(* 문법 파일을 읽어 기계가 소비할 수 있는지 확인하는 도구. *)
let read file =
  let ic = open_in_bin file in
  let n = in_channel_length ic in
  let s = really_input_string ic n in
  close_in ic;
  s

let () =
  if Array.length Sys.argv > 1 && Sys.argv.(1) = "--lexical" then (
    print_string (Coollang.Lexical_doc.render ());
    print_newline ();
    exit 0);
  let file = if Array.length Sys.argv > 1 then Sys.argv.(1) else "docs/grammar.ebnf" in
  match Coollang.Ebnf.parse_result (read file) with
  | Error e -> Printf.printf "%s:%d: %s\n" file e.line e.msg
  | Ok g ->
      Printf.printf "프로덕션 %d개\n" (List.length g);
      Printf.printf "\n정의되지 않은 채 참조된 이름:\n";
      List.iter (fun n -> Printf.printf "  %s\n" n) (Coollang.Ebnf.undefined g);
      Printf.printf "\n어디서도 참조되지 않는 프로덕션 (시작 기호 module 제외):\n";
      List.iter
        (fun n -> Printf.printf "  %s\n" n)
        (Coollang.Ebnf.unreachable g ~start:"module");
      (* 문법이 쓰는 단말 전부. 렉서가 만드는 토큰과 대조하기 위한 것. *)
      let terms = Hashtbl.create 64 in
      let rec walk : Coollang.Ebnf.expr -> unit = function
        | Term s -> Hashtbl.replace terms s ()
        | Ref _ | RefArg _ -> ()
        | Seq xs | Alt xs -> List.iter walk xs
        | Opt e | Rep e -> walk e
        | Except (a, b) -> walk a; walk b
      in
      List.iter (fun (r : Coollang.Ebnf.rule) -> walk r.body) g;
      let ts = Hashtbl.fold (fun k () acc -> k :: acc) terms [] |> List.sort compare in
      Printf.printf "\n문법이 쓰는 단말 %d개:\n  %s\n" (List.length ts)
        (String.concat " " ts);
      (* 어휘 절의 이름은 파서 층에서 단말이다 *)
      let tokens =
        [ "ident"; "int_lit"; "string_lit"; "NEWLINE"; "letter"; "digit"; "char" ]
      in
      let g = Coollang.Ebnf.expand g in
      let a = Coollang.Ebnf.analyze ~tokens g in
      Printf.printf "\n비어도 되는(nullable) 프로덕션:\n  %s\n"
        (String.concat " "
           (List.filter_map
              (fun (r : Coollang.Ebnf.rule) ->
                if Coollang.Ebnf.nullable a r.name then Some r.name else None)
              g));
      Printf.printf "\nFIRST 표본:\n";
      List.iter
        (fun n ->
          Printf.printf "  %-14s %s\n" n
            (String.concat " "
               (Coollang.Ebnf.SS.elements (Coollang.Ebnf.first a n))))
        [ "decl"; "stmt"; "primary"; "type"; "pattern"; "item" ];
      let cs = Coollang.Ebnf.conflicts ~tokens ~greedy:[ "NEWLINE" ] g in
      let real = List.filter (fun (c : Coollang.Ebnf.conflict) -> not c.c_greedy) cs in
      let soft = List.filter (fun (c : Coollang.Ebnf.conflict) -> c.c_greedy) cs in
      Printf.printf "\n== LL(1) 충돌: 진짜 %d건, greedy로 해소 %d건 ==\n"
        (List.length real) (List.length soft);
      List.iter
        (fun (c : Coollang.Ebnf.conflict) ->
          Printf.printf "\n%s (%s:%d) [%s]\n  겹치는 토큰: %s\n  %s\n" c.c_rule file
            c.c_line c.c_kind
            (String.concat " " c.c_tokens)
            c.c_detail)
        real;
      if soft <> [] then begin
        Printf.printf "\n-- greedy로 해소되는 것 --\n";
        List.iter
          (fun (c : Coollang.Ebnf.conflict) ->
            Printf.printf "  %s:%d %s [%s]\n" file c.c_line c.c_rule
              (String.concat " " c.c_tokens))
          soft
      end