/*
 * Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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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 < field.length; i++) {
 if (isSet(i)) {
 sj.add(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;
 }
}