/*
  * Written by Doug Lea with assistance from members of JCP JSR-166
  * Expert Group and released to the public domain, as explained at
  * http://creativecommons.org/licenses/publicdomain
  */

package org.apache.beehive.netui.util.internal.concurrent;

/**
  * A <tt>TimeUnit</tt> represents time durations at a given unit of
  * granularity and provides utility methods to convert across units,
  * and to perform timing and delay operations in these units.  A
  * <tt>TimeUnit</tt> does not maintain time information, but only
  * helps organize and use time representations that may be maintained
  * separately across various contexts.  A nanosecond is defined as one
  * thousandth of a microsecond, a microsecond as one thousandth of a
  * millisecond, a millisecond as one thousandth of a second, a minute
  * as sixty seconds, an hour as sixty minutes, and a day as twenty four
  * hours.
  *
  * <p>A <tt>TimeUnit</tt> is mainly used to inform time-based methods
  * how a given timing parameter should be interpreted. For example,
  * the following code will timeout in 50 milliseconds if the {@link
  * org.apache.beehive.netui.util.concurrent.locks.Lock lock} is not available:
  *
  * <pre>  Lock lock = ...;
  *  if ( lock.tryLock(50L, TimeUnit.MILLISECONDS) ) ...
  * </pre>
  * while this code will timeout in 50 seconds:
  * <pre>
  *  Lock lock = ...;
  *  if ( lock.tryLock(50L, TimeUnit.SECONDS) ) ...
  * </pre>
  *
  * Note however, that there is no guarantee that a particular timeout
  * implementation will be able to notice the passage of time at the
  * same granularity as the given <tt>TimeUnit</tt>.
  *
  * @since 1.5
  * @author Doug Lea
  */
abstract class TimeUnit implements java.io.Serializable {

     public static final TimeUnit NANOSECONDS = new TimeUnit(0, "NANOSECONDS") {
         public long toNanos(long d)   { return d; }
         public long toMicros(long d)  { return d/(C1/C0); }
         public long toMillis(long d)  { return d/(C2/C0); }
         public long toSeconds(long d) { return d/(C3/C0); }
         public long toMinutes(long d) { return d/(C4/C0); }
         public long toHours(long d)   { return d/(C5/C0); }
         public long toDays(long d)    { return d/(C6/C0); }
         public long convert(long d, TimeUnit u) { return u.toNanos(d); }
         int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
     };
     public static final TimeUnit MICROSECONDS = new TimeUnit(1, "MICROSECONDS") {
         public long toNanos(long d)   { return x(d, C1/C0, MAX/(C1/C0)); }
         public long toMicros(long d)  { return d; }
         public long toMillis(long d)  { return d/(C2/C1); }
         public long toSeconds(long d) { return d/(C3/C1); }
         public long toMinutes(long d) { return d/(C4/C1); }
         public long toHours(long d)   { return d/(C5/C1); }
         public long toDays(long d)    { return d/(C6/C1); }
         public long convert(long d, TimeUnit u) { return u.toMicros(d); }
         int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
     };
     public static final TimeUnit MILLISECONDS = new TimeUnit(2, "MILLISECONDS") {
         public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }
         public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }
         public long toMillis(long d)  { return d; }
         public long toSeconds(long d) { return d/(C3/C2); }
         public long toMinutes(long d) { return d/(C4/C2); }
         public long toHours(long d)   { return d/(C5/C2); }
         public long toDays(long d)    { return d/(C6/C2); }
         public long convert(long d, TimeUnit u) { return u.toMillis(d); }
         int excessNanos(long d, long m) { return 0; }
     };
     public static final TimeUnit SECONDS = new TimeUnit(3, "SECONDS") {
         public long toNanos(long d)   { return x(d, C3/C0, MAX/(C3/C0)); }
         public long toMicros(long d)  { return x(d, C3/C1, MAX/(C3/C1)); }
         public long toMillis(long d)  { return x(d, C3/C2, MAX/(C3/C2)); }
         public long toSeconds(long d) { return d; }
         public long toMinutes(long d) { return d/(C4/C3); }
         public long toHours(long d)   { return d/(C5/C3); }
         public long toDays(long d)    { return d/(C6/C3); }
         public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
         int excessNanos(long d, long m) { return 0; }
     };
     public static final TimeUnit MINUTES = new TimeUnit(4, "MINUTES") {
         public long toNanos(long d)   { return x(d, C4/C0, MAX/(C4/C0)); }
         public long toMicros(long d)  { return x(d, C4/C1, MAX/(C4/C1)); }
         public long toMillis(long d)  { return x(d, C4/C2, MAX/(C4/C2)); }
         public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
         public long toMinutes(long d) { return d; }
         public long toHours(long d)   { return d/(C5/C4); }
         public long toDays(long d)    { return d/(C6/C4); }
         public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
         int excessNanos(long d, long m) { return 0; }
     };
     public static final TimeUnit HOURS = new TimeUnit(5, "HOURS") {
         public long toNanos(long d)   { return x(d, C5/C0, MAX/(C5/C0)); }
         public long toMicros(long d)  { return x(d, C5/C1, MAX/(C5/C1)); }
         public long toMillis(long d)  { return x(d, C5/C2, MAX/(C5/C2)); }
         public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
         public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
         public long toHours(long d)   { return d; }
         public long toDays(long d)    { return d/(C6/C5); }
         public long convert(long d, TimeUnit u) { return u.toHours(d); }
         int excessNanos(long d, long m) { return 0; }
     };
     public static final TimeUnit DAYS = new TimeUnit(6, "DAYS") {
         public long toNanos(long d)   { return x(d, C6/C0, MAX/(C6/C0)); }
         public long toMicros(long d)  { return x(d, C6/C1, MAX/(C6/C1)); }
         public long toMillis(long d)  { return x(d, C6/C2, MAX/(C6/C2)); }
         public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
         public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
         public long toHours(long d)   { return x(d, C6/C5, MAX/(C6/C5)); }
         public long toDays(long d)    { return d; }
         public long convert(long d, TimeUnit u) { return u.toDays(d); }
         int excessNanos(long d, long m) { return 0; }
     };

     private static final TimeUnit[] values = new TimeUnit[]
         { NANOSECONDS, MICROSECONDS, MILLISECONDS, SECONDS, MINUTES, HOURS, DAYS };

     public static TimeUnit[] values() {
         return (TimeUnit[])values.clone();
     }

