/* SpinnerDateModel.java --
   Copyright (C) 2002, 2004, 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package javax.swing;

import java.io.Serializable;
import java.util.Calendar;
import java.util.Date;

import javax.swing.event.ChangeEvent;

/**
 * A date model used by the {@link JSpinner} component.  This implements a 
 * spinner model for dates, rotating a calendar field such as  month, year, 
 * day, week, hour, minute.
 *
 * @author Sven de Marothy
 * @since 1.4
 */
public class SpinnerDateModel extends AbstractSpinnerModel
  implements Serializable
{
  /** The current date. */
  private Calendar date;
  
  /** 
   * The start or earliest permitted date (<code>null</code> for no 
   * minimum). 
   */
  private Comparable start;

  /** 
   * The end or latest permitted date (<code>null</code> for no 
   * maximum). 
   */
  private Comparable end;
  
  /**
   * The calendar field used to calculate the previous or next date. 
   */
  private int calendarField;

  /**
   * For compatability with Sun's JDK
   * FIXME: Which fields should be serialized?
   */
  private static final long serialVersionUID = -4802518107105940612L;

  /**
   * Constructs a <code>SpinnerDateModel</code> using the current date,
   * no start or end limit, and {@link Calendar#DAY_OF_MONTH} as the calendar 
   * field.
   */
  public SpinnerDateModel()
  {
    this(new Date(), null, null, Calendar.DAY_OF_MONTH);
  }

  /**
   * Constructs a SpinnerDateModel which spins a given calendar field,
   * using a given date and start and end date limits.
   * @param value - the initial Date value
   * @param start - start limit, as a Date object, or <code>null</code>
   * for no lower limit.
   * @param end - end limit, or <code>null</code> for no upper limit.
   * @param calendarField - the <code>Calendar</code> field to spin,
   * (Calendar.ZONE_OFFSET and Calendar.DST_OFFSET are invalid)
   */
  public SpinnerDateModel(Date value, Comparable start, Comparable end,
                          int calendarField)
  {
    if (value == null) 
      throw new IllegalArgumentException("Null 'value' argument.");
    if (start != null && start.compareTo(value) > 0)
      throw new IllegalArgumentException("Require value on or after start.");
    if (end != null && end.compareTo(value) < 0)
      throw new IllegalArgumentException("Require value on or before end.");
    date = Calendar.getInstance();
    date.setTime(value);
    this.start = start;
    this.end = end;
    setCalendarField(calendarField);
  }

  /**
   * Returns the {@link Calendar} field used to calculate the previous and 
   * next dates in the sequence.
   * 
   * @return The date field code.
   */
  public int getCalendarField()
  {
    return calendarField;
  }

  /**
   * Returns the current date.
   * 
   * @return The current date.
   */
  public Date getDate()
  {
    return date.getTime();
  }

  /**
   * Returns the start date, or <code>null</code> if there is no minimum date.
   * 
   * @return The start date.
   */
  public Comparable getStart()
  {
    return start;
  }

  /**
   * Returns the end date, or <code>null</code> if there is no maximum date.
   * 
   * @return The end date.
   */
  public Comparable getEnd()
  {
    return end;
  }

  /**
   * Returns the current date in the sequence (this method returns the same as 
   * {@link #getDate()}.
   * 
   * @return The current date.
   */
  public Object getValue()
  {
    return date.getTime();
  }

  /**
   * Returns the next date in the sequence, or <code>null</code> if the
   * next date is after the end date.  The current date is not changed.
   * 
   * @return The next date, or <code>null</code> if the current value is
   *         the latest date represented by the model.
   */
  public Object getNextValue()
  {
    Calendar nextCal = Calendar.getInstance();
    nextCal.setTime(date.getTime());
    nextCal.roll(calendarField, true);
    Date nextDate = nextCal.getTime();
    if (end != null)
      if (end.compareTo(nextDate) < 0)
        return null;
    return nextDate;
  }

  /**
   * Returns the previous date in the sequence, or <code>null</code> if the
   * previous date is prior to the start date.  The current date is not 
   * changed.
   * 
   * @return The previous date, or <code>null</code> if the current value is
   *         the earliest date represented by the model.
   */
  public Object getPreviousValue()
  {
    Calendar prevCal = Calendar.getInstance();
    prevCal.setTime(date.getTime());
    prevCal.roll(calendarField, false);
    Date prevDate = prevCal.getTime();
    if (start != null)
      if (start.compareTo(prevDate) > 0)
        return null;
    return prevDate;
  }

  /**
   * Sets the date field to change when calculating the next and previous 
   * values. It must be a valid {@link Calendar} field, excluding 
   * {@link Calendar#ZONE_OFFSET} and {@link Calendar#DST_OFFSET}.
   * 
   * @param calendarField  the calendar field to set.
   * 
   * @throws IllegalArgumentException if <code>calendarField</code> is not 
   *         a valid code.
   */
  public void setCalendarField(int calendarField)
  {
    if (calendarField < 0 || calendarField >= Calendar.FIELD_COUNT
        || calendarField == Calendar.ZONE_OFFSET
        || calendarField == Calendar.DST_OFFSET)
      throw new IllegalArgumentException("Illegal calendarField");

    if (this.calendarField != calendarField)
      {
        this.calendarField = calendarField;
        fireStateChanged();
      }
  }

  /**
   * Sets the start date and, if the new date is different to the old date,
   * sends a {@link ChangeEvent} to all registered listeners.  A 
   * <code>null</code> date is interpreted as "no start date".  No check
   * is made to ensure that the new start date is on or before the current 
   * date - the caller is responsible for ensuring that this relationship 
   * holds.
   * 
   * @param start  the new start date (<code>null</code> permitted).
   */
  public void setStart(Comparable start)
  {
    if (this.start != start)
      {
        this.start = start;
        fireStateChanged();
      }
  }

  /**
   * Sets the end date and, if the new date is different to the old date,
   * sends a {@link ChangeEvent} to all registered listeners.  A 
   * <code>null</code> date is interpreted as "no end date".  No check
   * is made to ensure that the new end date is on or after the current date - 
   * the caller is responsible for ensuring that this relationship holds.
   * 
   * @param end  the new end date (<code>null</code> permitted).
   */
  public void setEnd(Comparable end)
  {
    if (this.end != end)
      {
        this.end = end;
        fireStateChanged();
      }
  }

  /**
   * Sets the current date and, if the new value is different to the old
   * value, sends a {@link ChangeEvent} to all registered listeners.
   *
   * @param value  the new date (<code>null</code> not permitted, must be an 
   *               instance of <code>Date</code>).
   *               
   * @throws IllegalArgumentException if <code>value</code> is not an instance 
   *         of <code>Date</code>.
   */
  public void setValue(Object value)
  {
    if (! (value instanceof Date) || value == null)
      throw new IllegalArgumentException("Value not a date.");
    
    if (!date.getTime().equals(value)) 
      {
        date.setTime((Date) value);
        fireStateChanged();
      }
  }
}