import type { Db } from '@evofw/db'
import { repos } from '@evofw/db'
import { refreshAllHostnameRules } from '../policy/resolve-hostname.js'
import { rebuildListCascade, publishListCascade } from './entries.js'
import { uniqCidrs } from '../uniq.js'
import { decryptSecret } from '../secret-cipher.js'
import { fetchEvobgpPages } from '../evobgp.js'
import { safeFetchJson, SOURCE_LIMITS } from '../safe-fetch.js'



async function fetchJsonUrl(url: string): Promise<string[]> {
  const { data } = await safeFetchJson(url)
  const out: string[] = []
  let recognized = false
  const push = (v: unknown) => {
    if (out.length >= SOURCE_LIMITS.elements) throw new Error('JSON prefix element limit exceeded')
    if (typeof v !== 'string' || !v.trim()) throw new Error('Invalid JSON prefix item')
    out.push(v.trim())
  }
  if (Array.isArray(data)) {
    recognized = true
    for (const item of data) {
      if (typeof item === 'string') push(item)
      else if (item && typeof item === 'object') {
        const o = item as Record<string, unknown>
        push(o.cidr ?? o.prefix ?? o.ip ?? o.network)
      } else throw new Error('Invalid JSON prefix item')
    }
  } else if (data && typeof data === 'object') {
    const o = data as Record<string, unknown>
    const arr = (o.prefixes ?? o.cidrs ?? o.ips ?? o.items) as unknown
    if (Array.isArray(arr)) {
      recognized = true
      for (const item of arr) {
        if (typeof item === 'string') push(item)
        else if (item && typeof item === 'object') {
          const x = item as Record<string, unknown>
          push(x.cidr ?? x.prefix ?? x.ip)
        } else throw new Error('Invalid JSON prefix item')
      }
    }
  }
  if (!recognized) throw new Error('Invalid JSON prefix response')
  return uniqCidrs(out)
}

const UUID_RE =
  /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i

async function resolveEvobgpCommunityId(
  base: string,
  token: string,
  communityIdOrLabel: string,
): Promise<string> {
  const key = communityIdOrLabel.trim()
  if (!key) throw new Error('community_id required')
  if (UUID_RE.test(key)) return key

  // Heal lists created when Autocomplete stored label instead of UUID.
  const pages = await fetchEvobgpPages(base, token, '/v1/communities', 200)
  const items = pages.flatMap((page) => {
    if (!Array.isArray(page.items)) throw new Error('Invalid EvoBGP communities')
    return page.items as { id?: string; community?: string; title?: string | null }[]
  })
  const hit = items.find((c) => {
    if (!c.id || !c.community) return false
    if (c.id === key || c.community === key) return true
    if (c.title && `${c.community} · ${c.title}` === key) return true
    return false
  })
  if (!hit?.id) {
    throw new Error(`EvoBGP community not found: ${key}`)
  }
  return hit.id
}

async function fetchEvobgpCommunity(apiUrl: string, token: string, communityId: string): Promise<{ cidrs: string[]; resolvedId: string }> {
  const base = apiUrl.replace(/\/$/, '')
  const resolvedId = await resolveEvobgpCommunityId(base, token, communityId)
  const pages = await fetchEvobgpPages(base, token, `/v1/communities/${encodeURIComponent(resolvedId)}/prefixes`, 5000)
  const cidrs = pages.flatMap((page) => {
    if (Array.isArray(page.prefixes)) return page.prefixes as string[]
    if (Array.isArray(page.items)) return page.items.map((item) => {
      if (!item || typeof item !== 'object' || typeof item.prefix !== 'string') throw new Error('Invalid EvoBGP prefix item')
      return item.prefix as string
    })
    throw new Error('Invalid EvoBGP prefix page')
  })
  return { cidrs: uniqCidrs(cidrs), resolvedId }
}

let activeRefreshes = 0
const waiting: (() => void)[] = []
const refreshing = new WeakMap<Db, Map<string, Promise<void>>>()

async function withRefreshSlot(work: () => Promise<void>): Promise<void> {
  if (activeRefreshes >= 2) await new Promise<void>(resolve => waiting.push(resolve))
  else activeRefreshes++
  try { await work() } finally {
    const next = waiting.shift()
    if (next) next()
    else activeRefreshes--
  }
}

/** Coalesce duplicate triggers per DB/list; at most two refreshes process-wide. */
export function refreshIpList(db: Db, listId: string): Promise<void> {
  let running = refreshing.get(db)
  if (!running) { running = new Map(); refreshing.set(db, running) }
  const existing = running.get(listId)
  if (existing) return existing
  const task = withRefreshSlot(() => performRefresh(db, listId)).finally(() => running!.delete(listId))
  running.set(listId, task)
  return task
}

async function performRefresh(db: Db, listId: string): Promise<void> {
  const list = repos.getIpList(db, listId)
  if (!list) return
  const sourceSettings = [repos.getSetting(db, 'evobgp_api_url'), repos.getSetting(db, 'evobgp_api_token')]

  let config: Record<string, unknown> = {}
  try {
    config = JSON.parse(list.configJson || '{}') as Record<string, unknown>
  } catch {
    config = {}
  }

  try {
    let cidrs: string[] = []
    if (list.type === 'static' || list.type === 'domains') {
      await rebuildListCascade(db, listId)
      repos.updateIpList(db, listId, { refreshedAt: new Date().toISOString(), lastError: null })
      return
    } else if (list.type === 'json_url') {
      const url = String(config.url ?? '')
      if (!url) throw new Error('config.url required')
      cidrs = await fetchJsonUrl(url)

    } else if (list.type === 'evobgp_community') {
      const apiUrl =
        String(config.api_url ?? '') ||
        repos.getSetting(db, 'evobgp_api_url') ||
        ''
      const token =
        decryptSecret(String(config.api_token ?? '') || null) ??
        decryptSecret(repos.getSetting(db, 'evobgp_api_token'))
      const communityId = String(config.community_id ?? '')
      if (!apiUrl || !token || !communityId) {
        throw new Error('evobgp_api_url, token and community_id required')
      }
      const fetched = await fetchEvobgpCommunity(apiUrl, token, communityId)
      cidrs = fetched.cidrs

      // Persist resolved UUID if list was saved with autocomplete label.
      if (fetched.resolvedId !== communityId) {
        config.community_id = fetched.resolvedId
      }
    } else throw new Error('Unsupported list source type')

    if (!cidrs.length && config.allow_empty !== true) throw new Error('Empty source snapshot quarantined; set config.allow_empty=true to publish it')
    if (list.type === 'evobgp_community' && sourceSettings.some((value, index) => value !== repos.getSetting(db, index === 0 ? 'evobgp_api_url' : 'evobgp_api_token'))) {
      throw new Error('EvoBGP settings changed during refresh; retry refresh')
    }
    await publishListCascade(db, listId, { cidrs, configJson: JSON.stringify(config), expected: list })
  } catch (err) {
    const current = repos.getIpList(db, listId)
    if (!current || current.configJson !== list.configJson || current.type !== list.type || current.contentHash !== list.contentHash || current.updatedAt !== list.updatedAt) return
    repos.updateIpList(db, listId, {
      lastError: (err instanceof Error ? err.message : String(err)).slice(0, 512),
    })
  }
}

export async function refreshAllLists(db: Db): Promise<void> {
  for (const list of repos.listIpLists(db)) {
    await refreshIpList(db, list.id)
  }
  await refreshAllHostnameRules(db)
}