# Week.java

    /* ===========================================================
     * JFreeChart : a free chart library for the Java(tm) platform
     * ===========================================================
     *
     * (C) Copyright 2000-2007, by Object Refinery Limited 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.
     *
     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
     * in the United States and other countries.]
     *
     * ---------
     * Week.java
     * ---------
     * (C) Copyright 2001-2007, by Object Refinery Limited and Contributors.
     *
     * Original Author:  David Gilbert (for Object Refinery Limited);
     * Contributor(s):   Aimin Han;
     *
     * Changes
     * -------
     * 11-Oct-2001 : Version 1 (DG);
     * 18-Dec-2001 : Changed order of parameters in constructor (DG);
     * 19-Dec-2001 : Added a new constructor as suggested by Paul English (DG);
     * 29-Jan-2002 : Worked on the parseWeek() method (DG);
     * 13-Feb-2002 : Fixed bug in Week(Date) constructor (DG);
     * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to
     *               evaluate with reference to a particular time zone (DG);
     * 05-Apr-2002 : Reinstated this class to the JCommon library (DG);
     * 24-Jun-2002 : Removed unnecessary main method (DG);
     * 10-Sep-2002 : Added getSerialIndex() method (DG);
     * 06-Oct-2002 : Fixed errors reported by Checkstyle (DG);
     * 18-Oct-2002 : Changed to observe 52 or 53 weeks per year, consistent with
     *               GregorianCalendar. Thanks to Aimin Han for the code (DG);
     * 02-Jan-2003 : Removed debug code (DG);
     * 13-Mar-2003 : Moved to com.jrefinery.data.time package, and implemented
     *               Serializable (DG);
     * 21-Oct-2003 : Added hashCode() method (DG);
     * 24-May-2004 : Modified getFirstMillisecond() and getLastMillisecond() to
     *               take account of firstDayOfWeek setting in Java's Calendar
     *               class (DG);
     * 30-Sep-2004 : Replaced getTime().getTime() with getTimeInMillis() (DG);
     * 04-Nov-2004 : Reverted change of 30-Sep-2004, because it won't work for
     *               JDK 1.3 (DG);
     * ------------- JFREECHART 1.0.x ---------------------------------------------
     * 06-Mar-2006 : Fix for bug 1448828, incorrect calculation of week and year
     *               for the first few days of some years (DG);
     * 05-Oct-2006 : Updated API docs (DG);
     * 06-Oct-2006 : Refactored to cache first and last millisecond values (DG);
     * 09-Jan-2007 : Fixed bug in next() (DG);
     * 28-Aug-2007 : Added new constructor to avoid problem in creating new
     *               instances (DG);
     * 19-Dec-2007 : Fixed bug in deprecated constructor (DG);
     *
     */

    package org.jfree.data.time;

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

    /**
     * A calendar week.  All years are considered to have 53 weeks, numbered from 1
     * to 53, although in many cases the 53rd week is empty.  Most of the time, the
     * 1st week of the year *begins* in the previous calendar year, but it always
     * finishes in the current year (this behaviour matches the workings of the
     * <code>GregorianCalendar</code> class).
     * <P>
     * This class is immutable, which is a requirement for all
     * {@link RegularTimePeriod} subclasses.
     */
    public class Week extends RegularTimePeriod implements Serializable {

        /** For serialization. */
        private static final long serialVersionUID = 1856387786939865061L;

        /** Constant for the first week in the year. */
        public static final int FIRST_WEEK_IN_YEAR = 1;

        /** Constant for the last week in the year. */
        public static final int LAST_WEEK_IN_YEAR = 53;

        /** The year in which the week falls. */
        private short year;

        /** The week (1-53). */
        private byte week;

        /** The first millisecond. */
        private long firstMillisecond;

        /** The last millisecond. */
        private long lastMillisecond;

        /**
         * Creates a new time period for the week in which the current system
         * date/time falls.
         */
        public Week() {
            this(new Date());
        }

        /**
         * Creates a time period representing the week in the specified year.
         *
         * @param week  the week (1 to 53).
         * @param year  the year (1900 to 9999).
         */
        public Week(int week, int year) {
            if ((week < FIRST_WEEK_IN_YEAR) && (week > LAST_WEEK_IN_YEAR)) {
                throw new IllegalArgumentException(
                        "The 'week' argument must be in the range 1 - 53.");
            }
            this.week = (byte) week;
            this.year = (short) year;
            peg(Calendar.getInstance());
        }

