flowgraph/src/reactive/node-status.ts

import { effect } from "@preact/signals-core";
import type { Signal, ReadonlySignal } from "@preact/signals-core";
import type { NodeStatus } from "../schema/enums.js";

const TERMINAL_STATUSES: Set<NodeStatus> = new Set([
  "completed",
  "failed",
  "aborted",
  "skipped",
]);

export interface NodeStatusContext {
  statusMap: Map<string, Signal<NodeStatus>>;
  predecessors: string[];
}

export function computePreconditions(
  _nodeKey: string,
  ctx: NodeStatusContext,
): boolean {
  if (ctx.predecessors.length === 0) return true;
  return ctx.predecessors.every((pred: string) => {
    const predStatus = ctx.statusMap.get(pred);
    if (!predStatus) return false;
    return predStatus.value === "completed" || predStatus.value === "skipped";
  });
}

export function computeBlockedByFailure(
  _nodeKey: string,
  ctx: NodeStatusContext,
): boolean {
  return ctx.predecessors.some((pred: string) => {
    const predStatus = ctx.statusMap.get(pred);
    if (!predStatus) return false;
    return predStatus.value === "failed" || predStatus.value === "aborted";
  });
}

export function registerStartEffect(
  status: Signal<NodeStatus>,
  preconditions: ReadonlySignal<boolean>,
  effectDisposers: (() => void)[],
): void {
  const disposer = effect(() => {
    if (preconditions.value) {
      const current = status.value;
      if (current === "idle" || current === "waiting") {
        status.value = "ready";
      }
    }
  });
  effectDisposers.push(disposer);
}

export interface AbortEffectOptions {
  abortDependents?: boolean;
}

export function registerAbortEffect(
  status: Signal<NodeStatus>,
  blockedByFailure: ReadonlySignal<boolean>,
  effectDisposers: (() => void)[],
  options?: AbortEffectOptions,
): void {
  const disposer = effect(() => {
    if (blockedByFailure.value) {
      const current = status.value;
      if (options?.abortDependents) {
        if (!TERMINAL_STATUSES.has(current)) {
          status.value = "aborted";
        }
      } else {
        if (current === "idle" || current === "waiting") {
          status.value = "aborted";
        }
      }
    }
  });
  effectDisposers.push(disposer);
}