open Nock_lib
open Noun
open Serial

let read_file path =
  let ic = open_in_bin path in
  let len = in_channel_length ic in
  let bytes = really_input_string ic len in
  close_in ic;
  Bytes.of_string bytes

let rec find_project_root dir =
  let pills_dir = Filename.concat dir "pills" in
  if Sys.file_exists pills_dir && Sys.is_directory pills_dir then
    dir
  else
    let parent = Filename.dirname dir in
    if String.equal parent dir then
      invalid_arg "unable to locate project root containing pills/"
    else
      find_project_root parent

let project_root =
  let exe_dir = Filename.dirname Sys.executable_name in
  find_project_root exe_dir

let pill_path name = Filename.concat project_root (Filename.concat "pills" name)

let pill_paths = List.map pill_path [ "baby.pill"; "ivory.pill" ]

let test_pill path () =
  Printf.printf "[pill] %s\n%!" path;
  let bytes = read_file path in
  let cue_noun = cue bytes in
  Alcotest.(check bool) (path ^ " parsed") true (Noun.is_cell cue_noun)

let tests = List.map (fun path -> path, `Quick, test_pill path) pill_paths

let error_to_string = function
  | Boot.Invalid_pill s -> Printf.sprintf "invalid pill: %s" s
  | Boot.Unsupported s -> Printf.sprintf "unsupported pill: %s" s

let count_list noun =
  let rec loop acc = function
    | Atom z when Z.equal z Z.zero -> acc
    | Cell (_, t) -> loop (acc + 1) t
    | _ -> Alcotest.fail "expected null-terminated list"
  in
  loop 0 noun

let solid_event_count path =
  let noun = cue (read_file path) in
  match noun with
  | Cell (tag, rest) ->
      let pill_tag = Z.of_int 0x6c6c6970 in
      let solid_tag = Z.of_int 0x64696c6f in
      begin match tag, rest with
      | Atom z, Cell (typ, payload) when Z.equal z pill_tag ->
          begin match typ, payload with
          | Atom t, Cell (bot, Cell (mod_, use_)) when Z.equal t solid_tag ->
              count_list bot + count_list mod_ + count_list use_
          | _ -> Alcotest.fail "malformed solid payload"
          end
      | _ -> Alcotest.fail "invalid solid pill tag"
      end
  | _ -> Alcotest.fail "solid pill not a cell"

let test_boot_ivory () =
  let state = State.create () in
  match Boot.boot_ivory state (pill_path "ivory.pill") with
  | Ok () ->
      Alcotest.(check int64) "eve reset" 0L (State.event_number state);
      Alcotest.(check bool) "arvo core is cell" true (Noun.is_cell (State.arvo_core state))
  | Error err -> Alcotest.failf "boot_ivory failed: %s" (error_to_string err)

let test_boot_solid () =
  let solid_limit =
    match Sys.getenv_opt "SOLID_LIMIT" with
    | None -> None
    | Some value ->
        begin match int_of_string_opt value with
        | Some n when n > 0 -> Some n
        | _ -> Alcotest.fail "SOLID_LIMIT must be a positive integer"
        end
  in
  match solid_limit with
  | None ->
      Printf.printf "[solid] skipping; set SOLID_LIMIT to replay events\n%!"
  | Some requested_limit ->
      let ivory = pill_path "ivory.pill" in
      let solid = pill_path "solid.pill" in
      let state = State.create () in
      let total_events = solid_event_count solid in
      if total_events = 0 then Alcotest.fail "solid pill contained no events";
      let limit = min requested_limit total_events in
      match Boot.boot_ivory state ivory with
      | Error err -> Alcotest.failf "boot_ivory failed: %s" (error_to_string err)
      | Ok () ->
          let booted_core = State.arvo_core state in
          let seen = ref [] in
          let fake_apply _ event =
            seen := event :: !seen;
            Noun.zero
          in
          match Boot.boot_solid ~limit ~apply:fake_apply state solid with
          | Error err -> Alcotest.failf "boot_solid failed: %s" (error_to_string err)
          | Ok () ->
              let events = List.rev !seen in
              Alcotest.(check int) "event count" limit (List.length events);
              Alcotest.(check int64) "eve unchanged" 0L (State.event_number state);
              Alcotest.(check bool) "core unchanged"
                true (Noun.equal booted_core (State.arvo_core state))
  

let boot_tests = [
  "boot_ivory", `Quick, test_boot_ivory;
  "boot_solid", `Slow, test_boot_solid;
]

let () =
  Alcotest.run "pills"
    [ "pill roundtrips", tests;
      "boot", boot_tests;
    ]