feat(timezone): add Windows timezone name resolution

Add a `Windows_tz` module containing a CLDR-sourced mapping table from
Windows timezone names to canonical IANA names. Update
`timedesc_of_timestamp` to resolve Windows-style timezone identifiers
(e.g. `"W. Europe Standard Time"`) via this table before constructing a
`Timedesc.Time_zone.t`, falling back to the local timezone with a
warning if resolution fails entirely.

bin/dune

@@ -1,7 +1,7 @@
 (executable
  (public_name remind_sync)
  (name main)
- (modules main commandLine remind eventPredicates utils)
+ (modules main commandLine remind eventPredicates utils windows_tz)
  (preprocess
   (pps ppx_deriving.show))
  (libraries

bin/utils.ml

@@ -105,7 +105,18 @@ let timedesc_of_timestamp (ts : timestamp) : Timedesc.t =
   | `With_tzid (ts, (_b, tz_name)) ->
       (* The timestamp is stored as if it were UTC but must be interpreted in tz_name.
          We reconstruct the wall-clock time in tz_name, then convert to target_tz. *)
-      let tz = Timedesc.Time_zone.make_exn tz_name in
+      (* Resolve the timezone name: Windows names (e.g. "W. Europe Standard Time") are
+         mapped to IANA via the CLDR table; otherwise the name is used as-is (assumed
+         to already be a valid IANA name). If resolution fails entirely, fall back to
+         target_tz with a warning. *)
+      let tz =
+        let candidate = Option.value ~default:tz_name (Windows_tz.to_iana tz_name) in
+        match Timedesc.Time_zone.make candidate with
+        | Some tz -> tz
+        | None ->
+            Printf.eprintf "Warning: unresolvable timezone %S, falling back to local timezone\n" tz_name;
+            !target_tz
+      in
       let wrong_ts = Timedesc.Utils.timestamp_of_ptime ts in
       let date = Timedesc.date (Timedesc.of_timestamp_exn ~tz_of_date_time:Timedesc.Time_zone.utc wrong_ts) in
       let year, month, day = (Timedesc.Date.year date, Timedesc.Date.month date, Timedesc.Date.day date) in

