import { connectRedis } from './redis'

/**
 * Cache management utilities for dashboard and topic data
 */

export class DashboardCache {
  /**
   * Invalidate dashboard cache for a specific user
   */
  static async invalidateUserDashboard(userId: string): Promise<void> {
    try {
      const redisClient = await connectRedis()
      const cacheKey = `dashboard:user:${userId}`
      await redisClient.del(cacheKey)
      console.log(`Dashboard cache invalidated for user ${userId}`)
    } catch (error) {
      console.warn('Failed to invalidate dashboard cache:', error)
    }
  }

  /**
   * Invalidate dashboard caches for multiple users
   */
  static async invalidateMultipleUserDashboards(userIds: string[]): Promise<void> {
    try {
      const redisClient = await connectRedis()
      const cacheKeys = userIds.map((userId) => `dashboard:user:${userId}`)
      if (cacheKeys.length > 0) {
        await redisClient.del(cacheKeys)
        console.log(`Dashboard caches invalidated for ${userIds.length} users`)
      }
    } catch (error) {
      console.warn('Failed to invalidate multiple dashboard caches:', error)
    }
  }

  /**
   * Get cached dashboard data for a user
   */
  static async getUserDashboard(userId: string): Promise<any | null> {
    try {
      const redisClient = await connectRedis()
      const cacheKey = `dashboard:user:${userId}`
      const cachedData = await redisClient.get(cacheKey)

      if (!cachedData) return null

      // Handle both string and Buffer responses
      const dataString = Buffer.isBuffer(cachedData)
        ? cachedData.toString('utf-8')
        : String(cachedData)

      return JSON.parse(dataString)
    } catch (error) {
      console.warn('Failed to get cached dashboard data:', error)
      return null
    }
  }

  /**
   * Set dashboard cache for a user
   */
  static async setUserDashboard(userId: string, data: any, ttlSeconds = 300): Promise<void> {
    try {
      const redisClient = await connectRedis()
      const cacheKey = `dashboard:user:${userId}`
      await redisClient.setEx(cacheKey, ttlSeconds, JSON.stringify(data))
      console.log(`Dashboard data cached for user ${userId} (TTL: ${ttlSeconds}s)`)
    } catch (error) {
      console.warn('Failed to cache dashboard data:', error)
    }
  }
}

export class TopicCache {
  /**
   * Invalidate topic-specific caches when a topic is modified
   */
  static async invalidateTopicCaches(topicSlug: string, authorId: string): Promise<void> {
    try {
      const redisClient = await connectRedis()

      // Invalidate patterns that might be affected
      const cachePatterns = [
        `topic:${topicSlug}`, // Individual topic cache
        `topics:public:*`, // Public topic listings
        `topics:user:${authorId}:*`, // User's topic listings
        `dashboard:user:${authorId}`, // User's dashboard
      ]

      for (const pattern of cachePatterns) {
        if (pattern.includes('*')) {
          // For patterns with wildcards, we need to scan and delete
          const keys = await redisClient.keys(pattern)
          if (keys.length > 0) {
            await redisClient.del(keys)
            console.log(`Invalidated ${keys.length} cache keys matching pattern: ${pattern}`)
          }
        } else {
          // Direct key deletion
          await redisClient.del(pattern)
          console.log(`Cache key deleted: ${pattern}`)
        }
      }
    } catch (error) {
      console.warn('Failed to invalidate topic caches:', error)
    }
  }

  /**
   * Invalidate public topic listing caches
   */
  static async invalidatePublicTopicCaches(): Promise<void> {
    try {
      const redisClient = await connectRedis()
      const keys = await redisClient.keys('topics:public:*')
      if (keys.length > 0) {
        await redisClient.del(keys)
        console.log(`Invalidated ${keys.length} public topic cache keys`)
      }
    } catch (error) {
      console.warn('Failed to invalidate public topic caches:', error)
    }
  }
}

/**
 * Utility function to generate consistent cache keys
 */
export const CacheKeys = {
  userDashboard: (userId: string) => `dashboard:user:${userId}`,
  userTopics: (userId: string, page = 1, limit = 10) =>
    `topics:user:${userId}:page:${page}:limit:${limit}`,
  publicTopics: (page = 1, limit = 10, filters?: string) => {
    const filterKey = filters ? `:filters:${Buffer.from(filters).toString('base64')}` : ''
    return `topics:public:page:${page}:limit:${limit}${filterKey}`
  },
  individualTopic: (slug: string) => `topic:${slug}`,
  relatedTopics: (topicId: string) => `topics:related:${topicId}`,
}