Function findCreationClusters

web/src/server/free-session/abuse-detection.ts:503–535

(
  rows: { email: string; createdAt: Date }[],
)

}

function findCreationClusters(
  rows: { email: string; createdAt: Date }[],
): CreationCluster[] {
  const sorted = [...rows].sort(
    (a, b) => a.createdAt.getTime() - b.createdAt.getTime(),
  )
  // Greedy non-overlapping sweep: walk the sorted list, and whenever the next
  // account is within the window of the current cluster's first member, add
  // it. Emit clusters that reach the minimum size.
  const clusters: CreationCluster[] = []
  let i = 0
  while (i < sorted.length) {
    let j = i + 1
    while (
      j < sorted.length &&
      sorted[j].createdAt.getTime() - sorted[i].createdAt.getTime() <=
        CREATION_CLUSTER_WINDOW_MS
    ) {
      j++
    }
    if (j - i >= CREATION_CLUSTER_MIN_SIZE) {
      clusters.push({
        windowStart: sorted[i].createdAt,
        windowEnd: sorted[j - 1].createdAt,
        emails: sorted.slice(i, j).map((m) => m.email),
      })
      i = j
    } else {
      i++
    }
  }
  return clusters
}

export function formatSweepReport(report: SweepReport): {
  subject: string