multipartkit

-module(multipartkit@form).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/multipartkit/form.gleam").
-export([new/0, parts/1, unsafe_add_part/2, add_field/3, add_file/5, add_file_auto_with/5, add_file_auto/4]).
-export_type([form/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.

-opaque form() :: {form, list(multipartkit@part:part())}.

-file("src/multipartkit/form.gleam", 21).
?DOC(" A new empty form.\n").
-spec new() -> form().
new() ->
    {form, []}.

-file("src/multipartkit/form.gleam", 121).
?DOC(" Read the parts in insertion order.\n").
-spec parts(form()) -> list(multipartkit@part:part()).
parts(Form) ->
    lists:reverse(erlang:element(2, Form)).

-file("src/multipartkit/form.gleam", 125).
-spec push(form(), multipartkit@part:part()) -> form().
push(Form, The_part) ->
    {form, [The_part | erlang:element(2, Form)]}.

-file("src/multipartkit/form.gleam", 116).
?DOC(
    " Append a pre-built `Part` without validation or normalisation.\n"
    "\n"
    " The caller is responsible for keeping `headers`, `name`, `filename`, and\n"
    " `content_type` mutually consistent. Prefer `add_field` / `add_file` /\n"
    " `add_file_auto` for library-maintained consistency.\n"
).
-spec unsafe_add_part(form(), multipartkit@part:part()) -> form().
unsafe_add_part(Form, The_part) ->
    push(Form, The_part).

-file("src/multipartkit/form.gleam", 192).
-spec is_ascii_safe_loop(bitstring()) -> boolean().
is_ascii_safe_loop(Bytes) ->
    case Bytes of
        <<>> ->
            true;

        <<B, Rest/binary>> ->
            case (B =:= 16#09) orelse ((B >= 16#20) andalso (B =< 16#7E)) of
                true ->
                    is_ascii_safe_loop(Rest);

                false ->
                    false
            end;

        _ ->
            false
    end.

-file("src/multipartkit/form.gleam", 188).
?DOC(
    " True iff every code point in `s` is printable US-ASCII (0x20-0x7E)\n"
    " or HTAB. Matches the subset of bytes RFC 7230 §3.2.4 admits as\n"
    " header field values.\n"
).
-spec is_ascii_safe(binary()) -> boolean().
is_ascii_safe(S) ->
    is_ascii_safe_loop(gleam_stdlib:identity(S)).

-file("src/multipartkit/form.gleam", 211).
-spec ascii_fallback_loop(list(binary()), binary()) -> binary().
ascii_fallback_loop(Remaining, Acc) ->
    case Remaining of
        [] ->
            Acc;

        [Grapheme | Rest] ->
            case is_ascii_safe(Grapheme) of
                true ->
                    ascii_fallback_loop(Rest, <<Acc/binary, Grapheme/binary>>);

                false ->
                    ascii_fallback_loop(Rest, <<Acc/binary, "_"/utf8>>)
            end
    end.

-file("src/multipartkit/form.gleam", 207).
?DOC(
    " Replace every non-ASCII-safe code point in `s` with `_` so the\n"
    " result is safe for use inside a legacy `filename=\"...\"`. Used as\n"
    " the pre-RFC-5987 fallback alongside `filename*=`.\n"
).
-spec ascii_fallback(binary()) -> binary().
ascii_fallback(S) ->
    ascii_fallback_loop(gleam@string:to_graphemes(S), <<""/utf8>>).

-file("src/multipartkit/form.gleam", 253).
-spec is_attr_char(integer()) -> boolean().
is_attr_char(B) ->
    (((((((((((((((B >= 16#41) andalso (B =< 16#5A)) orelse ((B >= 16#61)
    andalso (B =< 16#7A)))
    orelse ((B >= 16#30) andalso (B =< 16#39)))
    orelse (B =:= 16#21))
    orelse (B =:= 16#23))
    orelse (B =:= 16#24))
    orelse (B =:= 16#26))
    orelse (B =:= 16#2B))
    orelse (B =:= 16#2D))
    orelse (B =:= 16#2E))
    orelse (B =:= 16#5E))
    orelse (B =:= 16#5F))
    orelse (B =:= 16#60))
    orelse (B =:= 16#7C))
    orelse (B =:= 16#7E).

-file("src/multipartkit/form.gleam", 277).
-spec hex_digit(integer()) -> binary().
hex_digit(N) ->
    case N of
        0 ->
            <<"0"/utf8>>;

        1 ->
            <<"1"/utf8>>;

        2 ->
            <<"2"/utf8>>;

        3 ->
            <<"3"/utf8>>;

        4 ->
            <<"4"/utf8>>;

        5 ->
            <<"5"/utf8>>;

        6 ->
            <<"6"/utf8>>;

        7 ->
            <<"7"/utf8>>;

        8 ->
            <<"8"/utf8>>;

        9 ->
            <<"9"/utf8>>;

        10 ->
            <<"A"/utf8>>;

        11 ->
            <<"B"/utf8>>;

        12 ->
            <<"C"/utf8>>;

        13 ->
            <<"D"/utf8>>;

        14 ->
            <<"E"/utf8>>;

        15 ->
            <<"F"/utf8>>;

        _ ->
            erlang:integer_to_binary(N)
    end.

