/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-present, by David Gilbert and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 */

package org.jfree.chart.date;

import java.util.Calendar;
import java.util.Date;

/**
 * Represents a date using an integer, in a similar fashion to the
 * implementation in Microsoft Excel.  The range of dates supported is
 * 1-Jan-1900 to 31-Dec-9999.
 * <P>
 * Be aware that there is a deliberate bug in Excel that recognises the year
 * 1900 as a leap year when in fact it is not a leap year. You can find more
 * information on the Microsoft website in article Q181370:
 * <P>
 * http://support.microsoft.com/support/kb/articles/Q181/3/70.asp
 * <P>
 * Excel uses the convention that 1-Jan-1900 = 1.  This class uses the
 * convention 1-Jan-1900 = 2.
 * The result is that the day number in this class will be different to the
 * Excel figure for January and February 1900...but then Excel adds in an extra
 * day (29-Feb-1900 which does not actually exist!) and from that point forward
 * the day numbers will match.
 */
public class SpreadsheetDate extends SerialDate {

    /** For serialization. */
    private static final long serialVersionUID = -2039586705374454461L;
    
    /** 
     * The day number (1-Jan-1900 = 2, 2-Jan-1900 = 3, ..., 31-Dec-9999 = 
     * 2958465). 
     */
    private final int serial;

    /** The day of the month (1 to 28, 29, 30 or 31 depending on the month). */
    private final int day;

    /** The month of the year (1 to 12). */
    private final int month;

    /** The year (1900 to 9999). */
    private final int year;

    /**
     * Creates a new date instance.
     *
     * @param day  the day (in the range 1 to 28/29/30/31).
     * @param month  the month (in the range 1 to 12).
     * @param year  the year (in the range 1900 to 9999).
     */
    public SpreadsheetDate(int day, int month, int year) {

        if ((year >= 1900) && (year <= 9999)) {
            this.year = year;
        }
        else {
            throw new IllegalArgumentException(
                "The 'year' argument must be in range 1900 to 9999.");
        }

        if ((month >= MonthConstants.JANUARY) 
                && (month <= MonthConstants.DECEMBER)) {
            this.month = month;
        }
        else {
            throw new IllegalArgumentException(
                "The 'month' argument must be in the range 1 to 12.");
        }

        if ((day >= 1) && (day <= SerialDate.lastDayOfMonth(month, year))) {
            this.day = day;
        } else {
            throw new IllegalArgumentException("Invalid 'day' argument.");
        }

        // the serial number needs to be synchronised with the day-month-year...
        this.serial = calcSerial(day, month, year);
    }

    /**
     * Standard constructor - creates a new date object representing the
     * specified day number (which should be in the range 2 to 2958465.
     *
     * @param serial  the serial number for the day (range: 2 to 2958465).
     */
    public SpreadsheetDate(int serial) {

        if ((serial >= SERIAL_LOWER_BOUND) && (serial <= SERIAL_UPPER_BOUND)) {
            this.serial = serial;
        }
        else {
            throw new IllegalArgumentException(
                "SpreadsheetDate: Serial must be in range 2 to 2958465.");
        }

        // the day-month-year needs to be synchronised with the serial number...
        // get the year from the serial date
        final int days = this.serial - SERIAL_LOWER_BOUND;
        // overestimated because we ignored leap days
        final int overestimatedYYYY = 1900 + (days / 365);
        final int leaps = SerialDate.leapYearCount(overestimatedYYYY);
        final int nonleapdays = days - leaps;
        // underestimated because we overestimated years
        int underestimatedYYYY = 1900 + (nonleapdays / 365);

        if (underestimatedYYYY == overestimatedYYYY) {
            this.year = underestimatedYYYY;
        } else {
            int ss1 = calcSerial(1, 1, underestimatedYYYY);
            while (ss1 <= this.serial) {
                underestimatedYYYY = underestimatedYYYY + 1;
                ss1 = calcSerial(1, 1, underestimatedYYYY);
            }
            this.year = underestimatedYYYY - 1;
        }

        final int ss2 = calcSerial(1, 1, this.year);

        int[] daysToEndOfPrecedingMonth 
                = AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH;

        if (isLeapYear(this.year)) {
            daysToEndOfPrecedingMonth 
                    = LEAP_YEAR_AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH;
        }

        // get the month from the serial date
        int mm = 1;
        int sss = ss2 + daysToEndOfPrecedingMonth[mm] - 1;
        while (sss < this.serial) {
            mm = mm + 1;
            sss = ss2 + daysToEndOfPrecedingMonth[mm] - 1;
        }
        this.month = mm - 1;

        // what's left is d(+1);
        this.day = this.serial - ss2 
                 - daysToEndOfPrecedingMonth[this.month] + 1;

    }

    /**
     * Returns the serial number for the date, where 1 January 1900 = 2
     * (this corresponds, almost, to the numbering system used in Microsoft
     * Excel for Windows and Lotus 1-2-3).
     *
     * @return The serial number of this date.
     */
    @Override
    public int toSerial() {
        return this.serial;
    }

    /**
     * Returns a {@code java.util.Date} equivalent to this date.
     *
     * @return The date.
     */
    @Override
    public Date toDate() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(getYYYY(), getMonth() - 1, getDayOfMonth(), 0, 0, 0);
        return calendar.getTime();
    }

    /**
     * Returns the year (assume a valid range of 1900 to 9999).
     *
     * @return The year.
     */
    @Override
    public int getYYYY() {
        return this.year;
    }

