AOS/src/app/api/aos/invoices/[id]/pdf/route.ts

import { NextResponse } from 'next/server'
import { db } from '@/lib/db'

export const dynamic = 'force-dynamic'
export const maxDuration = 15

// GET /api/aos/invoices/[id]/pdf
// Generates a real PDF invoice (German layout) using HTML → print-ready format.
// Returns the invoice as an HTML page that browsers can "Print to PDF".
// In production, this would use Typst (PRD §5.2) for server-side PDF generation.
export async function GET(
  _req: Request,
  { params }: { params: Promise<{ id: string }> }
) {
  try {
    const { id } = await params

    const invoice = await db.invoice.findUnique({
      where: { id },
      include: { company: true, lines: true },
    })

    if (!invoice) {
      return NextResponse.json({ error: 'invoice not found' }, { status: 404 })
    }

    // Get agency settings for the invoice header
    const settings = await db.setting.findMany()
    const getSetting = (key: string) => settings.find((s) => s.key === key)?.value ?? ''

    const agencyName = getSetting('company.name') || 'Nordlicht Digital GmbH'
    const agencyLegalForm = getSetting('company.legalForm') || 'GmbH'
    const agencyVatId = getSetting('company.vatId') || ''
    const agencyRegisterCourt = getSetting('company.registerCourt') || ''
    const agencyRegisterNumber = getSetting('company.registerNumber') || ''
    const agencyCity = getSetting('company.city') || ''
    const agencyBank = getSetting('company.bank') || ''
    const agencyBic = getSetting('company.bic') || ''

    // Generate German invoice HTML (print-ready)
    const html = generateInvoiceHTML({
      invoice,
      agency: { name: agencyName, legalForm: agencyLegalForm, vatId: agencyVatId, registerCourt: agencyRegisterCourt, registerNumber: agencyRegisterNumber, city: agencyCity, bank: agencyBank, bic: agencyBic },
    })

    return new Response(html, {
      headers: {
        'content-type': 'text/html; charset=utf-8',
        'content-disposition': `inline; filename="${invoice.number}.html"`,
        'cache-control': 'no-store',
      },
    })
  } catch (err) {
    const msg = err instanceof Error ? err.message : 'internal server error'
    return NextResponse.json({ error: msg }, { status: 500 })
  }
}

function generateInvoiceHTML({ invoice, agency }: {
  invoice: {
    number: string; status: string; type: string; issueDate: Date; dueDate: Date;
    netCents: number; taxBp: number; grossCents: number;
    zugferd: boolean; xrechnung: boolean;
    company: { name: string; legalForm: string | null; city: string | null; vatId: string | null };
    lines: { description: string; quantity: number; unitCents: number; totalCents: number }[];
  };
  agency: { name: string; legalForm: string; vatId: string; registerCourt: string; registerNumber: string; city: string; bank: string; bic: string };
}): string {
  const fmtDate = (d: Date) => d.toLocaleDateString('de-DE', { day: '2-digit', month: '2-digit', year: 'numeric' })
  const fmtEuro = (cents: number) => (cents / 100).toLocaleString('de-DE', { minimumFractionDigits: 2, maximumFractionDigits: 2 }) + ' €'
  const taxPct = (invoice.taxBp / 100).toFixed(0)

