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feat: Improve POSIX time zone string generation (#4087)
Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>
This commit is contained in:
James Rich
GitHub
parent
869222f3e1
commit
0f00332e94
2 changed files with 106 additions and 75 deletions
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@ -19,14 +19,13 @@
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package org.meshtastic.core.ui.timezone
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import java.time.DayOfWeek
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import java.time.Instant
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import java.time.LocalDateTime
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import java.time.Year
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import java.time.ZoneId
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import java.time.ZoneOffset
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import java.time.ZonedDateTime
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import java.time.format.DateTimeFormatter
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import java.time.temporal.ChronoField
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import java.time.temporal.WeekFields
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import java.time.zone.ZoneOffsetTransitionRule
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import java.util.Locale
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import kotlin.math.abs
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@ -34,101 +33,117 @@ import kotlin.math.abs
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* Generates a POSIX time zone string from a [ZoneId]. Uses the specification found
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* [here](https://www.postgresql.org/docs/current/datetime-posix-timezone-specs.html).
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*/
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@Suppress("ReturnCount")
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fun ZoneId.toPosixString(): String {
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val now = Instant.now()
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val upcomingTransition = rules.nextTransition(now)
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val rules = this.rules
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// No upcoming transition means this time zone does not support DST.
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if (upcomingTransition == null) {
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with(now.asZonedDateTime()) {
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return "${timeZoneShortName()}${formattedOffsetString()}"
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}
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if (rules.isFixedOffset || rules.transitionRules.isEmpty()) {
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val now = Instant.now()
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val zdt = ZonedDateTime.ofInstant(now, this)
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return "${formatAbbreviation(zdt.timeZoneShortName())}${formatPosixOffset(zdt.offset)}"
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}
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val upcomingInstant = upcomingTransition.instant
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val followingTransition = rules.nextTransition(upcomingInstant)
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val springRule = rules.transitionRules.lastOrNull { it.offsetAfter.totalSeconds > it.offsetBefore.totalSeconds }
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val fallRule = rules.transitionRules.lastOrNull { it.offsetAfter.totalSeconds < it.offsetBefore.totalSeconds }
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val (stdTransition, dstTransition) =
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if (rules.isDaylightSavings(upcomingInstant)) {
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followingTransition to upcomingTransition
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} else {
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upcomingTransition to followingTransition
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}
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val stdDate = stdTransition.instant.asZonedDateTime()
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val dstDate = dstTransition.instant.asZonedDateTime()
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if (springRule == null || fallRule == null) {
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val now = Instant.now()
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val zdt = ZonedDateTime.ofInstant(now, this)
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return "${formatAbbreviation(zdt.timeZoneShortName())}${formatPosixOffset(zdt.offset)}"
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}
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return buildString {
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append(stdDate.timeZoneShortName())
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append(stdDate.formattedOffsetString())
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append(dstDate.timeZoneShortName())
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val stdAbbrev = getTransitionAbbreviation(this@toPosixString, fallRule)
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val dstAbbrev = getTransitionAbbreviation(this@toPosixString, springRule)
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append(formatAbbreviation(stdAbbrev))
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append(formatPosixOffset(springRule.offsetBefore))
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append(formatAbbreviation(dstAbbrev))
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// Don't append the DST offset if it is only 1 hour off.
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@Suppress("MagicNumber")
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if (abs(stdDate.offset.totalSeconds - dstDate.offset.totalSeconds) != 3600) {
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append(dstDate.formattedOffsetString())
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if (springRule.offsetAfter.totalSeconds - springRule.offsetBefore.totalSeconds != 3600) {
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append(formatPosixOffset(springRule.offsetAfter))
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}
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append(dstTransition.dateTimeBefore.transitionRuleString())
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append(stdTransition.dateTimeBefore.transitionRuleString())
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append(formatTransitionRule(springRule))
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append(formatTransitionRule(fallRule))
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}
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}
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/** Returns the time zone short. e.g. "EST" or "EDT". */
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private fun ZonedDateTime.timeZoneShortName(): String {
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internal fun ZonedDateTime.timeZoneShortName(): String {
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val formatter = DateTimeFormatter.ofPattern("zzz", Locale.ENGLISH)
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val shortName = format(formatter)
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return if (shortName.startsWith("GMT")) "GMT" else shortName
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}
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/**
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* Returns the time zone offset string with the format "<HOURS>:<MINUTES>:<SECONDS>". Minutes and seconds are only shown
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* if they are non-zero.
