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

-export([format_syntax_error/2, format_lex_error/2]).
-export_type([position/0]).

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

-spec resolve_position(binary(), integer(), position()) -> position().
resolve_position(Input, Target_index, Current) ->
    case Current of
        {position, Index, Row, Col} when Index =:= Target_index ->
            {position, Target_index, Row, Col};

        {position, Index@1, Row@1, Col@1} ->
            case gleam@string:first(Input) of
                {ok, Char} ->
                    case Char of
                        <<"\n"/utf8>> ->
                            resolve_position(
                                gleam@string:drop_left(Input, 1),
                                Target_index,
                                {position, Index@1 + 1, Row@1 + 1, 0}
                            );

                        _ ->
                            resolve_position(
                                gleam@string:drop_left(Input, 1),
                                Target_index,
                                {position, Index@1 + 1, Row@1, Col@1 + 1}
                            )
                    end;

                {error, _} ->
                    out_of_bounds
            end;

        out_of_bounds ->
            out_of_bounds
    end.

-spec format_syntax_error(handles@lexer:syntax_error(), binary()) -> binary().
format_syntax_error(Error, Template) ->
    case Error of
        {missing_body, Start, _} ->
            case resolve_position(Template, Start, {position, 0, 0, 0}) of
                {position, _, Row, Col} ->
                    gleam@string:concat(
                        [<<"Tag is missing a body "/utf8>>,
                            <<"(row="/utf8>>,
                            gleam@int:to_string(Row),
                            <<", col="/utf8>>,
                            gleam@int:to_string(Col),
                            <<")"/utf8>>]
                    );

                out_of_bounds ->
                    erlang:error(#{gleam_error => panic,
                            message => <<"Unable to resolve error position in template"/utf8>>,
                            module => <<"handles/format"/utf8>>,
                            function => <<"format_syntax_error"/utf8>>,
                            line => 78})
            end;

        {missing_block_kind, Start@1, _} ->
            case resolve_position(Template, Start@1, {position, 0, 0, 0}) of
                {position, _, Row@1, Col@1} ->
                    gleam@string:concat(
                        [<<"Tag is of unknown block kind "/utf8>>,
                            <<"(row="/utf8>>,
                            gleam@int:to_string(Row@1),
                            <<", col="/utf8>>,
                            gleam@int:to_string(Col@1),
                            <<")"/utf8>>]
                    );

                out_of_bounds ->
                    erlang:error(#{gleam_error => panic,
                            message => <<"Unable to resolve error position in template"/utf8>>,
                            module => <<"handles/format"/utf8>>,
                            function => <<"format_syntax_error"/utf8>>,
                            line => 91})
            end;

        {unexpected_block_argument, Start@2, _} ->
            case resolve_position(Template, Start@2, {position, 0, 0, 0}) of
                {position, _, Row@2, Col@2} ->
                    gleam@string:concat(
                        [<<"Tag is a closing block, which does not take any arguments "/utf8>>,
                            <<"(row="/utf8>>,
                            gleam@int:to_string(Row@2),
                            <<", col="/utf8>>,
                            gleam@int:to_string(Col@2),
                            <<")"/utf8>>]
                    );

                out_of_bounds ->
                    erlang:error(#{gleam_error => panic,
                            message => <<"Unable to resolve error position in template"/utf8>>,
                            module => <<"handles/format"/utf8>>,
                            function => <<"format_syntax_error"/utf8>>,
                            line => 104})
            end
    end.

-spec format_lex_error(handles@lexer:lex_error(), binary()) -> binary().
format_lex_error(Error, Template) ->
    case Error of
        {unbalanced_tag, Index, _} ->
            case resolve_position(Template, Index, {position, 0, 0, 0}) of
                {position, _, Row, Col} ->
                    gleam@string:concat(
                        [<<"Tag is missing closing braces }} "/utf8>>,
                            <<"(row="/utf8>>,
                            gleam@int:to_string(Row),
                            <<", col="/utf8>>,
                            gleam@int:to_string(Col),
                            <<")"/utf8>>]
                    );

                out_of_bounds ->
                    erlang:error(#{gleam_error => panic,
                            message => <<"Unable to resolve error position in template"/utf8>>,
                            module => <<"handles/format"/utf8>>,
                            function => <<"format_lex_error"/utf8>>,
                            line => 55})
            end;

        {syntax_error, Errors} ->
            _pipe = Errors,
            gleam@list:fold(
                _pipe,
                <<""/utf8>>,
                fun(Acc, Err) ->
                    gleam@string:concat(
                        [Acc, <<"\n"/utf8>>, format_syntax_error(Err, Template)]
                    )
                end
            )
    end.