(* flan — milestone 2 driver. *)

let with_errors path f =
  try f () with
  | Flan.Loc.Error (loc, msg) ->
    Printf.eprintf "%s: %s\n" (Flan.Loc.to_string loc) msg;
    ignore path;
    exit 1

let summarise (d : Flan.Ast.decl) =
  let open Flan.Ast in
  match d.d with
  | Package n -> Printf.sprintf "package %s" n
  | Import (a, p) -> Printf.sprintf "import %s %S" a p
  | Defalias (n, _) -> Printf.sprintf "defalias %s" n
  | Defstruct (n, fs) -> Printf.sprintf "defstruct %s (%d fields)" n (List.length fs)
  | Defunion (n, vs) -> Printf.sprintf "defunion %s (%d cases)" n (List.length vs)
  | Defvar (n, _, _) -> Printf.sprintf "defvar %s" n
  | Defconst (n, _, _) -> Printf.sprintf "defconst %s" n
  | Defn fn ->
    Printf.sprintf "defn %s (%d params, %s return, %d body forms)"
      fn.name (List.length fn.params)
      (match fn.ret with None -> "Unit" | Some _ -> "explicit")
      (List.length fn.fbody)

let () =
  match Array.to_list Sys.argv with
  | _ :: "read" :: files when files <> [] ->
    List.iter
      (fun path ->
         with_errors path (fun () ->
           Flan.Reader.read_file path
           |> List.iter (fun f -> print_endline (Flan.Form.to_string f))))
      files
  | _ :: "parse" :: files when files <> [] ->
    List.iter
      (fun path ->
         with_errors path (fun () ->
           Flan.Reader.read_file path
           |> Flan.Parse.program
           |> List.iter (fun d -> print_endline (summarise d))))
      files
  | _ ->
    prerr_endline "usage: flan (read|parse) <file.flan>...";
    exit 2