// hooks/use-sync-status.ts (완전히 개선된 버전)
import useSWR, { mutate as globalMutate } from 'swr'
import useSWRMutation from 'swr/mutation'
import * as React from 'react'

// 🔧 타입 정의 강화
interface SyncStatus {
  syncEnabled: boolean
  pendingChanges: number
  syncedChanges: number
  failedChanges: number
  lastSyncAt?: string | null
  error?: string | null
  projectId?: number
  targetSystem?: string
  lastUpdated?: string
}

interface ApiError extends Error {
  status: number
  response?: any
}

interface SyncBatch {
  id: string
  projectId: number
  targetSystem: string
  status: 'PENDING' | 'RUNNING' | 'COMPLETED' | 'FAILED'
  startedAt?: string
  completedAt?: string
  itemCount: number
  successCount: number
  failureCount: number
  errors?: string[]
}

interface SyncConfig {
  projectId: number
  targetSystem: string
  autoSyncEnabled: boolean
  syncInterval: number
  batchSize: number
  retryAttempts: number
  notificationEnabled: boolean
}

// 🔧 환경 설정
const MAX_CONTRACTS = parseInt(process.env.NEXT_PUBLIC_MAX_SYNC_CONTRACTS || '20', 10)

// 🔧 개선된 fetcher 함수
const fetcher = async (url: string): Promise<any> => {
  try {
    const response = await fetch(url, {
      headers: {
        'Content-Type': 'application/json',
      }
    })

    if (!response.ok) {
      const errorData = await response.json().catch(() => ({}))
      const error = new Error(errorData.message || `HTTP ${response.status}: ${response.statusText}`) as ApiError
      error.status = response.status
      error.response = errorData
      throw error
    }

    return response.json()
  } catch (error) {
    if (error instanceof TypeError && error.message === 'Failed to fetch') {
      // 네트워크 오류
      const networkError = new Error('네트워크 연결을 확인해주세요') as ApiError
      networkError.status = 0
      throw networkError
    }
    throw error
  }
}

// 🔧 안전한 기본값 생성
const createDefaultSyncStatus = (error?: string, projectId?: number): SyncStatus => ({
  syncEnabled: false,
  pendingChanges: 0,
  syncedChanges: 0,
  failedChanges: 0,
  lastSyncAt: null,
  error,
  projectId,
  lastUpdated: new Date().toISOString()
})

// ✅ 단일 계약 동기화 상태 조회
export function useSyncStatus(projectId: number | null, targetSystem: string = 'SHI') {
  const key = projectId 
    ? `/api/sync/status?projectId=${projectId}&targetSystem=${targetSystem}`
    : null

  const { data, error, isLoading, mutate: localMutate } = useSWR<SyncStatus>(
    key,
    fetcher,
    {
      refreshInterval: 30000,
      revalidateOnFocus: true,
      revalidateOnReconnect: true,
      shouldRetryOnError: (error: ApiError) => {
        // 4xx 에러는 재시도하지 않음
        return error.status >= 500 || error.status === 0
      },
      errorRetryCount: 3,
      errorRetryInterval: 2000,
      dedupingInterval: 5000,
      keepPreviousData: true,
      // 서버 사이드 렌더링에서는 요청하지 않음
      isPaused: () => typeof window === 'undefined'
    }
  )

  const refetch = React.useCallback(() => {
    if (key) {
      localMutate()
    }
  }, [key, localMutate])

  // 항상 안전한 데이터 반환
  const safeData: SyncStatus = React.useMemo(() => {
    if (data && typeof data === 'object') {
      return {
        syncEnabled: Boolean(data.syncEnabled),
        pendingChanges: Number(data.pendingChanges) || 0,
        syncedChanges: Number(data.syncedChanges) || 0,
        failedChanges: Number(data.failedChanges) || 0,
        lastSyncAt: data.lastSyncAt || null,
        error: data.error || (error ? (error as ApiError).message : null),
        projectId: projectId || data.projectId,
        targetSystem: targetSystem,
        lastUpdated: new Date().toISOString()
      }
    }
    
    return createDefaultSyncStatus(
      error ? (error as ApiError).message : undefined,
      projectId || undefined
    )
  }, [data, error, projectId, targetSystem])

  return {
    syncStatus: safeData,
    isLoading: isLoading && Boolean(projectId),
    error: error as ApiError | null,
    refetch
  }
}

// ❌ useMultipleSyncStatus 제거 (Hook 규칙 위반 때문에)
// 대신 useDynamicSyncStatus 사용 권장

// ✅ 다중 계약 동기화 상태 조회 (Hook 규칙 준수)
export function useDynamicSyncStatus(projectIds: number[], targetSystem: string = 'SHI') {
  // Hook 규칙 준수: 고정된 수의 Hook 호출
  const paddedContractIds = React.useMemo(() => {
    // 입력 검증 및 경고
    if (projectIds.length > MAX_CONTRACTS) {
      console.warn(`Contract count (${projectIds.length}) exceeds maximum (${MAX_CONTRACTS}). Only first ${MAX_CONTRACTS} will be processed.`)
    }
    
