feat: support multiple input files

- Accept multiple positional arguments instead of a single required file
- Extract `read_file` helper to separate file reading from parsing
- Collect all valid reminders across files before printing
- Handle per-file errors gracefully without aborting the whole run

bin/commandLine.ml

@@ -1,17 +1,16 @@
 open Cmdliner
 open Cmdliner.Term.Syntax
 
-let ical_file =
-  let doc = "TODO" in
-  let docv = "ICAL" in
-  Arg.(required & pos ~rev:true 0 (some string) None & info [] ~docv ~doc)
+let files =
+  let doc = "Files to process" in
+  Arg.(non_empty & pos_all string [] & info [] ~docv:"FILE" ~doc)
 
 let main_command f =
   let doc = "Convert iCalendar files to remind format" in
   let man = [] in
   Cmd.make (Cmd.info "ical2rem" ~version:"%%VERSION%%" ~doc ~man)
   @@
-  let+ ical_file = ical_file in
-  f ical_file
+  let+ files = files in
+  f files
 
 let main f = Cmd.eval @@ main_command f

bin/main.ml

@@ -7,38 +7,57 @@ module Map = MoreLabels.Map.Make (String)
   (e.g., due to updates or recurring events or cancellations).
 *)
 
-let ical2rem ical_file =
-  let ic = open_in ical_file in
+let read_file filename =
+  let ic = open_in filename in
   let n = in_channel_length ic in
   let s = Bytes.create n in
   really_input ic s 0 n;
   close_in ic;
-  let cal_or_error = Icalendar.parse (Bytes.unsafe_to_string s) in
-  match cal_or_error with
-  | Error e ->
-      if e = ": not enough input" then
-        exit 0 (* This is a common error when the file is empty, so we treat it as a non-error case *)
-      else prerr_endline ("Error parsing iCalendar file: " ^ e)
-  | Ok (_, components) -> begin
-      let events_map : Icalendar.event list Map.t =
-        ListLabels.fold_left ~init:Map.empty components ~f:(fun acc comp ->
-            match comp with
-            | `Event ev ->
-                let uid = Utils.get_uid ev in
-                let event_list = Map.find_opt uid acc |> Option.value ~default:[] in
-                Map.add ~key:uid ~data:(ev :: event_list) acc
-            | _ -> acc (* Ignore non-event components *))
-      in
-      (* Now revert all the lists *)
-      let events_map = Map.map ~f:List.rev events_map in
-      (* Printf.printf "Events: %d\n\n" (Map.cardinal events_map); *)
+  Bytes.unsafe_to_string s
 
-      Map.iter events_map ~f:(fun ~key:uid ~data:events ->
-          let rem_or_error = EventPredicates.remind_of_event events in
-          match rem_or_error with
-          | Ok rem -> begin Printf.printf "%s\n" (Remind.string_of_rem rem) end
-          | Error (EventPredicates.Invalid_date s) -> Printf.eprintf "UID: %s Invalid date: %s\n" uid s
-          | Error Skip -> Printf.eprintf "UID: %s Skipped\n" uid)
-    end
+let ical2rem ical_files =
+  let good_rems =
+    ListLabels.fold_left ~init:[] ical_files ~f:(fun good_rems_acc filename ->
+        try
+          Printf.eprintf "\nProcessing file: %s\n" filename;
+          let file_content = read_file filename in
+          match Icalendar.parse file_content with
+          | Error e ->
+              if e <> ": not enough input" then prerr_endline ("Error parsing iCalendar file: " ^ e);
+              good_rems_acc
+          | Ok (_, components) -> begin
+              let events_map : Icalendar.event list Map.t =
+                ListLabels.fold_left ~init:Map.empty components ~f:(fun acc comp ->
+                    match comp with
+                    | `Event ev ->
+                        let uid = Utils.get_uid ev in
+                        let event_list = Map.find_opt uid acc |> Option.value ~default:[] in
+                        Map.add ~key:uid ~data:(ev :: event_list) acc
+                    | _ -> acc (* Ignore non-event components *))
+              in
+
+              let events_map = Map.map ~f:List.rev events_map in
+
+              let good_rems =
+                Map.fold ~init:[] events_map ~f:(fun ~key:uid ~data:events good_rems ->
+                    let rem_or_error = EventPredicates.remind_of_event events in
+                    match rem_or_error with
+                    | Ok rem -> rem :: good_rems
+                    | Error (EventPredicates.Invalid_date s) ->
+                        Printf.eprintf "UID: %s Invalid date: %s\n" uid s;
+                        good_rems
+                    | Error Skip ->
+                        Printf.eprintf "UID: %s Skipped\n" uid;
+                        good_rems)
+              in
+              let good_rems = List.rev good_rems in
+              good_rems @ good_rems_acc
+            end
+        with e ->
+          prerr_endline ("Error reading file " ^ filename ^ ": " ^ Printexc.to_string e);
+          good_rems_acc)
+  in
+
+  ListLabels.iter good_rems ~f:(fun rem -> Printf.printf "%s\n" (Remind.string_of_rem rem))
 
 let () = if !Sys.interactive then () else exit (CommandLine.main ical2rem)