/*
 * @(#)SpinnerDateModel.java	1.5 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.swing;

import java.util.*;
import java.io.Serializable;


/**
 * A <code>SpinnerModel</code> for sequences of <code>Date</code>s. 
 * The upper and lower bounds of the sequence are defined by properties called 
 * <code>start</code> and <code>end</code> and the size
 * of the increase or decrease computed by the <code>nextValue</code>
 * and <code>previousValue</code> methods is defined by a property
 * called <code>calendarField</code>.  The <code>start</code> 
 * and <code>end</code> properties can be <code>null</code> to
 * indicate that the sequence has no lower or upper limit.  
 * <p>
 * The value of the <code>calendarField</code> property must be one of the
 * <code>java.util.Calendar</code> constants that specify a field
 * within a <code>Calendar</code>.  The <code>getNextValue</code> 
 * and <code>getPreviousValue</code> 
 * methods change the date forward or backwards by this amount.  
 * For example, if <code>calendarField</code> is <code>Calendar.DAY_OF_WEEK</code>,
 * then <code>nextValue</code> produces a <code>Date</code> that's 24
 * hours after the current <code>value</code>, and <code>previousValue</code>
 * produces a <code>Date</code> that's 24 hours earlier.
 * <p>
 * The legal values for <code>calendarField</code> are:
 * <ul>
 *   <li><code>Calendar.ERA</code>
 *   <li><code>Calendar.YEAR</code>
 *   <li><code>Calendar.MONTH</code>
 *   <li><code>Calendar.WEEK_OF_YEAR</code>
 *   <li><code>Calendar.WEEK_OF_MONTH</code>
 *   <li><code>Calendar.DAY_OF_MONTH</code>
 *   <li><code>Calendar.DAY_OF_YEAR</code>
 *   <li><code>Calendar.DAY_OF_WEEK</code>
 *   <li><code>Calendar.DAY_OF_WEEK_IN_MONTH</code>
 *   <li><code>Calendar.AM_PM</code>
 *   <li><code>Calendar.HOUR</code>
 *   <li><code>Calendar.HOUR_OF_DAY</code>
 *   <li><code>Calendar.MINUTE</code>
 *   <li><code>Calendar.SECOND</code>
 *   <li><code>Calendar.MILLISECOND</code>
 * </ul>
 * <p>
 * This model inherits a <code>ChangeListener</code>.  The
 * <code>ChangeListeners</code> are notified whenever the models
 * <code>value</code>, <code>calendarField</code>, 
 * <code>start</code>, or <code>end</code> properties changes.
 * 
 * @see JSpinner
 * @see SpinnerModel
 * @see AbstractSpinnerModel
 * @see SpinnerListModel
 * @see SpinnerNumberModel
 * @see Calendar#add
 *
 * @version 1.5 12/03/01
 * @author Hans Muller
 * @since 1.4
 */
public class SpinnerDateModel extends AbstractSpinnerModel implements Serializable
{
    private Comparable start, end;
    private Calendar value;
    private int calendarField;


    private boolean calendarFieldOK(int calendarField) {
	switch(calendarField) {
	case Calendar.ERA:
	case Calendar.YEAR:
	case Calendar.MONTH:
	case Calendar.WEEK_OF_YEAR:
	case Calendar.WEEK_OF_MONTH:
	case Calendar.DAY_OF_MONTH:
	case Calendar.DAY_OF_YEAR:
	case Calendar.DAY_OF_WEEK:
	case Calendar.DAY_OF_WEEK_IN_MONTH:
	case Calendar.AM_PM:
	case Calendar.HOUR:
	case Calendar.HOUR_OF_DAY:
	case Calendar.MINUTE:
	case Calendar.SECOND:
	case Calendar.MILLISECOND:
	    return true;
	default:
	    return false;
	}
    }
    