    // 🔥 명시적 타입 선언
    const padded: (number | null)[] = [...projectIds.slice(0, MAX_CONTRACTS)]
    
    // null로 패딩
    while (padded.length < MAX_CONTRACTS) {
      padded.push(null)
    }
    
    return padded
  }, [projectIds])
  // 각 contractId에 대해 고정된 수의 Hook 호출
  const allResults = paddedContractIds.map((projectId) => {
    const result = useSyncStatus(projectId, targetSystem)
    return projectId ? { projectId, ...result } : null
  })

  // 유효한 결과만 필터링
  const validResults = React.useMemo(() => {
    return allResults.filter((result): result is {
      projectId: number
      syncStatus: SyncStatus
      isLoading: boolean
      error: ApiError | null
      refetch: () => void
    } => result !== null)
  }, [allResults])

  // 전체 통계 계산
  const totalStats = React.useMemo(() => {
    let totalPending = 0
    let totalSynced = 0
    let totalFailed = 0
    let hasError = false
    let isLoading = false

    validResults.forEach(({ syncStatus, error, isLoading: loading }) => {
      if (error) hasError = true
      if (loading) isLoading = true
      
      if (syncStatus && typeof syncStatus === 'object') {
        totalPending += Number(syncStatus.pendingChanges) || 0
        totalSynced += Number(syncStatus.syncedChanges) || 0
        totalFailed += Number(syncStatus.failedChanges) || 0
      }
    })

    return {
      totalPending,
      totalSynced,
      totalFailed,
      hasError,
      isLoading,
      canSync: totalPending > 0 && !hasError && projectIds.length > 0
    }
  }, [validResults, projectIds.length])

  const refetchAll = React.useCallback(() => {
    validResults.forEach(({ refetch }) => {
      try {
        refetch()
      } catch (error) {
        console.warn('Failed to refetch sync status:', error)
      }
    })
  }, [validResults])

  return {
    contractStatuses: validResults,
    totalStats,
    refetchAll
  }
}

// ✅ 클라이언트 전용 동기화 상태 조회 (서버 사이드 렌더링 호환)
export function useClientSyncStatus(projectIds: number[], targetSystem: string = 'SHI',) {
  const [isClient, setIsClient] = React.useState(false)

  React.useEffect(() => {
    setIsClient(true)
  }, [])

  const syncResult = useDynamicSyncStatus(
    isClient ? projectIds : [],
    targetSystem
  )

  // 서버 사이드에서는 안전한 기본값 반환
  if (!isClient) {
    return {
      contractStatuses: [],
      totalStats: {
        totalPending: 0,
        totalSynced: 0,
        totalFailed: 0,
        hasError: false,
        isLoading: true,
        canSync: false
      },
      refetchAll: () => {}
    }
  }

  return syncResult
}

// ✅ 동기화 배치 목록 조회
export function useSyncBatches(projectId: number | null, targetSystem: string = 'SHI') {
  const key = projectId 
    ? `/api/sync/batches?projectId=${projectId}&targetSystem=${targetSystem}`
    : null

  const { data, error, isLoading } = useSWR<SyncBatch[]>(
    key,
    fetcher,
    {
      revalidateOnFocus: false,
      shouldRetryOnError: false,
      refreshInterval: 10000, // 10초마다 갱신
    }
  )

  return {
    syncBatches: data || [],
    isLoading: isLoading && Boolean(projectId),
    error: error as ApiError | null
  }
}

// ✅ 동기화 설정 조회
export function useSyncConfig(projectId: number | null, targetSystem: string = 'SHI') {
  const key = projectId 
    ? `/api/sync/config?projectId=${projectId}&targetSystem=${targetSystem}`
    : null

  const { data, error, isLoading, mutate: localMutate } = useSWR<SyncConfig>(
    key,
    fetcher,
    {
      revalidateOnFocus: false,
      shouldRetryOnError: false,
    }
  )

  const refetch = React.useCallback(() => {
    if (key) {
      localMutate()
    }
  }, [key, localMutate])

  return {
    syncConfig: data,
    isLoading: isLoading && Boolean(projectId),
    error: error as ApiError | null,
    refetch
  }
}

// ✅ 동기화 트리거 (뮤테이션)
export function useTriggerSync() {
  const { trigger, isMutating, error } = useSWRMutation(
    '/api/sync/trigger',
    async (url: string, { arg }: { arg: { projectId: number; targetSystem?: string } }) => {
      const response = await fetch(url, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(arg)
      })
      
      if (!response.ok) {
        const errorData = await response.json().catch(() => ({}))
        const error = new Error(errorData.message || `동기화 실패: HTTP ${response.status}`) as ApiError
        error.status = response.status
        error.response = errorData
        throw error
      }
      
      return response.json()
    }
  )

  const triggerSync = React.useCallback(async (arg: { projectId: number; targetSystem?: string }) => {
    try {
      const result = await trigger(arg)
      
