// Per-route runtime state: sequence cursors + rate-limit windows.
// Keyed by route file; reset on server restart.

const seqCursor = new Map<string, number>()

/** Return the next index in a sequence of length n, advancing the cursor. */
export function nextSeqIndex(key: string, n: number): number {
  const i = seqCursor.get(key) ?? 0
  seqCursor.set(key, i + 1)
  return i % n
}

const rlHits = new Map<string, number[]>()

/** Sliding-window rate limit. Returns remaining + whether this call is allowed. */
export function rateCheck(key: string, max: number, windowMs: number, now: number) {
  const hits = (rlHits.get(key) ?? []).filter((t) => now - t < windowMs)
  if (hits.length >= max) {
    rlHits.set(key, hits)
    const retryMs = windowMs - (now - hits[0])
    return { allowed: false, remaining: 0, retryMs }
  }
  hits.push(now)
  rlHits.set(key, hits)
  return { allowed: true, remaining: max - hits.length, retryMs: 0 }
}