1 files changed, 344 insertions, 0 deletions
diff --git a/intl/components/src/TimeZone.cpp b/intl/components/src/TimeZone.cpp
new file mode 100644
index 0000000000..145dd3f071
--- /dev/null
+++ b/intl/components/src/TimeZone.cpp
@@ -0,0 +1,344 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/intl/TimeZone.h"
+
+#include "mozilla/Vector.h"
+
+#include <algorithm>
+#include <string_view>
+
+#include "unicode/uenum.h"
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+#  include "unicode/basictz.h"
+#endif
+
+namespace mozilla::intl {
+
+/* static */
+Result<UniquePtr<TimeZone>, ICUError> TimeZone::TryCreate(
+    Maybe<Span<const char16_t>> aTimeZoneOverride) {
+  const UChar* zoneID = nullptr;
+  int32_t zoneIDLen = 0;
+  if (aTimeZoneOverride) {
+    zoneIDLen = static_cast<int32_t>(aTimeZoneOverride->Length());
+    zoneID = aTimeZoneOverride->Elements();
+  }
+
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  UniquePtr<icu::TimeZone> tz;
+  if (zoneID) {
+    tz.reset(
+        icu::TimeZone::createTimeZone(icu::UnicodeString(zoneID, zoneIDLen)));
+  } else {
+    tz.reset(icu::TimeZone::createDefault());
+  }
+  MOZ_ASSERT(tz);
+
+  if (*tz == icu::TimeZone::getUnknown()) {
+    return Err(ICUError::InternalError);
+  }
+
+  return MakeUnique<TimeZone>(std::move(tz));
+#else
+  // An empty string is used for the root locale. This is regarded as the base
+  // locale of all locales, and is used as the language/country neutral locale
+  // for locale sensitive operations.
+  const char* rootLocale = "";
+
+  UErrorCode status = U_ZERO_ERROR;
+  UCalendar* calendar =
+      ucal_open(zoneID, zoneIDLen, rootLocale, UCAL_DEFAULT, &status);
+
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  // https://tc39.es/ecma262/#sec-time-values-and-time-range
+  //
+  // A time value supports a slightly smaller range of -8,640,000,000,000,000 to
+  // 8,640,000,000,000,000 milliseconds.
+  constexpr double StartOfTime = -8.64e15;
+
+  // Ensure all computations are performed in the proleptic Gregorian calendar.
+  ucal_setGregorianChange(calendar, StartOfTime, &status);
+
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return MakeUnique<TimeZone>(calendar);
+#endif
+}
+
+Result<int32_t, ICUError> TimeZone::GetRawOffsetMs() {
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  return mTimeZone->getRawOffset();
+#else
+  // Reset the time in case the calendar has been modified.
+  UErrorCode status = U_ZERO_ERROR;
+  ucal_setMillis(mCalendar, ucal_getNow(), &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  int32_t offset = ucal_get(mCalendar, UCAL_ZONE_OFFSET, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return offset;
+#endif
+}
+
+Result<int32_t, ICUError> TimeZone::GetDSTOffsetMs(int64_t aUTCMilliseconds) {
+  UDate date = UDate(aUTCMilliseconds);
+
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  constexpr bool dateIsLocalTime = false;
+  int32_t rawOffset, dstOffset;
+  UErrorCode status = U_ZERO_ERROR;
+
+  mTimeZone->getOffset(date, dateIsLocalTime, rawOffset, dstOffset, status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return dstOffset;
+#else
+  UErrorCode status = U_ZERO_ERROR;
+  ucal_setMillis(mCalendar, date, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  int32_t dstOffset = ucal_get(mCalendar, UCAL_DST_OFFSET, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return dstOffset;
+#endif
+}
+
