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

import std/[asyncdispatch, monotimes, times, posix, times, epoll]
import preserves
import ../syndicate, ../protocols/timer
from ../protocols/dataspace import Observe

export timer

type Observe = dataspace.Observe

#[
proc timerfd_create(clock_id: ClockId, flags: cint): cint
     {.importc: "timerfd_create", header: "<sys/timerfd.h>".}
proc timerfd_settime(ufd: cint, flags: cint,
                      utmr: var Itimerspec, otmr: var Itimerspec): cint
     {.importc: "timerfd_settime", header: "<sys/timerfd.h>".}
proc eventfd(count: cuint, flags: cint): cint
     {.importc: "eventfd", header: "<sys/eventfd.h>".}
]#

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

proc spawnTimers*(ds: Cap): Actor {.discardable.} =
  ## Spawn a timer actor.
  bootActor("timers") do (root: Facet):
    let pat = inject(grab Observe(pattern: dropType LaterThan), {0: grabLit()})
    #[
    during(ds, pat) do (seconds: float):
      let period = seconds - now()
      if period < 0.001 or true:
        let h = publish(ds, LaterThan(seconds: seconds).toPreserves)
        ]#

    #[
    else:
      let fdi = timerfd_create(CLOCK_MONOTONIC, O_CLOEXEC or O_NONBLOCK)

      addCallback(sleepAsync(period * 1_000), turn) do (turn: Turn):
        discard publish(turn, ds, LaterThan(seconds: seconds))
        ]#

#[
proc after*(ds: Cap; dur: Duration; cb: proc () {.closure.}) =
  ## Execute `act` after some duration of time.
  let later = now() + dur.inMilliseconds.float64 * 1_000.0
  onPublish(ds, grab LaterThan(seconds: later)):
    cb()
]#

# TODO: periodic timer