import { NextRequest, NextResponse } from 'next/server'
import { exec } from 'child_process'
import { promisify } from 'util'
import fs from 'fs/promises'

const execAsync = promisify(exec)

export async function GET() {
  try {
    // Get server statistics
    const stats = await Promise.all([
      getCPUUsage(),
      getMemoryUsage(),
      getDiskUsage(),
      getNetworkStats(),
      getCSFStats(),
      getSystemUptime()
    ])
    
    const [cpu, memory, disk, network, csf, uptime] = stats
    
    return NextResponse.json({
      success: true,
      data: {
        cpu_usage: cpu,
        memory_usage: memory,
        disk_usage: disk,
        network: network,
        csf_stats: csf,
        uptime: uptime,
        timestamp: new Date().toISOString()
      }
    })
    
  } catch (error: any) {
    console.error('Stats API error:', error)
    return NextResponse.json({
      success: false,
      error: `Failed to retrieve statistics: ${error.message}`
    }, { status: 500 })
  }
}

async function getCPUUsage(): Promise<number> {
  try {
    // Get CPU usage from /proc/loadavg
    const { stdout } = await execAsync('cat /proc/loadavg')
    const loadAvg = parseFloat(stdout.split(' ')[0])
    
    // Convert to percentage (assuming single core, adjust for multi-core)
    const { stdout: cpuInfo } = await execAsync('nproc')
    const cores = parseInt(cpuInfo.trim())
    
    return Math.min((loadAvg / cores) * 100, 100)
  } catch {
    return 0
  }
}

async function getMemoryUsage(): Promise<{ used: number; total: number; percentage: number }> {
  try {
    const { stdout } = await execAsync('free -b')
    const lines = stdout.split('\\n')
    const memLine = lines[1].split(/\\s+/)
    
    const total = parseInt(memLine[1])
    const used = parseInt(memLine[2])
    const percentage = (used / total) * 100
    
    return {
      used,
      total,
      percentage: Math.round(percentage * 100) / 100
    }
  } catch {
    return { used: 0, total: 0, percentage: 0 }
  }
}

async function getDiskUsage(): Promise<{ used: number; total: number; percentage: number }> {
  try {
    const { stdout } = await execAsync('df -B1 / | tail -1')
    const parts = stdout.split(/\\s+/)
    
    const total = parseInt(parts[1])
    const used = parseInt(parts[2])
    const percentage = (used / total) * 100
    
    return {
      used,
      total,
      percentage: Math.round(percentage * 100) / 100
    }
  } catch {
    return { used: 0, total: 0, percentage: 0 }
  }
}

async function getNetworkStats(): Promise<{ in_bytes: number; out_bytes: number; connections: number }> {
  try {
    // Get network interface stats
    const { stdout } = await execAsync('cat /proc/net/dev | grep -E "(eth0|ens|enp)" | head -1')
    
    if (stdout) {
      const parts = stdout.split(/\\s+/)
      const inBytes = parseInt(parts[1]) || 0
      const outBytes = parseInt(parts[9]) || 0
      
      // Get active connections
      const { stdout: connStdout } = await execAsync('netstat -tn | grep ESTABLISHED | wc -l')
      const connections = parseInt(connStdout.trim()) || 0
      
      return {
        in_bytes: inBytes,
        out_bytes: outBytes,
        connections
      }
    }
    
    return { in_bytes: 0, out_bytes: 0, connections: 0 }
  } catch {
    return { in_bytes: 0, out_bytes: 0, connections: 0 }
  }
}

async function getCSFStats(): Promise<{
  status: string;
  blocked_ips: number;
  allowed_ips: number;
  temp_blocks: number;
  rules_count: number;
}> {
  try {
    // Check CSF status
    let status = 'unknown'
    try {
      await execAsync('/usr/local/csf/bin/csf --status >/dev/null 2>&1')
      status = 'active'
    } catch {
      status = 'inactive'
    }
    
    // Count rules in files
    let blockedIps = 0
    let allowedIps = 0
    let tempBlocks = 0
    
    try {
      const denyContent = await fs.readFile('/etc/csf/csf.deny', 'utf-8')
      blockedIps = denyContent.split('\\n').filter(line => 
        line.trim() && !line.trim().startsWith('#')
      ).length
    } catch {}
    
    try {
      const allowContent = await fs.readFile('/etc/csf/csf.allow', 'utf-8')
      allowedIps = allowContent.split('\\n').filter(line => 
        line.trim() && !line.trim().startsWith('#')
      ).length
    } catch {}
    
    try {
      const { stdout } = await execAsync('/usr/local/csf/bin/csf --temp 2>/dev/null | grep -c "Temporary" || echo "0"')
      tempBlocks = parseInt(stdout.trim()) || 0
    } catch {}
    
    return {
      status,
      blocked_ips: blockedIps,
      allowed_ips: allowedIps,
      temp_blocks: tempBlocks,
      rules_count: blockedIps + allowedIps
    }
  } catch {
    return {
      status: 'unknown',
      blocked_ips: 0,
      allowed_ips: 0,
      temp_blocks: 0,
      rules_count: 0
    }
  }
}

async function getSystemUptime(): Promise<number> {
  try {
    const { stdout } = await execAsync('cat /proc/uptime')
    const uptime = parseFloat(stdout.split(' ')[0])
    return Math.floor(uptime)
  } catch {
    return 0
  }
}

// Real-time stats endpoint
export async function POST(request: NextRequest) {
  try {
    const body = await request.json()
    const { interval = 5000 } = body // Default 5 seconds
    
    // This would typically be handled by WebSocket
    // For now, return current stats
    const stats = await GET()
    const response = await stats.json()
    
    return NextResponse.json({
      success: true,
      data: {
        ...response.data,
        interval,
        next_update: Date.now() + interval
      }
    })
    
  } catch (error: any) {
    return NextResponse.json({
      success: false,
      error: `Failed to get real-time stats: ${error.message}`
    }, { status: 500 })
  }
}