metamon

-module(metamon@generator@edges).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/metamon/generator/edges.gleam").
-export([strings_ascii/0, ints_in/2, floats_in/2, strings_unicode/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(
    " Default edge values for the built-in generators. These are the\n"
    " \"must-try\" boundary inputs that the runner consumes before falling\n"
    " back to random generation. Curating a good edge set is the single\n"
    " biggest win for property-based testing on real-world code, so each\n"
    " builder here is documented with the rationale.\n"
).

-file("src/metamon/generator/edges.gleam", 50).
?DOC(
    " Edge ASCII strings.\n"
    "\n"
    " Empty, single-space, single-tab, single-newline, common short\n"
    " fragments that frequently break tokenisers and Gleam-identifier\n"
    " generators (keywords, leading digit, plus/minus prefix).\n"
).
-spec strings_ascii() -> list(binary()).
strings_ascii() ->
    [<<""/utf8>>,
        <<" "/utf8>>,
        <<"\t"/utf8>>,
        <<"\n"/utf8>>,
        <<"0"/utf8>>,
        <<"a"/utf8>>,
        <<"A"/utf8>>,
        <<"_"/utf8>>,
        <<"+1"/utf8>>,
        <<"-1"/utf8>>,
        <<"Type"/utf8>>,
        <<"case"/utf8>>,
        <<"fn"/utf8>>,
        <<"OAuth2Token"/utf8>>,
        <<"256sha"/utf8>>,
        <<"ipv4"/utf8>>,
        <<"null"/utf8>>].

-file("src/metamon/generator/edges.gleam", 88).
-spec filter_in_range(list(integer()), integer(), integer()) -> list(integer()).
filter_in_range(Items, Lo, Hi) ->
    case Items of
        [] ->
            [];

        [First | Rest] ->
            case (First >= Lo) andalso (First =< Hi) of
                true ->
                    [First | filter_in_range(Rest, Lo, Hi)];

                false ->
                    filter_in_range(Rest, Lo, Hi)
            end
    end.

-file("src/metamon/generator/edges.gleam", 99).
-spec filter_floats_in_range(list(float()), float(), float()) -> list(float()).
filter_floats_in_range(Items, Lo, Hi) ->
    case Items of
        [] ->
            [];

        [First | Rest] ->
            case (First >= Lo) andalso (First =< Hi) of
                true ->
                    [First | filter_floats_in_range(Rest, Lo, Hi)];

                false ->
                    filter_floats_in_range(Rest, Lo, Hi)
            end
    end.

-file("src/metamon/generator/edges.gleam", 148).
-spec contains(list(integer()), integer()) -> boolean().
contains(Items, Needle) ->
    case Items of
        [] ->
            false;

        [First | Rest] ->
            case First =:= Needle of
                true ->
                    true;

                false ->
                    contains(Rest, Needle)
            end
    end.

-file("src/metamon/generator/edges.gleam", 159).
-spec contains_float(list(float()), float()) -> boolean().
contains_float(Items, Needle) ->
    case Items of
        [] ->
            false;

        [First | Rest] ->
            case First =:= Needle of
                true ->
                    true;

                false ->
                    contains_float(Rest, Needle)
            end
    end.

-file("src/metamon/generator/edges.gleam", 174).
-spec reverse_into(list(ECV), list(ECV)) -> list(ECV).
reverse_into(Items, Acc) ->
    case Items of
        [] ->
            Acc;

        [First | Rest] ->
            reverse_into(Rest, [First | Acc])
    end.

-file("src/metamon/generator/edges.gleam", 170).
-spec reverse(list(ECS)) -> list(ECS).
reverse(Items) ->
    reverse_into(Items, []).

-file("src/metamon/generator/edges.gleam", 118).
-spec dedupe_loop(list(integer()), list(integer()), list(integer())) -> list(integer()).
dedupe_loop(Items, Seen, Acc) ->
    case Items of
        [] ->
            reverse(Acc);

        [First | Rest] ->
            case contains(Seen, First) of
                true ->
                    dedupe_loop(Rest, Seen, Acc);

                false ->
                    dedupe_loop(Rest, [First | Seen], [First | Acc])
            end
    end.

-file("src/metamon/generator/edges.gleam", 114).
-spec dedupe(list(integer())) -> list(integer()).
dedupe(Items) ->
    dedupe_loop(Items, [], []).

-file("src/metamon/generator/edges.gleam", 12).
?DOC(
    " Edge ints in the closed interval `[lo, hi]`.\n"
    "\n"
    " Always-tried candidates: `0`, `1`, `-1`, `lo`, `hi`. We also include\n"
    " \"common bug magnets\" (`Int.max`, `Int.min`, neighbouring values\n"
    " around 0) when they fall inside the range.\n"
).
-spec ints_in(integer(), integer()) -> list(integer()).
ints_in(Lo, Hi) ->
    Candidates = [0,
        1,
        -1,
        Lo,
        Hi,
        Lo + 1,
        Hi - 1,
        9007199254740991,
        -9007199254740991],
    _pipe = Candidates,
    _pipe@1 = filter_in_range(_pipe, Lo, Hi),
    dedupe(_pipe@1).

-file("src/metamon/generator/edges.gleam", 133).
-spec dedupe_floats_loop(list(float()), list(float()), list(float())) -> list(float()).
dedupe_floats_loop(Items, Seen, Acc) ->
    case Items of
        [] ->
            reverse(Acc);

        [First | Rest] ->
            case contains_float(Seen, First) of
                true ->
                    dedupe_floats_loop(Rest, Seen, Acc);

                false ->
                    dedupe_floats_loop(Rest, [First | Seen], [First | Acc])
            end
    end.

-file("src/metamon/generator/edges.gleam", 129).
-spec dedupe_floats(list(float())) -> list(float()).
dedupe_floats(Items) ->
    dedupe_floats_loop(Items, [], []).

-file("src/metamon/generator/edges.gleam", 38).
?DOC(
    " Edge floats in `[lo, hi]`.\n"
    "\n"
    " Includes `lo`, `hi`, `0.0`, plus IEEE-754 bug magnets where\n"
    " representable: smallest positive subnormal-ish constants are not\n"
    " emitted to keep behaviour identical across BEAM and JS targets.\n"
).
-spec floats_in(float(), float()) -> list(float()).
floats_in(Lo, Hi) ->
    Candidates = [Lo, Hi, +0.0, 1.0, -1.0],
    _pipe = Candidates,
    _pipe@1 = filter_floats_in_range(_pipe, Lo, Hi),
    dedupe_floats(_pipe@1).

-file("src/metamon/generator/edges.gleam", 181).
-spec list_append(list(ECZ), list(ECZ)) -> list(ECZ).
list_append(Left, Right) ->
    case Left of
        [] ->
            Right;

        [First | Rest] ->
            [First | list_append(Rest, Right)]
    end.

-file("src/metamon/generator/edges.gleam", 77).
?DOC(
    " Edge Unicode-aware strings.\n"
    "\n"
    " Adds RTL/BiDi, an emoji, and U+0000 (NUL) which routinely breaks\n"
    " C-FFI bridges. Surrogate halves are intentionally not emitted —\n"
    " they are not valid Gleam strings.\n"
).
-spec strings_unicode() -> list(binary()).
strings_unicode() ->
    Extras = [<<"\x{0000}"/utf8>>,
        <<"\x{200E}helloworld"/utf8>>,
        <<"héllo"/utf8>>,
        <<"𝕏 unicode"/utf8>>,
        <<"🦊"/utf8>>],
    list_append(strings_ascii(), Extras).