import { NextRequest, NextResponse } from 'next/server'
import { db } from '@/lib/db'
import { startOfDay, endOfDay, startOfWeek, endOfWeek, startOfMonth, endOfMonth, startOfYear, endOfYear, format } from 'date-fns'

export async function GET(request: NextRequest) {
  try {
    const searchParams = request.nextUrl.searchParams
    const range = searchParams.get('range') || 'month'

    const now = new Date()
    let startDate: Date
    let endDate: Date

    switch (range) {
      case 'today':
        startDate = startOfDay(now)
        endDate = endOfDay(now)
        break
      case 'week':
        startDate = startOfWeek(now, { weekStartsOn: 1 })
        endDate = endOfWeek(now, { weekStartsOn: 1 })
        break
      case 'year':
        startDate = startOfYear(now)
        endDate = endOfYear(now)
        break
      case 'month':
      default:
        startDate = startOfMonth(now)
        endDate = endOfMonth(now)
        break
    }

    // Get sales with details
    const sales = await db.vente.findMany({
      where: {
        date: { gte: startDate, lte: endDate },
        statut: 'PAYEE'
      },
      include: {
        client: {
          select: {
            nom: true,
            prenom: true
          }
        },
        employe: {
          select: {
            nom: true,
            prenom: true
          }
        },
        lignes: {
          include: {
            produit: {
              select: {
                reference: true,
                designation: true,
                categorie: true
              }
            }
          }
        },
        paiements: true
      },
      orderBy: {
        date: 'desc'
      }
    })

    // Generate CSV content
    const headers = [
      'Numéro vente',
      'Date',
      'Client',
      'Employé',
      'Produits',
      'Quantité totale',
      'Montant HT',
      'Montant TVA',
      'Montant TTC',
      'Remise',
      'Modes de paiement',
      'Statut atelier'
    ]

    const rows = sales.map((sale) => {
      const products = sale.lignes.map((l) => 
        `${l.produit.designation} (${l.produit.categorie})`
      ).join('; ')
      const quantities = sale.lignes.reduce((sum, l) => sum + l.quantite, 0)
      const paymentMethods = sale.paiements.map((p) => p.mode).join(', ')
      const atelierStatus = sale.statutAtelier

      return [
        sale.numero,
        format(sale.date, 'dd/MM/yyyy HH:mm'),
        sale.client ? `${sale.client.prenom} ${sale.client.nom}` : '',
        sale.employe ? `${sale.employe.prenom} ${sale.employe.nom}` : '',
        `"${products}"`,
        quantities.toString(),
        sale.montantHT.toFixed(2),
        sale.montantTVA.toFixed(2),
        sale.montantTTC.toFixed(2),
        sale.remise.toFixed(2),
        paymentMethods,
        atelierStatus
      ].join(',')
    })

    const csvContent = [headers.join(','), ...rows].join('\n')

    // Return as CSV file
    return new NextResponse(csvContent, {
      headers: {
        'Content-Type': 'text/csv; charset=utf-8',
        'Content-Disposition': `attachment; filename="ventes_${format(now, 'yyyy-MM-dd')}.csv"`
      }
    })
  } catch (error) {
    console.error('Error exporting sales data:', error)
    return NextResponse.json(
      { error: 'Failed to export sales data' },
      { status: 500 }
    )
  }
}