import { NextRequest, NextResponse } from 'next/server'
import { withAdminAuth } from '@/lib/admin-middleware'
import { connectDB } from '@/lib/mongodb'
import { User } from '@/models/user'
import { Transaction } from '@/models/transaction'
import { Billing } from '@/models/billing'
import { DeveloperRequest } from '@/models/developer-request'

export async function GET(request: NextRequest) {
  return withAdminAuth(request, async (req, admin) => {
    try {
      await connectDB()

      const { searchParams } = new URL(request.url)
      const reportType = searchParams.get('type')
      const format = searchParams.get('format') || 'json'
      const dateFrom = searchParams.get('dateFrom')
      const dateTo = searchParams.get('dateTo')

      // Build date filter
      const dateFilter: any = {}
      if (dateFrom || dateTo) {
        dateFilter.createdAt = {}
        if (dateFrom) dateFilter.createdAt.$gte = new Date(dateFrom)
        if (dateTo) dateFilter.createdAt.$lte = new Date(dateTo)
      }

      let data: any = {}

      switch (reportType) {
        case 'users':
          data = await User.find(dateFilter)
            .select('-password -refreshToken')
            .sort({ createdAt: -1 })
          break

        case 'transactions':
          data = await Transaction.find(dateFilter)
            .populate('userId', 'name email siliconId')
            .sort({ createdAt: -1 })
          break

        case 'billing':
          data = await Billing.find(
            dateFilter.createdAt ? { created_at: dateFilter.createdAt } : {}
          ).sort({ created_at: -1 })
          break

        case 'developer-requests':
          const devFilter = dateFilter.createdAt ? { createdAt: dateFilter.createdAt } : {}
          data = await (DeveloperRequest as any)
            .find(devFilter)
            .populate('userId', 'name email siliconId')
            .sort({ createdAt: -1 })
          break

        case 'summary':
          // Generate comprehensive summary report
          const [users, transactions, billings, developerRequests] = await Promise.all([
            User.find(dateFilter).select('-password -refreshToken'),
            Transaction.find(dateFilter).populate('userId', 'name email siliconId'),
            Billing.find(dateFilter.createdAt ? { created_at: dateFilter.createdAt } : {}),
            (DeveloperRequest as any)
              .find(dateFilter.createdAt ? { createdAt: dateFilter.createdAt } : {})
              .populate('userId', 'name email siliconId'),
          ])

          // Calculate summary statistics
          const userStats = {
            total: users.length,
            verified: users.filter((u) => u.isVerified).length,
            admins: users.filter((u) => u.role === 'admin').length,
            totalBalance: users.reduce((sum, u) => sum + (u.balance || 0), 0),
          }

          const transactionStats = {
            total: transactions.length,
            totalAmount: transactions.reduce((sum, t) => sum + t.amount, 0),
            credits: transactions.filter((t) => t.type === 'credit').length,
            debits: transactions.filter((t) => t.type === 'debit').length,
          }

          const billingStats = {
            total: billings.length,
            totalRevenue: billings.reduce((sum, b) => sum + b.amount, 0),
            completed: billings.filter((b) => b.payment_status === 'paid').length,
            pending: billings.filter((b) => b.payment_status === 'pending').length,
          }

          const developerStats = {
            total: developerRequests.length,
            pending: developerRequests.filter((d) => d.status === 'pending').length,
            inProgress: developerRequests.filter((d) => d.status === 'in_progress').length,
            completed: developerRequests.filter((d) => d.status === 'completed').length,
          }

          data = {
            summary: {
              users: userStats,
              transactions: transactionStats,
              billing: billingStats,
              developerRequests: developerStats,
            },
            users: users.slice(0, 100), // Limit for performance
            transactions: transactions.slice(0, 100),
            billings: billings.slice(0, 100),
            developerRequests: developerRequests.slice(0, 100),
          }
          break

        default:
          return NextResponse.json({ error: 'Invalid report type' }, { status: 400 })
      }

      if (format === 'csv') {
        // Convert to CSV format
        const csv = convertToCSV(data, reportType)

        return new NextResponse(csv, {
          headers: {
            'Content-Type': 'text/csv',
            'Content-Disposition': `attachment; filename="${reportType}_report_${new Date().toISOString().split('T')[0]}.csv"`,
          },
        })
      }

      return NextResponse.json({
        reportType,
        generatedAt: new Date().toISOString(),
        generatedBy: admin.name,
        dateRange: { from: dateFrom, to: dateTo },
        data,
      })
    } catch (error) {
      console.error('Admin reports error:', error)
      return NextResponse.json({ error: 'Failed to generate report' }, { status: 500 })
    }
  })
}

function convertToCSV(data: any, reportType: string): string {
  if (!Array.isArray(data)) {
    if (reportType === 'summary' && data.summary) {
      // For summary reports, create a simple CSV with key metrics
      const lines = [
        'Metric,Value',
        `Total Users,${data.summary.users.total}`,
        `Verified Users,${data.summary.users.verified}`,
        `Admin Users,${data.summary.users.admins}`,
        `Total Balance,${data.summary.users.totalBalance}`,
        `Total Transactions,${data.summary.transactions.total}`,
        `Transaction Amount,${data.summary.transactions.totalAmount}`,
        `Total Billing Records,${data.summary.billing.total}`,
        `Total Revenue,${data.summary.billing.totalRevenue}`,
        `Developer Requests,${data.summary.developerRequests.total}`,
      ]
      return lines.join('\n')
    }
    return 'No data available'
  }

  if (data.length === 0) {
    return 'No data available'
  }

  // Get headers from first object
  const headers = Object.keys(data[0]).filter(
    (key) => typeof data[0][key] !== 'object' || data[0][key] === null
  )

  // Create CSV content
  const csvHeaders = headers.join(',')
  const csvRows = data.map((row) =>
    headers
      .map((header) => {
        const value = row[header]
        if (value === null || value === undefined) return ''
        if (typeof value === 'string' && value.includes(',')) {
          return `"${value.replace(/"/g, '""')}"`
        }
        return value
      })
      .join(',')
  )

  return [csvHeaders, ...csvRows].join('\n')
}