Implement NIP-85 fallback WOT ranking

src/app/util/wot/getPubkeyRank.ts

@@ -0,0 +1,96 @@
+import {request} from "@welshman/net"
+import {clamp} from "@welshman/lib"
+import type {TrustedEvent} from "@welshman/util"
+
+const DEFAULT_ASSERTION_RELAYS =
+  "wss://nip85.brainstorm.world,wss://nip85.nosfabrica.com,wss://nip85.uid.ovh"
+
+const toAssertionRelayUrl = (url: string) => {
+  const trimmed = url.trim()
+
+  if (!trimmed) return ""
+  if (trimmed.startsWith("http://")) return trimmed.replace(/^http:/, "ws:")
+  if (trimmed.startsWith("https://")) return trimmed.replace(/^https:/, "wss:")
+  if (!/^[a-z]+:\/\//i.test(trimmed)) return `wss://${trimmed}`
+
+  return trimmed
+}
+
+const ASSERTION_RELAYS = String(import.meta.env.VITE_ASSERTION_RELAYS || DEFAULT_ASSERTION_RELAYS)
+  .split(",")
+  .map(toAssertionRelayUrl)
+  .filter(Boolean)
+
+const rankCache = new Map<string, number | null>()
+const pendingRankRequests = new Map<string, Promise<number | null>>()
+
+const getMedian = (values: number[]) => {
+  const sorted = [...values].sort((a, b) => a - b)
+  const middle = Math.floor(sorted.length / 2)
+
+  if (sorted.length % 2 === 1) {
+    return sorted[middle]
+  }
+
+  return (sorted[middle - 1] + sorted[middle]) / 2
+}
+
+const getRankFromEvent = (event: TrustedEvent) => {
+  const rankTag = event.tags?.find((tag: string[]) => tag[0] === "rank")
+  const rankValue = rankTag ? Number(rankTag[1]) : null
+
+  if (rankValue === null || !Number.isFinite(rankValue)) {
+    return null
+  }
+
+  return clamp([0, 100], rankValue)
+}
+
+const fetchPubkeyRank = async (pubkey: string): Promise<number | null> => {
+  if (ASSERTION_RELAYS.length === 0) {
+    return 50
+  }
+
+  try {
+    const events = await request({
+      relays: ASSERTION_RELAYS,
+      autoClose: true,
+      filters: [{kinds: [30382], "#d": [pubkey], limit: 8}],
+    })
+
+    const ranks = events.map(getRankFromEvent).filter((rank): rank is number => rank !== null)
+
+    if (ranks.length === 0) {
+      return 50
+    }
+
+    const median = getMedian(ranks)
+
+    return median
+  } catch {
+    return 50
+  }
+}
+
+export const getPubkeyRank = (pubkey: string): Promise<number | null> => {
+  if (rankCache.has(pubkey)) {
+    return Promise.resolve(rankCache.get(pubkey) ?? 50)
+  }
+
+  const pending = pendingRankRequests.get(pubkey)
+
+  if (pending) {
+    return pending
+  }
+
+  const requestPromise = fetchPubkeyRank(pubkey).then(rank => {
+    rankCache.set(pubkey, rank ?? 50)
+    pendingRankRequests.delete(pubkey)
+
+    return rank ?? 50
+  })
+
+  pendingRankRequests.set(pubkey, requestPromise)
+
+  return requestPromise
+}