syndicate-nim/src/syndicate/actors/timers.nim

# SPDX-FileCopyrightText: ☭ Emery Hemingway
# SPDX-License-Identifier: Unlicense

import std/[asyncdispatch, monotimes, times]
import preserves
import syndicate

import ../protocols/timer
from syndicate/protocols/dataspace import Observe

export timer

type Observe = dataspace.Observe

proc now: float64 = getTime().toUnixFloat()

proc spawnTimers*(turn: var Turn; ds: Cap): Actor {.discardable.} =
  ## Spawn a timer actor.
  spawn("timer", turn) do (turn: var Turn):

    during(turn, ds, inject(grab Observe(pattern: dropType LaterThan), {0: grabLit()})) do (seconds: float):
      let period = seconds - now()
      if period < 0.001:
        discard publish(turn, ds, LaterThan(seconds: seconds))
      else:
        addCallback(sleepAsync(period * 1_000), turn) do (turn: var Turn):
          discard publish(turn, ds, LaterThan(seconds: seconds))

proc after*(turn: var Turn; ds: Cap; dur: Duration; act: TurnAction) =
  ## Execute `act` after some duration of time.
  let later = now() + dur.inMilliseconds.float64 * 1_000.0
  onPublish(turn, ds, grab LaterThan(seconds: later)):
    act(turn)

# TODO: periodic timer