// V8a — `ProductionCheckpoint` production wiring for the `Checkpoint` seam (PIC-10).
//
// Constructs one `Checkpoint` per `thetaAbort` (per invocation) from the injected
// `Clock` seam. `before(kind, site)`:
//   - for `loop-iter`, releases the event loop for one macrotask turn before
//     resolving — scheduling that resolution through the injected `Clock`'s
//     `setTimeout(fn, 0)` (the PIC-12 timer surface), never a bare global
//     `setTimeout`, so a Pi-dispatched abort can land before the next
//     loop-iteration signal-check;
//   - for every other kind (`query`, `tool-call`, `invoke`, `binder-call`),
//     resolves on the microtask queue (an already-resolved promise), because
//     those checkpoints precede real async I/O that already yields.
// It adds no `before(...)` sites beyond the five enumerated `CheckpointKind`s.
//
// Spec: host-interfaces-services.md PIC-10.

import type { Clock } from "./clock";
import type { Checkpoint, CheckpointKind, CheckpointSite } from "./checkpoint";

export class ProductionCheckpoint implements Checkpoint {
  readonly #clock: Clock;

  constructor(clock: Clock) {
    this.#clock = clock;
  }

  before(kind: CheckpointKind, _site: CheckpointSite): Promise<void> {
    if (kind === "loop-iter") {
      // One macrotask turn, scheduled through the injected Clock seam's
      // setTimeout(fn, 0) (PIC-12 timer surface) — never a bare global timer —
      // so a Pi-dispatched abort can land before the next signal-check.
      return new Promise<void>((resolve) => {
        this.#clock.setTimeout(resolve, 0);
      });
    }
    // query / tool-call / invoke / binder-call: resolve on the microtask queue;
    // these checkpoints precede real async I/O that already yields the loop.
    return Promise.resolve();
  }
}