-module(gleam__stdlib).
-include_lib("eunit/include/eunit.hrl").

-export([expect_equal/2, expect_not_equal/2, expect_true/1, expect_false/1,
         expect_is_ok/1, expect_is_error/1, atom_from_string/1,
         atom_create_from_string/1, atom_to_string/1, map_fetch/2,
         iodata_append/2, iodata_prepend/2, identity/1, decode_int/1,
         decode_string/1, decode_bool/1, decode_float/1, decode_thunk/1,
         decode_tuple/1, decode_list/1, decode_field/2]).

expect_equal(A, Expected) -> ?assertEqual(Expected, A).
expect_not_equal(A, Expected) -> ?assertNotEqual(Expected, A).
expect_true(A) -> ?assert(A).
expect_false(A) -> ?assertNot(A).
expect_is_ok(A) -> ?assertMatch({ok, _}, A).
expect_is_error(A) -> ?assertMatch({error, _}, A).

map_fetch(Map, Key) ->
  case maps:find(Key, Map) of
    error -> {error, not_found};
    OkFound -> OkFound
  end.

atom_create_from_string(S) ->
  binary_to_atom(S, utf8).

atom_to_string(S) ->
  atom_to_binary(S, utf8).

atom_from_string(S) ->
  try {ok, binary_to_existing_atom(S, utf8)} catch
    error:badarg -> {error, atom_not_loaded}
  end.

iodata_append(Iodata, String) -> [Iodata, String].
iodata_prepend(Iodata, String) -> [String, Iodata].

identity(X) -> X.

decode_error_msg(Type, Data) ->
  {error, iolist_to_binary(io_lib:format("Expected ~s, got `~p`", [Type, Data]))}.

decode_string(Data) when is_binary(Data) -> {ok, Data};
decode_string(Data) -> decode_error_msg("a String", Data).

decode_int(Data) when is_integer(Data) -> {ok, Data};
decode_int(Data) -> decode_error_msg("an Int", Data).

decode_float(Data) when is_float(Data) -> {ok, Data};
decode_float(Data) -> decode_error_msg("a Float", Data).

decode_bool(Data) when is_boolean(Data) -> {ok, Data};
decode_bool(Data) -> decode_error_msg("a Bool", Data).

decode_thunk(Data) when is_function(Data, 0) -> {ok, Data};
decode_thunk(Data) -> decode_error_msg("a zero arity function", Data).

decode_tuple(Data = {_, _}) -> {ok, Data};
decode_tuple(Data) -> decode_error_msg("a 2 element tuple", Data).

decode_list(Data) when is_list(Data) -> {ok, Data};
decode_list(Data) -> decode_error_msg("a List", Data).

decode_field(Data, Key) ->
  case Data of
    #{Key := Value} ->
      {ok, Value};

    _ ->
      decode_error_msg(io_lib:format("a map with key `~p`", [Key]), Data)
  end.