import { Func, Inbox, Lifecycle, spawn, loop, STOP } from 'anneal'
import { Event as NEvent } from 'nostr-tools'
import { compareEvents, getReplaceableCoordinateFromEvent, isReplaceableEvent } from '@/lib/event'

export type EventCacheActor = {
  cache: Inbox<NEvent>
  lookup: Func<string, NEvent | undefined>
  lookupMany: Func<string[], (NEvent | undefined)[]>
  lookupReplaceable: Func<string, NEvent | undefined>
  lc: Lifecycle
}

export function createEventCacheActor(): EventCacheActor {
  const events = new Map<string, NEvent>()
  const replaceables = new Map<string, NEvent>()

  const cache = new Inbox<NEvent>(0)
  const lookup = new Func<string, NEvent | undefined>()
  const lookupMany = new Func<string[], (NEvent | undefined)[]>()
  const lookupReplaceable = new Func<string, NEvent | undefined>()
  const lc = new Lifecycle()

  spawn(lc, async () => {
    await loop(
      lc.on(() => STOP),
      cache.on((event) => {
        events.set(event.id, event)
        if (isReplaceableEvent(event.kind)) {
          const coord = getReplaceableCoordinateFromEvent(event)
          const existing = replaceables.get(coord)
          if (!existing || compareEvents(event, existing) > 0) {
            replaceables.set(coord, event)
          }
        }
      }),
      lookup.on(({ req: id, reply }) => {
        reply(events.get(id))
      }),
      lookupMany.on(({ req: ids, reply }) => {
        reply(ids.map((id) => events.get(id)))
      }),
      lookupReplaceable.on(({ req: coord, reply }) => {
        reply(replaceables.get(coord))
      })
    )
  })

  return { cache, lookup, lookupMany, lookupReplaceable, lc }
}