import { getDb } from '../../utils/db'

export default defineEventHandler(async (event) => {
  const db = getDb()
  const DEVIATION_THRESHOLD = 2.0
  
  const servers = db.prepare(`
    SELECT target_id, server_name 
    FROM server_targets 
    WHERE is_active = 1 
    ORDER BY server_name
  `).all() as any[]
  
  const now = new Date()
  const currentHour = now.getHours()
  const currentDayOfWeek = now.getDay()
  const isWeekend = currentDayOfWeek === 0 || currentDayOfWeek === 6
  const dayType = isWeekend ? 'weekend' : 'weekday'
  
  const anomalies: any[] = []
  const serverResults: any[] = []
  
  // 로그 저장용
  const insertLog = db.prepare(`
    INSERT INTO anomaly_logs (target_id, server_name, detect_type, metric, level, current_value, threshold_value, message)
    VALUES (?, ?, 'baseline', ?, ?, ?, ?, ?)
  `)
  
  const recentLogExists = db.prepare(`
    SELECT 1 FROM anomaly_logs 
    WHERE target_id = ? AND detect_type = 'baseline' AND metric = ?
    AND detected_at > datetime('now', '-1 minute', 'localtime')
    LIMIT 1
  `)
  
  for (const server of servers) {
    const historicalData = db.prepare(`
      SELECT cpu_percent, memory_percent, collected_at
      FROM server_snapshots
      WHERE target_id = ?
        AND collected_at >= datetime('now', '-14 days', 'localtime')
        AND strftime('%H', collected_at) = ?
        AND (
          (? = 'weekend' AND strftime('%w', collected_at) IN ('0', '6'))
          OR
          (? = 'weekday' AND strftime('%w', collected_at) NOT IN ('0', '6'))
        )
      ORDER BY collected_at DESC
    `).all(server.target_id, currentHour.toString().padStart(2, '0'), dayType, dayType) as any[]

    const current = db.prepare(`
      SELECT cpu_percent, memory_percent
      FROM server_snapshots
      WHERE target_id = ?
      ORDER BY collected_at DESC
      LIMIT 1
    `).get(server.target_id) as any

    if (!current || historicalData.length < 5) {
      serverResults.push({
        target_id: server.target_id,
        server_name: server.server_name,
        current_hour: currentHour,
        day_type: dayType,
        cpu_current: current?.cpu_percent ?? null,
        mem_current: current?.memory_percent ?? null,
        cpu_baseline: null,
        mem_baseline: null,
        cpu_deviation: null,
        mem_deviation: null,
        sample_count: historicalData.length,
        status: 'insufficient'
      })
      continue
    }
    
    const currCpu = current.cpu_percent ?? 0
    const currMem = current.memory_percent ?? 0
    
    const cpuValues = historicalData.map(s => s.cpu_percent ?? 0)
    const memValues = historicalData.map(s => s.memory_percent ?? 0)
    
    const cpuAvg = cpuValues.reduce((a, b) => a + b, 0) / cpuValues.length
    const memAvg = memValues.reduce((a, b) => a + b, 0) / memValues.length
    
    const cpuVariance = cpuValues.reduce((sum, val) => sum + Math.pow(val - cpuAvg, 2), 0) / cpuValues.length
    const memVariance = memValues.reduce((sum, val) => sum + Math.pow(val - memAvg, 2), 0) / memValues.length
    const cpuStd = Math.sqrt(cpuVariance)
    const memStd = Math.sqrt(memVariance)

    const cpuDeviation = cpuStd > 0.1 ? (currCpu - cpuAvg) / cpuStd : 0
    const memDeviation = memStd > 0.1 ? (currMem - memAvg) / memStd : 0
    
    let status = 'normal'
    const maxDev = Math.max(Math.abs(cpuDeviation), Math.abs(memDeviation))
    if (maxDev >= 3.0) status = 'danger'
    else if (maxDev >= DEVIATION_THRESHOLD) status = 'warning'
    
    serverResults.push({
      target_id: server.target_id,
      server_name: server.server_name,
      current_hour: currentHour,
      day_type: dayType,
      cpu_current: currCpu,
      mem_current: currMem,
      cpu_baseline: { avg: cpuAvg, std: cpuStd },
      mem_baseline: { avg: memAvg, std: memStd },
      cpu_deviation: cpuDeviation,
      mem_deviation: memDeviation,
      sample_count: historicalData.length,
      status
    })

    // CPU 이상감지 + 로그 저장
    if (Math.abs(cpuDeviation) >= DEVIATION_THRESHOLD) {
      const level = Math.abs(cpuDeviation) >= 3.0 ? 'danger' : 'warning'
      const direction = cpuDeviation >= 0 ? '높음' : '낮음'
      const dayLabel = isWeekend ? '주말' : '평일'
      const message = `CPU ${dayLabel} ${currentHour}시 베이스라인 대비 ${Math.abs(cpuDeviation).toFixed(1)}σ ${direction} (기준: ${cpuAvg.toFixed(1)}%, 현재: ${currCpu.toFixed(1)}%)`
      
      anomalies.push({
        target_id: server.target_id,
        server_name: server.server_name,
        metric: 'CPU',
        current: currCpu,
        baseline_avg: cpuAvg,
        deviation: cpuDeviation,
        direction: cpuDeviation >= 0 ? 'up' : 'down',
        level,
        hour: currentHour,
        day_type: dayType
      })
      
      if (!recentLogExists.get(server.target_id, 'CPU')) {
        insertLog.run(server.target_id, server.server_name, 'CPU', level, currCpu, cpuDeviation, message)
      }
    }

    // Memory 이상감지 + 로그 저장
    if (Math.abs(memDeviation) >= DEVIATION_THRESHOLD) {
      const level = Math.abs(memDeviation) >= 3.0 ? 'danger' : 'warning'
      const direction = memDeviation >= 0 ? '높음' : '낮음'
      const dayLabel = isWeekend ? '주말' : '평일'
      const message = `Memory ${dayLabel} ${currentHour}시 베이스라인 대비 ${Math.abs(memDeviation).toFixed(1)}σ ${direction} (기준: ${memAvg.toFixed(1)}%, 현재: ${currMem.toFixed(1)}%)`
      
      anomalies.push({
        target_id: server.target_id,
        server_name: server.server_name,
        metric: 'Memory',
        current: currMem,
        baseline_avg: memAvg,
        deviation: memDeviation,
        direction: memDeviation >= 0 ? 'up' : 'down',
        level,
        hour: currentHour,
        day_type: dayType
      })
      
      if (!recentLogExists.get(server.target_id, 'Memory')) {
        insertLog.run(server.target_id, server.server_name, 'Memory', level, currMem, memDeviation, message)
      }
    }
  }
  
  anomalies.sort((a, b) => Math.abs(b.deviation) - Math.abs(a.deviation))
  
  return {
    anomalies,
    servers: serverResults,
    context: {
      current_hour: currentHour,
      day_type: dayType,
      day_type_label: isWeekend ? '주말' : '평일',
      threshold: DEVIATION_THRESHOLD
    },
    timestamp: new Date().toISOString()
  }
})