/*
    *  Copyright 2001-2009 Stephen Colebourne
    *
    *  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 org.joda.time.field;
  
  import java.io.Serializable;
  
  import org.joda.time.DurationField;
  import org.joda.time.DurationFieldType;
  
  /**
   * Duration field class representing a field with a fixed unit length of one
   * millisecond.
   * <p>
   * MillisDurationField is thread-safe and immutable.
   *
   * @author Brian S O'Neill
   * @since 1.0
   */
  public final class MillisDurationField extends DurationField implements Serializable {
  
      /** Serialization lock. */
      private static final long serialVersionUID = 2656707858124633367L;
  
      /** Singleton instance. */
      public static final DurationField INSTANCE = new MillisDurationField();
  
      /**
       * Restricted constructor.
       */
      private MillisDurationField() {
          super();
      }
      
      //------------------------------------------------------------------------
      public DurationFieldType getType() {
          return DurationFieldType.millis();
      }
  
      public String getName() {
          return "millis";
      }
  
      /**
       * Returns true as this field is supported.
       * 
       * @return true always
       */
      public boolean isSupported() {
          return true;
      }
  
      /**
       * Returns true as this field is precise.
       * 
       * @return true always
       */
      public final boolean isPrecise() {
          return true;
      }
  
      /**
       * Returns the amount of milliseconds per unit value of this field.
       *
       * @return one always
       */
      public final long getUnitMillis() {
          return 1;
      }
  
      //------------------------------------------------------------------------
      public int getValue(long duration) {
          return FieldUtils.safeToInt(duration);
      }
  
      public long getValueAsLong(long duration) {
          return duration;
      }
  
      public int getValue(long duration, long instant) {
          return FieldUtils.safeToInt(duration);
      }
  
      public long getValueAsLong(long duration, long instant) {
          return duration;
      }
  
     public long getMillis(int value) {
         return value;
     }
 
     public long getMillis(long value) {
         return value;
     }
 
     public long getMillis(int value, long instant) {
         return value;
     }
 
     public long getMillis(long value, long instant) {
         return value;
     }
 
     public long add(long instant, int value) {
         return FieldUtils.safeAdd(instant, value);
     }
 
     public long add(long instant, long value) {
         return FieldUtils.safeAdd(instant, value);
     }
 
     public int getDifference(long minuendInstant, long subtrahendInstant) {
         return FieldUtils.safeToInt(FieldUtils.safeSubtract(minuendInstant, subtrahendInstant));
     }
 
     public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
         return FieldUtils.safeSubtract(minuendInstant, subtrahendInstant);
     }
 
     //------------------------------------------------------------------------
     public int compareTo(DurationField otherField) {
         long otherMillis = otherField.getUnitMillis();
         long thisMillis = getUnitMillis();
         // cannot do (thisMillis - otherMillis) as can overflow
         if (thisMillis == otherMillis) {
             return 0;
         }
         if (thisMillis < otherMillis) {
             return -1;
         } else {
             return 1;
         }
     }
 
     public boolean equals(Object obj) {
         if (obj instanceof MillisDurationField) {
             return getUnitMillis() == ((MillisDurationField) obj).getUnitMillis();
         }
         return false;
     }
 
     public int hashCode() {
         return (int) getUnitMillis();
     }
 
     /**
      * Get a suitable debug string.
      * 
      * @return debug string
      */
     public String toString() {
         return "DurationField[millis]";
     }
 
     /**
      * Deserialize to the singleton.
      */
     private Object readResolve() {
         return INSTANCE;
     }
 
 }