        /**
         * Creates a time period representing the week in the specified year.
         *
         * @param week  the week (1 to 53).
         * @param year  the year (1900 to 9999).
         */
        public Week(int week, Year year) {
            if ((week < FIRST_WEEK_IN_YEAR) && (week > LAST_WEEK_IN_YEAR)) {
                throw new IllegalArgumentException(
                        "The 'week' argument must be in the range 1 - 53.");
            }
            this.week = (byte) week;
            this.year = (short) year.getYear();
            peg(Calendar.getInstance());
       }

        /**
         * Creates a time period for the week in which the specified date/time
         * falls.
         *
         * @param time  the time (<code>null</code> not permitted).
         */
        public Week(Date time) {
            // defer argument checking...
            this(time, RegularTimePeriod.DEFAULT_TIME_ZONE, Locale.getDefault());
        }

        /**
         * Creates a time period for the week in which the specified date/time
         * falls, calculated relative to the specified time zone.
         *
         * @param time  the date/time (<code>null</code> not permitted).
         * @param zone  the time zone (<code>null</code> not permitted).
         *
         * @deprecated As of 1.0.7, use {@link #Week(Date, TimeZone, Locale)}.
         */
        public Week(Date time, TimeZone zone) {
            // defer argument checking...
            this(time, zone, Locale.getDefault());
        }

        /**
         * Creates a time period for the week in which the specified date/time
         * falls, calculated relative to the specified time zone.
         *
         * @param time  the date/time (<code>null</code> not permitted).
         * @param zone  the time zone (<code>null</code> not permitted).
         * @param locale  the locale (<code>null</code> not permitted).
         *
         * @since 1.0.7
         */
        public Week(Date time, TimeZone zone, Locale locale) {
            if (time == null) {
                throw new IllegalArgumentException("Null 'time' argument.");
            }
            if (zone == null) {
                throw new IllegalArgumentException("Null 'zone' argument.");
            }
            if (locale == null) {
                throw new IllegalArgumentException("Null 'locale' argument.");
            }
            Calendar calendar = Calendar.getInstance(zone, locale);
            calendar.setTime(time);

            // sometimes the last few days of the year are considered to fall in
            // the *first* week of the following year.  Refer to the Javadocs for
            // GregorianCalendar.
            int tempWeek = calendar.get(Calendar.WEEK_OF_YEAR);
            if (tempWeek == 1
                    && calendar.get(Calendar.MONTH) == Calendar.DECEMBER) {
                this.week = 1;
                this.year = (short) (calendar.get(Calendar.YEAR) + 1);
            }
            else {
                this.week = (byte) Math.min(tempWeek, LAST_WEEK_IN_YEAR);
                int yyyy = calendar.get(Calendar.YEAR);
                // alternatively, sometimes the first few days of the year are
                // considered to fall in the *last* week of the previous year...
                if (calendar.get(Calendar.MONTH) == Calendar.JANUARY
                        && this.week >= 52) {
                    yyyy--;
                }
                this.year = (short) yyyy;
            }
            peg(calendar);
        }

        /**
         * Returns the year in which the week falls.
         *
         * @return The year (never <code>null</code>).
         */
        public Year getYear() {
            return new Year(this.year);
        }

        /**
         * Returns the year in which the week falls, as an integer value.
         *
         * @return The year.
         */
        public int getYearValue() {
            return this.year;
        }

        /**
         * Returns the week.
         *
         * @return The week.
         */
        public int getWeek() {
            return this.week;
        }

        /**
         * Returns the first millisecond of the week.  This will be determined
         * relative to the time zone specified in the constructor, or in the
         * calendar instance passed in the most recent call to the
         * {@link #peg(Calendar)} method.
         *
         * @return The first millisecond of the week.
         *
         * @see #getLastMillisecond()
         */
        public long getFirstMillisecond() {
            return this.firstMillisecond;
        }

        /**
         * Returns the last millisecond of the week.  This will be
         * determined relative to the time zone specified in the constructor, or
         * in the calendar instance passed in the most recent call to the
         * {@link #peg(Calendar)} method.
         *
         * @return The last millisecond of the week.
         *
         * @see #getFirstMillisecond()
         */
        public long getLastMillisecond() {
            return this.lastMillisecond;
        }

        /**
         * Recalculates the start date/time and end date/time for this time period
         * relative to the supplied calendar (which incorporates a time zone).
         *
         * @param calendar  the calendar (<code>null</code> not permitted).
         *
         * @since 1.0.3
         */
        public void peg(Calendar calendar) {
            this.firstMillisecond = getFirstMillisecond(calendar);
            this.lastMillisecond = getLastMillisecond(calendar);
        }

