-module(commonmark@internal@parser@helpers).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([ol_marker/1, ul_marker/1, trim_indent/2, determine_indent/1, indent_pattern/1]).

-spec ol_marker(binary()) -> commonmark@ast:ordered_list_marker().
ol_marker(Marker) ->
    case Marker of
        <<"."/utf8>> ->
            period_list_marker;

        <<")"/utf8>> ->
            bracket_list_marker;

        _ ->
            erlang:error(#{gleam_error => panic,
                    message => (<<"Invalid ordered list marker: "/utf8,
                        Marker/binary>>),
                    module => <<"commonmark/internal/parser/helpers"/utf8>>,
                    function => <<"ol_marker"/utf8>>,
                    line => 12})
    end.

-spec ul_marker(binary()) -> commonmark@ast:unordered_list_marker().
ul_marker(Marker) ->
    case Marker of
        <<"*"/utf8>> ->
            asterisk_list_marker;

        <<"-"/utf8>> ->
            dash_list_marker;

        <<"+"/utf8>> ->
            plus_list_marker;

        _ ->
            erlang:error(#{gleam_error => panic,
                    message => (<<"Invalid unordered list marker: "/utf8,
                        Marker/binary>>),
                    module => <<"commonmark/internal/parser/helpers"/utf8>>,
                    function => <<"ul_marker"/utf8>>,
                    line => 21})
    end.

-spec do_trim_indent(binary(), integer(), integer()) -> binary().
do_trim_indent(Line, N, Removed) ->
    Remaining = N - Removed,
    Next_tab_stop = 4 - (Removed rem 4),
    case Line of
        _ when Remaining =< 0 ->
            Line;

        <<"\t"/utf8, Rest/binary>> when Remaining < Next_tab_stop ->
            <<(gleam@string:repeat(<<" "/utf8>>, Next_tab_stop - Remaining))/binary,
                Rest/binary>>;

        <<" "/utf8, Rest@1/binary>> ->
            do_trim_indent(Rest@1, N, Removed + 1);

        <<"\t"/utf8, Rest@2/binary>> ->
            do_trim_indent(Rest@2, N, Removed + Next_tab_stop);

        _ ->
            Line
    end.

-spec trim_indent(binary(), integer()) -> binary().
trim_indent(Line, N) ->
    do_trim_indent(Line, N, 0).

-spec determine_indent(gleam@option:option(binary())) -> integer().
determine_indent(Indent) ->
    case Indent of
        none ->
            0;

        {some, S} ->
            gleam@string:length(S)
    end.

-spec indent_pattern(integer()) -> binary().
indent_pattern(Indent) ->
    case Indent of
        0 ->
            <<""/utf8>>;

        I when I >= 4 ->
            <<"(?: {0,3}\t|    )"/utf8, (indent_pattern(I - 4))/binary>>;

        I@1 ->
            <<<<"(?: {"/utf8, (gleam@int:to_string(I@1))/binary>>/binary,
                "}|\t)"/utf8>>
    end.