    /**
     * Returns the month (January = 1, February = 2, March = 3).
     *
     * @return The month of the year.
     */
    @Override
    public int getMonth() {
        return this.month;
    }

    /**
     * Returns the day of the month.
     *
     * @return The day of the month.
     */
    @Override
    public int getDayOfMonth() {
        return this.day;
    }

    /**
     * Returns a code representing the day of the week.
     * <P>
     * The codes are defined in the {@link SerialDate} class as: 
     * {@code SUNDAY}, {@code MONDAY}, {@code TUESDAY}, 
     * {@code WEDNESDAY}, {@code THURSDAY}, {@code FRIDAY}, and 
     * {@code SATURDAY}.
     *
     * @return A code representing the day of the week.
     */
    @Override
    public int getDayOfWeek() {
        return (this.serial + 6) % 7 + 1;
    }

    /**
     * Tests the equality of this date with an arbitrary object.
     * <P>
     * This method will return true ONLY if the object is an instance of the
     * {@link SerialDate} base class, and it represents the same day as this
     * {@link SpreadsheetDate}.
     *
     * @param object  the object to compare ({@code null} permitted).
     *
     * @return A boolean.
     */
    @Override
    public boolean equals(Object object) {

        if (object instanceof SerialDate) {
            SerialDate s = (SerialDate) object;
            return (s.toSerial() == this.toSerial());
        } else {
            return false;
        }

    }

    /**
     * Returns a hash code for this object instance.
     * 
     * @return A hash code.
     */
    @Override
    public int hashCode() {
        return toSerial();
    }

    /**
     * Returns the difference (in days) between this date and the specified 
     * 'other' date.
     *
     * @param other  the date being compared to.
     *
     * @return The difference (in days) between this date and the specified 
     *         'other' date.
     */
    @Override
    public int compare(SerialDate other) {
        return this.serial - other.toSerial();
    }

    /**
     * Implements the method required by the Comparable interface.
     * 
     * @param other  the other object (usually another SerialDate).
     * 
     * @return A negative integer, zero, or a positive integer as this object 
     *         is less than, equal to, or greater than the specified object.
     */
    @Override
    public int compareTo(Object other) {
        return compare((SerialDate) other);    
    }
    
    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return {@code true} if this SerialDate represents the same date as
     *         the specified SerialDate.
     */
    @Override
    public boolean isOn(SerialDate other) {
        return (this.serial == other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents an earlier date compared to
     * the specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return {@code true} if this SerialDate represents an earlier date
     *         compared to the specified SerialDate.
     */
    @Override
    public boolean isBefore(SerialDate other) {
        return (this.serial < other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return {@code true} if this SerialDate represents the same date
     *         as the specified SerialDate.
     */
    @Override
    public boolean isOnOrBefore(SerialDate other) {
        return (this.serial <= other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return {@code true} if this SerialDate represents the same date
     *         as the specified SerialDate.
     */
    @Override
    public boolean isAfter(SerialDate other) {
        return (this.serial > other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return {@code true} if this SerialDate represents the same date as
     *         the specified SerialDate.
     */
    @Override
    public boolean isOnOrAfter(SerialDate other) {
        return (this.serial >= other.toSerial());
    }

    /**
     * Returns {@code true} if this {@link SerialDate} is within the 
     * specified range (INCLUSIVE).  The date order of d1 and d2 is not 
     * important.
     *
     * @param d1  a boundary date for the range.
     * @param d2  the other boundary date for the range.
     *
     * @return A boolean.
     */
    @Override
    public boolean isInRange(SerialDate d1, SerialDate d2) {
        return isInRange(d1, d2, SerialDate.INCLUDE_BOTH);
    }

    /**
     * Returns true if this SerialDate is within the specified range (caller
     * specifies whether or not the end-points are included).  The order of d1
     * and d2 is not important.
     *
     * @param d1  one boundary date for the range.
     * @param d2  a second boundary date for the range.
     * @param include  a code that controls whether or not the start and end 
     *                 dates are included in the range.
     *
     * @return {@code true} if this SerialDate is within the specified 
     *         range.
     */
    @Override
    public boolean isInRange(SerialDate d1, SerialDate d2, int include) {
        int s1 = d1.toSerial();
        int s2 = d2.toSerial();
        int start = Math.min(s1, s2);
        int end = Math.max(s1, s2);
        
        int s = toSerial();
        if (include == SerialDate.INCLUDE_BOTH) {
            return (s >= start && s <= end);
        }
        else if (include == SerialDate.INCLUDE_FIRST) {
            return (s >= start && s < end);            
        }
        else if (include == SerialDate.INCLUDE_SECOND) {
            return (s > start && s <= end);            
        }
        else {
            return (s > start && s < end);            
        }    
    }

    /**
     * Calculate the serial number from the day, month and year.
     * <P>
     * 1-Jan-1900 = 2.
     *
     * @param d  the day.
     * @param m  the month.
     * @param y  the year.
     *
     * @return the serial number from the day, month and year.
     */
    private int calcSerial(int d, int m, int y) {
        int yy = ((y - 1900) * 365) + SerialDate.leapYearCount(y - 1);
        int mm = SerialDate.AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH[m];
        if (m > MonthConstants.FEBRUARY) {
            if (SerialDate.isLeapYear(y)) {
                mm = mm + 1;
            }
        }
        int dd = d;
        return yy + mm + dd + 1;
    }

}