1 files changed, 68 insertions, 0 deletions
diff --git a/src/battlemap/movement.erl b/src/battlemap/movement.erl
new file mode 100644
index 0000000..7fc5db1
--- /dev/null
+++ b/src/battlemap/movement.erl
@@ -0,0 +1,68 @@
+-module(movement).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-export
+(
+   [
+      cross/4,
+      steps_between/2
+   ]
+).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+location_after_step (Step, X, Y) ->
+   case Step of
+      <<"L">> -> {(X - 1), Y};
+      <<"R">> -> {(X + 1), Y};
+      <<"U">> -> {X, (Y - 1)};
+      <<"D">> -> {X, (Y + 1)}
+   end.
+
+location_to_array_index (ArrayWidth, X, Y) ->
+   if
+      (X < 0) -> -1;
+      (Y < 0) -> -1;
+      (X >= ArrayWidth) -> error;
+      true -> ((Y * ArrayWidth) + X)
+   end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+cross (_Battlemap, _ForbiddenLocations, [], Cost, X, Y) ->
+   {{X, Y}, Cost};
+cross (Battlemap, ForbiddenLocations, [Step|NextSteps], Cost, X, Y) ->
+   BattlemapTiles = battlemap:get_tiles(Battlemap),
+
+   {NextX, NextY} = location_after_step(Step, X, Y),
+   NextTileIX =
+      location_to_array_index(array:size(BattlemapTiles), NextX, NextY),
+   NextTile = array:get(array:get(NextTileIX, BattlemapTiles)),
+   NextCost = (Cost + tile:get_cost(NextTile)),
+   IsForbidden =
+      array:foldl
+      (
+         fun (_IX, Location, Prev) ->
+            (Prev or ({NextX, NextY} == Location))
+         end,
+         ForbiddenLocations
+      ),
+
+   IsForbidden = false,
+
+   cross(Battlemap, ForbiddenLocations, NextSteps, NextCost, NextX, NextY).
+
+cross (Battlemap, ForbiddenLocations, Path, {X, Y}) ->
+   cross(Battlemap, ForbiddenLocations, Path, 0, X, Y).
+
+steps_between ({OX, OY}, {DX, DY}) ->
+   (abs(DY - OY) + abs(DX - OX)).