 hours" into Duration
   * instances.
   *
   * <p>
   * The recognized units of time are the "millisecond", "second", "minute" "hour"
   * and "day". The unit name may be followed by an "s". Thus, "2 day" and "2
   * days" are equivalent. In the absence of a time unit specification,
   * milliseconds are assumed.
   * 
   * <p>
   * Note: the conversion magic is entirely due to the fact that this class
   * follows the {@link #valueOf} convention.
   *
   * @author Ceki Gulcu
   */
  public class Duration {
  
      private final static String DOUBLE_PART = "([0-9]*(.[0-9]+)?)";
      private final static int DOUBLE_GROUP = 1;
  
      private final static String UNIT_PART = "(|milli(second)?|second(e)?|minute|hour|day)s?";
      private final static int UNIT_GROUP = 3;
  
      private static final Pattern DURATION_PATTERN = Pattern.compile(DOUBLE_PART + "\\s*" + UNIT_PART,
              Pattern.CASE_INSENSITIVE);
  
      static final long SECONDS_COEFFICIENT = 1000;
      static final long MINUTES_COEFFICIENT = 60 * SECONDS_COEFFICIENT;
      static final long HOURS_COEFFICIENT = 60 * MINUTES_COEFFICIENT;
      static final long DAYS_COEFFICIENT = 24 * HOURS_COEFFICIENT;
  
      final long millis;
  
      public Duration(long millis) {
          this.millis = millis;
      }
  
      public static Duration buildByMilliseconds(double value) {
          return new Duration((long) (value));
      }
  
      public static Duration buildBySeconds(double value) {
          return new Duration((long) (SECONDS_COEFFICIENT * value));
      }
  
      public static Duration buildByMinutes(double value) {
          return new Duration((long) (MINUTES_COEFFICIENT * value));
      }
  
      public static Duration buildByHours(double value) {
          return new Duration((long) (HOURS_COEFFICIENT * value));
      }
  
      public static Duration buildByDays(double value) {
          return new Duration((long) (DAYS_COEFFICIENT * value));
      }
  
      public static Duration buildUnbounded() {
          return new Duration(Long.MAX_VALUE);
      }
  
      public long getMilliseconds() {
          return millis;
      }
  
      public static Duration valueOf(String durationStr) {
          Matcher matcher = DURATION_PATTERN.matcher(durationStr);
  
          if (matcher.matches()) {
              String doubleStr = matcher.group(DOUBLE_GROUP);
              String unitStr = matcher.group(UNIT_GROUP);
  
              double doubleValue = Double.valueOf(doubleStr);
              if (unitStr.equalsIgnoreCase("milli") || unitStr.equalsIgnoreCase("millisecond") || unitStr.length() == 0) {
                  return buildByMilliseconds(doubleValue);
              } else if (unitStr.equalsIgnoreCase("second") || unitStr.equalsIgnoreCase("seconde")) {
                  return buildBySeconds(doubleValue);
             } else if (unitStr.equalsIgnoreCase("minute")) {
                 return buildByMinutes(doubleValue);
             } else if (unitStr.equalsIgnoreCase("hour")) {
                 return buildByHours(doubleValue);
             } else if (unitStr.equalsIgnoreCase("day")) {
                 return buildByDays(doubleValue);
             } else {
                 throw new IllegalStateException("Unexpected " + unitStr);
             }
         } else {
             throw new IllegalArgumentException("String value [" + durationStr + "] is not in the expected format.");
         }
     }
 
     @Override
     public String toString() {
         if (millis < SECONDS_COEFFICIENT) {
             return millis + " milliseconds";
         } else if (millis < MINUTES_COEFFICIENT) {
             return millis / SECONDS_COEFFICIENT + " seconds";
         } else if (millis < HOURS_COEFFICIENT) {
             return millis / MINUTES_COEFFICIENT + " minutes";
         } else {
             return millis / HOURS_COEFFICIENT + " hours";
         }
 
     }
 }