(* Hierarchical data structure *)

type value =
  | Int of int
  | Float of float
  | String of string
  | Data of t
  | Array of value array

and field = {
  key : string;
  pretty_key : string option;
  format : string option;
  value : value;
}

and t = field list

let make items =
  List.map
    (fun (key, pretty_key, value) -> { key; pretty_key; format = None; value })
    items

let int key ?pretty ?format value =
  { key; pretty_key = pretty; format; value = Int value }

let float key ?pretty ?format value =
  { key; pretty_key = pretty; format; value = Float value }

let string key ?pretty ?format value =
  { key; pretty_key = pretty; format; value = String value }

let data key ?pretty value =
  { key; pretty_key = pretty; format = None; value = Data value }

let array key ?pretty value =
  { key; pretty_key = pretty; format = None; value = Array value }

let hex key ?pretty bytes len =
  let s = Rtl433_util.bytes_to_hex bytes len in
  { key; pretty_key = pretty; format = None; value = String s }

let find key data = List.find_opt (fun f -> f.key = key) data

let get_int key data =
  match find key data with Some { value = Int i; _ } -> Some i | _ -> None

let get_float key data =
  match find key data with Some { value = Float f; _ } -> Some f | _ -> None

let get_string key data =
  match find key data with Some { value = String s; _ } -> Some s | _ -> None

let rec pp_value fmt = function
  | Int i -> Format.fprintf fmt "%d" i
  | Float f -> Format.fprintf fmt "%g" f
  | String s -> Format.fprintf fmt "%S" s
  | Data d -> pp fmt d
  | Array a ->
      Format.fprintf fmt "[%a]"
        (Format.pp_print_list ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ") pp_value)
        (Array.to_list a)

and pp fmt data =
  Format.fprintf fmt "{%a}"
    (Format.pp_print_list
       ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
       (fun fmt f -> Format.fprintf fmt "%s: %a" f.key pp_value f.value))
    data

let to_json data =
  let buf = Buffer.create 256 in
  let rec emit_value = function
    | Int i -> Buffer.add_string buf (string_of_int i)
    | Float f -> Buffer.add_string buf (string_of_float f)
    | String s ->
        Buffer.add_char buf '"';
        Buffer.add_string buf (String.escaped s);
        Buffer.add_char buf '"'
    | Data d -> emit_data d
    | Array a ->
        Buffer.add_char buf '[';
        Array.iteri
          (fun i v ->
            if i > 0 then Buffer.add_char buf ',';
            emit_value v)
          a;
        Buffer.add_char buf ']'
  and emit_data fields =
    Buffer.add_char buf '{';
    List.iteri
      (fun i f ->
        if i > 0 then Buffer.add_char buf ',';
        Buffer.add_char buf '"';
        Buffer.add_string buf f.key;
        Buffer.add_string buf "\":";
        emit_value f.value)
      fields;
    Buffer.add_char buf '}'
  in
  emit_data data;
  Buffer.contents buf

(* Mutable storage for last decoded output *)
let last_output : t option ref = ref None

let set_last_output data = last_output := Some data
let get_last_output () = !last_output
let clear_last_output () = last_output := None