(* Tests for preloaded package detection and CRC verification.

   Uses Impl.check_preload_status directly (pure function, no JS deps)
   with mock lookup functions to simulate different scenarios. *)

open Js_top_worker.Impl

let make_dcs ?(crcs = []) modules =
  { dcs_url = "test://";
    dcs_toplevel_modules = modules;
    dcs_file_prefixes = [];
    dcs_module_crcs = crcs;
    dcs_cma_units = [] }

let print_status = function
  | Preloaded -> print_string "Preloaded"
  | Not_loaded -> print_string "Not_loaded"
  | Partially_loaded { loaded; missing } ->
      Printf.printf "Partially_loaded(loaded=[%s], missing=[%s])"
        (String.concat "," loaded) (String.concat "," missing)
  | Crc_mismatch ms ->
      Printf.printf "Crc_mismatch([%s])" (String.concat "; " ms)

(* Mock helpers *)
let available_set = ref []
let binary_crcs = ref []
let server_crcs = ref []

let is_available m = List.mem m !available_set
let get_binary_crc m = List.assoc_opt m !binary_crcs
let get_universe_crc m = List.assoc_opt m !server_crcs

let setup ~available ~binary ~server =
  available_set := available;
  binary_crcs := binary;
  server_crcs := server

let check dcs =
  check_preload_status ~is_available ~get_binary_crc ~get_universe_crc dcs

let%expect_test "all modules linked, CRCs match — Preloaded" =
  setup ~available:["Foo"; "Bar"]
    ~binary:[("Foo", "abc123"); ("Bar", "def456")]
    ~server:[("Foo", "abc123"); ("Bar", "def456")];
  let dcs = make_dcs ~crcs:[("Foo", "abc123"); ("Bar", "def456")]
    ["Foo"; "Bar"] in
  print_status (check dcs);
  [%expect {| Preloaded |}]

let%expect_test "no modules linked — Not_loaded" =
  setup ~available:[] ~binary:[] ~server:[];
  let dcs = make_dcs ~crcs:[("Foo", "abc123")] ["Foo"] in
  print_status (check dcs);
  [%expect {| Not_loaded |}]

let%expect_test "CRC mismatch" =
  setup ~available:["Foo"]
    ~binary:[("Foo", "binary_crc")]
    ~server:[("Foo", "universe_crc")];
  let dcs = make_dcs ~crcs:[("Foo", "universe_crc")] ["Foo"] in
  print_status (check dcs);
  [%expect {| Crc_mismatch([Foo (universe=universe_crc binary=binary_crc)]) |}]

let%expect_test "partial load" =
  setup ~available:["Foo"]
    ~binary:[("Foo", "abc123")]
    ~server:[];
  let dcs = make_dcs ~crcs:[("Foo", "abc123"); ("Bar", "def456")]
    ["Foo"; "Bar"] in
  print_status (check dcs);
  [%expect {| Partially_loaded(loaded=[Foo], missing=[Bar]) |}]

let%expect_test "no CRCs in universe — still Preloaded" =
  setup ~available:["Foo"]
    ~binary:[("Foo", "abc123")]
    ~server:[];
  let dcs = make_dcs ["Foo"] in
  print_status (check dcs);
  [%expect {| Preloaded |}]

let%expect_test "empty module list — Not_loaded" =
  setup ~available:[] ~binary:[] ~server:[];
  let dcs = make_dcs [] in
  print_status (check dcs);
  [%expect {| Not_loaded |}]

let%expect_test "server CRC overrides dcs_module_crcs" =
  (* get_universe_crc returns server_crcs, ignoring dcs.dcs_module_crcs *)
  setup ~available:["Foo"]
    ~binary:[("Foo", "binary_crc")]
    ~server:[("Foo", "real_server_crc")];
  let dcs = make_dcs ~crcs:[("Foo", "stale_json_crc")] ["Foo"] in
  print_status (check dcs);
  [%expect {| Crc_mismatch([Foo (universe=real_server_crc binary=binary_crc)]) |}]

let%expect_test "binary CRC missing — no mismatch" =
  setup ~available:["Foo"]
    ~binary:[]
    ~server:[("Foo", "server_crc")];
  let dcs = make_dcs ~crcs:[("Foo", "server_crc")] ["Foo"] in
  print_status (check dcs);
  [%expect {| Preloaded |}]

let%expect_test "multiple modules, one mismatch" =
  setup ~available:["Foo"; "Bar"]
    ~binary:[("Foo", "abc123"); ("Bar", "wrong")]
    ~server:[("Foo", "abc123"); ("Bar", "def456")];
  let dcs = make_dcs ~crcs:[("Foo", "abc123"); ("Bar", "def456")]
    ["Foo"; "Bar"] in
  print_status (check dcs);
  [%expect {| Crc_mismatch([Bar (universe=def456 binary=wrong)]) |}]