-module(handles@internal@tokenizer).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([do_run/3, run/1]).
-export_type([token/0, action/0]).

-type token() :: {constant, integer(), binary()} |
    {property, integer(), list(binary())} |
    {partial, integer(), binary(), list(binary())} |
    {block_start, integer(), handles@internal@block:kind(), list(binary())} |
    {block_end, integer(), handles@internal@block:kind()}.

-type action() :: {add_token, binary(), integer(), token()} |
    {stop, handles@error:tokenizer_error()} |
    done.

-spec split_body(binary()) -> list(binary()).
split_body(Body) ->
    _pipe = Body,
    _pipe@1 = gleam@string:trim(_pipe),
    _pipe@2 = gleam@string:split(_pipe@1, <<" "/utf8>>),
    gleam@list:filter(
        _pipe@2,
        fun(It) ->
            begin
                _pipe@3 = It,
                _pipe@4 = gleam@string:trim(_pipe@3),
                gleam@string:length(_pipe@4)
            end
            > 0
        end
    ).

-spec split_arg(binary()) -> list(binary()).
split_arg(Arg) ->
    case begin
        _pipe = Arg,
        gleam@string:trim(_pipe)
    end of
        <<"."/utf8>> ->
            [];

        Arg@1 ->
            gleam@string:split(Arg@1, <<"."/utf8>>)
    end.

-spec capture_tag_body(binary(), integer()) -> {ok, {binary(), binary()}} |
    {error, handles@error:tokenizer_error()}.
capture_tag_body(Input, Index) ->
    _pipe = Input,
    _pipe@1 = gleam@string:split_once(_pipe, <<"}}"/utf8>>),
    gleam@result:map_error(_pipe@1, fun(_) -> {unbalanced_tag, Index + 2} end).

-spec tokenize(binary(), integer()) -> action().
tokenize(Input, Index) ->
    case Input of
        <<""/utf8>> ->
            done;

        <<"{{>"/utf8, Rest/binary>> ->
            case capture_tag_body(Rest, Index) of
                {error, Err} ->
                    {stop, Err};

                {ok, {Body, Rest@1}} ->
                    case split_body(Body) of
                        [] ->
                            {stop, {missing_partial_id, Index + 2}};

                        [_] ->
                            {stop, {missing_argument, Index + 2}};

                        [Id, Arg] ->
                            {add_token,
                                Rest@1,
                                (Index + 5) + gleam@string:length(Body),
                                {partial, Index + 2, Id, split_arg(Arg)}};

                        _ ->
                            {stop, {unexpected_multiple_arguments, Index + 2}}
                    end
            end;

        <<"{{#"/utf8, Rest@2/binary>> ->
            case capture_tag_body(Rest@2, Index) of
                {error, Err@1} ->
                    {stop, Err@1};

                {ok, {Body@1, Rest@3}} ->
                    case split_body(Body@1) of
                        [] ->
                            {stop, {missing_block_kind, Index + 2}};

                        [_] ->
                            {stop, {missing_argument, Index + 2}};

                        [<<"if"/utf8>>, Arg@1] ->
                            {add_token,
                                Rest@3,
                                (Index + 5) + gleam@string:length(Body@1),
                                {block_start, Index + 2, 'if', split_arg(Arg@1)}};

                        [<<"unless"/utf8>>, Arg@2] ->
                            {add_token,
                                Rest@3,
                                (Index + 5) + gleam@string:length(Body@1),
                                {block_start,
                                    Index + 2,
                                    unless,
                                    split_arg(Arg@2)}};

                        [<<"each"/utf8>>, Arg@3] ->
                            {add_token,
                                Rest@3,
                                (Index + 5) + gleam@string:length(Body@1),
                                {block_start, Index + 2, each, split_arg(Arg@3)}};

                        [_, _] ->
                            {stop, {unexpected_block_kind, Index + 2}};

                        _ ->
                            {stop, {unexpected_multiple_arguments, Index + 2}}
                    end
            end;

        <<"{{/"/utf8, Rest@4/binary>> ->
            case capture_tag_body(Rest@4, Index) of
                {error, Err@2} ->
                    {stop, Err@2};

                {ok, {Body@2, Rest@5}} ->
                    case split_body(Body@2) of
                        [] ->
                            {stop, {missing_block_kind, Index + 2}};

                        [_, _] ->
                            {stop, {unexpected_argument, Index + 2}};

                        [<<"if"/utf8>>] ->
                            {add_token,
                                Rest@5,
                                (Index + 5) + gleam@string:length(Body@2),
                                {block_end, Index + 2, 'if'}};

                        [<<"unless"/utf8>>] ->
                            {add_token,
                                Rest@5,
                                (Index + 5) + gleam@string:length(Body@2),
                                {block_end, Index + 2, unless}};

                        [<<"each"/utf8>>] ->
                            {add_token,
                                Rest@5,
                                (Index + 5) + gleam@string:length(Body@2),
                                {block_end, Index + 2, each}};

                        [_] ->
                            {stop, {unexpected_block_kind, Index + 2}};

                        _ ->
                            {stop, {unexpected_argument, Index + 2}}
                    end
            end;

        <<"{{"/utf8, Rest@6/binary>> ->
            case capture_tag_body(Rest@6, Index) of
                {error, Err@3} ->
                    {stop, Err@3};

                {ok, {Body@3, Rest@7}} ->
                    case split_body(Body@3) of
                        [] ->
                            {stop, {missing_argument, Index + 2}};

                        [Arg@4] ->
                            {add_token,
                                Rest@7,
                                (Index + 4) + gleam@string:length(Body@3),
                                {property, Index + 2, split_arg(Arg@4)}};

                        _ ->
                            {stop, {unexpected_multiple_arguments, Index + 2}}
                    end
            end;

        _ ->
            case begin
                _pipe = Input,
                _pipe@1 = gleam@string:split_once(_pipe, <<"{{"/utf8>>),
                gleam@result:map(
                    _pipe@1,
                    fun(_capture) ->
                        gleam@pair:map_second(
                            _capture,
                            fun(It) -> <<"{{"/utf8, It/binary>> end
                        )
                    end
                )
            end of
                {ok, {Str, Rest@8}} ->
                    {add_token,
                        Rest@8,
                        Index + gleam@string:length(Str),
                        {constant, Index, Str}};

                _ ->
                    {add_token,
                        <<""/utf8>>,
                        Index + gleam@string:length(Input),
                        {constant, Index, Input}}
            end
    end.

-spec do_run(binary(), integer(), list(token())) -> {ok, list(token())} |
    {error, handles@error:tokenizer_error()}.
do_run(Input, Index, Tokens) ->
    case tokenize(Input, Index) of
        done ->
            {ok, lists:reverse(Tokens)};

        {stop, Err} ->
            {error, Err};

        {add_token, Rest, Index@1, Token} ->
            do_run(Rest, Index@1, [Token | Tokens])
    end.

-spec run(binary()) -> {ok, list(token())} |
    {error, handles@error:tokenizer_error()}.
run(Input) ->
    do_run(Input, 0, []).