// lib/session/repository.ts
import db from '@/db/db'
import { 
    loginSessions, 
  tempAuthSessions, 
  pageVisits,
  type NewLoginSession,
  type NewTempAuthSession,
  type NewPageVisit,
  type LoginSession
} from '@/db/schema'
import { eq, and, desc, lt } from 'drizzle-orm'
import { v4 as uuidv4 } from 'uuid'


// 성능 최적화를 위한 캐시
const sessionCache = new Map<string, { data: any; timestamp: number }>()
const CACHE_TTL = 5 * 60 * 1000 // 5분 캐시

export class SessionRepository {
  // 임시 인증 세션 관리 (기존 메모리 저장소 대체)
  static async createTempAuthSession(data: {
    userId: number
    email: string
    authMethod: string
    expiresAt: Date
  }): Promise<string> {
    const tempAuthKey = `temp_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
    
    try {
      await db.insert(tempAuthSessions).values({
        tempAuthKey,
        userId: data.userId,
        email: data.email,
        authMethod: data.authMethod,
        expiresAt: data.expiresAt,
      })
      
      return tempAuthKey
    } catch (error) {
      console.error('Failed to create temp auth session:', error)
      throw error
    }
  }

  static async getTempAuthSession(tempAuthKey: string) {
    try {
      const result = await db
        .select()
        .from(tempAuthSessions)
        .where(
          and(
            eq(tempAuthSessions.tempAuthKey, tempAuthKey),
            eq(tempAuthSessions.isUsed, false)
          )
        )
        .limit(1)

      const session = result[0]
      if (!session || new Date() > session.expiresAt) {
        return null
      }

      return session
    } catch (error) {
      console.error('Failed to get temp auth session:', error)
      return null
    }
  }

  static async markTempAuthSessionAsUsed(tempAuthKey: string) {
    try {
      await db
        .update(tempAuthSessions)
        .set({ isUsed: true })
        .where(eq(tempAuthSessions.tempAuthKey, tempAuthKey))
    } catch (error) {
      console.error('Failed to mark temp auth session as used:', error)
    }
  }

  static async cleanupExpiredTempSessions() {
    try {
      await db
        .delete(tempAuthSessions)
        .where(lt(tempAuthSessions.expiresAt, new Date()))
    } catch (error) {
      console.error('Failed to cleanup expired temp sessions:', error)
    }
  }

  // 로그인 세션 관리
  static async createLoginSession(data: {
    userId: number
    ipAddress: string
    userAgent?: string
    authMethod: string
    sessionExpiredAt?: Date
    nextAuthSessionId?: string
  }): Promise<LoginSession> {
    try {
      const sessionData: NewLoginSession = {
        userId: data.userId,
        ipAddress: data.ipAddress,
        userAgent: data.userAgent,
        authMethod: data.authMethod,
        sessionExpiredAt: data.sessionExpiredAt,
        nextAuthSessionId: data.nextAuthSessionId,
      }

      const result = await db.insert(loginSessions).values(sessionData).returning()
      
      // 캐시에서 해당 사용자의 활성 세션 정보 제거
      sessionCache.delete(`active_session_${data.userId}`)
      
      return result[0]
    } catch (error) {
      console.error('Failed to create login session:', error)
      throw error
    }
  }

  static async updateLoginSession(sessionId: string, updates: {
    lastActivityAt?: Date
    sessionExpiredAt?: Date
    logoutAt?: Date
    isActive?: boolean
  }) {
    try {
      await db
        .update(loginSessions)
        .set({
          ...updates,
          updatedAt: new Date()
        })
        .where(eq(loginSessions.id, sessionId))
      
      // 캐시 무효화 (세션이 업데이트되었으므로)
      for (const [key] of sessionCache) {
        if (key.includes(sessionId)) {
          sessionCache.delete(key)
        }
      }
    } catch (error) {
      console.error('Failed to update login session:', error)
    }
  }

  // 캐시를 활용한 활성 세션 조회
  static async getActiveSessionByUserId(userId: number) {
    const cacheKey = `active_session_${userId}`
    const cached = sessionCache.get(cacheKey)
    
