-module(dummy_navigator).
-behaviour(gen_server).
-export([
  %% api
  start_link/2,
  goto_barcode/2,
  teleport_butler/2,
  lift/2,
  get_location/1,
  get_lift_state/1,
  %% cb
  init/1,
  handle_call/3,
  handle_cast/2
]).

-record(state, {
  butler_id,
  current_location,
  lift_state = down,
  going_to_barcode,
  count
}).

%% api
start_link(BId, Location) ->
  gen_server:start_link(?MODULE, [BId, Location], []).

goto_barcode(Pid, Barcode) ->
  gen_server:cast(Pid, {goto_barcode, Barcode}).

%% teleportation for testing
teleport_butler(Pid, Barcode) ->
  gen_server:cast(Pid, {teleport, Barcode}).

lift(Pid, Direction) ->
  gen_server:cast(Pid, {lift, Direction}).

get_location(Pid) ->
  gen_server:call(Pid, get_location).

get_lift_state(Pid) ->
  gen_server:call(Pid, get_lift_state).


%% cb

init([BId, Location]) ->
  gproc:add_local_name({?MODULE, BId}),
  {ok, #state{
    butler_id = BId,
    current_location = Location,
    lift_state = down,
    count = 0
  }}.

handle_call(get_location, _From, State) ->
  {reply, State#state.current_location, State};
handle_call(get_lift_state, _From, State) ->
  {reply, State#state.lift_state, State}.

handle_cast({goto_barcode, Barcode}, State = #state{butler_id = BId, current_location = PrevLocation, lift_state = LiftState}) ->
  {noreply, NewState = #state{current_location = NewLocation}} = handle_goto_barcode({goto_barcode, Barcode}, State),
  %% broadcast this
  gproc:send({p, l, {pubsub, on_butler_move}},
              {self(), {pubsub, on_butler_move}, {BId, PrevLocation, NewLocation, LiftState}}),
  {noreply, NewState};
handle_cast({teleport, Barcode}, State) ->
  {noreply, State#state{count = 0, current_location = Barcode, going_to_barcode = undefined}};
handle_cast({lift, up}, State) ->
  {noreply, State#state{lift_state = up}};
handle_cast({lift, down}, State) ->
  {noreply, State#state{lift_state = down}}.

%% if already at this barcode, just reset counters and do nothing
handle_goto_barcode({goto_barcode, CurrentBarcode}, State = #state{current_location = CurrentBarcode}) ->
  {noreply, State};
%% after 5 counts of requests of going to same barcode, just go to it
handle_goto_barcode({goto_barcode, GoingToBarcode}, State = #state{count = 5, going_to_barcode = GoingToBarcode}) ->
  {noreply, State#state{current_location = GoingToBarcode, going_to_barcode = undefined, count = 0}};
%% if its same as going_to_barcode but count is not 5 yet, then move butler to some random barcode and increase count
handle_goto_barcode({goto_barcode, GoingToBarcode}, State = #state{count = Count, going_to_barcode = GoingToBarcode}) ->
  {noreply, State#state{count = Count + 1, current_location = butler_functions:gen_random_barcode()}};
%% if its not current barcode or going to barcode, reset counter and make it the going to barcode. also randomly move butler somewhere
handle_goto_barcode({goto_barcode, Barcode}, State = #state{going_to_barcode = GoingToBarcode}) when Barcode =/= GoingToBarcode ->
  {noreply, State#state{count = 0, current_location = butler_functions:gen_random_barcode(), going_to_barcode = Barcode}}.