-module(btl_battle_action).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-record
(
   move,
   {
      path :: list(btl_direction:enum())
   }
).

-record
(
   switch_weapon,
   {
   }
).

-record
(
   attack,
   {
      target_ix :: non_neg_integer()
   }
).

-type category() :: ('move' | 'switch_weapon' | 'attack' | 'nothing').
-opaque type() :: (#move{} | #switch_weapon{} | #attack{}).

-export_type([category/0, type/0]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
   [
      maybe_decode_move/1,
      maybe_decode_weapon_switch/1,
      maybe_decode_attack/1,
      can_follow/2
   ]
).

-export
(
   [
      get_path/1,
      get_target_ix/1,
      get_category/1
   ]
).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec maybe_decode_move (list(btl_direction:type())) -> list(type()).
maybe_decode_move ([]) -> [];
maybe_decode_move (PathInBinary) ->
   Path = lists:map(fun btl_direction:decode/1, PathInBinary),

   [#move { path = Path }].

-spec maybe_decode_attack (integer()) -> list(type()).
maybe_decode_attack (TargetIX) when (TargetIX < 0) -> [];
maybe_decode_attack (TargetIX) -> [#attack { target_ix = TargetIX }].

-spec maybe_decode_weapon_switch (boolean()) -> list(type()).
maybe_decode_weapon_switch (false) -> [];
maybe_decode_weapon_switch (true) -> [#switch_weapon{}].

-spec can_follow (category(), category()) -> boolean().
can_follow (nothing, attack) -> true;
can_follow (nothing, switch_weapon) -> true;
can_follow (nothing, move) -> true;
can_follow (move, switch_weapon) -> true;
can_follow (move, attack) -> true;
can_follow (_, _) -> false.

-spec get_path (type()) -> list(btl_direction:type()).
get_path (Action) when is_record(Action, move) ->
   Action#move.path;
get_path (_) ->
   [].

-spec get_target_ix (type()) -> non_neg_integer().
get_target_ix (Action) when is_record(Action, attack) ->
   Action#attack.target_ix;
get_target_ix (_) ->
   [].

-spec get_category (type()) -> category().
get_category (Action) when is_record(Action, attack) -> attack;
get_category (Action) when is_record(Action, move) -> move;
get_category (Action) when is_record(Action, switch_weapon) -> switch_weapon;
get_category (Action) ->
   io:format("How'd you get there?~p~n", [Action]),
   true = Action.