multipartkit

-module(multipartkit@internal@scan).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/multipartkit/internal/scan.gleam").
-export([dash_pattern/1, find_delimiter/3]).
-export_type([delim_kind/0, scan_outcome/0, after_class/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(false).

-type delim_kind() :: delimiter | closing.

-type scan_outcome() :: {found, integer(), delim_kind(), integer()} | incomplete.

-type after_class() :: {class_delimiter, integer()} |
    {class_closing, integer()} |
    class_invalid |
    class_incomplete.

-file("src/multipartkit/internal/scan.gleam", 32).
?DOC(false).
-spec dash_pattern(binary()) -> bitstring().
dash_pattern(Boundary) ->
    gleam@bit_array:append(<<"--"/utf8>>, gleam_stdlib:identity(Boundary)).

-file("src/multipartkit/internal/scan.gleam", 72).
?DOC(false).
-spec is_at_line_start(bitstring(), integer()) -> boolean().
is_at_line_start(Buf, P) ->
    case P of
        0 ->
            true;

        _ ->
            case gleam_stdlib:bit_array_slice(Buf, P - 1, 1) of
                {ok, <<10>>} ->
                    true;

                _ ->
                    false
            end
    end.

-file("src/multipartkit/internal/scan.gleam", 83).
?DOC(false).
-spec body_end_for(bitstring(), integer()) -> integer().
body_end_for(Buf, P) ->
    case P of
        0 ->
            0;

        _ ->
            case (P >= 2) andalso (gleam_stdlib:bit_array_slice(Buf, P - 2, 2)
            =:= {ok, <<"\r\n"/utf8>>}) of
                true ->
                    P - 2;

                false ->
                    case gleam_stdlib:bit_array_slice(Buf, P - 1, 1) of
                        {ok, <<10>>} ->
                            P - 1;

                        _ ->
                            P
                    end
            end
    end.

-file("src/multipartkit/internal/scan.gleam", 130).
?DOC(false).
-spec consume_closing_tail(bitstring(), integer(), integer()) -> integer().
consume_closing_tail(Buf, At, Total) ->
    case At >= Total of
        true ->
            At;

        false ->
            case gleam_stdlib:bit_array_slice(Buf, At, 2) of
                {ok, <<"\r\n"/utf8>>} ->
                    At + 2;

                _ ->
                    case gleam_stdlib:bit_array_slice(Buf, At, 1) of
                        {ok, <<10>>} ->
                            At + 1;

                        _ ->
                            At
                    end
            end
    end.

-file("src/multipartkit/internal/scan.gleam", 106).
?DOC(false).
-spec classify_after(bitstring(), integer(), integer()) -> after_class().
classify_after(Buf, At, Total) ->
    case At >= Total of
        true ->
            class_incomplete;

        false ->
            case gleam_stdlib:bit_array_slice(Buf, At, 2) of
                {ok, <<"--"/utf8>>} ->
                    {class_closing, consume_closing_tail(Buf, At + 2, Total)};

                {ok, <<"\r\n"/utf8>>} ->
                    {class_delimiter, At + 2};

                {ok, <<10, _>>} ->
                    {class_delimiter, At + 1};

                _ ->
                    case gleam_stdlib:bit_array_slice(Buf, At, 1) of
                        {ok, <<10>>} ->
                            {class_delimiter, At + 1};

                        {ok, _} ->
                            case (At + 2) > Total of
                                true ->
                                    class_incomplete;

                                false ->
                                    class_invalid
                            end;

                        {error, nil} ->
                            class_incomplete
                    end
            end
    end.

-file("src/multipartkit/internal/scan.gleam", 47).
?DOC(false).
-spec scan_loop(bitstring(), bitstring(), integer(), integer()) -> scan_outcome().
scan_loop(Buf, Pattern, From, Total) ->
    case multipartkit@internal@bytes:find_index(Buf, Pattern, From) of
        {error, nil} ->
            incomplete;

        {ok, P} ->
            case is_at_line_start(Buf, P) of
                false ->
                    scan_loop(Buf, Pattern, P + 1, Total);

                true ->
                    Body_end_excl = body_end_for(Buf, P),
                    After_pattern = P + erlang:byte_size(Pattern),
                    case classify_after(Buf, After_pattern, Total) of
                        {class_delimiter, After} ->
                            {found, Body_end_excl, delimiter, After};

                        {class_closing, After@1} ->
                            {found, Body_end_excl, closing, After@1};

                        class_invalid ->
                            scan_loop(Buf, Pattern, P + 1, Total);

                        class_incomplete ->
                            incomplete
                    end
            end
    end.

-file("src/multipartkit/internal/scan.gleam", 38).
?DOC(false).
-spec find_delimiter(bitstring(), bitstring(), integer()) -> scan_outcome().
find_delimiter(Buf, Pattern, From) ->
    Total = erlang:byte_size(Buf),
    scan_loop(Buf, Pattern, From, Total).