-module(bson@encoder).
-compile(no_auto_import).

-export([encode/1]).
-export_type([entity/0]).

-type entity() :: {entity, bson@types:kind(), bitstring()}.

-spec encode(list({binary(), bson@types:value()})) -> bitstring().
encode(Doc) ->
    case document(Doc) of
        {entity, _@1, Value} ->
            Value
    end.

-spec document(list({binary(), bson@types:value()})) -> entity().
document(Doc) ->
    Doc@1 = begin
        _pipe = Doc,
        _pipe@1 = gleam@list:reverse(_pipe),
        _pipe@2 = gleam@list:map(_pipe@1, fun(Kv) -> encode_kv(Kv) end),
        gleam@bit_string:concat(_pipe@2)
    end,
    Size = gleam@bit_string:byte_size(Doc@1) + 5,
    {entity,
     {kind, <<16#03>>},
     begin
         _pipe@3 = [<<Size:32/little>>, Doc@1, <<0>>],
         gleam@bit_string:concat(_pipe@3)
     end}.

-spec encode_kv({binary(), bson@types:value()}) -> bitstring().
encode_kv(Pair) ->
    Key = <<(erlang:element(1, Pair))/binary, 0>>,
    Value@7 = case erlang:element(2, Pair) of
        null ->
            null();

        {str, Value} ->
            string(Value);

        {array, Value@1} ->
            array(Value@1);

        {double, Value@2} ->
            double(Value@2);

        {boolean, Value@3} ->
            boolean(Value@3);

        {integer, Value@4} ->
            integer(Value@4);

        {document, Value@5} ->
            document(Value@5);

        {object_id, Value@6} ->
            object_id(Value@6)
    end,
    case Value@7 of
        {entity, Kind, Value@8} ->
            _pipe = [erlang:element(2, Kind), Key, Value@8],
            gleam@bit_string:concat(_pipe)
    end.

-spec array(list(bson@types:value())) -> entity().
array(List) ->
    case begin
        _pipe = List,
        _pipe@2 = gleam@list:index_map(
            _pipe,
            fun(Index, Item) ->
                {begin
                     _pipe@1 = Index,
                     gleam@int:to_string(_pipe@1)
                 end,
                 Item}
            end
        ),
        _pipe@3 = gleam@list:reverse(_pipe@2),
        document(_pipe@3)
    end of
        {entity, _@1, Value} ->
            {entity, {kind, <<16#04>>}, Value}
    end.

-spec string(binary()) -> entity().
string(Value) ->
    Length = gleam@bit_string:byte_size(<<Value/binary>>) + 1,
    {entity, {kind, <<16#02>>}, <<Length:32/little, Value/binary, 0>>}.

-spec double(float()) -> entity().
double(Value) ->
    {entity, {kind, <<16#01>>}, <<Value/little-float>>}.

-spec null() -> entity().
null() ->
    {entity, {kind, <<16#0A>>}, <<>>}.

-spec boolean(boolean()) -> entity().
boolean(Value) ->
    case Value of
        true ->
            {entity, {kind, <<16#08>>}, <<1>>};

        false ->
            {entity, {kind, <<16#08>>}, <<0>>}
    end.

-spec integer(integer()) -> entity().
integer(Value) ->
    case (Value < 2147483647) andalso (Value > -2147483648) of
        true ->
            {entity, {kind, <<16#10>>}, <<Value:32/little>>};

        false ->
            {entity, {kind, <<16#12>>}, <<Value:64/little>>}
    end.

-spec object_id(bson@object_id:object_id()) -> entity().
object_id(Value) ->
    {entity,
     {kind, <<16#07>>},
     begin
         _pipe = Value,
         bson@object_id:to_bit_string(_pipe)
     end}.