%% a process for running an instance of the bt
-module(bt_engine).
-behaviour(gen_server).
-include("./bt_node_behaviours/nodes.hrl").

-record(state, {
  bt :: any(),
  blackboard :: blackboard()
}).

-export([
  %% api
  start_link/1,
  start_link/3,
  %% cb
  tick/2,
  init/1,
  handle_call/3,
  handle_cast/2
]).

%% API
start_link({Tree, BB}) ->
  gen_server:start_link(?MODULE, [Tree, BB], []).

start_link(RootFilePath, TreeName, Args) ->
  {Tree, BB} = parser:parse(RootFilePath, TreeName, Args),
  start_link({Tree, BB}).

tick(Pid, Event) ->
  gen_server:call(Pid, Event).

%% Callbacks
init([Tree, BB]) ->
  {ok,
    #state{
      bt = Tree,
      blackboard = BB
    }
  }.

handle_call(Event, _From, #state{bt = Tree, blackboard = BB}) ->
  {Status, NewTree, NewBB} = runner:run(Tree, BB, Event),
  {
    reply,
    Status,
    #state{
      bt = NewTree,
      blackboard = NewBB
    }
  }.

%% not using
handle_cast(_, State) -> {noreply, State}.