-module(yaml_parse_sequence).
-export([
    parse/6
]).
-include("../bt_node_behaviours/bt_nodes.hrl").

get_child_and_blackboard({Child = {ChildName, _}, Idx}, Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory) ->
  IdxString = integer_to_list(Idx),
  ChildNamespace = bt_parser_utils:get_namespace(Namespace, ChildName ++ "_" ++ IdxString),
  bt_yaml_parser:parse(Child, ChildNamespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory).

-spec parse(
  Sequence :: {string(), list({term(), term()})}, 
  Namespace :: list(string()), 
  ParentContext :: map(),
  Blackboard :: map(),
  YAMLDictionary :: term(),
  FileDirectory :: string()
) -> {ParsedTree :: sequence(), Blackboard :: blackboard()}.
parse(Sequence = {"sequence", List}, Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory) ->
  Decorators = proplists:get_value("decorators", List, []),
  parse(Sequence, Decorators, Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory).

-spec parse(
  Sequence :: {string(), list({term(), term()})},
  Decorators :: list({term(), term()}),
  Namespace :: list(string()), 
  ParentContext :: map(),
  Blackboard :: map(),
  YAMLDictionary :: term(),
  FileDirectory :: string()
) -> {ParsedTree :: sequence(), Blackboard :: blackboard()}.
parse(_Sequence = {"sequence", List}, [], Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory) ->
   %% order of traversal is dependent on implementation, so not using it. instead using list comprehension
  ChildList = proplists:get_value("children", List),
  ChildrenBlackboardPairs = [
    get_child_and_blackboard(X, Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory)
    || X <- lists:zip(ChildList, lists:seq(1, length(ChildList)))
  ],
  %% merge all the blackboards
  NewBlackboard = lists:foldl(
    fun({_ChildTree, ChildBlackboard}, Acc) -> maps:merge(ChildBlackboard, Acc) end,
    Blackboard,
    ChildrenBlackboardPairs
  ),
  %% proplists:get_keys doesn't preserve order! use list comprehension
  ChildrenTrees = [X || {X, _} <- ChildrenBlackboardPairs],
  %% here name is actually filled in by the parent subtree (if any). the sequence entry in .yml shouldn't have a name...
  Name = proplists:get_value("name", List, "sequence"),
  {#sequence{
    name = Name,
    namespace = Namespace,
    children = ChildrenTrees
  }, NewBlackboard};

parse(Sequence = {"sequence", _List}, [Decorator | RestOfDecorators], Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory) ->
  ParsedDecorator = yaml_parser_utils:get_decorator(Decorator, ParentContext),
  {Child, NewBlackboard} = parse(Sequence, RestOfDecorators, Namespace, ParentContext, Blackboard, YAMLDictionary, FileDirectory),
  {
    ParsedDecorator#decorator{
      child = Child
    },
    NewBlackboard
  }.