import { prisma } from "@/lib/db";

const cancelledIds = new Set<string>();

export class JobCancelledError extends Error {
  constructor(message = "任務已停止") {
    super(message);
    this.name = "JobCancelledError";
  }
}

export function markJobCancelledLocal(jobId: string) {
  cancelledIds.add(jobId);
}

export function clearJobCancelledLocal(jobId: string) {
  cancelledIds.delete(jobId);
}

export async function isJobCancelled(jobId: string): Promise<boolean> {
  if (cancelledIds.has(jobId)) return true;
  const job = await prisma.backgroundJob.findUnique({
    where: { id: jobId },
    select: { status: true },
  });
  return job?.status === "cancelled";
}

export async function assertJobNotCancelled(jobId?: string) {
  if (!jobId) return;
  if (await isJobCancelled(jobId)) {
    throw new JobCancelledError();
  }
}

export async function cancelJob(jobId: string): Promise<{ ok: boolean; error?: string }> {
  const job = await prisma.backgroundJob.findUnique({ where: { id: jobId } });
  if (!job) return { ok: false, error: "找不到任務" };
  if (job.status === "completed") return { ok: false, error: "任務已完成" };
  if (job.status === "failed") return { ok: false, error: "任務已失敗" };
  if (job.status === "cancelled") return { ok: true };

  markJobCancelledLocal(jobId);
  await prisma.backgroundJob.update({
    where: { id: jobId },
    data: {
      status: "cancelled",
      progress: "已停止",
      completedAt: new Date(),
    },
  });

  return { ok: true };
}