open Parser

(* Map a param name/type hint to a nushell type *)
let nushell_type_of_param = function
  | "FILE" | "file" | "PATH" | "path" | "DIR" | "dir" | "DIRECTORY"
  | "FILENAME" | "PATTERNFILE" -> "path"
  | "NUM" | "N" | "COUNT" | "NUMBER" | "int" | "INT" | "COLS" | "WIDTH"
  | "LINES" | "DEPTH" | "depth" -> "int"
  | _ -> "string"

(* Escape a nushell string: wrap in double quotes, escape inner quotes *)
let escape_nu s =
  let buf = Buffer.create (String.length s + 2) in
  String.iter (fun c ->
    match c with
    | '"' -> Buffer.add_string buf "\\\""
    | '\\' -> Buffer.add_string buf "\\\\"
    | _ -> Buffer.add_char buf c
  ) s;
  Buffer.contents buf

(* Format a single flag for nushell extern *)
let format_flag entry =
  let buf = Buffer.create 64 in
  Buffer.add_string buf "    ";
  (* Flag name *)
  (match entry.switch with
   | Both (s, l) ->
     Buffer.add_string buf (Printf.sprintf "--%s(-%c)" l s)
   | Long l ->
     Buffer.add_string buf (Printf.sprintf "--%s" l)
   | Short s ->
     Buffer.add_string buf (Printf.sprintf "-%c" s));
  (* Type annotation *)
  (match entry.param with
   | Some (Mandatory name) ->
     Buffer.add_string buf ": ";
     Buffer.add_string buf (nushell_type_of_param name)
   | Some (Optional name) ->
     Buffer.add_string buf ": ";
     Buffer.add_string buf (nushell_type_of_param name)
   | None -> ());
  (* Description as comment *)
  if String.length entry.desc > 0 then begin
    (* Pad to align comments *)
    let current_len = Buffer.length buf in
    let target = max (current_len + 1) 40 in
    for _ = current_len to target - 1 do
      Buffer.add_char buf ' '
    done;
    Buffer.add_string buf "# ";
    Buffer.add_string buf entry.desc
  end;
  Buffer.contents buf

(* Generate nushell extern definition for a command *)
let generate_extern cmd_name result =
  let buf = Buffer.create 1024 in
  (* Main extern with flags *)
  Buffer.add_string buf (Printf.sprintf "export extern \"%s\" [\n" (escape_nu cmd_name));
  List.iter (fun entry ->
    Buffer.add_string buf (format_flag entry);
    Buffer.add_char buf '\n'
  ) result.entries;
  Buffer.add_string buf "]\n";
  (* Subcommand externs *)
  List.iter (fun (sc : subcommand) ->
    Buffer.add_string buf
      (Printf.sprintf "\nexport extern \"%s %s\" [  # %s\n]\n"
         (escape_nu cmd_name) (escape_nu sc.name) (escape_nu sc.desc))
  ) result.subcommands;
  Buffer.contents buf

(* Generate a complete nushell module *)
let generate_module cmd_name result =
  Printf.sprintf "module %s-completions {\n%s}\n"
    cmd_name (generate_extern cmd_name result)

(* Generate from manpage entries (no subcommands) *)
let generate_extern_from_entries cmd_name entries =
  let result = { entries; subcommands = [] } in
  generate_extern cmd_name result