bin/windows_tz.ml

@@ -0,0 +1,149 @@
+(** Mapping from Windows timezone names to canonical IANA timezone names. Source: Unicode CLDR
+    common/supplemental/windowsZones.xml, territory="001" entries.
+    https://github.com/unicode-org/cldr/blob/main/common/supplemental/windowsZones.xml *)
+
+let table : (string * string) list =
+  [
+    ("AUS Central Standard Time", "Australia/Darwin");
+    ("AUS Eastern Standard Time", "Australia/Sydney");
+    ("Afghanistan Standard Time", "Asia/Kabul");
+    ("Alaskan Standard Time", "America/Anchorage");
+    ("Aleutian Standard Time", "America/Adak");
+    ("Altai Standard Time", "Asia/Barnaul");
+    ("Arab Standard Time", "Asia/Riyadh");
+    ("Arabian Standard Time", "Asia/Dubai");
+    ("Arabic Standard Time", "Asia/Baghdad");
+    ("Argentina Standard Time", "America/Buenos_Aires");
+    ("Astrakhan Standard Time", "Europe/Astrakhan");
+    ("Atlantic Standard Time", "America/Halifax");
+    ("Aus Central W. Standard Time", "Australia/Eucla");
+    ("Azerbaijan Standard Time", "Asia/Baku");
+    ("Azores Standard Time", "Atlantic/Azores");
+    ("Bahia Standard Time", "America/Bahia");
+    ("Bangladesh Standard Time", "Asia/Dhaka");
+    ("Belarus Standard Time", "Europe/Minsk");
+    ("Bougainville Standard Time", "Pacific/Bougainville");
+    ("Canada Central Standard Time", "America/Regina");
+    ("Cape Verde Standard Time", "Atlantic/Cape_Verde");
+    ("Caucasus Standard Time", "Asia/Yerevan");
+    ("Cen. Australia Standard Time", "Australia/Adelaide");
+    ("Central America Standard Time", "America/Guatemala");
+    ("Central Asia Standard Time", "Asia/Bishkek");
+    ("Central Brazilian Standard Time", "America/Cuiaba");
+    ("Central Europe Standard Time", "Europe/Budapest");
+    ("Central European Standard Time", "Europe/Warsaw");
+    ("Central Pacific Standard Time", "Pacific/Guadalcanal");
+    ("Central Standard Time (Mexico)", "America/Mexico_City");
+    ("Central Standard Time", "America/Chicago");
+    ("Chatham Islands Standard Time", "Pacific/Chatham");
+    ("China Standard Time", "Asia/Shanghai");
+    ("Cuba Standard Time", "America/Havana");
+    ("Dateline Standard Time", "Etc/GMT+12");
+    ("E. Africa Standard Time", "Africa/Nairobi");
+    ("E. Australia Standard Time", "Australia/Brisbane");
+    ("E. Europe Standard Time", "Europe/Chisinau");
+    ("E. South America Standard Time", "America/Sao_Paulo");
+    ("Easter Island Standard Time", "Pacific/Easter");
+    ("Eastern Standard Time (Mexico)", "America/Cancun");
+    ("Eastern Standard Time", "America/New_York");
+    ("Egypt Standard Time", "Africa/Cairo");
+    ("Ekaterinburg Standard Time", "Asia/Yekaterinburg");
+    ("FLE Standard Time", "Europe/Kiev");
+    ("Fiji Standard Time", "Pacific/Fiji");
+    ("GMT Standard Time", "Europe/London");
+    ("GTB Standard Time", "Europe/Bucharest");
+    ("Georgian Standard Time", "Asia/Tbilisi");
+    ("Greenland Standard Time", "America/Godthab");
+    ("Greenwich Standard Time", "Atlantic/Reykjavik");
+    ("Haiti Standard Time", "America/Port-au-Prince");
+    ("Hawaiian Standard Time", "Pacific/Honolulu");
+    ("India Standard Time", "Asia/Calcutta");
+    ("Iran Standard Time", "Asia/Tehran");
+    ("Israel Standard Time", "Asia/Jerusalem");
+    ("Jordan Standard Time", "Asia/Amman");
+    ("Kaliningrad Standard Time", "Europe/Kaliningrad");
+    ("Korea Standard Time", "Asia/Seoul");
+    ("Libya Standard Time", "Africa/Tripoli");
+    ("Line Islands Standard Time", "Pacific/Kiritimati");
+    ("Lord Howe Standard Time", "Australia/Lord_Howe");
+    ("Magadan Standard Time", "Asia/Magadan");
+    ("Magallanes Standard Time", "America/Punta_Arenas");
+    ("Marquesas Standard Time", "Pacific/Marquesas");
+    ("Mauritius Standard Time", "Indian/Mauritius");