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*/
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@Suppress("MagicNumber")
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private fun ZonedDateTime.formattedOffsetString(): String {
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val offsetSeconds = -offset.totalSeconds
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internal fun formatAbbreviation(abbrev: String): String = if (abbrev.all { it.isLetter() }) abbrev else "<$abbrev>"
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internal fun getTransitionAbbreviation(zone: ZoneId, rule: ZoneOffsetTransitionRule): String {
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val transition = rule.createTransition(Year.now().value)
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return ZonedDateTime.ofInstant(transition.instant, zone).timeZoneShortName()
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}
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@Suppress("MagicNumber")
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internal fun formatPosixOffset(offset: ZoneOffset): String {
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val offsetSeconds = -offset.totalSeconds
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val hours = offsetSeconds / 3600
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val remainingSeconds = abs(offsetSeconds) % 3600
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val minutes = remainingSeconds / 60
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val seconds = remainingSeconds % 60
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return buildString {
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if (offsetSeconds < 0 && hours == 0) append("-")
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append(hours)
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appendMinSec(minutes = minutes, seconds = seconds) { ":%02d".format(Locale.ENGLISH, it) }
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}
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}
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/**
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* Returns a transition rule string with the format
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* ",M<MONTH>.<WEEK_OF_MONTH>.<DAY_OF_WEEK>/<HOURS>:<MINUTES>:<SECONDS>". Time is omitted if it is 2:00:00, since that
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* is the spec default. Otherwise, append time with non-zero values.
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*/
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@Suppress("MagicNumber")
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private fun LocalDateTime.transitionRuleString() = buildString {
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val weekOfMonth = get(ChronoField.ALIGNED_WEEK_OF_MONTH)
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val dayOfWeek = get(WeekFields.of(DayOfWeek.SUNDAY, 7).dayOfWeek()) - 1
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append(",M$monthValue.$weekOfMonth.$dayOfWeek")
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when {
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// No-op for spec default
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hour == 2 && minute == 0 && second == 0 -> Unit
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else -> {
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append("/$hour")
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appendMinSec(minutes = minute, seconds = second) { ":$it" }
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if (minutes != 0 || seconds != 0) {
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append(":%02d".format(Locale.ENGLISH, minutes))
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if (seconds != 0) {
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append(":%02d".format(Locale.ENGLISH, seconds))
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}
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}
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}
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}
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private inline fun StringBuilder.appendMinSec(minutes: Int, seconds: Int, format: (Int) -> String) {
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if (minutes != 0 || seconds != 0) {
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// This covers both "30m:30s" and "00m:30s"
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append(format(minutes))
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// This prevents "30m:00s"
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if (seconds != 0) append(format(seconds))
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@Suppress("MagicNumber")
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internal fun formatTransitionRule(rule: ZoneOffsetTransitionRule): String {
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val month = rule.month.value
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val dayOfWeek = rule.dayOfWeek.value % 7
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val dayIndicator = rule.dayOfMonthIndicator
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val occurrence =
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when {
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dayIndicator < 0 -> 5
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dayIndicator > rule.month.length(false) - 7 -> 5
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else -> ((dayIndicator - 1) / 7) + 1
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}
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val wallTime =
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when (rule.timeDefinition) {
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ZoneOffsetTransitionRule.TimeDefinition.UTC ->
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rule.localTime.plusSeconds(rule.offsetBefore.totalSeconds.toLong())
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ZoneOffsetTransitionRule.TimeDefinition.STANDARD -> {
