-module(pmod_gyro).

-behavior(gen_server).

-include("pmod_gyro.hrl").

% API
-export([start_link/2]).

% Callbacks
-export([init/1]).
-export([handle_call/3]).
-export([handle_cast/2]).
-export([handle_info/2]).
-export([code_change/3]).
-export([terminate/2]).

-define(SPI_MODE, #{cpol => high, cpha => trailing}).

%--- API -----------------------------------------------------------------------

% @private
start_link(Slot, _Opts) ->
    gen_server:start_link(?MODULE, Slot, []).

%--- Callbacks -----------------------------------------------------------------

% @private
init(Slot) ->
    verify_device(Slot),
    grisp_devices:register(Slot, ?MODULE),
    {ok, Slot}.

% @private
handle_call(Request, From, _State) -> error({unknown_request, Request, From}).

% @private
handle_cast(Request, _State) -> error({unknown_cast, Request}).

% @private
handle_info(Info, _State) -> error({unknown_info, Info}).

% @private
code_change(_OldVsn, State, _Extra) -> {ok, State}.

% @private
terminate(_Reason, _State) -> ok.

%--- Internal ------------------------------------------------------------------

verify_device(Slot) ->
    case grisp_spi:send_recv(Slot, ?SPI_MODE, <<?RW_READ:1, ?MS_SAME:1, ?WHO_AM_I:6>>, 1, 1) of
        <<?DEVID>> -> ok;
        Other      -> error({device_mismatch, {who_am_i, Other}})
    end.