     /**
      * The index of this unit. This value is no longer used in this
      * version of this class, but is retained for serialization
      * compatibility with previous version.
      */
     private final int index;

     /** name of this unit */
     private final String name;

     /** Internal constructor */
     TimeUnit(int index, String name) {
         this.index = index;
         this.name = name;
     }

     // Handy constants for conversion methods
     static final long C0 = 1;
     static final long C1 = C0 * 1000;
     static final long C2 = C1 * 1000;
     static final long C3 = C2 * 1000;
     static final long C4 = C3 * 60;
     static final long C5 = C4 * 60;
     static final long C6 = C5 * 24;

     static final long MAX = Long.MAX_VALUE;

     /**
      * Scale d by m, checking for overflow.
      * This has a short name to make above code more readable.
      */
     static long x(long d, long m, long over) {
         if (d >  over) return Long.MAX_VALUE;
         if (d < -over) return Long.MIN_VALUE;
         return d * m;
     }

     /**
      * Convert the given time duration in the given unit to this
      * unit.  Conversions from finer to coarser granularities
      * truncate, so lose precision. For example converting
      * <tt>999</tt> milliseconds to seconds results in
      * <tt>0</tt>. Conversions from coarser to finer granularities
      * with arguments that would numerically overflow saturate to
      * <tt>Long.MIN_VALUE</tt> if negative or <tt>Long.MAX_VALUE</tt>
      * if positive.
      *
      * @param duration the time duration in the given <tt>unit</tt>
      * @param unit the unit of the <tt>duration</tt> argument
      * @return the converted duration in this unit,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      */
     public abstract long convert(long duration, TimeUnit unit);

     /**
      * Equivalent to <tt>NANOSECONDS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toNanos(long duration);

     /**
      * Equivalent to <tt>MICROSECONDS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toMicros(long duration);

     /**
      * Equivalent to <tt>MILLISECONDS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toMillis(long duration);

     /**
      * Equivalent to <tt>SECONDS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toSeconds(long duration);

     /**
      * Equivalent to <tt>MINUTES.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toMinutes(long duration);

     /**
      * Equivalent to <tt>HOURS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration,
      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
      * @see #convert
      */
     public abstract long toHours(long duration);

     /**
      * Equivalent to <tt>DAYS.convert(duration, this)</tt>.
      * @param duration the duration
      * @return the converted duration
      * @see #convert
      */
     public abstract long toDays(long duration);

     /**
      * Utility to compute the excess-nanosecond argument to wait,
      * sleep, join.
      * @param d the duration
      * @param m the number of millisecondss
      * @return the number of nanoseconds
      */
     abstract int excessNanos(long d, long m);

     /**
      * Perform a timed <tt>Object.wait</tt> using this time unit.
      * This is a convenience method that converts timeout arguments
      * into the form required by the <tt>Object.wait</tt> method.
      *
      * <p>For example, you could implement a blocking <tt>poll</tt>
      * method (see {@link BlockingQueue#poll BlockingQueue.poll})
      * using:
      *
      * <pre>  public synchronized  Object poll(long timeout, TimeUnit unit) throws InterruptedException {
      *    while (empty) {
      *      unit.timedWait(this, timeout);
      *      ...
      *    }
      *  }</pre>
      *
      * @param obj the object to wait on
      * @param timeout the maximum time to wait.
      * @throws InterruptedException if interrupted while waiting.
      * @see java.lang.Object#wait(long, int)
      */
     public void timedWait(Object obj, long timeout)
         throws InterruptedException {
         if (timeout > 0) {
             long ms = toMillis(timeout);
             int ns = excessNanos(timeout, ms);
             obj.wait(ms, ns);
         }
     }

     /**
      * Perform a timed <tt>Thread.join</tt> using this time unit.
      * This is a convenience method that converts time arguments into the
      * form required by the <tt>Thread.join</tt> method.
      * @param thread the thread to wait for
      * @param timeout the maximum time to wait
      * @throws InterruptedException if interrupted while waiting.
      * @see java.lang.Thread#join(long, int)
      */
     public void timedJoin(Thread thread, long timeout)
         throws InterruptedException {
         if (timeout > 0) {
             long ms = toMillis(timeout);
             int ns = excessNanos(timeout, ms);
             thread.join(ms, ns);
         }
     }

     /**
      * Perform a <tt>Thread.sleep</tt> using this unit.
      * This is a convenience method that converts time arguments into the
      * form required by the <tt>Thread.sleep</tt> method.
      * @param timeout the minimum time to sleep
      * @throws InterruptedException if interrupted while sleeping.
      * @see java.lang.Thread#sleep
      */
     public void sleep(long timeout) throws InterruptedException {
         if (timeout > 0) {
             long ms = toMillis(timeout);
             int ns = excessNanos(timeout, ms);
             Thread.sleep(ms, ns);
         }
     }

     public String toString() {
         return name;
     }
}