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if (rule.offsetAfter.totalSeconds > rule.offsetBefore.totalSeconds) {
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rule.localTime
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} else {
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rule.localTime.plusSeconds(
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(rule.offsetBefore.totalSeconds - rule.offsetAfter.totalSeconds).toLong(),
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)
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}
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}
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else -> rule.localTime
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}
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return buildString {
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append(",M$month.$occurrence.$dayOfWeek")
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if (wallTime.hour != 2 || wallTime.minute != 0 || wallTime.second != 0) {
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append("/${wallTime.hour}")
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if (wallTime.minute != 0 || wallTime.second != 0) {
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append(":%02d".format(Locale.ENGLISH, wallTime.minute))
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if (wallTime.second != 0) {
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append(":%02d".format(Locale.ENGLISH, wallTime.second))
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}
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}
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}
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}
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}
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context(zoneId: ZoneId)
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private fun Instant.asZonedDateTime() = ZonedDateTime.ofInstant(this, zoneId)
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@ -20,6 +20,7 @@ package org.meshtastic.core.ui.timezone
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import org.junit.Assert.assertEquals
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import org.junit.Test
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import java.time.ZoneId
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import java.time.ZoneOffset
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class ZoneIdExtensionsTest {
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@ -36,20 +37,35 @@ class ZoneIdExtensionsTest {
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"US/Eastern" to "EST5EDT,M3.2.0,M11.1.0",
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"America/Sao_Paulo" to "BRT3",
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"UTC" to "UTC0",
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"Europe/London" to "GMT0BST,M3.5.0/1,M10.4.0",
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"Europe/Lisbon" to "WET0WEST,M3.5.0/1,M10.4.0",
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"Europe/Budapest" to "CET-1CEST,M3.5.0,M10.4.0/3",
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"Europe/Kiev" to "EET-2EEST,M3.5.0/3,M10.4.0/4",
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"Africa/Cairo" to "EET-2EEST,M4.4.5/0,M10.5.5/0",
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"Europe/London" to "GMT0BST,M3.5.0/1,M10.5.0",
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"Europe/Lisbon" to "WET0WEST,M3.5.0/1,M10.5.0",
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"Europe/Budapest" to "CET-1CEST,M3.5.0,M10.5.0/3",
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"Europe/Kiev" to "EET-2EEST,M3.5.0/3,M10.5.0/4",
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"Africa/Cairo" to "EET-2EEST,M4.5.5/0,M10.5.5/0",
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"Asia/Kolkata" to "IST-5:30",
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"Asia/Hong_Kong" to "HKT-8",
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"Asia/Tokyo" to "JST-9",
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"Australia/Perth" to "AWST-8",
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"Australia/Adelaide" to "ACST-9:30ACDT,M10.1.0,M4.1.0/3",
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"Australia/Sydney" to "AEST-10AEDT,M10.1.0,M4.1.0/3",
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"Pacific/Auckland" to "NZST-12NZDT,M9.4.0,M4.1.0/3",
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"Pacific/Auckland" to "NZST-12NZDT,M9.5.0,M4.1.0/3",
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)
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zoneMap.forEach { (tz, expected) -> assertEquals(expected, ZoneId.of(tz).toPosixString()) }
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}
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@Test
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fun `test formatAbbreviation`() {
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assertEquals("PST", formatAbbreviation("PST"))
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assertEquals("<GMT-8>", formatAbbreviation("GMT-8"))
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}
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@Test
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fun `test formatPosixOffset`() {
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assertEquals("8", formatPosixOffset(ZoneOffset.ofHours(-8)))
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assertEquals("-1", formatPosixOffset(ZoneOffset.ofHours(1)))
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assertEquals("-5:30", formatPosixOffset(ZoneOffset.ofHoursMinutes(5, 30)))
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assertEquals("0", formatPosixOffset(ZoneOffset.ofHours(0)))
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assertEquals("-0:30", formatPosixOffset(ZoneOffset.ofTotalSeconds(30 * 60)))
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}
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}
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