ics: print the timezone name in the ICS file

Add the correct timezone in generated ICS files.  The timezone is
fetched from /etc/timezone.

Even though this is not standard, if a tool needs it, it should be able
to understand it correctly.

Signed-off-by: Alban Gruin <alban at pa1ch dot fr>

3 files changed, 28 insertions, 3 deletions

diff --git a/src/ics.ml b/src/ics.ml
index 6dd747d..d1bb808 100644
--- a/src/ics.ml
+++ b/src/ics.ml
@@ -61,8 +61,19 @@ type t = Event.t list
 
 let make events = events
 
-let to_string events =
+let gen_vtimezone tz =
+  if tz <> "" then
+  ["BEGIN:VTIMEZONE";
+   "TZID:" ^ tz;
+   "END:VTIMEZONE\n"]
+  |> List.map ics_split_line
+  |> String.concat "\n"
+  else
+    ""
+
+let to_string tz events =
   let date = current_date () in
+  let vtimezone = gen_vtimezone tz in
   let rec gen_events id str = function
     | [] -> str
     | event :: l ->
@@ -70,5 +81,6 @@ let to_string events =
   "BEGIN:VCALENDAR\n\
    VERSION:2.0\n\
    PRODID:-//ucs//\n"
+  ^ vtimezone
   ^ gen_events 0 "" events
   ^ "END:VCALENDAR\n"
diff --git a/src/ics.mli b/src/ics.mli
index 219f851..a4cbbd6 100644
--- a/src/ics.mli
+++ b/src/ics.mli
@@ -26,4 +26,4 @@ end
 type t
 
 val make : Event.t list -> t
-val to_string : t -> string
+val to_string : string -> t -> string
diff --git a/src/server.ml b/src/server.ml
index d3cf00e..c1a0ba9 100644
--- a/src/server.ml
+++ b/src/server.ml
@@ -47,7 +47,20 @@ let respond ?(mime="text/html; charset=utf-8") ?(status=`OK) body =
   let headers = Header.init_with "Content-Type" mime in
   Server.respond_string ~status ~body ~headers ()
 
+let get_tz () =
+  Lwt_unix.file_exists "/etc/timezone" >>= fun exists ->
+  if exists then
+    Lwt_io.(open_file ~mode:Input "/etc/timezone") >>= fun file ->
+    Lwt.finalize
+      (fun () ->
+         Lwt_io.read file >|=
+         String.trim)
+      (fun () -> Lwt_io.close file)
+  else
+    Lwt.return ""
+
 let serve base_url celcat_url mode stop =
+  get_tz () >>= fun tzname ->
   let fetch = fetch celcat_url in
   let callback _conn req _body =
     let meth = Request.meth req and
@@ -68,7 +81,7 @@ let serve base_url celcat_url mode stop =
        let group = String.(sub file 0 (length file - 4)) in
        fetch group >>= fun body ->
        Course.decode body
-       |> Ics.to_string
+       |> Ics.to_string tzname
        |> respond ~mime:"text/calendar; charset=utf-8"
     | `GET, _, _ ->
        Server.respond_string ~status:`Not_found ~body:"Not found\n" ()