/**
 * R2 增强：崩溃恢复（WAL 重放）。
 * 启动时若启用了 WAL（GW_WAL=1），用 recoverInFlight() 找出「已 claim 未 settle」的任务，
 * 统一重投队列并记录恢复审计；重复 claim 由幂等键去重。
 */
import { TASK_STATE } from "./protocol.js";

/** 从 WAL 恢复在途任务：返回恢复的任务数。 */
export function recoverFromWal(store) {
  if (!store.wal) return { recovered: 0, reason: "wal-disabled", tasks: [] };
  const inFlight = store.wal.recoverInFlight();
  const tasks = [];
  for (const rec of inFlight) {
    const t = store.tasks.get(rec.taskId);
    if (!t) continue;
    // 仅在仍处于 assigned/running 时重投（done/dead 不再动）
    if (![TASK_STATE.ASSIGNED, TASK_STATE.RUNNING].includes(t.state)) continue;
    t.state = TASK_STATE.QUEUED;
    t.nodeId = null;
    t.notBefore = Date.now() + 300;
    t.history.push({ at: Date.now(), note: "崩溃恢复：WAL 重投（claim 未 settle）" });
    store.addAudit({ kind: "task.recover", taskId: t.id, from: "wal" });
    tasks.push(t);
  }
  store.scheduleSave?.();
  return { recovered: tasks.length, reason: "wal-replay", tasks };
}

/** recovery-demo：演示「claim 后崩溃 → 重启 → WAL 恢复」。 */
export async function runRecoveryDemo({ stateRoot = null } = {}) {
  const { WAL } = await import("./wal.js");
  const { GatewayStore } = await import("./store.js");
  const { tmpdir } = await import("node:os");
  const { join } = await import("node:path");
  const { mkdtempSync, rmSync } = await import("node:fs");
  const dir = stateRoot || mkdtempSync(join(tmpdir(), "gw-recovery-"));

  // 阶段 1：正常运行，claim 了一些任务但没有 settle（模拟崩溃）
  const wal1 = new WAL(dir, "demo");
  const store1 = new GatewayStore({ persist: false, wal: wal1 });
  const a = store1.createTask({ title: "recover-A" });
  const b = store1.createTask({ title: "recover-B" });
  const c = store1.createTask({ title: "recover-C" });
  // 模拟 claim（WAL 已记录）
  for (const t of [a, b]) {
    store1.walAppend("task.claimed", { taskId: t.id, key: "claim:" + t.id + ":n1", data: { nodeId: "n1" } });
    t.state = TASK_STATE.ASSIGNED;
    t.nodeId = "n1";
  }
  // c 正常完成（settle 已入 WAL）
  store1.walAppend("task.settled", { taskId: c.id, key: "settle:" + c.id + ":n1", data: { ok: true } });
  c.state = TASK_STATE.DONE;

  // 阶段 2：崩溃重启，用同一 WAL 新建 store，重放恢复
  const wal2 = new WAL(dir, "demo"); // 同一 owner 重放
  const store2 = new GatewayStore({ persist: false, wal: wal2 });
  store2.tasks.set(a.id, { ...a, state: TASK_STATE.ASSIGNED, nodeId: "n1" });
  store2.tasks.set(b.id, { ...b, state: TASK_STATE.ASSIGNED, nodeId: "n1" });
  store2.tasks.set(c.id, { ...c, state: TASK_STATE.DONE });
  const res = recoverFromWal(store2);
  const summary = {
    walFile: wal2.file,
    claimedUnsettled: res.tasks.length,
    recovered: res.tasks.map((t) => t.id),
    requeuedStates: res.tasks.map((t) => t.state),
    settledTaskUntouched: store2.tasks.get(c.id).state,
  };
  console.log("=== recovery-demo ===");
  console.log(JSON.stringify(summary, null, 2));
  if (!stateRoot) rmSync(dir, { recursive: true, force: true });
  return summary;
}