/** 异步 Job 研究执行（Phase 4）：POST /api/jobs 提交 → 轮询 GET /api/jobs/{id}。
 *
 * 大样本研究（全市场）可能耗时数十秒到分钟级，经异步 Job 后台执行，
 * 避免 HTTP 长阻塞（AGENT §19）。页面提交后即时返回 job_id，再轮询到终态。
 */
import { useCallback, useEffect, useRef, useState } from "react";

import { apiGet, apiPost } from "./api";
import type { ResearchSpec } from "./types";

export interface JobSubmit {
  job_id: string;
  status: string;
}

export interface JobStatusResp {
  job_id: string;
  status: string;
  /** 执行阶段（data_loading / backtesting / analysis…）—— 用于给用户真实进度而非假进度条 */
  stage?: string | null;
  /** 归档后的实验 id（后端在 Job 完成时写入） */
  experiment_id?: string | null;
  result?: unknown;
  error?: string | null;
  spec?: Record<string, unknown>;
  started_at?: string | null;
  finished_at?: string | null;
}

export function submitJob(spec: ResearchSpec): Promise<JobSubmit> {
  return apiPost<JobSubmit>("/jobs", spec);
}

/** 任务终态（success / failed / cancelled / timeout）与结果 */
export interface JobOutcome<T> {
  status: string;
  result: T | null;
  error?: string;
  /** 归档实验 id：结果出来后前端可直接给出「去对比」入口 */
  experimentId?: string | null;
}

/** 轮询直到 success / failed / cancelled，或超时（默认 10 分钟）。 */
export async function waitJob<T>(
  jobId: string,
  timeoutMs = 600_000,
  onStage?: (info: { stage: string; elapsedMs: number }) => void,
): Promise<JobOutcome<T>> {
  const deadline = Date.now() + timeoutMs;
  const t0 = Date.now();
  while (Date.now() < deadline) {
    const job = await apiGet<JobStatusResp>(`/jobs/${jobId}`);
    // 阶段来自后端真实执行状态，避免前端用假进度条假装在跑
    if (onStage && job.stage) onStage({ stage: job.stage, elapsedMs: Date.now() - t0 });
    if (job.status === "success") {
      return {
        status: job.status,
        result: (job.result as T) ?? null,
        experimentId: job.experiment_id ?? null,
      };
    }
    if (job.status === "failed" || job.status === "cancelled") {
      return { status: job.status, result: null, error: job.error ?? undefined };
    }
    await new Promise((resolve) => setTimeout(resolve, 1500));
  }
  return { status: "timeout", result: null, error: "等待结果超时，请稍后在「实验」页查看归档" };
}

/** 阶段中文名（后端 stage 枚举 → 用户可读） */
export const STAGE_LABEL: Record<string, string> = {
  queued: "排队中",
  data_loading: "加载行情与因子数据",
  selection: "逐择股日选股",
  backtesting: "撮合与净值结算",
  analysis: "汇总指标与曲线",
  done: "完成",
};

/** 执行阶段时间线（顺序即推进顺序，用于「阶段小圆点」） */
export const STAGE_ORDER = ["queued", "data_loading", "selection", "backtesting", "analysis", "done"];

/** 取消排队中/执行中的作业（POST /api/jobs/{id}/cancel；已结束的会返回 cancelled=false）。 */
export function cancelJob(
  jobId: string,
): Promise<{ job_id: string; status: string; cancelled: boolean }> {
  return apiPost<{ job_id: string; status: string; cancelled: boolean }>(
    `/jobs/${encodeURIComponent(jobId)}/cancel`,
    {},
  );
}


/** 提交一个回测组合为异步 Job（POST /api/combos/run，不保存组合）。 */
export async function submitComboJob(combo: unknown): Promise<JobSubmit> {
  return apiPost<JobSubmit>("/combos/run", combo);
}

/**
 * 运行**已保存**的回测组合（POST /api/combos/{id}/run）。
 *
 * 与 submitComboJob 的区别：这里用库里的那份参数，页面上未保存的改动不参与 ——
 * 「从组合库直接运行」必须跑库里存的那套，否则用户改了一半的表单会污染既有组合的结果。
 */
export async function runSavedCombo(comboId: string): Promise<JobSubmit> {
  return apiPost<JobSubmit>(`/combos/${encodeURIComponent(comboId)}/run`, {});
}

/* ------------------------------------------------------------------ *
 * 统一的「提交 → 轮询 → 终态」状态机（useJobRunner）
 *
 * 为什么要有它：以前每个页面各写一遍 running/jobId/error，结果参差不齐 ——
 * 有的页面点了「运行」只在按钮上转圈，用户不知道到底提交没提交、跑到哪一步；
 * 有的页面「已用秒数」只在后端阶段变化时才更新，看起来像卡死了（0s 一动不动）。
 * 这里把状态、秒表、取消、终态收敛到一处，页面只管渲染。
 * ------------------------------------------------------------------ */

export type JobPhase =
  | "idle"
  | "submitting"
  | "queued"
  | "running"
  | "success"
  | "failed"
  | "cancelled"
  | "timeout";

export interface JobRunState<T> {
  phase: JobPhase;
  /** 作业号（提交成功后立即拿到；这是「到底提交没提交」的凭据） */
  jobId: string;
  /** 后端上报的执行阶段（queued/data_loading/selection/backtesting/analysis/done） */
  stage: string;
  /** 已用毫秒：**每秒自增**，不依赖后端阶段变化，所以界面不会看起来卡住 */
  elapsedMs: number;
  /** 这次跑的是什么（如「因子测试 · momentum_60」），显示在反馈条上 */
  label: string;
  /** 批量场景的进度（第 index / total 个），单跑时为 null */
  progress: { index: number; total: number } | null;
  error: string;
  result: T | null;
  experimentId: string | null;
  /** 提交时刻（本地时间，用于「发起于 hh:mm:ss」） */
  startedAt: Date | null;
  /** 正在请求取消 */
  cancelling: boolean;
}