    /**
     * Creates a <code>SpinnerDateModel</code> that represents a sequence of dates
     * between <code>start</code> and <code>end</code>.  The 
     * <code>nextValue</code> and <code>previousValue</code> methods 
     * compute elements of the sequence by advancing or reversing
     * the current date <code>value</code> by the 
     * <code>calendarField</code> time unit.  For a precise description
     * of what it means to increment or decrement a <code>Calendar</code>
     * <code>field</code>, see the <code>add</code> method in 
     * <code>java.util.Calendar</code>.
     * <p>
     * The <code>start</code> and <code>end</code> parameters can be
     * <code>null</code> to indicate that the range doesn't have an
     * upper or lower bound.  If <code>value</code> or
     * <code>calendarField</code> is <code>null</code>, or if both 
     * <code>start</code> and <code>end</code> are specified and 
     * <code>mininum &gt; maximum</code> then an
     * <code>IllegalArgumentException</code> is thrown.
     * Similarly if <code>(minimum &lt;= value &lt;= maximum)</code> is false,
     * an IllegalArgumentException is thrown.
     * 
     * @param value the current (non <code>null</code>) value of the model
     * @param start the first date in the sequence or <code>null</code>
     * @param end the last date in the sequence or <code>null</code>
     * @param calendarField one of 
     *   <ul>
     *    <li><code>Calendar.ERA</code>
     *    <li><code>Calendar.YEAR</code>
     *    <li><code>Calendar.MONTH</code>
     *    <li><code>Calendar.WEEK_OF_YEAR</code>
     *    <li><code>Calendar.WEEK_OF_MONTH</code>
     *    <li><code>Calendar.DAY_OF_MONTH</code>
     *    <li><code>Calendar.DAY_OF_YEAR</code>
     *    <li><code>Calendar.DAY_OF_WEEK</code>
     *    <li><code>Calendar.DAY_OF_WEEK_IN_MONTH</code>
     *    <li><code>Calendar.AM_PM</code>
     *    <li><code>Calendar.HOUR</code>
     *    <li><code>Calendar.HOUR_OF_DAY</code>
     *    <li><code>Calendar.MINUTE</code>
     *    <li><code>Calendar.SECOND</code>
     *    <li><code>Calendar.MILLISECOND</code>
     *   </ul>
     * 
     * @throws IllegalArgumentException if <code>value</code> or
     *    <code>calendarField</code> are <code>null</code>,
     *    if <code>calendarField</code> isn't valid,
     *    or if the following expression is 
     *    false: <code>(start &lt;= value &lt;= end)</code>.
     * 
     * @see Calendar#add
     * @see #setValue
     * @see #setStart
     * @see #setEnd
     * @see #setCalendarField
     */
    public SpinnerDateModel(Date value, Comparable start, Comparable end, int calendarField) {
	if (value == null) {
	    throw new IllegalArgumentException("value is null");
	}
	if (!calendarFieldOK(calendarField)) {
	    throw new IllegalArgumentException("invalid calendarField");
	}
	if (!(((start == null) || (start.compareTo(value) <= 0)) && 
	      ((end == null) || (end.compareTo(value) >= 0)))) {
	    throw new IllegalArgumentException("(start <= value <= end) is false");
	}
	this.value = Calendar.getInstance();
	this.start = start;
	this.end = end;
	this.calendarField = calendarField;

	this.value.setTime(value);
    }


    /**
     * Constructs a <code>SpinnerDateModel</code> whose initial
     * <code>value</code> is the current date, <code>calendarField</code>
     * is equal to <code>Calendar.DAY_OF_MONTH</code>, and for which 
     * there are no <code>start</code>/<code>end</code> limits.
     */
    public SpinnerDateModel() {
	this(new Date(), null, null, Calendar.DAY_OF_MONTH);
    }


