/// SPDX-License-Identifier: GPL-3.0-or-later
/// SPDX-FileCopyrightText: Copyright © 2016-2021 Tony Garnock-Jones <tonyg@leastfixedpoint.com>

import { preserves, Observe, Dataspace, floatValue, Facet } from "@syndicate-lang/core";

export message type PeriodicTick(intervalMS);
export assertion type TimeLaterThan(deadlineMS);

export function sleep<T>(thisFacet: Facet<T>, ms: number, cb: () => void): void {
  react {
    stop on asserted TimeLaterThan(+(new Date()) + ms) {
      cb();
    }
  }
}

boot {
    spawn named 'timer/PeriodicTick' {
        during Observe(PeriodicTick($intervalMS)) =>
            spawn named (preserves`PeriodicTick(${intervalMS})`) {
                let handle: any | null = null;
                let finish: (() => void) | null = thisFacet.actor.dataspace.backgroundTask();
                on start {
                    handle = setInterval(thisFacet.wrapExternal((thisFacet) => {
                        send message PeriodicTick(intervalMS);
                    }), floatValue(intervalMS as any));
                }
                on stop {
                    if (handle) {
                        clearInterval(handle);
                        handle = null;
                    }
                    if (finish) {
                        finish();
                        finish = null;
                    }
                }
            }
    }

    spawn named 'timer/TimeLaterThan' {
        during Observe(TimeLaterThan($deadlineMS)) =>
            spawn named (preserves`TimeLaterThan(${deadlineMS})`) {
                let handle: any | null = null;
                let finish: (() => void) | null = thisFacet.actor.dataspace.backgroundTask();
                on start {
                    let delta = floatValue(deadlineMS as any) - (+(new Date()));
                    handle = setTimeout(thisFacet.wrapExternal((thisFacet) => {
                        handle = null;
                        if (finish) finish();
                        finish = null;
                        react {
                            assert TimeLaterThan(deadlineMS);
                        }
                    }), delta);
                }
                on stop {
                    if (handle) {
                        clearTimeout(handle);
                        handle = null;
                    }
                    if (finish) {
                        finish();
                        finish = null;
                    }
                }
            }
    }
}