import { formatAnalyzeError } from "@/lib/ai/analyze-topic";
import { JobCancelledError, isJobCancelled } from "@/lib/jobs/cancel";
import { prisma } from "@/lib/db";
import { getActiveAccountId } from "@/lib/account-context";
import { analyzeTopic } from "@/lib/services/analyze";
import { runScanForTopic } from "@/lib/services/scan";
import { runStyle8DAnalysis } from "@/lib/services/style-analysis";
import type { AnalyzeTopicPayload, JobType, ScanPayload, Style8DPayload } from "./types";
import { ZodError } from "zod";

/** 超過此時間未更新進度，視為伺服器重啟或 API 掛死 */
const STALE_JOB_MS: Partial<Record<JobType, number>> = {
  "analyze-topic": 8 * 60 * 1000,
  "style-8d": 8 * 60 * 1000,
  scan: 25 * 60 * 1000,
};

const STALE_JOB_ERROR =
  "任務逾時或伺服器重啟導致中斷，請重新執行（若經常發生可改用較快的 AI 模型）。";

/** 將卡死的 pending/running 任務標為失敗，避免 UI 永遠轉圈 */
export async function recoverStaleBackgroundJobs(): Promise<number> {
  const active = await prisma.backgroundJob.findMany({
    where: { status: { in: ["pending", "running"] } },
    select: { id: true, type: true, updatedAt: true },
  });
  const now = Date.now();
  let recovered = 0;

  for (const job of active) {
    const maxMs = STALE_JOB_MS[job.type as JobType] ?? 12 * 60 * 1000;
    if (now - job.updatedAt.getTime() <= maxMs) continue;

    await prisma.backgroundJob.update({
      where: { id: job.id },
      data: {
        status: "failed",
        progress: "失敗",
        error: STALE_JOB_ERROR,
        completedAt: new Date(),
      },
    });
    recovered += 1;
  }

  return recovered;
}

function formatJobError(error: unknown, type: JobType): string {
  if (typeof error === "string") return error;
  if (type === "analyze-topic") return formatAnalyzeError(error);
  if (type === "style-8d" && error instanceof ZodError) {
    return "AI 有回覆，但 8D 欄位格式仍不完整。請重試一次；若持續發生，請在設定更換研究模型。";
  }
  return error instanceof Error ? error.message : "任務失敗";
}

export async function runBackgroundJob(jobId: string) {
  const job = await prisma.backgroundJob.findUnique({ where: { id: jobId } });
  if (!job || job.status !== "pending") return;
  if (await isJobCancelled(jobId)) return;

  await prisma.backgroundJob.update({
    where: { id: jobId },
    data: { status: "running", progress: "執行中…" },
  });

  const type = job.type as JobType;

  try {
    let result: unknown;

    if (type === "analyze-topic") {
      let payload: AnalyzeTopicPayload;
      try {
        payload = JSON.parse(job.payload ?? "{}") as AnalyzeTopicPayload;
      } catch {
        throw new Error("任務資料損毀，請重新建立任務");
      }
      await prisma.backgroundJob.update({
        where: { id: jobId },
        data: { progress: "AI 分析中，約需 1～4 分鐘…" },
      });
      result = await analyzeTopic(payload.topicId, payload.brief, {
        jobId,
        onProgress: async (message) => {
          await prisma.backgroundJob.update({
            where: { id: jobId },
            data: { progress: message },
          });
        },
      });
    } else if (type === "style-8d") {
      let payload: Style8DPayload;
      try {
        payload = JSON.parse(job.payload ?? "{}") as Style8DPayload;
      } catch {
        throw new Error("任務資料損毀，請重新建立任務");
      }
      result = await runStyle8DAnalysis(payload.accountId, payload.benchmarkUsername, jobId);
    } else if (type === "scan") {
      let payload: ScanPayload;
      try {
        payload = JSON.parse(job.payload ?? "{}") as ScanPayload;
      } catch {
        throw new Error("任務資料損毀，請重新建立任務");
      }
      if (payload.selectedTags?.length) {
        await prisma.topic.update({
          where: { id: payload.topicId },
          data: { selectedTags: JSON.stringify(payload.selectedTags) },
        });
      }
      await prisma.backgroundJob.update({
        where: { id: jobId },
        data: { progress: "海巡中，依標籤搜尋 Threads…" },
      });
      result = await runScanForTopic(payload.topicId, {
        useTags: payload.useTags,
        selectedTags: payload.selectedTags,
        jobId,
        onProgress: async (message) => {
          await prisma.backgroundJob.update({
            where: { id: jobId },
            data: { progress: message },
          });
        },
      });
    } else {
      throw new Error(`未知的任務類型：${job.type}`);
    }

    if (await isJobCancelled(jobId)) return;

    const latest = await prisma.backgroundJob.findUnique({ where: { id: jobId } });
    await prisma.backgroundJob.update({
      where: { id: jobId },
      data: {
        status: "completed",
        progress: latest?.progress ?? "完成",
        result: JSON.stringify(result),
        completedAt: new Date(),
      },
    });
  } catch (error) {
    if (error instanceof JobCancelledError || (await isJobCancelled(jobId))) {
      await prisma.backgroundJob.update({
        where: { id: jobId },
        data: {
          status: "cancelled",
          progress: "已停止",
          completedAt: new Date(),
        },
      });
      return;
    }

    const message = formatJobError(error, type);
    await prisma.backgroundJob.update({
      where: { id: jobId },
      data: {
        status: "failed",
        progress: "失敗",
        error: message,
        completedAt: new Date(),
      },
    });
  }
}

export async function findActiveJob(topicId: string, type: JobType) {
  await recoverStaleBackgroundJobs();
  const accountId = await getActiveAccountId();
  return prisma.backgroundJob.findFirst({
    where: { topicId, type, status: { in: ["pending", "running"] }, ...(accountId ? { accountId } : {}) },
    orderBy: { createdAt: "desc" },
  });
}

export async function findActiveAccountJob(accountId: string, type: JobType) {
  await recoverStaleBackgroundJobs();
  return prisma.backgroundJob.findFirst({
    where: { accountId, type, status: { in: ["pending", "running"] } },
    orderBy: { createdAt: "desc" },
  });
}

export async function enqueueJob(params: {
  type: JobType;
  topicId?: string;
  accountId?: string;
  label?: string;
  payload: unknown;
}) {
  await recoverStaleBackgroundJobs();
  const accountId = params.accountId ?? (await getActiveAccountId());
  const job = await prisma.backgroundJob.create({
    data: {
      accountId,
      type: params.type,
      topicId: params.topicId,
      label: params.label,
      payload: JSON.stringify(params.payload),
      status: "pending",
      progress: "排隊中…",
    },
  });

  return job;
}

export { cancelJob } from "./cancel";