/**
 * useCVMServerHealth
 * ─────────────────────────────────────────────────────────────────────────────
 * Owner-only health probe for the SkateSpots ContextVM (CVM) MCP server.
 *
 * A ContextVM server lives as a Nostr identity that publishes a server
 * announcement and listens for encrypted MCP requests on the ContextVM relay.
 * The most reliable "is it alive?" signal we can read from the browser is the
 * server's own events on that relay: the announcement (kind 31990) plus any
 * newer heartbeat/activity. We report status + how long ago the server was
 * last seen.
 *
 * NOTE: the user-facing Sasquatch data layer (`useCVMClient`) queries the data
 * relays DIRECTLY and does NOT depend on this server being up. This probe is
 * purely an operational status check for platform owners.
 */

import { useCallback, useState } from 'react';
import { useNostr } from '@nostrify/react';

/** The SkateSpots CVM server identity (see contextvm.org/s/<pubkey>). */
export const CVM_SERVER_PUBKEY =
  'e3564bb877adb0c99a7e4973ccb22e516d7d9eca0027d0bd62a04174ed670530';

/** The relay the CVM server announces on. */
export const CVM_RELAY = 'wss://relay.contextvm.org';

/** Freshness threshold: if the newest event is older than this, call it stale. */
const STALE_AFTER_MS = 60 * 60 * 1000; // 1 hour

export type CVMHealthStatus = 'idle' | 'checking' | 'online' | 'stale' | 'offline' | 'error';

export interface CVMHealthResult {
  status: CVMHealthStatus;
  /** Unix seconds of the newest event authored by the server, if any. */
  lastSeen: number | null;
  /** Number of server-authored events found on the probe. */
  eventCount: number;
  /** Human-readable error, when status === 'error'. */
  error: string | null;
  /** When the probe last ran (ms epoch). */
  checkedAt: number | null;
}

const INITIAL: CVMHealthResult = {
  status: 'idle',
  lastSeen: null,
  eventCount: 0,
  error: null,
  checkedAt: null,
};

export function useCVMServerHealth() {
  const { nostr } = useNostr();
  const [result, setResult] = useState<CVMHealthResult>(INITIAL);

  const check = useCallback(async () => {
    setResult((r) => ({ ...r, status: 'checking', error: null }));

    try {
      // Probe the ContextVM relay directly for anything the server has authored.
      // We ask for a small window across the kinds a CVM server emits:
      // 31990 (handler/announcement), plus recent activity of any kind.
      const relay = nostr.relay(CVM_RELAY);
      const signal = AbortSignal.timeout(8000);

      const events = await relay.query(
        [{ authors: [CVM_SERVER_PUBKEY], limit: 25 }],
        { signal },
      );

      if (!events.length) {
        setResult({
          status: 'offline',
          lastSeen: null,
          eventCount: 0,
          error: null,
          checkedAt: Date.now(),
        });
        return;
      }

      const lastSeen = Math.max(...events.map((e) => e.created_at));
      const ageMs = Date.now() - lastSeen * 1000;
      const status: CVMHealthStatus = ageMs <= STALE_AFTER_MS ? 'online' : 'stale';

      setResult({
        status,
        lastSeen,
        eventCount: events.length,
        error: null,
        checkedAt: Date.now(),
      });
    } catch (err) {
      setResult({
        status: 'error',
        lastSeen: null,
        eventCount: 0,
        error: err instanceof Error ? err.message : 'Could not reach the ContextVM relay',
        checkedAt: Date.now(),
      });
    }
  }, [nostr]);

  const reset = useCallback(() => setResult(INITIAL), []);

  return { ...result, check, reset };
}