open Yojson.Safe.Util;

module StringSet = Set.Make(String);
module Util = Flake_env__util;

[@deriving yojson]
type watch = {
  exists: bool,
  modtime: int,
  path: string,
};

[@deriving yojson]
type watches = array(watch);

let get = () => {
  let direnv_watch_str = Sys.getenv("DIRENV_WATCHES");
  let stdout_read_ch =
    Unix.open_process_in("direnv show_dump " ++ direnv_watch_str);
  switch (Yojson.Safe.from_channel(stdout_read_ch)) {
  | exception (Yojson.Json_error(msg)) => Error(msg)
  | safe_t =>
    switch (watches_of_yojson(safe_t)) {
    | exception _ =>
      Error("Failed parsing watches; Has the direnv JSON shape changed?")
    | body => Ok(body)
    }
  };
};

let get_path = doc => {
  let pth = doc |> member("path") |> to_string;
  String.sub(pth, 11, String.length(pth) - 11);
};

let rec get_paths_from_doc = (doc, paths) => {
  let p = get_path(doc);
  let sub_paths =
    List.concat(
      doc
      |> member("inputs")
      |> to_assoc
      |> List.map(((_k, v)) => get_paths_from_doc(v, paths)),
    );
  List.concat([[p], sub_paths]);
};

let get_input_paths = () => {
  switch (Util.nix(["flake", "archive", "--json", "--no-write-lock-file"])) {
  | (WEXITED(0), output) =>
    get_paths_from_doc(Yojson.Safe.from_string(output), [])
  | _ =>
    Printf.eprintf(
      "Failed to parse output of `nix flake archive --json`. Ignorning flake inputs. \n",
    );
    [];
  };
};