/*

 * Copyright (c) 2010, 2020, Oracle and/or its affiliates. All rights reserved.

 * 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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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 */

package java.text;

import java.util.Calendar;

import java.util.StringJoiner;

import static java.util.GregorianCalendar.*;

/**

 * {@code CalendarBuilder} keeps field-value pairs for setting

 * the calendar fields of the given {@code Calendar}. It has the

 * {@link Calendar#FIELD_COUNT FIELD_COUNT}-th field for the week year

 * support. Also {@code ISO_DAY_OF_WEEK} is used to specify

 * {@code DAY_OF_WEEK} in the ISO day of week numbering.

 *

 * <p>{@code CalendarBuilder} retains the semantic of the pseudo

 * timestamp for fields. {@code CalendarBuilder} uses a single

 * int array combining fields[] and stamp[] of {@code Calendar}.

 *

 * @author Masayoshi Okutsu

 */

class CalendarBuilder {

    /*

     * Pseudo time stamp constants used in java.util.Calendar

     */

    private static final int UNSET = 0;

    private static final int COMPUTED = 1;

    private static final int MINIMUM_USER_STAMP = 2;

    private static final int MAX_FIELD = FIELD_COUNT + 1;

    public static final int WEEK_YEAR = FIELD_COUNT;

    public static final int ISO_DAY_OF_WEEK = 1000; // pseudo field index

    // stamp[] (lower half) and field[] (upper half) combined

    private final int[] field;

    private int nextStamp;

    private int maxFieldIndex;

    CalendarBuilder() {

        field = new int[MAX_FIELD * 2];

        nextStamp = MINIMUM_USER_STAMP;

        maxFieldIndex = -1;

    }

    CalendarBuilder set(int index, int value) {

        if (index == ISO_DAY_OF_WEEK) {

            index = DAY_OF_WEEK;

            value = toCalendarDayOfWeek(value);

        }

        field[index] = nextStamp++;

        field[MAX_FIELD + index] = value;

        if (index > maxFieldIndex && index < FIELD_COUNT) {

            maxFieldIndex = index;

        }

        return this;

    }

    CalendarBuilder addYear(int value) {

        field[MAX_FIELD + YEAR] += value;

        field[MAX_FIELD + WEEK_YEAR] += value;

        return this;

    }

    boolean isSet(int index) {

        if (index == ISO_DAY_OF_WEEK) {

            index = DAY_OF_WEEK;

        }

        return field[index] > UNSET;

    }

    CalendarBuilder clear(int index) {

        if (index == ISO_DAY_OF_WEEK) {

            index = DAY_OF_WEEK;

        }

        field[index] = UNSET;

        field[MAX_FIELD + index] = 0;

        return this;

    }

    Calendar establish(Calendar cal) {

        boolean weekDate = isSet(WEEK_YEAR)

                            && field[WEEK_YEAR] > field[YEAR];

        if (weekDate && !cal.isWeekDateSupported()) {

            // Use YEAR instead

            if (!isSet(YEAR)) {

                set(YEAR, field[MAX_FIELD + WEEK_YEAR]);

            }

            weekDate = false;

        }

        cal.clear();

        // Set the fields from the min stamp to the max stamp so that

        // the field resolution works in the Calendar.

        for (int stamp = MINIMUM_USER_STAMP; stamp < nextStamp; stamp++) {

            for (int index = 0; index <= maxFieldIndex; index++) {

                if (field[index] == stamp) {

                    cal.set(index, field[MAX_FIELD + index]);

                    break;

                }

            }

        }

        if (weekDate) {

            int weekOfYear = isSet(WEEK_OF_YEAR) ? field[MAX_FIELD + WEEK_OF_YEAR] : 1;

            int dayOfWeek = isSet(DAY_OF_WEEK) ?

                                field[MAX_FIELD + DAY_OF_WEEK] : cal.getFirstDayOfWeek();

            if (!isValidDayOfWeek(dayOfWeek) && cal.isLenient()) {

                if (dayOfWeek >= 8) {

                    dayOfWeek--;

                    weekOfYear += dayOfWeek / 7;

                    dayOfWeek = (dayOfWeek % 7) + 1;

                } else {

                    while (dayOfWeek <= 0) {

                        dayOfWeek += 7;

                        weekOfYear--;

                    }

                }

                dayOfWeek = toCalendarDayOfWeek(dayOfWeek);

            }

            cal.setWeekDate(field[MAX_FIELD + WEEK_YEAR], weekOfYear, dayOfWeek);

        }

        return cal;

    }

    public String toString() {

        StringJoiner sj = new StringJoiner(",", "CalendarBuilder:[", "]");

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

            if (isSet(i)) {

                sj.add(i + "=" + field[i] + ":" + field[MAX_FIELD + i]);

            }

        }

        return sj.toString();

    }

    static int toISODayOfWeek(int calendarDayOfWeek) {

        return calendarDayOfWeek == SUNDAY ? 7 : calendarDayOfWeek - 1;

    }

    static int toCalendarDayOfWeek(int isoDayOfWeek) {

        if (!isValidDayOfWeek(isoDayOfWeek)) {

            // adjust later for lenient mode

            return isoDayOfWeek;

        }

        return isoDayOfWeek == 7 ? SUNDAY : isoDayOfWeek + 1;

    }

    static boolean isValidDayOfWeek(int dayOfWeek) {

        return dayOfWeek > 0 && dayOfWeek <= 7;

    }

}