let quote s = Printf.sprintf "%S" s

(* Each entry is an opam field, the command to append to it, and a substring
   that identifies our command if it is already present (for idempotency). The
   per-package hooks deliberately don't mention the odd binary — they are
   plain coreutils so recording works even when odd isn't installed — so
   the marker can't just be [exe]. *)
let fields ~exe =
  [
    (* post-install (incl. same-version rebuilds): mark the package stale.
       [mkdir -p] then [touch], passing prefix/name as $1/$2 to avoid quoting
       opam variables into the script. *)
    ( "post-install-commands",
      {|["sh" "-c" "mkdir -p \"$1/odoc/$2\" && touch \"$1/odoc/$2/.odd-stale\"" "--" "%{prefix}%" "%{name}%"] {error-code = 0}|},
      ".odd-stale" );
    (* post-remove: delete the package's docs outright. Run as an argv list (no
       shell), so a prefix with spaces needs no quoting. *)
    ( "post-remove-commands",
      {|["rm" "-rf" "%{prefix}%/odoc/%{name}%"] {error-code = 0}|},
      "/odoc/%{name}%" );
    (* post-session: the one hook that needs odd — rebuild stale packages
       and refresh the landing page. *)
    ( "post-session-commands",
      Printf.sprintf {|[%s "sync" "--prefix" "%%{prefix}%%"] {success}|}
        (quote exe),
      exe );
  ]

let opam_option_arg field value = Printf.sprintf "%s+=%s" field value

let print ~exe =
  List.iter
    (fun (field, value, _marker) ->
      Printf.printf "opam option --global '%s'\n" (opam_option_arg field value))
    (fields ~exe)

let already_set field marker =
  let cmd = Bos.Cmd.(v "opam" % "option" % "--global" % field) in
  match Bos.OS.Cmd.(run_out ~err:err_null cmd |> to_string ~trim:true) with
  | Ok current -> Astring.String.is_infix ~affix:marker current
  | Error _ -> false

let apply ~exe =
  List.fold_left
    (fun acc (field, value, marker) ->
      Result.bind acc @@ fun () ->
      if already_set field marker then (
        Printf.printf "%s already configured; skipping\n" field;
        Ok ())
      else
        let cmd =
          Bos.Cmd.(
            v "opam" % "option" % "--global" % opam_option_arg field value)
        in
        match Bos.OS.Cmd.run cmd with
        | Ok () ->
            Printf.printf "added to %s\n" field;
            Ok ()
        | Error (`Msg m) ->
            Error (`Msg (Printf.sprintf "failed to set %s: %s" field m)))
    (Ok ()) (fields ~exe)