+Result<int32_t, ICUError> TimeZone::GetOffsetMs(int64_t aUTCMilliseconds) {
+  UDate date = UDate(aUTCMilliseconds);
+
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  constexpr bool dateIsLocalTime = false;
+  int32_t rawOffset, dstOffset;
+  UErrorCode status = U_ZERO_ERROR;
+
+  mTimeZone->getOffset(date, dateIsLocalTime, rawOffset, dstOffset, status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return rawOffset + dstOffset;
+#else
+  UErrorCode status = U_ZERO_ERROR;
+  ucal_setMillis(mCalendar, date, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  int32_t rawOffset = ucal_get(mCalendar, UCAL_ZONE_OFFSET, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  int32_t dstOffset = ucal_get(mCalendar, UCAL_DST_OFFSET, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return rawOffset + dstOffset;
+#endif
+}
+
+Result<int32_t, ICUError> TimeZone::GetUTCOffsetMs(int64_t aLocalMilliseconds) {
+  // https://tc39.es/ecma262/#sec-local-time-zone-adjustment
+  //
+  // LocalTZA ( t, isUTC )
+  //
+  // When t_local represents local time repeating multiple times at a negative
+  // time zone transition (e.g. when the daylight saving time ends or the time
+  // zone offset is decreased due to a time zone rule change) or skipped local
+  // time at a positive time zone transitions (e.g. when the daylight saving
+  // time starts or the time zone offset is increased due to a time zone rule
+  // change), t_local must be interpreted using the time zone offset before the
+  // transition.
+  constexpr UTimeZoneLocalOption skippedTime = UCAL_TZ_LOCAL_FORMER;
+  constexpr UTimeZoneLocalOption repeatedTime = UCAL_TZ_LOCAL_FORMER;
+
+  UDate date = UDate(aLocalMilliseconds);
+
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  int32_t rawOffset, dstOffset;
+  UErrorCode status = U_ZERO_ERROR;
+
+  // All ICU TimeZone classes derive from BasicTimeZone, so we can safely
+  // perform the static_cast.
+  // Once <https://unicode-org.atlassian.net/browse/ICU-13705> is fixed we
+  // can remove this extra cast.
+  auto* basicTz = static_cast<icu::BasicTimeZone*>(mTimeZone.get());
+  basicTz->getOffsetFromLocal(date, skippedTime, repeatedTime, rawOffset,
+                              dstOffset, status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return rawOffset + dstOffset;
+#else
+  UErrorCode status = U_ZERO_ERROR;
+  ucal_setMillis(mCalendar, date, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  int32_t rawOffset, dstOffset;
+  ucal_getTimeZoneOffsetFromLocal(mCalendar, skippedTime, repeatedTime,
+                                  &rawOffset, &dstOffset, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return rawOffset + dstOffset;
+#endif
+}
+
+using TimeZoneIdentifierVector =
+    Vector<char16_t, TimeZone::TimeZoneIdentifierLength>;
+
+#if !MOZ_INTL_USE_ICU_CPP_TIMEZONE
+static bool IsUnknownTimeZone(const TimeZoneIdentifierVector& timeZone) {
+  constexpr std::string_view unknownTimeZone = UCAL_UNKNOWN_ZONE_ID;
+
+  return timeZone.length() == unknownTimeZone.length() &&
+         std::equal(timeZone.begin(), timeZone.end(), unknownTimeZone.begin(),
+                    unknownTimeZone.end());
+}
+
+static ICUResult SetDefaultTimeZone(TimeZoneIdentifierVector& timeZone) {
+  // The string mustn't already be null-terminated.
+  MOZ_ASSERT_IF(!timeZone.empty(), timeZone.end()[-1] != '\0');
+
+  // The time zone identifier must be a null-terminated string.
