import prisma from '~/server/utils/prisma'

export default defineEventHandler(async (event) => {
  try {
    // Check authentication
    const user = event.context.user;
    if (!user || !user.userID) {
      return {
        statusCode: 401,
        body: { success: false, message: 'Unauthorized' }
      }
    }
    
    // Get system status metrics
    const now = new Date()
    const oneDayAgo = new Date(now)
    oneDayAgo.setDate(oneDayAgo.getDate() - 1)
    
    // Get total sent in last 24 hours
    const totalSent = await prisma.notification_logs.count({
      where: {
        created_at: {
          gte: oneDayAgo,
          lte: now
        },
        status: 'Sent'
      }
    })
    
    // Get success rate in last 24 hours
    const totalAttempted = await prisma.notification_logs.count({
      where: {
        created_at: {
          gte: oneDayAgo,
          lte: now
        },
        action: {
          in: ['Notification Sent', 'Delivery Attempted']
        }
      }
    })
    
    const successfulDeliveries = await prisma.notification_logs.count({
      where: {
        created_at: {
          gte: oneDayAgo,
          lte: now
        },
        status: 'Sent'
      }
    })
    
    const successRate = totalAttempted > 0 
      ? ((successfulDeliveries / totalAttempted) * 100).toFixed(2)
      : 0
    
    // Get error rate in last 24 hours
    const failedDeliveries = await prisma.notification_logs.count({
      where: {
        created_at: {
          gte: oneDayAgo,
          lte: now
        },
        status: 'Failed'
      }
    })
    
    const errorRate = totalAttempted > 0 
      ? ((failedDeliveries / totalAttempted) * 100).toFixed(2)
      : 0
    
    // Get average response time (mock data since we need actual measurements)
    const avgResponseTime = "145"
    
    // Calculate status based on metrics
    const getSystemStatus = (metric, thresholds) => {
      if (metric <= thresholds.healthy) return 'healthy'
      if (metric <= thresholds.warning) return 'warning'
      return 'critical'
    }
    
    // Get queue status
    const queueStatus = await getQueueStatus(prisma)
    
    // Get recent activity
    const recentActivity = await getRecentActivity(prisma)
    
    // Get performance metrics
    const performanceMetrics = {
      cpu: 23,  // Mock data
      memory: 67,  // Mock data
      queueLoad: calculateQueueLoad(queueStatus)
    }
    
    // Get error alerts (mock data)
    const errorAlerts = await getErrorAlerts(prisma, oneDayAgo, now)

    return {
      statusCode: 200,
      body: {
        success: true,
        data: {
          systemStatus: [
            {
              title: "System Health",
              value: errorRate < 1 ? "Healthy" : errorRate < 5 ? "Warning" : "Critical",
              icon: "ic:outline-favorite",
              status: getSystemStatus(errorRate, { healthy: 1, warning: 5 })
            },
            {
              title: "Throughput",
              value: `${Math.round(totalSent / 24)}/hr`,
              icon: "ic:outline-speed",
              status: 'healthy'  // Simplified for now
            },
            {
              title: "Error Rate",
              value: `${errorRate}%`,
              icon: "ic:outline-error-outline",
              status: getSystemStatus(errorRate, { healthy: 1, warning: 5 })
            },
            {
              title: "Response Time",
              value: `${avgResponseTime}ms`,
              icon: "ic:outline-timer",
              status: getSystemStatus(parseFloat(avgResponseTime), { healthy: 100, warning: 200 })
            }
          ],
          performanceMetrics,
          queueStatus,
          recentActivity,
          errorAlerts
        }
      }
    }
  } catch (error) {
    console.error('Error fetching monitoring data:', error)
    return {
      statusCode: 500,
      body: { success: false, message: 'Failed to fetch monitoring data', error: error.message }
    }
  }
})

// Helper functions
async function getQueueStatus(prisma) {
  const channels = ['Email', 'SMS', 'Push Notification', 'Webhook']
  
  // In a real implementation, this would query the notification_queue table
  // For now, we'll use mock data
  return [
    {
      name: "Email Queue",
      count: "1,247",
      description: "Pending emails",
      status: "active",
      utilization: 78
    },
    {
      name: "SMS Queue",
      count: "89",
      description: "Pending SMS",
      status: "active",
      utilization: 23
    },
    {
      name: "Push Queue",
      count: "3,456",
      description: "Pending push notifications",
      status: "warning",
      utilization: 92
    },
    {
      name: "Webhook Queue",
      count: "12",
      description: "Pending webhooks",
      status: "active",
      utilization: 8
    }
  ]
}

function calculateQueueLoad(queueStatus) {
  // Calculate average utilization across all queues
  const totalUtilization = queueStatus.reduce((sum, queue) => sum + queue.utilization, 0)
  return Math.round(totalUtilization / queueStatus.length)
}

async function getRecentActivity(prisma) {
  // Get the most recent 5 log entries
  const recentLogs = await prisma.notification_logs.findMany({
    orderBy: {
      created_at: 'desc'
    },
    take: 5
  })
  
  // Format for the frontend
  return recentLogs.map(log => {
    const timeAgo = formatTimeAgo(log.created_at)
    
    return {
      action: log.action,
      description: log.details || 'No details provided',
      status: log.status ? log.status.toLowerCase() : 'unknown',
      time: timeAgo,
      source: log.channel_type || 'System'
    }
  })
}

function formatTimeAgo(timestamp) {
  const now = new Date()
  const time = new Date(timestamp)
  const diffInMinutes = Math.floor((now - time) / (1000 * 60))

  if (diffInMinutes < 1) return "Just now"
  if (diffInMinutes < 60) return `${diffInMinutes} minutes ago`
  if (diffInMinutes < 1440) return `${Math.floor(diffInMinutes / 60)} hours ago`
  return `${Math.floor(diffInMinutes / 1440)} days ago`
}

async function getErrorAlerts(prisma, startDate, endDate) {
  // Get recent errors
  const recentErrors = await prisma.notification_logs.findMany({
    where: {
      created_at: {
        gte: startDate,
        lte: endDate
      },
      status: 'Failed',
      error_message: {
        not: null
      }
    },
    orderBy: {
      created_at: 'desc'
    },
    take: 3
  })
  
  // Format for the frontend
  return recentErrors.map(error => {
    const timeAgo = formatTimeAgo(error.created_at)
    
    // Determine severity based on error code or other factors
    let severity = 'warning'
    if (error.error_code && error.error_code.startsWith('CRIT')) {
      severity = 'critical'
    }
    
    return {
      title: error.action || 'Error Detected',
      description: error.error_message || 'Unknown error occurred',
      timestamp: timeAgo,
      component: error.channel_type || 'System',
      severity
    }
  })
}