/*
    * Copyright (C) 2020-2023 Dipl.-Inform. Kai Hofmann. All rights reserved!
    */
   package de.powerstat.validation.values;
   
   
   import java.util.Objects;
   
   import de.powerstat.validation.interfaces.IValueObject;
  
  
  /**
   * Day.
   *
   * Not DSGVO relevant.
   *
   * TODO Constructor with day, month
   * TODO Constructor with day, month, year
   * TODO Listener
   * TODO hoursWithin = 24
   * TODO min, max
   */
  public final class Day implements Comparable<Day>, IValueObject
   {
    /**
     * Overflow constant.
     */
    private static final String OVERFLOW = "Overflow"; //$NON-NLS-1$
  
    /**
     * Underflow constant.
     */
    private static final String UNDERFLOW = "Underflow"; //$NON-NLS-1$
  
    /* *
     * Cache for singletons.
     */
    // private static final Map<Integer, Day> CACHE = new WeakHashMap<>();
  
    /**
     * Day.
     */
    private final int day;
  
  
    /**
     * Constructor.
     *
     * @param day Day 1-31
     * @throws IndexOutOfBoundsException When the day is less than 1 or greater than 31
     */
    private Day(final int day)
     {
      super();
      if ((day < 1) || (day > 31))
       {
        throw new IndexOutOfBoundsException("Day number out of range (1-31)!"); //$NON-NLS-1$
       }
      this.day = day;
     }
  
  
    /**
     * Day factory.
     *
     * @param day Day 1-31
     * @return Day object
     */
    public static Day of(final int day)
     {
      /*
      synchronized (Day.class)
       {
        Day obj = Day.CACHE.get(day);
        if (obj != null)
         {
          return obj;
         }
        obj = new Day(day);
        Day.CACHE.put(Integer.valueOf(day), obj);
        return obj;
       }
      */
      return new Day(day);
     }
  
  
    /**
     * Day factory.
     *
     * @param value String value
     * @return Day object
     */
    public static Day of(final String value)
     {
      return of(Integer.parseInt(value));
     }
  
  
   /**
    * Returns the value of this Day as an int.
    *
    * @return The numeric value represented by this object after conversion to type int.
    */
   public int intValue()
    {
     return this.day;
    }
 
 
   /**
    * Returns the value of this Day as an String.
    *
    * @return The numeric value represented by this object after conversion to type String.
    */
   @Override
   public String stringValue()
    {
     return String.valueOf(this.day);
    }
 
 
   /**
    * Calculate hash code.
    *
    * @return Hash
    * @see java.lang.Object#hashCode()
    */
   @Override
   public int hashCode()
    {
     return Integer.hashCode(this.day);
    }
 
 
   /**
    * Is equal with another object.
    *
    * @param obj Object
    * @return true when equal, false otherwise
    * @see java.lang.Object#equals(java.lang.Object)
    */
   @Override
   public boolean equals(final Object obj)
    {
     if (this == obj)
      {
       return true;
      }
     if (!(obj instanceof Day))
      {
       return false;
      }
     final Day other = (Day)obj;
     return this.day == other.day;
    }
 
 
   /**
    * Returns the string representation of this Day.
    *
    * The exact details of this representation are unspecified and subject to change, but the following may be regarded as typical:
    *
    * "Day[day=1]"
    *
    * @return String representation of this Day
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString()
    {
     final var builder = new StringBuilder();
     builder.append("Day[day=").append(this.day).append(']'); //$NON-NLS-1$
     return builder.toString();
    }
 
 
   /**
    * Compare with another object.
    *
    * @param obj Object to compare with
    * @return 0: equal; 1: greater; -1: smaller
    * @see java.lang.Comparable#compareTo(java.lang.Object)
    */
   @Override
   public int compareTo(final Day obj)
    {
     Objects.requireNonNull(obj, "obj"); //$NON-NLS-1$
     return Integer.compare(this.day, obj.day);
    }
 
 
   /**
    * Add days to this day.
    *
    * @param days Days to add to this day
    * @return New day after adding the days to this day
    * @throws ArithmeticException In case of an overflow
    */
   public Day add(final Days days)
    {
     final int newDay = Math.toIntExact(Math.addExact(this.day, days.longValue()));
     if (newDay > 31) // TODO depends on month and year
      {
       // TODO Listener
       throw new ArithmeticException(Day.OVERFLOW);
      }
     return Day.of(newDay);
    }
 
 
   /**
    * Subtract days from this day.
    *
    * @param days Days to subtract from this day
    * @return New day after subtracting days from this day
    * @throws ArithmeticException In case of an underflow
    */
   public Day subtract(final Days days)
    {
     final int newDay = Math.toIntExact(Math.subtractExact(this.day, days.longValue()));
     if (newDay <= 0)
      {
       // TODO Listener
       throw new ArithmeticException(Day.UNDERFLOW);
      }
     return Day.of(newDay);
    }
 
 
   /**
    * Increment this day.
    *
    * @return New day after incrementing this day
    * @throws ArithmeticException In case of an overflow
    */
   public Day increment()
    {
     final int newDay = Math.incrementExact(this.day);
     if (newDay == 32) // TODO depends on month and year
      {
       // TODO Listener
       throw new ArithmeticException(Day.OVERFLOW);
      }
     return Day.of(newDay);
    }
 
 
   /**
    * Decrement this day.
    *
    * @return New day after decrement this day
    * @throws ArithmeticException In case of an overflow
    */
   public Day decrement()
    {
     final int newDay = Math.decrementExact(this.day);
     if (newDay == 0)
      {
       // TODO Listener
       throw new ArithmeticException(Day.UNDERFLOW);
      }
     return Day.of(newDay);
    }
 
  }