-module(btl_action).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-record
(
   move,
   {
      actor_ix :: non_neg_integer(),
      path :: list(shr_direction:enum())
      movement_points :: non_neg_integer()
   }
).

-record
(
   switch_weapon,
   {
      actor_ix :: non_neg_integer()
   }
).

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

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

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

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

-export
(
   [
      new_interrupted_move/2
   ]
).

-export
(
   [
      get_path/1,
      get_movement_points/1,
      get_target_index/1,
      get_actor_index/1,
      get_category/1
   ]
).

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

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

   [#move{ actor_ix = CharacterIX, path = Path }].

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

-spec maybe_decode_weapon_switch
   (
      non_neg_integer(),
      boolean()
   )
   -> list(type()).
maybe_decode_weapon_switch (_CharacterIX, false) -> [];
maybe_decode_weapon_switch (CharacterIX, true) ->
   [#switch_weapon{ actor_ix = CharacterIX }].

-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(shr_direction:type()).
get_path (Action) when is_record(Action, move) ->
   Action#move.path;
get_path (Action) when is_record(Action, interrupted_move) ->
   Action#interrupted_move.path;
get_path (_) ->
   [].

-spec get_movement_points (type()) -> non_neg_integer().
get_movement_points (Action) when is_record(Action, interrupted_move) ->
   Action#interrupted_move.movement_points;
get_movement_points (_) -> 0.

-spec get_target_index (type()) -> non_neg_integer().
get_target_index (Action) when is_record(Action, attack) ->
   Action#attack.target_ix;
get_target_index (Action) when is_record(Action, attack_of_opportunity) ->
   Action#attack_of_opportunity.target_ix;
get_target_index (_) ->
   0.

-spec get_actor_index (type()) -> (non_neg_integer() | -1).
get_actor_index (Action) when is_record(Action, attack) ->
   Action#attack.actor_ix;
get_actor_index (Action) when is_record(Action, attack_of_opportunity) ->
   Action#attack_of_opportunity.actor_ix;
get_actor_index (Action) when is_record(Action, move) ->
   Action#move.actor_ix;
get_actor_index (Action) when is_record(Action, switch_weapon) ->
   Action#switch_weapon.actor_ix;
get_actor_index (_) ->
   -1.

-spec new_interrupted_move
   (
      list(shr_direction:type()),
      non_neg_integer()
   )
   -> type().
new_interrupted_move (Path, MovementPoints) ->
   #interrupted_move{ path = Path, movement_points = MovementPoints }.

-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) when is_record(Action, interrupted_move) ->
   interrupted_move;
get_category (Action) when is_record(Action, attack_of_opportunity) ->
  attack_of_opportunity.

-spec from_map_marker
   (
      btl_character:type(),
      shr_map_marker:type()
   )
   -> list(type()).
from_map_marker (_Character, Marker) ->
   case shr_map_marker:get_category(Marker) of
      matk ->
         [
            #attack_of_opportunity
            {
               target_ix = shr_map_marker:get_character_index(Marker)
            }
         ];

      _ -> []
   end.