/**
 * presence-sync — read each connected agent's HF status (via the
 * cross-plugin `globalThis.__hfAgentStatus.get(agentId)` exposed by
 * HarborForge.OpenclawPlugin) and push diffs to Fabric.Backend.Guild
 * `PUT /api/agents/:userId/presence` so the backend can apply
 * busy-discard on `announce`-type channel deliveries.
 *
 * Push model: we only PUT when an agent's status actually changes
 * (since the last push). The HF-side accessor has its own TTL cache
 * to absorb the every-30s polling.
 *
 * Auth: the endpoint sits behind ApiKeyGuard (global APP_GUARD per
 * app.module.js) which expects `Authorization: Bearer <guild-token>`
 * — NOT the agent's fabricApiKey directly. So before each PUT we do
 * a fresh agent-login (or reuse a cached token if still within its
 * 15-min JWT TTL) and pull the guildAccessToken matching the target
 * guild. Status changes are rare enough that login overhead is fine.
 *
 * If HF plugin isn't loaded (`__hfAgentStatus` undefined), the loop
 * is a no-op — Fabric backend defaults presence to 'unknown' which is
 * treated as not-busy. Announce-channel delivery still works; busy
 * filtering simply doesn't kick in.
 */
import type { FabricClient } from './fabric-client.js';

type HfStatus = 'idle' | 'on_call' | 'busy' | 'exhausted' | 'offline';
type Bridge = { get(agentId: string): Promise<HfStatus | undefined> };
type Logger = { info: (m: string) => void; warn: (m: string) => void };

export interface PresenceSyncAccount {
  agentId: string;
  fabricUserId: string; // the agent's Fabric Center user id (UUID)
  guildBaseUrl: string; // e.g. https://fabric.hangman-lab.top/guild/<id>
  guildNodeId: string;  // which guildAccessTokens[].guildNodeId to pick
  fabricApiKey: string; // existing per-account key (used for agent-login)
}

// Guild access JWTs expire every 900s. Refresh ~2 min early to stay
// safely inside the window even if a tick runs late.
const TOKEN_TTL_MS = (15 - 2) * 60 * 1000;

interface CachedToken {
  token: string;
  expiresAt: number; // epoch ms
}

export class PresenceSync {
  private timer: ReturnType<typeof setInterval> | null = null;
  private readonly lastStatus = new Map<string, HfStatus>(); // by agentId
  private readonly accounts = new Map<string, PresenceSyncAccount>();
  private readonly tokenCache = new Map<string, CachedToken>(); // by agentId

  // Mutex flag: a tick iterates accounts serially with `await` on each
  // agent-login + PUT round-trip, so a single tick can easily run 20+s
  // when there are many accounts. setInterval(intervalMs) does NOT wait
  // for the previous tick to finish — without this guard the next tick
  // fires on top of a still-running one and two parallel iterations
  // PUT the same agentId within milliseconds. That tipped the backend's
  // first-time-insert race (separate fix in Fabric.Backend.Guild) into
  // 500s on prod. Guarded ticks just skip a beat instead.
  private inflight = false;

  constructor(private readonly logger: Logger, private readonly client: FabricClient) {}

  setAccounts(accounts: PresenceSyncAccount[]): void {
    this.accounts.clear();
    for (const a of accounts) this.accounts.set(a.agentId, a);
  }

  start(intervalMs = 30_000): void {
    if (this.timer) return;
    this.timer = setInterval(() => {
      this.tick().catch((err) => this.logger.warn(`fabric: presence-sync error: ${String(err)}`));
    }, intervalMs);
    // run once immediately so initial state lands fast
    void this.tick();
  }

  stop(): void {
    if (this.timer) {
      clearInterval(this.timer);
      this.timer = null;
    }
  }

  /**
   * Fetch a fresh guildAccessToken for `acct`, caching it under the
   * agentId until just before its JWT expiry. Returns null on login
   * failure or if the session has no matching guild — caller logs +
   * skips the PUT.
   */
  private async ensureGuildToken(acct: PresenceSyncAccount): Promise<string | null> {
    const now = Date.now();
    const cached = this.tokenCache.get(acct.agentId);
    if (cached && cached.expiresAt > now) return cached.token;

    let session;
    try {
      session = await this.client.agentLogin(acct.fabricApiKey);
    } catch (err) {
      this.logger.warn(`fabric: presence-sync agent-login failed for ${acct.agentId}: ${String(err)}`);
      return null;
    }
    const entry = session.guildAccessTokens.find((g) => g.guildNodeId === acct.guildNodeId);
    if (!entry?.token) {
      this.logger.warn(
        `fabric: presence-sync no guild token for ${acct.agentId} guild=${acct.guildNodeId}`,
      );
      return null;
    }
    this.tokenCache.set(acct.agentId, { token: entry.token, expiresAt: now + TOKEN_TTL_MS });
    return entry.token;
  }

  private async tick(): Promise<void> {
    // Mutex: see the `inflight` field declaration for the why. Drop
    // overlapping ticks rather than letting them run concurrently —
    // status is gated by `lastStatus !== bridge.get`, so skipping a
    // beat costs nothing the next beat won't catch.
    if (this.inflight) return;
    this.inflight = true;
    try {
      await this.tickInner();
    } finally {
      this.inflight = false;
    }
  }

  private async tickInner(): Promise<void> {
    const bridge = (globalThis as Record<string, unknown>)['__hfAgentStatus'] as Bridge | undefined;
    if (!bridge || typeof bridge.get !== 'function') return; // HF plugin not loaded — skip

    for (const [agentId, acct] of this.accounts) {
      let status: HfStatus | undefined;
      try {
        status = await bridge.get(agentId);
      } catch {
        continue;
      }
      if (!status) continue;
      if (this.lastStatus.get(agentId) === status) continue; // no change → no PUT

      const guildToken = await this.ensureGuildToken(acct);
      if (!guildToken) continue;

      try {
        // Endpoint: PUT /api/agents/:userId/presence. ApiKeyGuard (global
        // APP_GUARD) requires `Authorization: Bearer <guildAccessToken>`
        // — NOT the agent's raw fabricApiKey. Pre-v1: this loop sent
        // x-api-key and got 401 "missing bearer token" forever. The /api
        // prefix is required because the guild backend sets a global
        // 'api' prefix in main.ts setGlobalPrefix('api').
        const url = `${acct.guildBaseUrl.replace(/\/$/, '')}/api/agents/${encodeURIComponent(acct.fabricUserId)}/presence`;
        const res = await fetch(url, {
          method: 'PUT',
          headers: {
            'content-type': 'application/json',
            authorization: `Bearer ${guildToken}`,
          },
          body: JSON.stringify({ status, source: 'hf-plugin' }),
        });
        if (res.ok) {
          this.lastStatus.set(agentId, status);
          this.logger.info(`fabric: presence-sync ${agentId} → ${status}`);
        } else {
          // 401 here usually means the cached token went stale unexpectedly
          // (server-side rotation or clock skew) — drop the cache so the
          // next tick re-logs-in.
          if (res.status === 401) this.tokenCache.delete(agentId);
          this.logger.warn(`fabric: presence-sync PUT ${agentId} failed: ${res.status}`);
        }
      } catch (err) {
        this.logger.warn(`fabric: presence-sync PUT ${agentId} threw: ${String(err)}`);
      }
    }
  }
}