com.oracle.truffle.js.runtime.util.ZoneRulesBasedTimeZone Maven / Gradle / Ivy

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 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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package com.oracle.truffle.js.runtime.util;

import org.graalvm.shadowed.com.ibm.icu.util.GregorianCalendar;
import org.graalvm.shadowed.com.ibm.icu.util.TimeZone;
import com.oracle.truffle.js.runtime.Errors;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneOffset;
import java.time.zone.ZoneRules;
import java.util.Date;
import java.util.List;

/**
 * Implementation of ICU4J {@code TimeZone} that takes time-zone data from the provided
 * {@code ZoneRules} object (instead of ICU4J tzdb-related data files).
 */
public class ZoneRulesBasedTimeZone extends TimeZone {
    private static final long serialVersionUID = 3774721234048749245L;
    private final ZoneRules rules;

    @SuppressWarnings("deprecation")
    public ZoneRulesBasedTimeZone(String id, ZoneRules rules) {
        super(id);
        this.rules = rules;
    }

    @Override
    public int getOffset(int era, int year, int month, int day, int dayOfWeek, int milliseconds) {
        LocalDate date = LocalDate.of((era == GregorianCalendar.BC) ? -year : year, month + 1, day);
        LocalTime time = LocalTime.ofNanoOfDay(1000000L * milliseconds);
        LocalDateTime dateTime = LocalDateTime.of(date, time);
        List offsets = rules.getValidOffsets(dateTime);
        ZoneOffset offset;
        if (offsets.size() == 1) {
            offset = offsets.get(0);
        } else {
            offset = rules.getTransition(dateTime).getOffsetAfter();
        }
        return toMillis(offset);
    }

    @Override
    public int getRawOffset() {
        return toMillis(rules.getStandardOffset(Instant.now()));
    }

    @Override
    public boolean useDaylightTime() {
        return !rules.isFixedOffset();
    }

    @Override
    public boolean inDaylightTime(Date date) {
        Instant instant = Instant.ofEpochMilli(date.getTime());
        return !rules.getDaylightSavings(instant).isZero();
    }

    @Override
    public void setRawOffset(int offsetMillis) {
        throw Errors.shouldNotReachHere();
    }

    private static int toMillis(ZoneOffset offset) {
        return offset.getTotalSeconds() * 1000;
    }

}