-file("src/multipartkit/form.gleam", 273).
-spec percent_byte(integer()) -> binary().
percent_byte(B) ->
    <<<<"%"/utf8, (hex_digit(B div 16))/binary>>/binary,
        (hex_digit(B rem 16))/binary>>.

-file("src/multipartkit/form.gleam", 231).
-spec percent_encode_loop(bitstring(), binary()) -> binary().
percent_encode_loop(Bytes, Acc) ->
    case Bytes of
        <<>> ->
            Acc;

        <<B, Rest/binary>> ->
            Chunk = case is_attr_char(B) of
                false ->
                    percent_byte(B);

                true ->
                    _pipe = gleam@bit_array:to_string(<<B>>),
                    gleam@result:unwrap(_pipe, percent_byte(B))
            end,
            percent_encode_loop(Rest, <<Acc/binary, Chunk/binary>>);

        _ ->
            Acc
    end.

-file("src/multipartkit/form.gleam", 227).
?DOC(
    " Percent-encode the UTF-8 byte representation of `s` per RFC 5987\n"
    " §3.2.1 attr-char. Bytes that match the attr-char production\n"
    " (`ALPHA / DIGIT / \"!\" / \"#\" / \"$\" / \"&\" / \"+\" / \"-\" / \".\" / \"^\" /\n"
    " \"_\" / \"`\" / \"|\" / \"~\"`) pass through unencoded; every other byte\n"
    " is emitted as `%HH` with uppercase hex digits.\n"
).
-spec percent_encode_rfc5987(binary()) -> binary().
percent_encode_rfc5987(S) ->
    percent_encode_loop(gleam_stdlib:identity(S), <<""/utf8>>).

-file("src/multipartkit/form.gleam", 302).
?DOC(
    " Strip CR, LF, and NUL from `value`. Used to neutralise header injection\n"
    " in any value that ends up on a header line — `name`, `filename`, and\n"
    " `content_type`.\n"
).
-spec sanitize_value(binary()) -> binary().
sanitize_value(Value) ->
    _pipe = Value,
    _pipe@1 = gleam@string:replace(_pipe, <<"\r\n"/utf8>>, <<""/utf8>>),
    _pipe@2 = gleam@string:replace(_pipe@1, <<"\r"/utf8>>, <<""/utf8>>),
    _pipe@3 = gleam@string:replace(_pipe@2, <<"\n"/utf8>>, <<""/utf8>>),
    gleam@string:replace(_pipe@3, <<"\x{0000}"/utf8>>, <<""/utf8>>).

-file("src/multipartkit/form.gleam", 314).
-spec escape_quoted(binary(), binary()) -> binary().
escape_quoted(Remaining, Acc) ->
    case gleam_stdlib:string_pop_grapheme(Remaining) of
        {error, nil} ->
            Acc;

        {ok, {<<"\\"/utf8>>, Rest}} ->
            escape_quoted(Rest, <<Acc/binary, "\\\\"/utf8>>);

        {ok, {<<"\""/utf8>>, Rest@1}} ->
            escape_quoted(Rest@1, <<Acc/binary, "\\\""/utf8>>);

        {ok, {Other, Rest@2}} ->
            escape_quoted(Rest@2, <<Acc/binary, Other/binary>>)
    end.

-file("src/multipartkit/form.gleam", 310).
-spec quote(binary()) -> binary().
quote(Value) ->
    <<<<"\""/utf8, (escape_quoted(Value, <<""/utf8>>))/binary>>/binary,
        "\""/utf8>>.

-file("src/multipartkit/form.gleam", 33).
?DOC(
    " Append a text field. `value` is encoded as UTF-8 in the part body. No\n"
    " filename is set.\n"
    "\n"
    " Carriage returns, line feeds, and NUL bytes in `name` are silently\n"
    " stripped to prevent header injection. The cached `name` on the resulting\n"
    " `Part` reflects the sanitized value, matching what a parse-after-encode\n"
    " round-trip would produce. Use `unsafe_add_part` if byte-exact\n"
    " preservation is required.\n"
).
-spec add_field(form(), binary(), binary()) -> form().
add_field(Form, Name, Value) ->
    Safe_name = sanitize_value(Name),
    Disposition = {<<"Content-Disposition"/utf8>>,
        <<"form-data; name="/utf8, (quote(Safe_name))/binary>>},
    New_part = multipartkit@part:unchecked_new(
        [Disposition],
        {some, Safe_name},
        none,
        none,
        <<Value/binary>>
    ),
    push(Form, New_part).

