"""Health-cost routes to food or non-hazard refuge, with current bodies fixed."""
import heapq

def health_route_cost(start, food, hazards, stacks, damage, blocked, width, height, *, refuge=False):
  """Cost until food resets health, or until leaving hazards for refuge.

  Food is consumed before elimination, so its final step needs no remaining
  health. Other steps must leave health positive. Bodies remain obstacles,
  including food-covered body cells; the caller removes the starting head.
  """
  queue = [(0, start)]
  best = {start: 0}
  while queue:
    cost, point = heapq.heappop(queue)
    if cost != best[point]:
      continue
    if point in food or (refuge and point not in hazards):
      return cost
    x, y = point
    for target in ((x, y + 1), (x, y - 1), (x - 1, y), (x + 1, y)):
      nx, ny = target
      if not (0 <= nx < width and 0 <= ny < height) or target in blocked:
        continue
      step = 0 if target in food else 1 + (damage * stacks.get(target, 1) if target in hazards else 0)
      value = cost + step
      if value < best.get(target, float('inf')):
        best[target] = value
        heapq.heappush(queue, (value, target))
  return None