import type { Payload } from "payload";
import { randomUUID } from "node:crypto";

const SESSION_IDLE_WINDOW_MS = 30 * 60 * 1000;

/**
 * Groups events into sessions without any client-side identifier: looks up
 * the most recent event from the same `visitorHash` within the last 30
 * minutes and reuses its sessionId, or mints a new one. One extra indexed
 * read per tracked request - acceptable at this site's traffic volume, and
 * simpler/safer than trying to hold a lock across an unauthenticated,
 * high-frequency public endpoint (unlike lib/booking/lock.ts's advisory
 * lock, an occasional extra spurious session here has no correctness
 * consequences worth the added complexity).
 */
export async function resolveSessionId(payload: Payload, visitorHash: string): Promise<string> {
  const since = new Date(Date.now() - SESSION_IDLE_WINDOW_MS).toISOString();
  const { docs } = await payload.find({
    collection: "analytics-events",
    where: {
      and: [{ visitorHash: { equals: visitorHash } }, { createdAt: { greater_than_equal: since } }],
    },
    sort: "-createdAt",
    limit: 1,
    depth: 0,
  });

  return docs[0]?.sessionId ?? randomUUID();
}