-file("src/multipartkit/form.gleam", 174).
?DOC(
    " Build the `; filename=...` portion of a Content-Disposition header\n"
    " for a file part.\n"
    "\n"
    " For ASCII-safe filenames (every code point is printable US-ASCII\n"
    " per RFC 7230 §3.2.4) the legacy `filename=\"...\"` form is sufficient\n"
    " and is emitted unchanged.\n"
    "\n"
    " For filenames that contain bytes outside that range, the legacy\n"
    " form would produce a header value that violates RFC 7230 §3.2.4 and\n"
    " is mangled or rejected by strict HTTP intermediaries. We emit BOTH:\n"
    "\n"
    " - `filename=\"<ascii-fallback>\"` — non-ASCII code points replaced\n"
    "   with `_`. Lets pre-RFC-5987 clients still see a sensible name.\n"
    " - `filename*=UTF-8''<percent-encoded>` — RFC 5987 §3.2.1 / RFC 6266\n"
    "   §4.3 form, faithful round-trip for spec-aware parsers.\n"
    "\n"
    " RFC 5987 §3.2.2: when both forms are present, the `*=` form takes\n"
    " precedence — multipartkit's own `content_disposition.parse` already\n"
    " honours that ordering, as do all browsers and the major HTTP\n"
    " servers.\n"
).
-spec filename_disposition_params(binary()) -> binary().
filename_disposition_params(Filename) ->
    case is_ascii_safe(Filename) of
        true ->
            <<"; filename="/utf8, (quote(Filename))/binary>>;

        false ->
            <<<<<<"; filename="/utf8, (quote(ascii_fallback(Filename)))/binary>>/binary,
                    "; filename*=UTF-8''"/utf8>>/binary,
                (percent_encode_rfc5987(Filename))/binary>>
    end.

-file("src/multipartkit/form.gleam", 129).
-spec build_file_part(binary(), binary(), binary(), bitstring()) -> multipartkit@part:part().
build_file_part(Name, Filename, Content_type, Body) ->
    Safe_name = sanitize_value(Name),
    Safe_filename = sanitize_value(Filename),
    Safe_content_type = sanitize_value(Content_type),
    Disposition_header = {<<"Content-Disposition"/utf8>>,
        <<<<"form-data; name="/utf8, (quote(Safe_name))/binary>>/binary,
            (filename_disposition_params(Safe_filename))/binary>>},
    Content_type_header = {<<"Content-Type"/utf8>>, Safe_content_type},
    multipartkit@part:unchecked_new(
        [Disposition_header, Content_type_header],
        {some, Safe_name},
        {some, Safe_filename},
        {some, Safe_content_type},
        Body
    ).

-file("src/multipartkit/form.gleam", 57).
?DOC(
    " Append a file part with an explicit content type.\n"
    "\n"
    " Carriage returns, line feeds, and NUL bytes in `name`, `filename`, and\n"
    " `content_type` are silently stripped to prevent header injection. The\n"
    " cached `name`, `filename`, and `content_type` on the resulting `Part`\n"
    " reflect the sanitized values. Use `unsafe_add_part` if byte-exact\n"
    " preservation is required.\n"
).
-spec add_file(form(), binary(), binary(), binary(), bitstring()) -> form().
add_file(Form, Name, Filename, Content_type, Body) ->
    push(Form, build_file_part(Name, Filename, Content_type, Body)).

-file("src/multipartkit/form.gleam", 93).
?DOC(
    " Append a file part, inferring the content type via the supplied\n"
    " `Inferer`.\n"
    "\n"
    " Inference precedence:\n"
    "\n"
    " 1. `inferer.from_filename(filename)`\n"
    " 2. `inferer.from_bytes(body)`\n"
    " 3. `application/octet-stream`\n"
    "\n"
    " The inferred content type is sanitized (CR / LF / NUL stripped) before\n"
    " being written to the header.\n"
).
-spec add_file_auto_with(
    form(),
    binary(),
    binary(),
    bitstring(),
    multipartkit@infer:inferer()
) -> form().
add_file_auto_with(Form, Name, Filename, Body, Inferer) ->
    Content_type = case (erlang:element(2, Inferer))(Filename) of
        {some, Value} ->
            Value;

        none ->
            case (erlang:element(3, Inferer))(Body) of
                {some, Value@1} ->
                    Value@1;

                none ->
                    <<"application/octet-stream"/utf8>>
            end
    end,
    add_file(Form, Name, Filename, Content_type, Body).

-file("src/multipartkit/form.gleam", 73).
?DOC(
    " Append a file part using the default (no-op) inferer.\n"
    "\n"
    " Equivalent to `add_file_auto_with(form, name, filename, body,\n"
    " infer.default_inferer())`. The default inferer returns `None` from both\n"
    " helpers in v0.1.0, so this falls through to `application/octet-stream`\n"
    " unless you call `add_file_auto_with` with a real inferer.\n"
).
-spec add_file_auto(form(), binary(), binary(), bitstring()) -> form().
add_file_auto(Form, Name, Filename, Body) ->
    add_file_auto_with(
        Form,
        Name,
        Filename,
        Body,
        multipartkit@infer:default_inferer()
    ).