+  if (!timeZone.append('\0')) {
+    return Err(ICUError::OutOfMemory);
+  }
+
+  UErrorCode status = U_ZERO_ERROR;
+  ucal_setDefaultTimeZone(timeZone.begin(), &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return Ok{};
+}
+#endif
+
+Result<bool, ICUError> TimeZone::SetDefaultTimeZone(
+    Span<const char> aTimeZone) {
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  icu::UnicodeString tzid(aTimeZone.data(), aTimeZone.size(), US_INV);
+  if (tzid.isBogus()) {
+    return Err(ICUError::OutOfMemory);
+  }
+
+  UniquePtr<icu::TimeZone> newTimeZone(icu::TimeZone::createTimeZone(tzid));
+  MOZ_ASSERT(newTimeZone);
+
+  if (*newTimeZone != icu::TimeZone::getUnknown()) {
+    // adoptDefault() takes ownership of the time zone.
+    icu::TimeZone::adoptDefault(newTimeZone.release());
+    return true;
+  }
+#else
+  TimeZoneIdentifierVector tzid;
+  if (!tzid.append(aTimeZone.data(), aTimeZone.size())) {
+    return Err(ICUError::OutOfMemory);
+  }
+
+  // Retrieve the current default time zone in case we need to restore it.
+  TimeZoneIdentifierVector defaultTimeZone;
+  MOZ_TRY(FillBufferWithICUCall(defaultTimeZone, ucal_getDefaultTimeZone));
+
+  // Try to set the new time zone.
+  MOZ_TRY(mozilla::intl::SetDefaultTimeZone(tzid));
+
+  // Check if the time zone was actually applied.
+  TimeZoneIdentifierVector newTimeZone;
+  MOZ_TRY(FillBufferWithICUCall(newTimeZone, ucal_getDefaultTimeZone));
+
+  // Return if the new time zone was successfully applied.
+  if (!IsUnknownTimeZone(newTimeZone)) {
+    return true;
+  }
+
+  // Otherwise restore the original time zone.
+  MOZ_TRY(mozilla::intl::SetDefaultTimeZone(defaultTimeZone));
+#endif
+
+  return false;
+}
+
+ICUResult TimeZone::SetDefaultTimeZoneFromHostTimeZone() {
+#if MOZ_INTL_USE_ICU_CPP_TIMEZONE
+  if (icu::TimeZone* defaultZone = icu::TimeZone::detectHostTimeZone()) {
+    icu::TimeZone::adoptDefault(defaultZone);
+  }
+#else
+  TimeZoneIdentifierVector hostTimeZone;
+  MOZ_TRY(FillBufferWithICUCall(hostTimeZone, ucal_getHostTimeZone));
+
+  MOZ_TRY(mozilla::intl::SetDefaultTimeZone(hostTimeZone));
+#endif
+
+  return Ok{};
+}
+
+Result<Span<const char>, ICUError> TimeZone::GetTZDataVersion() {
+  UErrorCode status = U_ZERO_ERROR;
+  const char* tzdataVersion = ucal_getTZDataVersion(&status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+  return MakeStringSpan(tzdataVersion);
+}
+
+Result<SpanEnumeration<char>, ICUError> TimeZone::GetAvailableTimeZones(
+    const char* aRegion) {
+  // Get the time zones that are commonly used in the given region. Uses the
+  // UCAL_ZONE_TYPE_ANY filter so we have more fine-grained control over the
+  // returned time zones and don't omit time zones which are considered links in
+  // ICU, but are treated as proper zones in IANA.
+  UErrorCode status = U_ZERO_ERROR;
+  UEnumeration* enumeration = ucal_openTimeZoneIDEnumeration(
+      UCAL_ZONE_TYPE_ANY, aRegion, nullptr, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return SpanEnumeration<char>(enumeration);
+}
+
+Result<SpanEnumeration<char>, ICUError> TimeZone::GetAvailableTimeZones() {
+  UErrorCode status = U_ZERO_ERROR;
+  UEnumeration* enumeration = ucal_openTimeZones(&status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  return SpanEnumeration<char>(enumeration);
+}
+
+#if !MOZ_INTL_USE_ICU_CPP_TIMEZONE
+TimeZone::~TimeZone() {
+  MOZ_ASSERT(mCalendar);
+  ucal_close(mCalendar);
+}
+#endif
+
+}  // namespace mozilla::intl