import type { JobHandler } from "./index.ts";
import type { DurableQueue } from "./durable.ts";

export interface WorkerDefinition<T> {
  name: string;
  handler: JobHandler<T>;
  onStart?: () => void | Promise<void>;
  onStop?: () => void | Promise<void>;
}

export function defineWorker<T>(definition: WorkerDefinition<T>): WorkerDefinition<T> {
  if (!definition.name.trim()) throw new TypeError("worker name cannot be empty");
  return Object.freeze({ ...definition });
}

/** Explicit process lifecycle for queue workers; safe to start and stop repeatedly. */
export function runWorker<T>(queue: DurableQueue, definition: WorkerDefinition<T>) {
  let started = false;
  return {
    async start() {
      if (started) return;
      started = true;
      queue.process(definition.name, definition.handler);
      await definition.onStart?.();
    },
    async stop(options?: { force?: boolean }) {
      if (!started) return;
      started = false;
      await queue.shutdown(options);
      await definition.onStop?.();
    },
    get running() {
      return started;
    },
  };
}