    /**
     * Changes the lower limit for Dates in this sequence. 
     * If <code>start</code> is <code>null</code>,
     * then there is no lower limit.  No bounds checking is done here: 
     * the new start value may invalidate the
     * <code>(start &lt;= value &lt;= end)</code>
     * invariant enforced by the constructors.  This is to simplify updating
     * the model.  Naturally one should ensure that the invariant is true
     * before calling the <code>nextValue</code>, <code>previousValue</code>,
     * or <code>setValue</code> methods.
     * <p>
     * Typically this property is a <code>Date</code> however it's possible to use 
     * a <code>Comparable</code> with a <code>compareTo</code> method for Dates.  
     * For example <code>start</code> might be an instance of a class like this:
     * <pre>
     * MyStartDate implements Comparable { 
     *     long t = 12345;
     *     public int compareTo(Date d) {
     *            return (t < d.getTime() ? -1 : (t == d.getTime() ? 0 : 1));
     *     }
     *     public int compareTo(Object o) {
     *            return compareTo((Date)o);
     *     }
     * }
     * </pre>
     * Note that the above example will throw a <code>ClassCastException</code>
     * if the <code>Object</code> passed to <code>compareTo(Object)</code>
     * is not a <code>Date</code>.
     * <p>
     * This method fires a <code>ChangeEvent</code> if the
     * <code>start</code> has changed.
     * 
     * @param start defines the first date in the sequence
     * @see #getStart
     * @see #setEnd
     * @see #addChangeListener
     */
    public void setStart(Comparable start) {
	if ((start == null) ? (this.start != null) : !start.equals(this.start)) {
	    this.start = start;
	    fireStateChanged();
	}
    }


    /**
     * Returns the first <code>Date</code> in the sequence.
     * 
     * @return the value of the <code>start</code> property
     * @see #setStart
     */
    public Comparable getStart() {
	return start;
    }


    /** 
     * Changes the upper limit for <code>Date</code>s in this sequence. 
     * If <code>start</code> is <code>null</code>, then there is no upper
     * limit.  No bounds checking is done here: the new 
     * start value may invalidate the <code>(start &lt;= value &lt;= end)</code>
     * invariant enforced by the constructors.  This is to simplify updating
     * the model.  Naturally, one should ensure that the invariant is true
     * before calling the <code>nextValue</code>, <code>previousValue</code>, 
     * or <code>setValue</code> methods.
     * <p>
     * Typically this property is a <code>Date</code> however it's possible to use 
     * <code>Comparable</code> with a <code>compareTo</code> method for 
     * <code>Date</code>s.  See <code>setStart</code> for an example.
     * <p>
     * This method fires a <code>ChangeEvent</code> if the <code>end</code>
     * has changed.
     * 
     * @param start defines the last date in the sequence
     * @see #getEnd
     * @see #setStart
     * @see #addChangeListener
     */
    public void setEnd(Comparable end) {
	if ((end == null) ? (this.end != null) : !end.equals(this.end)) {
	    this.end = end;
	    fireStateChanged();
	}
    }

    
    /**
     * Returns the last <code>Date</code> in the sequence.
     * 
     * @return the value of the <code>end</code> property
     * @see #setEnd
     */
    public Comparable getEnd() {
	return end;
    }


    /**
     * Changes the size of the date value change computed
     * by the <code>nextValue</code> and <code>previousValue</code> methods.
     * The <code>calendarField</code> parameter must be one of the 
     * <code>Calendar</code> field constants like <code>Calendar.MONTH</code> 
     * or <code>Calendar.MINUTE</code>.
     * The <code>nextValue</code> and <code>previousValue</code> methods
     * simply move the specified <code>Calendar</code> field forward or backward 
     * by one unit with the <code>Calendar.add</code> method.
     * 
     * @param size one of 
     *  <ul>
     *    <li><code>Calendar.ERA</code>
     *    <li><code>Calendar.YEAR</code>
     *    <li><code>Calendar.MONTH</code>
     *    <li><code>Calendar.WEEK_OF_YEAR</code>
     *    <li><code>Calendar.WEEK_OF_MONTH</code>
     *    <li><code>Calendar.DAY_OF_MONTH</code>
     *    <li><code>Calendar.DAY_OF_YEAR</code>
     *    <li><code>Calendar.DAY_OF_WEEK</code>
     *    <li><code>Calendar.DAY_OF_WEEK_IN_MONTH</code>
     *    <li><code>Calendar.AM_PM</code>
     *    <li><code>Calendar.HOUR</code>
     *    <li><code>Calendar.HOUR_OF_DAY</code>
     *    <li><code>Calendar.MINUTE</code>
     *    <li><code>Calendar.SECOND</code>
     *    <li><code>Calendar.MILLISECOND</code>
     *  </ul>
     * <p>
     * This method fires a <code>ChangeEvent</code> if the
     * <code>calendarField</code> has changed.
     * 
     * @see #getCalendarField
     * @see #getNextValue
     * @see #getPreviousValue
     * @see Calendar#add
     * @see #addChangeListener
     */
    public void setCalendarField(int calendarField) {
	if (!calendarFieldOK(calendarField)) {
	    throw new IllegalArgumentException("invalid calendarField");
	}
	if (calendarField != this.calendarField) {
	    this.calendarField = calendarField;
	    fireStateChanged();
	}
    } 


