when (NimMajor, NimMinor) < (1, 4):
  {.push raises: [Defect].}
else:
  {.push raises: [].}

import
  std/tables,
  stew/results,
  chronicles,
  chronos

import
  ./push_handler,
  ../topics,
  ../message

## Subscription manager
type SubscriptionManager* = object
    subscriptions: TableRef[(string, ContentTopic), FilterPushHandler]

proc init*(T: type SubscriptionManager): T =
  SubscriptionManager(subscriptions: newTable[(string, ContentTopic), FilterPushHandler]())

proc clear*(m: var SubscriptionManager) =
  m.subscriptions.clear()

proc registerSubscription*(m: SubscriptionManager, pubsubTopic: PubsubTopic, contentTopic: ContentTopic, handler: FilterPushHandler) =
  try:
    # TODO: Handle over subscription surprises
    m.subscriptions[(pubsubTopic, contentTopic)]= handler
  except CatchableError:
    error "failed to register filter subscription", error=getCurrentExceptionMsg()

proc removeSubscription*(m: SubscriptionManager, pubsubTopic: PubsubTopic, contentTopic: ContentTopic) =
  m.subscriptions.del((pubsubTopic, contentTopic))

proc notifySubscriptionHandler*(m: SubscriptionManager, pubsubTopic: PubsubTopic, contentTopic: ContentTopic, message: WakuMessage) =
  if not m.subscriptions.hasKey((pubsubTopic, contentTopic)):
    return

  try:
    let handler = m.subscriptions[(pubsubTopic, contentTopic)]
    asyncSpawn handler(pubsubTopic, message)
  except CatchableError:
    discard

proc getSubscriptionsCount*(m: SubscriptionManager): int =
  m.subscriptions.len()