@Override
public TransitionHistory load(String zoneID) {
try {
ZoneRules zoneRules = ZoneId.of(zoneID).getRules();
ZonalOffset initialOffset =
ZonalOffset.ofTotalSeconds(zoneRules.getOffset(Instant.MIN).getTotalSeconds());
List<ZonalTransition> transitions = new ArrayList<>();
List<DaylightSavingRule> rules = new ArrayList<>();
for (ZoneOffsetTransition zot : zoneRules.getTransitions()) {
Instant instant = zot.getInstant();
long posixTime = instant.getEpochSecond();
int previousOffset = zot.getOffsetBefore().getTotalSeconds();
int totalOffset = zot.getOffsetAfter().getTotalSeconds();
int dst = Math.toIntExact(zoneRules.getDaylightSavings(instant).getSeconds());
transitions.add(new ZonalTransition(posixTime, previousOffset, totalOffset, dst));
}
for (ZoneOffsetTransitionRule zotr : zoneRules.getTransitionRules()) {
DaylightSavingRule rule;
int dom = zotr.getDayOfMonthIndicator(); // -28 bis +31 (ohne 0)
DayOfWeek dayOfWeek = zotr.getDayOfWeek();
Month month = Month.valueOf(zotr.getMonth().getValue());
PlainTime timeOfDay =
(zotr.isMidnightEndOfDay()
? PlainTime.midnightAtEndOfDay()
: TemporalType.LOCAL_TIME.translate(zotr.getLocalTime()));
OffsetIndicator indicator;
switch (zotr.getTimeDefinition()) {
case STANDARD:
indicator = OffsetIndicator.STANDARD_TIME;
break;
case UTC:
indicator = OffsetIndicator.UTC_TIME;
break;
case WALL:
indicator = OffsetIndicator.WALL_TIME;
break;
default:
throw new UnsupportedOperationException(zotr.getTimeDefinition().name());
}
int dst =
(zotr.getOffsetAfter().getTotalSeconds() - zotr.getStandardOffset().getTotalSeconds());
if (dayOfWeek == null) {
rule = GregorianTimezoneRule.ofFixedDay(month, dom, timeOfDay, indicator, dst);
} else {
Weekday wd = Weekday.valueOf(dayOfWeek.getValue());
if (dom == -1) {
rule = GregorianTimezoneRule.ofLastWeekday(month, wd, timeOfDay, indicator, dst);
} else if (dom < 0) {
rule = new NegativeDayOfMonthPattern(month, dom, wd, timeOfDay, indicator, dst);
} else {
rule =
GregorianTimezoneRule.ofWeekdayAfterDate(month, dom, wd, timeOfDay, indicator, dst);
}
}
rules.add(rule);
}
return TransitionModel.of(initialOffset, transitions, rules);
} catch (ZoneRulesException ex) {
throw new IllegalArgumentException(ex);
}
}