      // 성공 후 관련 캐시 무효화
      const targetSystem = arg.targetSystem || 'SHI'
      const statusKey = `/api/sync/status?projectId=${arg.projectId}&targetSystem=${targetSystem}`
      const batchesKey = `/api/sync/batches?projectId=${arg.projectId}&targetSystem=${targetSystem}`
      
      globalMutate(statusKey)
      globalMutate(batchesKey)
      
      return result
    } catch (error) {
      console.error('Sync trigger failed:', error)
      throw error
    }
  }, [trigger])

  return {
    triggerSync,
    isLoading: isMutating,
    error: error as ApiError | null
  }
}

// ✅ 동기화 설정 업데이트 (뮤테이션)
export function useUpdateSyncConfig() {
  const { trigger, isMutating, error } = useSWRMutation(
    '/api/sync/config',
    async (url: string, { arg }: { arg: Partial<SyncConfig> & { projectId: number; targetSystem: string } }) => {
      const response = await fetch(url, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(arg)
      })
      
      if (!response.ok) {
        const errorData = await response.json().catch(() => ({}))
        const error = new Error(errorData.message || `설정 업데이트 실패: HTTP ${response.status}`) as ApiError
        error.status = response.status
        error.response = errorData
        throw error
      }
      
      return response.json()
    }
    // ✅ onSuccess 콜백 제거
  )

  // ✅ 수동 캐시 무효화를 포함한 래핑 함수
  const updateConfig = React.useCallback(async (arg: Partial<SyncConfig> & { projectId: number; targetSystem: string }) => {
    try {
      const result = await trigger(arg)
      
      // ✅ 성공 후 수동으로 캐시 무효화
      const { projectId, targetSystem } = arg
      const configKey = `/api/sync/config?projectId=${projectId}&targetSystem=${targetSystem}`
      globalMutate(configKey)
      
      return result
    } catch (error) {
      console.error('Sync config update failed:', error)
      throw error
    }
  }, [trigger])

  return {
    updateConfig,
    isLoading: isMutating,
    error: error as ApiError | null
  }
}
// ✅ 실시간 동기화 상태 훅 (높은 갱신 빈도)
export function useRealtimeSyncStatus(projectId: number | null, targetSystem: string = 'SHI') {
  const key = projectId 
    ? `/api/sync/status?projectId=${projectId}&targetSystem=${targetSystem}&realtime=true`
    : null

  const { data, error, isLoading } = useSWR<SyncStatus>(
    key,
    fetcher,
    {
      refreshInterval: 5000, // 5초마다 갱신
      revalidateOnFocus: true,
      revalidateOnReconnect: true,
      shouldRetryOnError: (error: ApiError) => error.status >= 500 || error.status === 0,
      dedupingInterval: 2000, // 실시간이므로 중복 제거 간격 단축
    }
  )

  const safeData = React.useMemo(() => {
    return data || createDefaultSyncStatus(
      error ? (error as ApiError).message : undefined,
      projectId || undefined
    )
  }, [data, error, projectId])

  return {
    syncStatus: safeData,
    isLoading: isLoading && Boolean(projectId),
    error: error as ApiError | null
  }
}

// 🔧 유틸리티 함수들
export const syncUtils = {
  // 캐시 수동 무효화
  invalidateCache: (projectId: number, targetSystem: string = 'SHI') => {
    const statusKey = `/api/sync/status?projectId=${projectId}&targetSystem=${targetSystem}`
    const batchesKey = `/api/sync/batches?projectId=${projectId}&targetSystem=${targetSystem}`
    const configKey = `/api/sync/config?projectId=${projectId}&targetSystem=${targetSystem}`
    
    globalMutate(statusKey)
    globalMutate(batchesKey)
    globalMutate(configKey)
  },

  // 모든 동기화 관련 캐시 무효화
  invalidateAllCache: () => {
    globalMutate((key) => typeof key === 'string' && key.startsWith('/api/sync/'))
  },

  // 에러 메시지 정리
  formatError: (error: ApiError | null): string => {
    if (!error) return ''
    
    if (error.status === 0) return '네트워크 연결을 확인해주세요'
    if (error.status === 401) return '인증이 필요합니다'
    if (error.status === 403) return '권한이 없습니다'
    if (error.status === 404) return '요청한 리소스를 찾을 수 없습니다'
    if (error.status >= 500) return '서버 오류가 발생했습니다'
    
    return error.message || '알 수 없는 오류가 발생했습니다'
  }
}