+    ("Middle East Standard Time", "Asia/Beirut");
+    ("Montevideo Standard Time", "America/Montevideo");
+    ("Morocco Standard Time", "Africa/Casablanca");
+    ("Mountain Standard Time (Mexico)", "America/Mazatlan");
+    ("Mountain Standard Time", "America/Denver");
+    ("Myanmar Standard Time", "Asia/Rangoon");
+    ("N. Central Asia Standard Time", "Asia/Novosibirsk");
+    ("Namibia Standard Time", "Africa/Windhoek");
+    ("Nepal Standard Time", "Asia/Katmandu");
+    ("New Zealand Standard Time", "Pacific/Auckland");
+    ("Newfoundland Standard Time", "America/St_Johns");
+    ("Norfolk Standard Time", "Pacific/Norfolk");
+    ("North Asia East Standard Time", "Asia/Irkutsk");
+    ("North Asia Standard Time", "Asia/Krasnoyarsk");
+    ("North Korea Standard Time", "Asia/Pyongyang");
+    ("Omsk Standard Time", "Asia/Omsk");
+    ("Pacific SA Standard Time", "America/Santiago");
+    ("Pacific Standard Time (Mexico)", "America/Tijuana");
+    ("Pacific Standard Time", "America/Los_Angeles");
+    ("Pakistan Standard Time", "Asia/Karachi");
+    ("Paraguay Standard Time", "America/Asuncion");
+    ("Qyzylorda Standard Time", "Asia/Qyzylorda");
+    ("Romance Standard Time", "Europe/Paris");
+    ("Russia Time Zone 10", "Asia/Srednekolymsk");
+    ("Russia Time Zone 11", "Asia/Kamchatka");
+    ("Russia Time Zone 3", "Europe/Samara");
+    ("Russian Standard Time", "Europe/Moscow");
+    ("SA Eastern Standard Time", "America/Cayenne");
+    ("SA Pacific Standard Time", "America/Bogota");
+    ("SA Western Standard Time", "America/La_Paz");
+    ("SE Asia Standard Time", "Asia/Bangkok");
+    ("Saint Pierre Standard Time", "America/Miquelon");
+    ("Sakhalin Standard Time", "Asia/Sakhalin");
+    ("Samoa Standard Time", "Pacific/Apia");
+    ("Sao Tome Standard Time", "Africa/Sao_Tome");
+    ("Saratov Standard Time", "Europe/Saratov");
+    ("Singapore Standard Time", "Asia/Singapore");
+    ("South Africa Standard Time", "Africa/Johannesburg");
+    ("South Sudan Standard Time", "Africa/Juba");
+    ("Sri Lanka Standard Time", "Asia/Colombo");
+    ("Sudan Standard Time", "Africa/Khartoum");
+    ("Syria Standard Time", "Asia/Damascus");
+    ("Taipei Standard Time", "Asia/Taipei");
+    ("Tasmania Standard Time", "Australia/Hobart");
+    ("Tocantins Standard Time", "America/Araguaina");
+    ("Tokyo Standard Time", "Asia/Tokyo");
+    ("Tomsk Standard Time", "Asia/Tomsk");
+    ("Tonga Standard Time", "Pacific/Tongatapu");
+    ("Transbaikal Standard Time", "Asia/Chita");
+    ("Turkey Standard Time", "Europe/Istanbul");
+    ("Turks And Caicos Standard Time", "America/Grand_Turk");
+    ("US Eastern Standard Time", "America/Indianapolis");
+    ("US Mountain Standard Time", "America/Phoenix");
+    ("UTC", "Etc/UTC");
+    ("UTC+12", "Etc/GMT-12");
+    ("UTC+13", "Etc/GMT-13");
+    ("UTC-02", "Etc/GMT+2");
+    ("UTC-08", "Etc/GMT+8");
+    ("UTC-09", "Etc/GMT+9");
+    ("UTC-11", "Etc/GMT+11");
+    ("Ulaanbaatar Standard Time", "Asia/Ulaanbaatar");
+    ("Venezuela Standard Time", "America/Caracas");
+    ("Vladivostok Standard Time", "Asia/Vladivostok");
+    ("Volgograd Standard Time", "Europe/Volgograd");
+    ("W. Australia Standard Time", "Australia/Perth");
+    ("W. Central Africa Standard Time", "Africa/Lagos");
+    ("W. Europe Standard Time", "Europe/Berlin");
+    ("W. Mongolia Standard Time", "Asia/Hovd");
+    ("West Asia Standard Time", "Asia/Tashkent");
+    ("West Bank Standard Time", "Asia/Hebron");
+    ("West Pacific Standard Time", "Pacific/Port_Moresby");
+    ("Yakutsk Standard Time", "Asia/Yakutsk");
+    ("Yukon Standard Time", "America/Whitehorse");
+  ]
+
+(** Look up a Windows timezone name and return the canonical IANA name, if known. *)
+let to_iana (windows_name : string) : string option = List.assoc_opt windows_name table