    // 캐시가 유효한 경우 반환
    if (cached && Date.now() - cached.timestamp < CACHE_TTL) {
      return cached.data
    }

    try {
      const result = await db
        .select()
        .from(loginSessions)
        .where(
          and(
            eq(loginSessions.userId, userId),
            eq(loginSessions.isActive, true)
          )
        )
        .orderBy(desc(loginSessions.loginAt))
        .limit(1)

      const session = result[0] || null
      
      // 캐시에 저장
      sessionCache.set(cacheKey, {
        data: session,
        timestamp: Date.now()
      })
      
      return session
    } catch (error) {
      console.error('Failed to get active session:', error)
      return null
    }
  }

  static async logoutSession(sessionId: string) {
    try {
      await db
        .update(loginSessions)
        .set({
          logoutAt: new Date(),
          isActive: false,
          updatedAt: new Date()
        })
        .where(eq(loginSessions.id, sessionId))
      
      // 캐시에서 관련된 세션 정보 제거
      for (const [key] of sessionCache) {
        if (key.includes(sessionId)) {
          sessionCache.delete(key)
        }
      }
    } catch (error) {
      console.error('Failed to logout session:', error)
    }
  }

  static async logoutAllUserSessions(userId: number) {
    try {
      await db
        .update(loginSessions)
        .set({
          logoutAt: new Date(),
          isActive: false,
          updatedAt: new Date()
        })
        .where(
          and(
            eq(loginSessions.userId, userId),
            eq(loginSessions.isActive, true)
          )
        )
      
      // 해당 사용자의 캐시 제거
      sessionCache.delete(`active_session_${userId}`)
    } catch (error) {
      console.error('Failed to logout all user sessions:', error)
    }
  }

  // 배치 처리를 위한 페이지 방문 기록 (성능 최적화)
  private static visitQueue: NewPageVisit[] = []
  private static isProcessingQueue = false

  static async recordPageVisit(data: {
    userId?: number
    sessionId?: string
    route: string
    pageTitle?: string
    referrer?: string
    ipAddress: string
    userAgent?: string
    queryParams?: string
    deviceType?: string
    browserName?: string
    osName?: string
  }) {
    const visitData: NewPageVisit = {
      userId: data.userId,
      sessionId: data.sessionId,
      route: data.route,
      pageTitle: data.pageTitle,
      referrer: data.referrer,
      ipAddress: data.ipAddress,
      userAgent: data.userAgent,
      queryParams: data.queryParams,
      deviceType: data.deviceType,
      browserName: data.browserName,
      osName: data.osName,
    }

    // 큐에 추가
    this.visitQueue.push(visitData)
    
    // 큐가 20개 이상이거나 3초마다 배치 처리
    if (this.visitQueue.length >= 20 || !this.isProcessingQueue) {
      this.processVisitQueue()
    }
  }

  // 배치 처리로 성능 최적화
  private static async processVisitQueue() {
    if (this.isProcessingQueue || this.visitQueue.length === 0) {
      return
    }

    this.isProcessingQueue = true
    
    try {
      const batch = this.visitQueue.splice(0, 100) // 최대 100개씩 처리
      
      if (batch.length > 0) {
        await db.insert(pageVisits).values(batch)
      }
    } catch (error) {
      console.error('Failed to process visit queue:', error)
    } finally {
      this.isProcessingQueue = false
      
      // 더 처리할 데이터가 있다면 재귀 호출
      if (this.visitQueue.length > 0) {
        setTimeout(() => this.processVisitQueue(), 100)
      }
    }
  }

  // 3초마다 큐 처리 (백그라운드)
  static {
    if (typeof setInterval !== 'undefined') {
      setInterval(() => {
        this.processVisitQueue()
      }, 3000)
    }
  }

  // 세션 활동 업데이트 (논블로킹, 에러 무시)
  static updateSessionActivity(sessionId: string): Promise<void> {
    return new Promise((resolve) => {
      // 비동기로 실행하되 메인 플로우를 블로킹하지 않음
      setImmediate(async () => {
        try {
          await this.updateLoginSession(sessionId, {
            lastActivityAt: new Date()
          })
        } catch (error) {
          // 에러를 로그만 남기고 무시
          console.error('Failed to update session activity (non-blocking):', error)
        }
        resolve()
      })
    })
  }

  static async updatePageVisitDuration(visitId: string, duration: number) {
    try {
      await db
        .update(pageVisits)
        .set({ duration })
        .where(eq(pageVisits.id, visitId))
    } catch (error) {
      console.error('Failed to update page visit duration:', error)
    }
  }

