Find matches after launched bubble collision

main.lua

@@ -91,6 +91,31 @@ local function find_nearest_slot(x, y)
   return nearest_slot_index
 end
 
+local function find_matches(start_index)
+  local bubble_type = game.bubble_slots[start_index].bubble_type
+  local to_check = {start_index}
+  local matches = {start_index}
+  local visited = {}
+  visited[start_index] = true
+
+  while #to_check > 0 do
+    local current_index = table.remove(to_check)
+    local slot = game.bubble_slots[current_index]
+
+    for i = 1, #slot.neighbours do
+      local neighbour_index = slot.neighbours[i]
+      local neighbour = game.bubble_slots[neighbour_index]
+      if not visited[neighbour_index] and neighbour.bubble_type == bubble_type then
+        matches[#matches+1] = neighbour_index
+        to_check[#to_check+1] = neighbour_index
+      end
+      visited[neighbour_index] = true
+    end
+  end
+
+  return matches
+end
+
 function love.load(arg)
   if arg[#arg] == "debug" then require("lldebugger").start() end
 
@@ -255,6 +280,8 @@ function love.update(dt)
       game.next_bubble.y = game.bubble_slots[nearest_slot_index].y
       game.next_bubble.velocity_x = 0
       game.next_bubble.velocity_y = 0
+
+      local matches = find_matches(nearest_slot_index)
     else
       game.next_bubble.x = next_x
       game.next_bubble.y = next_y