--Author: Valansch
local function is_depleted(drill)
  local position = drill.position
  local area = {}
  if drill.name == "electric-mining-drill" then
    area = {{position.x - 2, position.y - 2},{position.x + 2, position.y + 2}}
  else
      area = {{position.x - 1, position.y - 1},{position.x + 1, position.y + 1}}
  end
  return #drill.surface.find_entities_filtered{type="resource", area = area} == 1
end

local function mark_if_depleted(drill)
  if is_depleted(drill) then
    drill.order_deconstruction(drill.force)
  end
end

local function on_resource_depleted(event)
  local area = {{event.entity.position.x-1, event.entity.position.y-1}, {event.entity.position.x+1, event.entity.position.y + 1}}
  local drills = event.entity.surface.find_entities_filtered{area = area, type="mining-drill"}
  for _,drill in pairs(drills) do
    mark_if_depleted(drill)
  end
end

Event.register(defines.events.on_resource_depleted, on_resource_depleted)