import IP2Region from 'ip2region'
import { existsSync } from 'fs'
import { join } from 'path'
import { isPrivateIp, normalizeIpCandidate } from './clientIp'

interface IpGeodata {
  country: string
  province: string
  city: string
  isp: string
}

const ipLocationLabelCache = new Map<string, string>()
let ip2Region: IP2Region | null | undefined

export function getIpGeodataLabel(ip?: string | null) {
  const normalizedIp = normalizeIpCandidate(ip)
  if (!normalizedIp) {
    return null
  }

  const cachedLabel = ipLocationLabelCache.get(normalizedIp)
  if (cachedLabel) {
    return cachedLabel
  }

  const label = resolveIpGeodataLabel(normalizedIp)
  ipLocationLabelCache.set(normalizedIp, label)
  return label
}

function resolveIpGeodataLabel(ip: string) {
  if (isPrivateIp(ip)) {
    return '内网地址'
  }

  try {
    const geodata = getIp2Region()?.search(ip) as IpGeodata | null
    const parts = uniqueNonEmptyValues([
      geodata?.country,
      geodata?.province,
      geodata?.city,
      geodata?.isp
    ])

    return parts.length > 0 ? parts.join(' ') : '未知归属地'
  } catch {
    return '未知归属地'
  }
}

function getIp2Region() {
  if (ip2Region !== undefined) {
    return ip2Region
  }

  const dataDir = join(process.cwd(), 'node_modules', 'ip2region', 'data')
  const ipv4db = join(dataDir, 'ip2region.db')
  const ipv6db = join(dataDir, 'ipv6wry.db')

  if (!existsSync(ipv4db) || !existsSync(ipv6db)) {
    console.warn(`[geodata] ip2region database files not found in ${dataDir}`)
    ip2Region = null
    return ip2Region
  }

  ip2Region = new IP2Region({ ipv4db, ipv6db })
  return ip2Region
}

function uniqueNonEmptyValues(values: Array<string | undefined>) {
  return Array.from(new Set(values
    .map(value => value?.trim())
    .filter((value): value is string => !!value && value !== '0')))
}