function emptyState<T>(label = ""): JobRunState<T> {
  return {
    phase: "idle",
    jobId: "",
    stage: "",
    elapsedMs: 0,
    label,
    progress: null,
    error: "",
    result: null,
    experimentId: null,
    startedAt: null,
    cancelling: false,
  };
}

export interface JobRunOptions {
  /** 反馈条上显示的任务名（如「因子测试 · momentum_60」） */
  label?: string;
  /** 批量进度（第 index / total 个） */
  progress?: { index: number; total: number } | null;
  timeoutMs?: number;
}

export interface JobRunner<T> {
  state: JobRunState<T>;
  /** 提交并轮询到终态；返回终态结果（供页面继续处理，如渲染报告） */
  run: (
    submit: () => Promise<{ job_id: string }>,
    opts?: JobRunOptions,
  ) => Promise<JobOutcome<T>>;
  cancel: () => Promise<void>;
  reset: () => void;
}

/**
 * 作业运行状态机。
 *
 * 生命周期：idle → submitting（已点击，正在换 job_id）→ queued/running（轮询中，秒表走）
 * → success | failed | cancelled | timeout。**submitting 也是状态**：点了按钮立刻就有
 * 反馈文字，不会出现「点了没反应」的空白期。
 */
export function useJobRunner<T>(defaultLabel = ""): JobRunner<T> {
  const [state, setState] = useState<JobRunState<T>>(() => emptyState<T>(defaultLabel));
  const t0 = useRef(0);
  const timer = useRef<number | null>(null);
  const alive = useRef(true);
  const currentJob = useRef("");
  // 后端最近上报的阶段放在 ref 里：终态那一帧要写「最后一个阶段」，但不想让
  // `run` 依赖 state（否则每次 state 变化都换一个新函数，页面 effect 会连环触发）。
  const stageRef = useRef("");

  const stopTick = useCallback(() => {
    if (timer.current !== null) {
      window.clearInterval(timer.current);
      timer.current = null;
    }
  }, []);

  useEffect(
    () => () => {
      alive.current = false;
      if (timer.current !== null) window.clearInterval(timer.current);
    },
    [],
  );

  const patch = useCallback((next: Partial<JobRunState<T>>) => {
    if (!alive.current) return;
    setState((prev) => ({ ...prev, ...next }));
  }, []);

  const reset = useCallback(() => {
    stopTick();
    currentJob.current = "";
    if (alive.current) setState(emptyState<T>(defaultLabel));
  }, [defaultLabel, stopTick]);

  const run = useCallback(
    async (
      submit: () => Promise<{ job_id: string }>,
      opts: JobRunOptions = {},
    ): Promise<JobOutcome<T>> => {
      stopTick();
      currentJob.current = "";
      stageRef.current = "";
      t0.current = Date.now();
      setState({
        ...emptyState<T>(opts.label ?? defaultLabel),
        phase: "submitting",
        label: opts.label ?? defaultLabel,
        progress: opts.progress ?? null,
        startedAt: new Date(),
      });
      // 秒表独立于后端阶段：即使后端几秒内不报新阶段，「已用 Xs」也在动
      timer.current = window.setInterval(() => {
        if (!alive.current) return;
        setState((prev) =>
          prev.phase === "submitting" || prev.phase === "queued" || prev.phase === "running"
            ? { ...prev, elapsedMs: Date.now() - t0.current }
            : prev,
        );
      }, 500);
      try {
        const { job_id } = await submit();
        currentJob.current = job_id;
        stageRef.current = "queued";
        patch({ jobId: job_id, phase: "queued", stage: "queued" });
        const out = await waitJob<T>(job_id, opts.timeoutMs ?? 900_000, (info) => {
          stageRef.current = info.stage;
          patch({
            stage: info.stage,
            elapsedMs: info.elapsedMs,
            phase: info.stage && info.stage !== "queued" ? "running" : "queued",
          });
        });
        const finalPhase: JobPhase =
          out.status === "success"
            ? "success"
            : out.status === "cancelled"
              ? "cancelled"
              : out.status === "timeout"
                ? "timeout"
                : "failed";
        patch({
          phase: finalPhase,
          stage: out.status === "success" ? "done" : stageRef.current,
          elapsedMs: Date.now() - t0.current,
          result: out.result,
          experimentId: out.experimentId ?? null,
          error: out.error ?? "",
        });
        return out;
      } catch (e) {
        const msg = (e as Error).message;
        patch({ phase: "failed", error: msg, elapsedMs: Date.now() - t0.current });
        return { status: "failed", result: null, error: msg };
      } finally {
        stopTick();
      }
    },
    [defaultLabel, patch, stopTick],
  );

  const cancel = useCallback(async () => {
    const jobId = currentJob.current;
    if (!jobId) return;
    patch({ cancelling: true });
    try {
      await cancelJob(jobId);
      // 取消后轮询会在 1.5s 内看到 cancelled 终态；这里先把阶段文字改掉，
      // 让用户马上知道「取消请求已发出」而不是等下一个轮询周期。
      patch({ stage: "cancelling" });
    } finally {
      patch({ cancelling: false });
    }
  }, [patch]);

  return { state, run, cancel, reset };
}