        /**
         * Returns the week preceding this one.  This method will return
         * <code>null</code> for some lower limit on the range of weeks (currently
         * week 1, 1900).  For week 1 of any year, the previous week is always week
         * 53, but week 53 may not contain any days (you should check for this).
         *
         * @return The preceding week (possibly <code>null</code>).
         */
        public RegularTimePeriod previous() {

            Week result;
            if (this.week != FIRST_WEEK_IN_YEAR) {
                result = new Week(this.week - 1, this.year);
            }
            else {
                // we need to work out if the previous year has 52 or 53 weeks...
                if (this.year > 1900) {
                    int yy = this.year - 1;
                    Calendar prevYearCalendar = Calendar.getInstance();
                    prevYearCalendar.set(yy, Calendar.DECEMBER, 31);
                    result = new Week(prevYearCalendar.getActualMaximum(
                            Calendar.WEEK_OF_YEAR), yy);
                }
                else {
                    result = null;
                }
            }
            return result;

        }

        /**
         * Returns the week following this one.  This method will return
         * <code>null</code> for some upper limit on the range of weeks (currently
         * week 53, 9999).  For week 52 of any year, the following week is always
         * week 53, but week 53 may not contain any days (you should check for
         * this).
         *
         * @return The following week (possibly <code>null</code>).
         */
        public RegularTimePeriod next() {

            Week result;
            if (this.week < 52) {
                result = new Week(this.week + 1, this.year);
            }
            else {
                Calendar calendar = Calendar.getInstance();
                calendar.set(this.year, Calendar.DECEMBER, 31);
                int actualMaxWeek
                    = calendar.getActualMaximum(Calendar.WEEK_OF_YEAR);
                if (this.week < actualMaxWeek) {
                    result = new Week(this.week + 1, this.year);
                }
                else {
                    if (this.year < 9999) {
                        result = new Week(FIRST_WEEK_IN_YEAR, this.year + 1);
                    }
                    else {
                        result = null;
                    }
                }
            }
            return result;

        }

        /**
         * Returns a serial index number for the week.
         *
         * @return The serial index number.
         */
        public long getSerialIndex() {
            return this.year * 53L + this.week;
        }

        /**
         * Returns the first millisecond of the week, evaluated using the supplied
         * calendar (which determines the time zone).
         *
         * @param calendar  the calendar (<code>null</code> not permitted).
         *
         * @return The first millisecond of the week.
         *
         * @throws NullPointerException if <code>calendar</code> is
         *     <code>null</code>.
         */
        public long getFirstMillisecond(Calendar calendar) {
            Calendar c = (Calendar) calendar.clone();
            c.clear();
            c.set(Calendar.YEAR, this.year);
            c.set(Calendar.WEEK_OF_YEAR, this.week);
            c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
            c.set(Calendar.HOUR, 0);
            c.set(Calendar.MINUTE, 0);
            c.set(Calendar.SECOND, 0);
            c.set(Calendar.MILLISECOND, 0);
            //return c.getTimeInMillis();  // this won't work for JDK 1.3
            return c.getTime().getTime();
        }

        /**
         * Returns the last millisecond of the week, evaluated using the supplied
         * calendar (which determines the time zone).
         *
         * @param calendar  the calendar (<code>null</code> not permitted).
         *
         * @return The last millisecond of the week.
         *
         * @throws NullPointerException if <code>calendar</code> is
         *     <code>null</code>.
         */
        public long getLastMillisecond(Calendar calendar) {
            Calendar c = (Calendar) calendar.clone();
            c.clear();
            c.set(Calendar.YEAR, this.year);
            c.set(Calendar.WEEK_OF_YEAR, this.week + 1);
            c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
            c.set(Calendar.HOUR, 0);
            c.set(Calendar.MINUTE, 0);
            c.set(Calendar.SECOND, 0);
            c.set(Calendar.MILLISECOND, 0);
            //return c.getTimeInMillis();  // this won't work for JDK 1.3
            return c.getTime().getTime() - 1;
        }

        /**
         * Returns a string representing the week (e.g. "Week 9, 2002").
         *
         * TODO: look at internationalisation.
         *
         * @return A string representing the week.
         */
        public String toString() {
            return "Week " + this.week + ", " + this.year;
        }

        /**
         * Tests the equality of this Week object to an arbitrary object.  Returns
         * true if the target is a Week instance representing the same week as this
         * object.  In all other cases, returns false.
         *
         * @param obj  the object (<code>null</code> permitted).
         *
         * @return <code>true</code> if week and year of this and object are the
         *         same.
         */
        public boolean equals(Object obj) {

            if (obj == this) {
                return true;
            }
            if (!(obj instanceof Week)) {
                return false;
            }
            Week that = (Week) obj;
            if (this.week != that.week) {
                return false;
            }
            if (this.year != that.year) {
                return false;
            }
            return true;

