import { LRUCache } from 'lru-cache'

/**
 * Cache entry for group keys
 */
export interface GroupKeyCacheEntry {
  secretKey: string
  version: number
  isActive: boolean // Active keys use shorter TTL, historical use longer
}

export const DEFAULT_KEY_CACHE_MAX_SIZE = 1000
export const DEFAULT_ACTIVE_TTL = 60 * 60 * 1000 // 1 hour
export const DEFAULT_HISTORICAL_TTL = 24 * 60 * 60 * 1000 // 24 hours

/**
 * Create a cache for group keys with TTL support
 */
export function createKeyCache(
  maxSize: number,
): LRUCache<string, GroupKeyCacheEntry> {
  // This will have a custom TTL based on whether key is active or historical
  return new LRUCache<string, GroupKeyCacheEntry>({
    max: maxSize,
    ttlAutopurge: true,
    ttlResolution: 1000, // Check expiry every second
    updateAgeOnGet: false, // Don't refresh TTL on access (cache invalidation, not LRU)
    updateAgeOnHas: false,
  })
}

/**
 * Service auth token cache entry
 */
export interface ServiceAuthTokenEntry {
  token: string
  expiresAt: number // Unix timestamp in milliseconds
}

const DEFAULT_TOKEN_TTL = 60 * 1000 // 60 seconds

/**
 * Create a cache for service auth tokens with 60s TTL
 */
export function createTokenCache(): LRUCache<string, ServiceAuthTokenEntry> {
  return new LRUCache<string, ServiceAuthTokenEntry>({
    max: 100,
    ttl: DEFAULT_TOKEN_TTL,
    ttlAutopurge: true,
    ttlResolution: 1000,
    updateAgeOnGet: false,
    updateAgeOnHas: false,
  })
}

/**
 * Generate cache key for group key
 */
export function getGroupKeyCacheKey(groupId: string, version?: number): string {
  return version ? `${groupId}:${version}` : `${groupId}:latest`
}

/**
 * Generate cache key for service auth token
 */
export function getServiceAuthCacheKey(aud: string, lxm: string): string {
  return `${aud}:${lxm}`
}