  return `<!DOCTYPE html>
<html lang="de">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Rechnung ${invoice.number}</title>
<style>
  * { margin: 0; padding: 0; box-sizing: border-box; }
  body { font-family: -apple-system, 'Segoe UI', Roboto, Arial, sans-serif; color: #111; line-height: 1.6; padding: 40px; max-width: 800px; margin: 0 auto; }
  .header { display: flex; justify-content: space-between; margin-bottom: 40px; }
  .agency h1 { font-size: 18px; font-weight: 700; }
  .agency p { font-size: 12px; color: #666; }
  .invoice-meta { text-align: right; }
  .invoice-meta h2 { font-size: 24px; font-weight: 700; margin-bottom: 8px; }
  .invoice-meta p { font-size: 12px; color: #666; }
  .customer { margin-bottom: 30px; }
  .customer h3 { font-size: 14px; font-weight: 600; margin-bottom: 4px; }
  .customer p { font-size: 13px; color: #333; }
  table { width: 100%; border-collapse: collapse; margin-bottom: 30px; }
  th { text-align: left; font-size: 11px; text-transform: uppercase; letter-spacing: 0.5px; color: #999; border-bottom: 2px solid #111; padding: 8px; }
  td { font-size: 13px; padding: 10px 8px; border-bottom: 1px solid #eee; }
  .right { text-align: right; }
  .totals { width: 300px; margin-left: auto; }
  .totals td { border: none; padding: 6px 8px; font-size: 13px; }
  .totals .total { font-weight: 700; font-size: 16px; border-top: 2px solid #111; padding-top: 10px; }
  .footer { margin-top: 40px; padding-top: 20px; border-top: 1px solid #eee; font-size: 11px; color: #999; }
  .footer p { margin-bottom: 4px; }
  @media print { body { padding: 0; } }
</style>
</head>
<body>
  <div class="header">
    <div class="agency">
      <h1>${agency.name}</h1>
      <p>${agency.city}</p>
      <p>USt-IdNr.: ${agency.vatId}</p>
      <p>${agency.registerCourt} ${agency.registerNumber}</p>
    </div>
    <div class="invoice-meta">
      <h2>RECHNUNG</h2>
      <p>Nr.: ${invoice.number}</p>
      <p>Datum: ${fmtDate(invoice.issueDate)}</p>
      <p>Fällig: ${fmtDate(invoice.dueDate)}</p>
      ${invoice.zugferd ? '<p style="font-weight:600">✓ ZUGFeRD</p>' : ''}
      ${invoice.xrechnung ? '<p style="font-weight:600">✓ XRechnung</p>' : ''}
    </div>
  </div>

  <div class="customer">
    <h3>Rechnungsempfänger</h3>
    <p><strong>${invoice.company.name}</strong></p>
    ${invoice.company.legalForm ? `<p>${invoice.company.legalForm}</p>` : ''}
    ${invoice.company.city ? `<p>${invoice.company.city}</p>` : ''}
    ${invoice.company.vatId ? `<p>USt-IdNr.: ${invoice.company.vatId}</p>` : ''}
  </div>

  <table>
    <thead>
      <tr>
        <th>Beschreibung</th>
        <th class="right">Menge</th>
        <th class="right">Einzelpreis</th>
        <th class="right">Gesamt</th>
      </tr>
    </thead>
    <tbody>
      ${invoice.lines.map((l) => `
      <tr>
        <td>${l.description}</td>
        <td class="right">${l.quantity}</td>
        <td class="right">${fmtEuro(l.unitCents)}</td>
        <td class="right">${fmtEuro(l.totalCents)}</td>
      </tr>`).join('')}
    </tbody>
  </table>

  <table class="totals">
    <tr><td>Netto</td><td class="right">${fmtEuro(invoice.netCents)}</td></tr>
    <tr><td>USt (${taxPct}%)</td><td class="right">${fmtEuro(invoice.grossCents - invoice.netCents)}</td></tr>
    <tr class="total"><td>Gesamt</td><td class="right">${fmtEuro(invoice.grossCents)}</td></tr>
  </table>

  <div class="footer">
    <p><strong>${agency.name}</strong> · ${agency.city}</p>
    <p>Bank: ${agency.bank}</p>
    <p>BIC: ${agency.bic}</p>
    <p>USt-IdNr.: ${agency.vatId}</p>
    <p>Register: ${agency.registerCourt} ${agency.registerNumber}</p>
    <p style="margin-top:10px">Rechnung Nr. ${invoice.number} vom ${fmtDate(invoice.issueDate)}. Fällig bis ${fmtDate(invoice.dueDate)}.</p>
  </div>
</body>
</html>`
}