1 files changed, 114 insertions, 0 deletions
diff --git a/comm/calendar/base/src/TimezoneDatabase.cpp b/comm/calendar/base/src/TimezoneDatabase.cpp
new file mode 100644
index 0000000000..d93f78e1f4
--- /dev/null
+++ b/comm/calendar/base/src/TimezoneDatabase.cpp
@@ -0,0 +1,114 @@
+/* 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 "nsPrintfCString.h"
+#include "nsString.h"
+#include "unicode/strenum.h"
+#include "unicode/timezone.h"
+#include "unicode/ucal.h"
+#include "unicode/utypes.h"
+#include "unicode/vtzone.h"
+
+#include "TimezoneDatabase.h"
+
+NS_IMPL_ISUPPORTS(TimezoneDatabase, calITimezoneDatabase)
+
+NS_IMETHODIMP
+TimezoneDatabase::GetVersion(nsACString& aVersion) {
+  UErrorCode err = U_ZERO_ERROR;
+  const char* version = icu::VTimeZone::getTZDataVersion(err);
+  if (U_FAILURE(err)) {
+    NS_WARNING(nsPrintfCString("ICU error: %s", u_errorName(err)).get());
+    return NS_ERROR_FAILURE;
+  }
+
+  aVersion.Assign(version);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TimezoneDatabase::GetCanonicalTimezoneIds(nsTArray<nsCString>& aTimezoneIds) {
+  aTimezoneIds.Clear();
+
+  UErrorCode err = U_ZERO_ERROR;
+
+  // Because this list of IDs is not intended to be restrictive, we only request
+  // the canonical IDs to avoid providing lots of redundant options to users
+  icu::StringEnumeration* icuEnum = icu::VTimeZone::createTimeZoneIDEnumeration(
+      UCAL_ZONE_TYPE_CANONICAL, nullptr, nullptr, err);
+  if (U_FAILURE(err)) {
+    NS_WARNING(nsPrintfCString("ICU error: %s", u_errorName(err)).get());
+    return NS_ERROR_FAILURE;
+  }
+
+  const char* value;
+  err = U_ZERO_ERROR;
+  while ((value = icuEnum->next(nullptr, err)) != nullptr && U_SUCCESS(err)) {
+    nsCString tzid(value);
+    aTimezoneIds.AppendElement(tzid);
+  }
+
+  if (U_FAILURE(err)) {
+    // If we encountered any error during enumeration of the timezones, we want
+    // to return an empty list
+    aTimezoneIds.Clear();
+
+    NS_WARNING(nsPrintfCString("ICU error: %s", u_errorName(err)).get());
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TimezoneDatabase::GetTimezoneDefinition(const nsACString& tzid,
+                                        nsACString& _retval) {
+  _retval.Truncate();
+
+  NS_ConvertUTF8toUTF16 convertedTzid(tzid);
+
+  // It seems Windows can potentially build `convertedTzid` with wchar_t
+  // underlying, which makes the UnicodeString ctor ambiguous; be explicit here
+  const char16_t* convertedTzidPtr = convertedTzid.get();
+
+  icu::UnicodeString icuTzid(convertedTzidPtr,
+                             static_cast<int>(convertedTzid.Length()));
+
+  auto* icuTimezone = icu::VTimeZone::createVTimeZoneByID(icuTzid);
+  if (icuTimezone == nullptr) {
+    return NS_OK;
+  }
+
+  // Work around https://unicode-org.atlassian.net/browse/ICU-22175
+  // This workaround is overly complex because there's no simple, reliable way
+  // to determine if a VTimeZone is Etc/Unknown; getID() doesn't work because
+  // the ctor doesn't set the ID field, and hasSameRules() against Etc/Unknown
+  // will return true if icuTimezone is GMT
+  if (icuTimezone->hasSameRules(icu::TimeZone::getUnknown()) &&
+      !tzid.Equals("Etc/Unknown")) {
+    icu::UnicodeString actualTzid;
+    icu::TimeZone::createTimeZone(icuTzid)->getID(actualTzid);
+
+    if (actualTzid == UNICODE_STRING("Etc/Unknown", 11)) {
+      return NS_OK;
+    }
+  }
+
+  // Extract the VTIMEZONE definition from the timezone object
+  icu::UnicodeString vtimezoneDef;
+  UErrorCode err = U_ZERO_ERROR;
+  icuTimezone->write(vtimezoneDef, err);
+  if (U_FAILURE(err)) {
+    NS_WARNING(nsPrintfCString("ICU error: %s", u_errorName(err)).get());
+
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ConvertUTF16toUTF8 convertedDef(vtimezoneDef.getTerminatedBuffer());
+
+  _retval.Assign(convertedDef);
+
+  return NS_OK;
+}