-module(glemtext).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([parse/1]).
-export_type([gem_element/0]).

-type gem_element() :: {text, binary()} |
    {link, binary(), gleam@option:option(binary())} |
    {heading, integer(), binary()} |
    {list_item, binary()} |
    {blockquote, binary()} |
    {preformatted, gleam@option:option(binary()), binary()}.

-spec until_nl(binary()) -> boolean().
until_nl(C) ->
    C /= <<"\n"/utf8>>.

-spec get_line(list(binary())) -> {list(binary()), list(binary())}.
get_line(In) ->
    Line = begin
        _pipe = In,
        gleam@list:take_while(_pipe, fun until_nl/1)
    end,
    Rest = begin
        _pipe@1 = In,
        _pipe@2 = gleam@list:drop_while(_pipe@1, fun until_nl/1),
        gleam@list:drop(_pipe@2, 1)
    end,
    {Line, Rest}.

-spec parse_text(list(binary())) -> {gem_element(), list(binary())}.
parse_text(In) ->
    {Line, Rest} = get_line(In),
    Line@1 = gleam@string:join(Line, <<""/utf8>>),
    {{text, Line@1}, Rest}.

-spec take_preformatted_lines(list(binary())) -> {list(binary()),
    list(binary())}.
take_preformatted_lines(In) ->
    {Line, Rest} = get_line(In),
    case Line of
        [<<"`"/utf8>>, <<"`"/utf8>>, <<"`"/utf8>> | Rest@1] ->
            {_, Rest@2} = get_line(Rest@1),
            {[], Rest@2};

        [] ->
            {[], []};

        _ ->
            {Next, In@1} = take_preformatted_lines(Rest),
            Line@1 = begin
                _pipe = Line,
                gleam@string:join(_pipe, <<""/utf8>>)
            end,
            {[Line@1 | Next], In@1}
    end.

-spec drop_lines(list(binary())) -> list(binary()).
drop_lines(In) ->
    case In of
        [<<"\n"/utf8>> | Rest] ->
            drop_lines(Rest);

        _ ->
            In
    end.

-spec drop_ws(list(binary())) -> list(binary()).
drop_ws(In) ->
    case In of
        [<<" "/utf8>> | Rest] ->
            drop_ws(Rest);

        [<<"\t"/utf8>> | Rest@1] ->
            drop_ws(Rest@1);

        _ ->
            In
    end.

-spec parse_blockquote(list(binary())) -> {gem_element(), list(binary())}.
parse_blockquote(In) ->
    {Line, Rest} = get_line(In),
    Line@1 = begin
        _pipe = Line,
        _pipe@1 = drop_ws(_pipe),
        gleam@string:join(_pipe@1, <<""/utf8>>)
    end,
    {{blockquote, Line@1}, Rest}.

-spec parse_preformatted(list(binary())) -> {gem_element(), list(binary())}.
parse_preformatted(In) ->
    {Line, Rest} = get_line(In),
    Alt = begin
        _pipe = Line,
        _pipe@1 = drop_ws(_pipe),
        gleam@string:join(_pipe@1, <<""/utf8>>)
    end,
    Alt@1 = case Alt of
        <<""/utf8>> ->
            none;

        _ ->
            {some, Alt}
    end,
    {Pre_lines, In@1} = take_preformatted_lines(Rest),
    Pre_lines@1 = begin
        _pipe@2 = Pre_lines,
        gleam@string:join(_pipe@2, <<"\n"/utf8>>)
    end,
    {{preformatted, Alt@1, Pre_lines@1}, In@1}.

-spec parse_heading(integer(), list(binary())) -> {gem_element(),
    list(binary())}.
parse_heading(Level, In) ->
    {Line, Rest} = get_line(In),
    Line@1 = begin
        _pipe = Line,
        _pipe@1 = drop_ws(_pipe),
        gleam@string:join(_pipe@1, <<""/utf8>>)
    end,
    {{heading, Level, Line@1}, Rest}.

-spec parse_link(list(binary())) -> {gem_element(), list(binary())}.
parse_link(In) ->
    {Line, Rest} = get_line(In),
    {Url, Linerest} = begin
        _pipe = Line,
        _pipe@1 = drop_ws(_pipe),
        gleam@list:split_while(
            _pipe@1,
            fun(C) ->
                not ((C =:= <<" "/utf8>>) orelse (C =:= <<"\t"/utf8>>))
            end
        )
    end,
    Url@1 = gleam@string:join(Url, <<""/utf8>>),
    Label = begin
        _pipe@2 = Linerest,
        _pipe@3 = drop_ws(_pipe@2),
        gleam@string:join(_pipe@3, <<""/utf8>>)
    end,
    Label@1 = case Label of
        <<""/utf8>> ->
            none;

        _ ->
            {some, Label}
    end,
    {{link, Url@1, Label@1}, Rest}.

-spec parse_list(list(binary())) -> {gem_element(), list(binary())}.
parse_list(In) ->
    {Line, Rest} = get_line(In),
    Line@1 = begin
        _pipe = Line,
        _pipe@1 = drop_ws(_pipe),
        gleam@string:join(_pipe@1, <<""/utf8>>)
    end,
    {{list_item, Line@1}, Rest}.

-spec parse_document(list(binary()), list(gem_element())) -> list(gem_element()).
parse_document(In, Ast) ->
    case In of
        [<<"="/utf8>>, <<">"/utf8>> | Rest] ->
            {Link, In@1} = parse_link(Rest),
            parse_document(In@1, [Link | Ast]);

        [<<"*"/utf8>>, <<" "/utf8>> | Rest@1] ->
            {Item, In@2} = parse_list(Rest@1),
            parse_document(In@2, [Item | Ast]);

        [<<">"/utf8>> | Rest@2] ->
            {Quote, In@3} = parse_blockquote(Rest@2),
            parse_document(In@3, [Quote | Ast]);

        [<<"#"/utf8>>, <<" "/utf8>> | Rest@3] ->
            {Heading, In@4} = parse_heading(1, Rest@3),
            parse_document(In@4, [Heading | Ast]);

        [<<"#"/utf8>>, <<"#"/utf8>>, <<" "/utf8>> | Rest@4] ->
            {Heading@1, In@5} = parse_heading(2, Rest@4),
            parse_document(In@5, [Heading@1 | Ast]);

        [<<"#"/utf8>>, <<"#"/utf8>>, <<"#"/utf8>>, <<" "/utf8>> | Rest@5] ->
            {Heading@2, In@6} = parse_heading(3, Rest@5),
            parse_document(In@6, [Heading@2 | Ast]);

        [<<"`"/utf8>>, <<"`"/utf8>>, <<"`"/utf8>> | Rest@6] ->
            {Preformatted, In@7} = parse_preformatted(Rest@6),
            parse_document(In@7, [Preformatted | Ast]);

        [] ->
            Ast;

        _ ->
            {Text, In@8} = parse_text(In),
            parse_document(In@8, [Text | Ast])
    end.

-spec parse(binary()) -> list(gem_element()).
parse(Text) ->
    _pipe = Text,
    _pipe@1 = gleam@string:replace(_pipe, <<"\r\n"/utf8>>, <<"\n"/utf8>>),
    _pipe@2 = gleam@string:to_graphemes(_pipe@1),
    _pipe@3 = parse_document(_pipe@2, []),
    gleam@list:reverse(_pipe@3).