(* SPDX-License-Identifier: LGPL-3.0-only WITH OCaml-LGPL-linking-exception *)

let interactive = Unix.(isatty stdin)

let err q v =
  match q, v with
    | true, _ -> Printf.ifprintf stdout
    | _       -> Printf.eprintf
and out q v =
  match q, v with
    | true, _
    | _, true -> Printf.ifprintf stdout
    | _       -> Printf.printf

let header q v =
  out q v "SID                            \
           IDAUTH          \
           NSUB SUBAUTHS\n%!"

let emit q v s =
  let ss = Sid.to_string s
  and ia = Sid.get_ident_auth s
  and sas = Sid.get_sub_auths s in
  out q v "%-30s %-15s %-4d %s\n"
    ss
    (Stdint.Uint64.to_string ia)
    (Array.length sas)
    (Array.map Stdint.Uint32.to_string sas
     |> Array.to_list
     |> String.concat " ")

let handle_input q v s =
  match String.trim s with
    | "" -> `Nothing
    | s ->
      (match Sid.of_string s with
        | Ok s -> `Done s
        | Error e -> err q v "ERROR: %s\n%!" e; `Junk)

let from_argv sids =
  let rest = ref sids in
  let next () =
    match !rest with
      | [] -> `Done
      | hd::tl ->
        rest := tl;
        `Sid hd
  in
  next

let from_stdin () =
  try `Sid (input_line stdin)
  with End_of_file -> `Done

let traverse q v next =
  let rec aux n ne =
    match next () with
      | `Done -> if ne = 0 then Ok n else Error (n, ne)
      | `Sid s -> begin
          match handle_input q v s with
            | `Nothing -> aux n ne
            | `Junk -> aux (n + 1) (ne + 1)
            | `Done s -> begin
                if n = 0 then header q v;
                emit q v s;
                if interactive then flush_all ();
                aux (n + 1) ne
              end
        end
  in
  aux 0 0

let sidparse validate quiet args =
  let next =
    match args with
      | [] -> begin
          if interactive then
            err quiet validate "reading input from stdin\n%!";
          from_stdin
        end
      | sids -> from_argv sids
  in
  match traverse quiet validate next with
    | Ok _ -> 0
    | Error (n, ne) ->
      if not quiet then
        err quiet validate "processed %d items with %d errors\n" n ne;
      -1

open Cmdliner

let arg_validate =
  let doc = "Do not print table of constituent parts, only error messages." in
  Arg.(value & flag & info ["v"; "validate"] ~doc)

let arg_quiet =
  let doc = "Do not print anything at all." in
  Arg.(value & flag & info ["q"; "quiet"] ~doc)

let arg_sid =
  let doc = "Inputs specified on command line as positional arguments." in
  Arg.(value & (pos_all string []) & info [] ~docv:"SID" ~doc)

let cmd_sidparse =
  let exits = Term.exit_info ~doc:"errors occurred" (-1) :: Term.default_exits in
  let doc = "Process Windows security identifiers." in
  let man =
    [ `P "This command will parse SIDs (security identifiers) \
          from the command line and standard input."
    ; `P "The input is expected to consist of one SID per argument or \
          line, respectively, in “string format” (cf. [MS-DTYP] 2.4.21)."
    ; `S Manpage.s_see_also
    ; `P "Consult Microsoft’s documentation for more information. \
          SIDs are specified in MS-DTYP \
          (https://msdn.microsoft.com/en-us/library/cc230273.aspx) \
          with references to the Open Group RPC standard \
          (http://www.opengroup.org/dce/download/)."
    ; `S Manpage.s_examples
    ; `P "Parse a number of SIDs supplied on command line:"
    ; `Pre "$ sidparse S-1-0 S-1-1\n\
            SID                           IDAUTH         NSUB SUBAUTHS\n\
            S-1-0                         0              0\n\
            S-1-1                         1              0\n"
    ; `P "Parse a number of SIDs from standard input:"
    ; `Pre "$ sidparse <<THATSALL\n\
            S-1-0\n\
            S-1-42-1337-2187\n\
            THATSALL\n\
            SID                            IDAUTH          NSUB SUBAUTHS\n\
            S-1-0                          0               0    \n\
            S-1-42-1337-2187               42              2    1337 2187"
    ]
  in
  Term.(const sidparse $ arg_validate $ arg_quiet $ arg_sid),
  Term.info ~doc ~man ~exits "sidparse"

let () =
  Term.eval (cmd_sidparse)
  |> Term.exit_status
;;