    /**
     * Returns the <code>Calendar</code> field that is added to or subtracted from
     * by the <code>nextValue</code> and <code>previousValue</code> methods.
     * 
     * @return the value of the <code>calendarField</code> property
     * @see #setCalendarField
     */
    public int getCalendarField() {
	return calendarField;
    }


    /**
     * Returns the next <code>Date</code> in the sequence, or <code>null</code> if 
     * the next date is after <code>end</code>.
     * 
     * @return the next <code>Date</code> in the sequence, or <code>null</code> if 
     *     the next date is after <code>end</code>.
     * 
     * @see SpinnerModel#getNextValue
     * @see #getPreviousValue
     * @see #setCalendarField
     */
    public Object getNextValue() {
	Calendar cal = Calendar.getInstance();
	cal.setTime(value.getTime());
	cal.add(calendarField, 1);
	Date next = cal.getTime();
	return ((end == null) || (end.compareTo(next) >= 0)) ? next : null;
    }


    /**
     * Returns the previous <code>Date</code> in the sequence, or <code>null</code>
     * if the previous date is before <code>start</code>.
     * 
     * @return the previous <code>Date</code> in the sequence, or
     *     <code>null</code> if the previous date
     *     is before <code>start</code>
     * 
     * @see SpinnerModel#getPreviousValue
     * @see #getNextValue
     * @see #setCalendarField
     */
    public Object getPreviousValue() {
	Calendar cal = Calendar.getInstance();
	cal.setTime(value.getTime());
	cal.add(calendarField, -1);
	Date prev = cal.getTime();
	return ((start == null) || (start.compareTo(prev) <= 0)) ? prev : null;
    }


    /**
     * Returns the current element in this sequence of <code>Date</code>s.
     * This method is equivalent to <code>(Date)getValue</code>.
     *
     * @return the <code>value</code> property
     * @see #setValue
     */
    public Date getDate() {
	return value.getTime();
    }


    /**
     * Returns the current element in this sequence of <code>Date</code>s.
     * 
     * @return the <code>value</code> property
     * @see #setValue
     * @see #getDate
     */
    public Object getValue() {
	return value.getTime();
    }


    /**
     * Sets the current <code>Date</code> for this sequence.  
     * If <code>value</code> is <code>null</code>,
     * an <code>IllegalArgumentException</code> is thrown.  No bounds 
     * checking is done here: 
     * the new value may invalidate the <code>(start &lt= value &lt end)</code>
     * invariant enforced by the constructors.  Naturally, one should ensure 
     * that the <code>(start &lt;= value &lt;= maximum)</code> invariant is true
     * before calling the <code>nextValue</code>, <code>previousValue</code>,
     * or <code>setValue</code> methods.  
     * <p>
     * This method fires a <code>ChangeEvent</code> if the
     * <code>value</code> has changed.
     * 
     * @param value the current (non <code>null</code>)
     *    <code>Date</code> for this sequence
     * @throws IllegalArgumentException if value is <code>null</code>
     *    or not a <code>Date</code>
     * @see #getDate
     * @see #getValue
     * @see #addChangeListener
     */
    public void setValue(Object value) {
	if ((value == null) || !(value instanceof Date)) {
	    throw new IllegalArgumentException("null value");
	}
	if (!value.equals(this.value.getTime())) {
	    this.value.setTime((Date)value);
	    fireStateChanged();
	}
    }
}