  // 캐시 정리 (메모리 관리)
  static cleanupCache() {
    const now = Date.now()
    
    for (const [key, value] of sessionCache) {
      if (now - value.timestamp > CACHE_TTL) {
        sessionCache.delete(key)
      }
    }
  }

  // 모니터링을 위한 통계 정보 제공
  static getRepositoryStats() {
    return {
      cacheSize: sessionCache.size,
      queueSize: this.visitQueue?.length || 0,
      cacheTTL: CACHE_TTL,
      isProcessingQueue: this.isProcessingQueue
    }
  }

  // 캐시 크기 조회 (모니터링용)
  static getCacheSize(): number {
    return sessionCache.size
  }

  // 큐 크기 조회 (모니터링용)
  static getQueueSize(): number {
    return this.visitQueue?.length || 0
  }

  // 정기적인 캐시 정리 (10분마다)
  static {
    if (typeof setInterval !== 'undefined') {
      setInterval(() => {
        this.cleanupCache()
      }, 10 * 60 * 1000)
    }
  }
}

// 에러 처리를 위한 래퍼 함수들
export const safeSessionOperations = {
  async recordPageVisit(data: Parameters<typeof SessionRepository.recordPageVisit>[0]) {
    try {
      await SessionRepository.recordPageVisit(data)
    } catch (error) {
      console.error('Safe page visit recording failed:', error)
    }
  },

  async updateSessionActivity(sessionId: string) {
    try {
      await SessionRepository.updateSessionActivity(sessionId)
    } catch (error) {
      console.error('Safe session activity update failed:', error)
    }
  },

  async getActiveSession(userId: number) {
    try {
      return await SessionRepository.getActiveSessionByUserId(userId)
    } catch (error) {
      console.error('Safe get active session failed:', error)
      return null
    }
  }
}

// lib/session/monitoring.ts - 성능 모니터링 (수정된 버전)
export class SessionMonitoring {
  private static metrics = {
    pageVisitRecords: 0,
    sessionUpdates: 0,
    cacheHits: 0,
    cacheMisses: 0,
    errors: 0
  }

  static incrementMetric(metric: keyof typeof this.metrics) {
    this.metrics[metric]++
  }

  static getMetrics() {
    return { ...this.metrics }
  }

  static resetMetrics() {
    Object.keys(this.metrics).forEach(key => {
      this.metrics[key as keyof typeof this.metrics] = 0
    })
  }

  // 성능 통계 로깅 (수정된 버전)
  static logPerformanceStats() {
    const repoStats = SessionRepository.getRepositoryStats()
    
    console.log('Session Repository Performance:', {
      ...this.metrics,
      cacheHitRate: this.metrics.cacheHits / (this.metrics.cacheHits + this.metrics.cacheMisses) * 100 || 0,
      ...repoStats // cacheSize, queueSize 등 포함
    })
  }

  // 상세 성능 리포트 생성
  static getDetailedPerformanceReport() {
    const repoStats = SessionRepository.getRepositoryStats()
    const totalRequests = this.metrics.cacheHits + this.metrics.cacheMisses
    
    return {
      metrics: this.getMetrics(),
      repository: repoStats,
      performance: {
        cacheHitRate: totalRequests > 0 ? (this.metrics.cacheHits / totalRequests) * 100 : 0,
        errorRate: this.metrics.pageVisitRecords > 0 ? (this.metrics.errors / this.metrics.pageVisitRecords) * 100 : 0,
        queueUtilization: repoStats.queueSize / 100 * 100, // 100이 최대 큐 크기라고 가정
      },
      status: {
        healthy: this.metrics.errors / Math.max(this.metrics.pageVisitRecords, 1) < 0.01, // 1% 미만 에러율
        cacheEfficient: totalRequests > 0 ? (this.metrics.cacheHits / totalRequests) > 0.8 : true, // 80% 이상 캐시 히트율
        queueManageable: repoStats.queueSize < 50 // 큐 크기가 50 미만
      }
    }
  }
}