        }

        /**
         * Returns a hash code for this object instance.  The approach described by
         * Joshua Bloch in "Effective Java" has been used here:
         * <p>
         * <code>http://developer.java.sun.com/developer/Books/effectivejava
         * /Chapter3.pdf</code>
         *
         * @return A hash code.
         */
        public int hashCode() {
            int result = 17;
            result = 37 * result + this.week;
            result = 37 * result + this.year;
            return result;
        }

        /**
         * Returns an integer indicating the order of this Week object relative to
         * the specified object:
         *
         * negative == before, zero == same, positive == after.
         *
         * @param o1  the object to compare.
         *
         * @return negative == before, zero == same, positive == after.
         */
        public int compareTo(Object o1) {

            int result;

            // CASE 1 : Comparing to another Week object
            // --------------------------------------------
            if (o1 instanceof Week) {
                Week w = (Week) o1;
                result = this.year - w.getYear().getYear();
                if (result == 0) {
                    result = this.week - w.getWeek();
                }
            }

            // CASE 2 : Comparing to another TimePeriod object
            // -----------------------------------------------
            else if (o1 instanceof RegularTimePeriod) {
                // more difficult case - evaluate later...
                result = 0;
            }

            // CASE 3 : Comparing to a non-TimePeriod object
            // ---------------------------------------------
            else {
                // consider time periods to be ordered after general objects
                result = 1;
            }

            return result;

        }

        /**
         * Parses the string argument as a week.
         * <P>
         * This method is required to accept the format "YYYY-Wnn".  It will also
         * accept "Wnn-YYYY". Anything else, at the moment, is a bonus.
         *
         * @param s  string to parse.
         *
         * @return <code>null</code> if the string is not parseable, the week
         *         otherwise.
         */
        public static Week parseWeek(String s) {

            Week result = null;
            if (s != null) {

                // trim whitespace from either end of the string
                s = s.trim();

                int i = Week.findSeparator(s);
                if (i != -1) {
                    String s1 = s.substring(0, i).trim();
                    String s2 = s.substring(i + 1, s.length()).trim();

                    Year y = Week.evaluateAsYear(s1);
                    int w;
                    if (y != null) {
                        w = Week.stringToWeek(s2);
                        if (w == -1) {
                            throw new TimePeriodFormatException(
                                    "Can't evaluate the week.");
                        }
                        result = new Week(w, y);
                    }
                    else {
                        y = Week.evaluateAsYear(s2);
                        if (y != null) {
                            w = Week.stringToWeek(s1);
                            if (w == -1) {
                                throw new TimePeriodFormatException(
                                        "Can't evaluate the week.");
                            }
                            result = new Week(w, y);
                        }
                        else {
                            throw new TimePeriodFormatException(
                                    "Can't evaluate the year.");
                        }
                    }

                }
                else {
                    throw new TimePeriodFormatException(
                            "Could not find separator.");
                }

            }
            return result;

        }

        /**
         * Finds the first occurrence of ' ', '-', ',' or '.'
         *
         * @param s  the string to parse.
         *
         * @return <code>-1</code> if none of the characters was found, the
         *      index of the first occurrence otherwise.
         */
        private static int findSeparator(String s) {

            int result = s.indexOf('-');
            if (result == -1) {
                result = s.indexOf(',');
            }
            if (result == -1) {
                result = s.indexOf(' ');
            }
            if (result == -1) {
                result = s.indexOf('.');
            }
            return result;
        }

        /**
         * Creates a year from a string, or returns null (format exceptions
         * suppressed).
         *
         * @param s  string to parse.
         *
         * @return <code>null</code> if the string is not parseable, the year
         *         otherwise.
         */
        private static Year evaluateAsYear(String s) {

            Year result = null;
            try {
                result = Year.parseYear(s);
            }
            catch (TimePeriodFormatException e) {
                // suppress
            }
            return result;

        }

        /**
         * Converts a string to a week.
         *
         * @param s  the string to parse.
         * @return <code>-1</code> if the string does not contain a week number,
         *         the number of the week otherwise.
         */
        private static int stringToWeek(String s) {

            int result = -1;
            s = s.replace('W', ' ');
            s = s.trim();
            try {
                result = Integer.parseInt(s);
                if ((result < 1) || (result > LAST_WEEK_IN_YEAR)) {
                    result = -1;
                }
            }
            catch (NumberFormatException e) {
                // suppress
            }
            return result;

        }

    }