jumble/src/lib/feed-relay-urls.ts

import { normalizeHttpRelayUrl, normalizeRelayUrlByScheme, isHttpOrHttpsScheme } from '@/lib/url'
import type { TFeedSubRequest } from '@/types'

function relayDedupeKey(url: string): string {
  return (normalizeRelayUrlByScheme(url) || url.trim()).toLowerCase()
}

/** Deduped relay URLs from all timeline subrequests (REQ order preserved). */
export function uniqueRelayUrlsFromSubRequests(requests: readonly TFeedSubRequest[]): string[] {
  const seen = new Set<string>()
  const out: string[] = []
  for (const req of requests) {
    for (const raw of req.urls) {
      const n = normalizeRelayUrlByScheme(raw) || raw.trim()
      if (!n) continue
      const key = relayDedupeKey(n)
      if (seen.has(key)) continue
      seen.add(key)
      out.push(n)
    }
  }
  return out
}

/**
 * Keep viewer kind-10243 HTTP index relays in a capped feed stack (they are easy to drop when
 * favorites + NIP-65 WS fill {@link FAUX_SPELL_MAX_RELAYS}).
 */
export function pinHttpIndexRelaysInRelayCap(
  capped: readonly string[],
  sourceUrls: readonly string[],
  maxRelays: number
): string[] {
  const httpSources = sourceUrls
    .map((u) => normalizeHttpRelayUrl(u) || (isHttpOrHttpsScheme(u.trim()) ? u.trim() : ''))
    .filter(Boolean)
  if (httpSources.length === 0) return [...capped]

  const httpKeySet = new Set(httpSources.map((u) => u.toLowerCase()))
  const out = [...capped]
  const outKeys = new Set(out.map(relayDedupeKey))

  for (const http of httpSources) {
    const key = http.toLowerCase()
    if (outKeys.has(key)) continue

    while (out.length >= maxRelays) {
      let dropped = false
      for (let i = out.length - 1; i >= 0; i--) {
        const candidate = out[i]!
        const ck = relayDedupeKey(candidate)
        if (httpKeySet.has(ck) || isHttpOrHttpsScheme(candidate.trim())) continue
        out.splice(i, 1)
        outKeys.delete(ck)
        dropped = true
        break
      }
      if (!dropped) break
    }

    if (out.length >= maxRelays) continue
    out.push(http)
    outKeys.add(key)
  }

  return out.slice(0, maxRelays)
}

/**
 * Keep global mention / read aggregators in a capped stack (notifications `#p` REQs).
 * Long NIP-65 lists otherwise fill {@link FAUX_SPELL_MAX_RELAYS} before index relays are reached.
 */
export function pinMentionRelaysInRelayCap(
  capped: readonly string[],
  mentionSources: readonly string[],
  maxRelays: number,
  minPinned: number
): string[] {
  const pinKeys = new Set(
    mentionSources
      .slice(0, Math.max(0, minPinned))
      .map((u) => relayDedupeKey(u))
      .filter(Boolean)
  )
  if (pinKeys.size === 0) return [...capped]

  const mentionKeySet = new Set(mentionSources.map((u) => relayDedupeKey(u)).filter(Boolean))
  const out = [...capped]
  const outKeys = new Set(out.map(relayDedupeKey))

  for (const raw of mentionSources) {
    const key = relayDedupeKey(raw)
    if (!key || outKeys.has(key)) continue

    while (out.length >= maxRelays) {
      let dropped = false
      for (let i = out.length - 1; i >= 0; i--) {
        const candidate = out[i]!
        const ck = relayDedupeKey(candidate)
        if (pinKeys.has(ck) || mentionKeySet.has(ck)) continue
        out.splice(i, 1)
        outKeys.delete(ck)
        dropped = true
        break
      }
      if (!dropped) break
    }

    if (out.length >= maxRelays) continue
    out.push(raw)
    outKeys.add(key)
    pinKeys.add(key)
    if ([...pinKeys].every((k) => outKeys.has(k))) break
  }

  return out.slice(0, maxRelays)
}