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

-export([new_rule/2, new/0, add_rule/3, add_ignore/3, build/2, ok/1, valid_only/1, ignored_only/1, invalid_only/1, next/1, iterator/1, lex/1]).
-export_type([token/0, position/0, rule/0, lexer/0]).

-type token() :: {valid, binary(), binary()} |
    {ignored, binary(), binary()} |
    {invalid, binary()} |
    end_of_file.

-type position() :: {position, integer()}.

-opaque rule() :: {rule, binary(), binary(), gleam@regex:regex()}.

-opaque lexer() :: {lexer, list(rule()), list(rule()), binary(), integer()}.

-spec new_rule(binary(), binary()) -> rule().
new_rule(Name, Pattern) ->
    Options = {options, false, false},
    Pattern@1 = case Pattern of
        <<"^"/utf8, _/binary>> ->
            Pattern;

        _ ->
            <<"^"/utf8, Pattern/binary>>
    end,
    _assert_subject = gleam@regex:compile(Pattern@1, Options),
    {ok, Regex} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"glex"/utf8>>,
                        function => <<"new_rule"/utf8>>,
                        line => 28})
    end,
    {rule, Name, Pattern@1, Regex}.

-spec new() -> lexer().
new() ->
    {lexer, [], [], <<""/utf8>>, 0}.

-spec add_rule(lexer(), binary(), binary()) -> lexer().
add_rule(Lexer, Name, Pattern) ->
    Rule = new_rule(Name, Pattern),
    {lexer,
        gleam@list:concat([erlang:element(2, Lexer), [Rule]]),
        erlang:element(3, Lexer),
        erlang:element(4, Lexer),
        erlang:element(5, Lexer)}.

-spec add_ignore(lexer(), binary(), binary()) -> lexer().
add_ignore(Lexer, Name, Pattern) ->
    Rule = new_rule(Name, Pattern),
    {lexer,
        erlang:element(2, Lexer),
        gleam@list:concat([erlang:element(3, Lexer), [Rule]]),
        erlang:element(4, Lexer),
        erlang:element(5, Lexer)}.

-spec build(lexer(), binary()) -> lexer().
build(Lexer, Source) ->
    {lexer, erlang:element(2, Lexer), erlang:element(3, Lexer), Source, 0}.

-spec ok(list({token(), position()})) -> boolean().
ok(Tokens) ->
    _pipe = Tokens,
    gleam@list:all(_pipe, fun(Token) -> case Token of
                {{invalid, _}, _} ->
                    false;

                _ ->
                    true
            end end).

-spec valid_only(list({token(), position()})) -> list({token(), position()}).
valid_only(Tokens) ->
    _pipe = Tokens,
    gleam@list:filter(_pipe, fun(Token) -> case Token of
                {{valid, _, _}, _} ->
                    true;

                _ ->
                    false
            end end).

-spec ignored_only(list({token(), position()})) -> list({token(), position()}).
ignored_only(Tokens) ->
    _pipe = Tokens,
    gleam@list:filter(_pipe, fun(Token) -> case Token of
                {{ignored, _, _}, _} ->
                    true;

                _ ->
                    false
            end end).

-spec invalid_only(list({token(), position()})) -> list({token(), position()}).
invalid_only(Tokens) ->
    _pipe = Tokens,
    gleam@list:filter(_pipe, fun(Token) -> case Token of
                {{invalid, _}, _} ->
                    true;

                _ ->
                    false
            end end).

-spec advance(lexer(), binary(), integer()) -> lexer().
advance(Lexer, Source, Offset) ->
    {lexer,
        erlang:element(2, Lexer),
        erlang:element(3, Lexer),
        Source,
        erlang:element(5, Lexer) + Offset}.

-spec wrap_token(lexer(), token()) -> {token(), position()}.
wrap_token(Lexer, Token) ->
    {Token, {position, erlang:element(5, Lexer)}}.

-spec byte_size(binary()) -> integer().
byte_size(String) ->
    erlang:byte_size(<<String/binary>>).

-spec lex_rules(list(rule()), binary()) -> {ok, {binary(), binary()}} |
    {error, nil}.
lex_rules(Rules, Source) ->
    _pipe = Rules,
    _pipe@3 = gleam@list:flat_map(
        _pipe,
        fun(Rule) -> _pipe@1 = erlang:element(4, Rule),
            _pipe@2 = gleam@regex:scan(_pipe@1, Source),
            gleam@list:map(
                _pipe@2,
                fun(Match) ->
                    {erlang:element(2, Rule), erlang:element(2, Match)}
                end
            ) end
    ),
    gleam@list:first(_pipe@3).

-spec next(lexer()) -> {lexer(), {token(), position()}}.
next(Lexer) ->
    Ignore = lex_rules(erlang:element(3, Lexer), erlang:element(4, Lexer)),
    case Ignore of
        {ok, {Name, Value}} ->
            Rest = begin
                _pipe = erlang:element(4, Lexer),
                gleam@string:drop_left(_pipe, gleam@string:length(Value))
            end,
            {advance(Lexer, Rest, gleam@string:length(Value)),
                wrap_token(Lexer, {ignored, Name, Value})};

        {error, nil} ->
            Rules = lex_rules(
                erlang:element(2, Lexer),
                erlang:element(4, Lexer)
            ),
            case Rules of
                {ok, {Name@1, Value@1}} ->
                    Rest@1 = begin
                        _pipe@1 = erlang:element(4, Lexer),
                        gleam@string:drop_left(
                            _pipe@1,
                            gleam@string:length(Value@1)
                        )
                    end,
                    {advance(Lexer, Rest@1, gleam@string:length(Value@1)),
                        wrap_token(Lexer, {valid, Name@1, Value@1})};

                {error, nil} ->
                    case gleam@string:pop_grapheme(erlang:element(4, Lexer)) of
                        {error, nil} ->
                            {Lexer,
                                {end_of_file,
                                    {position, erlang:element(5, Lexer)}}};

                        {ok, {Grapheme, Rest@2}} ->
                            {advance(Lexer, Rest@2, byte_size(Grapheme)),
                                wrap_token(Lexer, {invalid, Grapheme})}
                    end
            end
    end.

-spec iterator(lexer()) -> gleam@iterator:iterator({token(), position()}).
iterator(Lexer) ->
    gleam@iterator:unfold(Lexer, fun(Lexer@1) -> case next(Lexer@1) of
                {_, {end_of_file, _}} ->
                    done;

                {Lexer@2, Wraped_token} ->
                    {next, Wraped_token, Lexer@2}
            end end).

-spec lex(lexer()) -> list({token(), position()}).
lex(Lexer) ->
    _pipe = iterator(Lexer),
    gleam@iterator:to_list(_pipe).