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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

/*

 * @test

 * @bug 5090555 5091805

 * @summary Make sure that rolling DAY_OF_WEEK stays in the same week

 * around year boundaries.

 * @run main/othervm RollDayOfWeekTest 5 5

 */

import java.util.*;

import static java.util.Calendar.*;

// Usage: java RollDayOfWeekTest [pastYears futureYears]

public class RollDayOfWeekTest {

    public static void main(String[] args) {

        int pastYears = 5, futureYears = 23;

        if (args.length == 2) {

            pastYears = Integer.parseInt(args[0]);

            pastYears = Math.max(1, Math.min(pastYears, 5));

            futureYears = Integer.parseInt(args[1]);

            futureYears = Math.max(1, Math.min(futureYears, 28));

        }

        System.out.printf("Test [%d .. %+d] year range.%n", -pastYears, futureYears);

        Calendar cal = new GregorianCalendar();

        int year = cal.get(YEAR) - pastYears;

        // Use the all combinations of firstDayOfWeek and

        // minimalDaysInFirstWeek values in the year range current

        // year - pastYears to current year + futureYears.

        for (int fdw = SUNDAY; fdw <= SATURDAY; fdw++) {

            for (int mdifw = 1; mdifw <= 7; mdifw++) {

                cal.clear();

                cal.setFirstDayOfWeek(fdw);

                cal.setMinimalDaysInFirstWeek(mdifw);

                cal.set(year, JANUARY, 1);

                checkRoll(cal, futureYears);

            }

        }

        // testing roll from BCE to CE

        year = -1;

        for (int fdw = SUNDAY; fdw <= SATURDAY; fdw++) {

            for (int mdifw = 1; mdifw <= 7; mdifw++) {

                cal.clear();

                cal.setFirstDayOfWeek(fdw);

                cal.setMinimalDaysInFirstWeek(mdifw);

                cal.set(year, JANUARY, 1);

                checkRoll(cal, 4);

            }

        }

    }

    static void checkRoll(Calendar cal, int years) {

        Calendar cal2 = null, cal3 = null, prev = null;

        // Check 28 years

        for (int x = 0; x < (int)(365.2425*years); x++) {

            cal2 = (Calendar) cal.clone();

            cal3 = (Calendar) cal.clone();

            // roll foreword

            for (int i = 0; i < 10; i++) {

                prev = (Calendar) cal2.clone();

                cal2.roll(Calendar.DAY_OF_WEEK, +1);

                roll(cal3, +1);

                long t2 = cal2.getTimeInMillis();

                long t3 = cal3.getTimeInMillis();

                if (t2 != t3) {

                    System.err.println("prev: " + prev.getTime() + "\n" + prev);

                    System.err.println("cal2: " + cal2.getTime() + "\n" + cal2);

                    System.err.println("cal3: " + cal3.getTime() + "\n" + cal3);

                    throw new RuntimeException("+1: t2=" + t2 + ", t3=" + t3);

                }

            }

            // roll backward

            for (int i = 0; i < 10; i++) {

                prev = (Calendar) cal2.clone();

                cal2.roll(Calendar.DAY_OF_WEEK, -1);

                roll(cal3, -1);

                long t2 = cal2.getTimeInMillis();

                long t3 = cal3.getTimeInMillis();

                if (t2 != t3) {

                    System.err.println("prev: " + prev.getTime() + "\n" + prev);

                    System.err.println("cal2: " + cal2.getTime() + "\n" + cal2);

                    System.err.println("cal3: " + cal3.getTime() + "\n" + cal3);

                    throw new RuntimeException("-1: t2=" + t2 + ", t3=" + t3);

                }

            }

            cal.add(DAY_OF_YEAR, +1);

        }

    }

    // Another way to roll within the same week.

    static void roll(Calendar cal, int n) {

        int doy = cal.get(DAY_OF_YEAR);

        int diff = cal.get(DAY_OF_WEEK) - cal.getFirstDayOfWeek();

        if (diff < 0) {

            diff += 7;

        }

        // dow1: first day of the week

        int dow1 = doy - diff;

        n %= 7;

        doy += n;

        if (doy < dow1) {

            doy += 7;

        } else if (doy >= dow1 + 7) {

            doy -= 7;

        }

        cal.set(DAY_OF_YEAR, doy);

    }

}