import { Router, Response } from 'express';
import { PrismaClient, UtilityBillingModel, RentAdjustmentType } from '@prisma/client';
import { AuthedRequest, requireAuth, requireRole } from '../middleware/auth';
import { generateContractPdf } from '../services/contractDocumentGenerator';

const prisma = new PrismaClient();

/**
 * Router für Kündigungsfristen-Erinnerungen.
 *
 * Nutzt die bereits vorhandenen Vertragsfelder (endDate, noticePeriodMonths)
 * — kein Extra-Datenmodell nötig. Ein Mieter sieht ausschließlich seinen
 * eigenen Vertrag; Vermieter/Admin sehen alle aktiven Verträge.
 */
export const contractsRouter = Router();

const CONTRACT_SELECT = {
  id: true,
  startDate: true,
  endDate: true,
  noticePeriodMonths: true,
  isActive: true,
  user: { select: { id: true, fullName: true } },
  room: { select: { id: true, roomNumber: true } },
};

function addMonths(date: Date, months: number): Date {
  const d = new Date(date);
  d.setMonth(d.getMonth() - months);
  return d;
}

// GET /contracts/notice-deadlines — für befristete Verträge (endDate gesetzt)
// wird die späteste Kündigungsfrist (endDate - noticePeriodMonths) berechnet.
// Unbefristete Verträge (endDate = NULL) zeigen nur die geltende Kündigungs-
// frist an, ohne konkretes Datum. Rückgabe ist nach Dringlichkeit sortiert.
contractsRouter.get('/contracts/notice-deadlines', requireAuth, async (req: AuthedRequest, res: Response) => {
  const isLandlord = req.user!.role === 'LANDLORD' || req.user!.role === 'ADMIN';

  const where: Record<string, unknown> = { isActive: true };
  if (!isLandlord) {
    where.userId = req.user!.id;
  }

  const contracts = await prisma.contract.findMany({
    where,
    select: CONTRACT_SELECT,
    orderBy: { endDate: 'asc' },
  });

  const now = new Date();
  const items = contracts.map((c) => {
    const noticeDeadline = c.endDate ? addMonths(c.endDate, c.noticePeriodMonths) : null;
    const daysUntilDeadline = noticeDeadline
      ? Math.ceil((noticeDeadline.getTime() - now.getTime()) / (1000 * 60 * 60 * 24))
      : null;
    return {
      contractId: c.id,
      user: c.user,
      room: c.room,
      startDate: c.startDate,
      endDate: c.endDate,
      noticePeriodMonths: c.noticePeriodMonths,
      noticeDeadline,
      daysUntilDeadline,
      isUrgent: daysUntilDeadline !== null && daysUntilDeadline <= 30 && daysUntilDeadline >= 0,
      isOverdue: daysUntilDeadline !== null && daysUntilDeadline < 0,
    };
  });

  items.sort((a, b) => {
    if (a.daysUntilDeadline === null) return 1;
    if (b.daysUntilDeadline === null) return -1;
    return a.daysUntilDeadline - b.daysUntilDeadline;
  });

  res.status(200).json({ deadlines: items });
});

// ----------------------------------------------------------------------------
// VERTRAGS-DOKUMENTE (unterschriebener Vertrag, Nachträge etc.)
// ----------------------------------------------------------------------------

const MAX_CONTRACT_DOCUMENTS = 10;

const CONTRACT_DOCUMENTS_SELECT = {
  id: true,
  startDate: true,
  endDate: true,
  isActive: true,
  contractDocumentUrls: true,
  totalWarmRent: true,
  depositAmount: true,
  paymentDueDay: true,
  noticePeriodMonths: true,
  rentAdjustmentType: true,
  rentAdjustmentClause: true,
  wifiIncluded: true,
  furnished: true,
  utilityBillingModel: true,
  landlordName: true,
  landlordAddress: true,
  propertyAddress: true,
  signedAt: true,
  user: { select: { id: true, fullName: true } },
  room: { select: { id: true, roomNumber: true, sizeSqm: true } },
};

const UTILITY_MODELS = Object.values(UtilityBillingModel);
const ADJUSTMENT_TYPES = Object.values(RentAdjustmentType);

function sanitizeDocumentUrls(input: unknown): string[] {
  if (!Array.isArray(input)) return [];
  return input.filter((u) => typeof u === 'string' && u.trim()).map((u) => (u as string).trim());
}

// Mieter sehen nur den eigenen Vertrag, Vermieter/Admin alle — dieselbe
// Sichtbarkeitsregel wie bei allen anderen privaten Vertragsdaten.
contractsRouter.get('/contracts/documents', requireAuth, async (req: AuthedRequest, res: Response) => {
  const isLandlord = req.user!.role === 'LANDLORD' || req.user!.role === 'ADMIN';
  const where: Record<string, unknown> = {};
  if (!isLandlord) where.userId = req.user!.id;

  const contracts = await prisma.contract.findMany({
    where,
    select: CONTRACT_DOCUMENTS_SELECT,
    orderBy: { startDate: 'desc' },
  });
  res.status(200).json({ contracts });
});

// Vermieter/Admin: Dateien zu einem Vertrag hinzufügen (mehrere auf einmal,
// werden an bereits vorhandene angehängt statt sie zu ersetzen).
contractsRouter.post(
  '/contracts/:id/documents',
  requireAuth,
  requireRole('LANDLORD', 'ADMIN'),
  async (req: AuthedRequest, res: Response) => {
    const contract = await prisma.contract.findUnique({ where: { id: req.params.id } });
    if (!contract) return res.status(404).json({ error: 'Vertrag nicht gefunden' });

    const newUrls = sanitizeDocumentUrls(req.body?.urls);
    if (!newUrls.length) return res.status(400).json({ error: 'urls (Array) ist erforderlich' });

    const merged = [...contract.contractDocumentUrls, ...newUrls].slice(0, MAX_CONTRACT_DOCUMENTS);
    const updated = await prisma.contract.update({
      where: { id: contract.id },
      data: { contractDocumentUrls: merged },
      select: CONTRACT_DOCUMENTS_SELECT,
    });
    res.status(200).json({ contract: updated });
  },
);

// Vermieter/Admin: einzelne Datei aus einem Vertrag entfernen.
contractsRouter.delete(
  '/contracts/:id/documents',
  requireAuth,
  requireRole('LANDLORD', 'ADMIN'),
  async (req: AuthedRequest, res: Response) => {
    const contract = await prisma.contract.findUnique({ where: { id: req.params.id } });
    if (!contract) return res.status(404).json({ error: 'Vertrag nicht gefunden' });

    const { url } = req.body || {};
    if (!url || typeof url !== 'string') return res.status(400).json({ error: 'url ist erforderlich' });

    const remaining = contract.contractDocumentUrls.filter((u) => u !== url);
    const updated = await prisma.contract.update({
      where: { id: contract.id },
      data: { contractDocumentUrls: remaining },
      select: CONTRACT_DOCUMENTS_SELECT,
    });
    res.status(200).json({ contract: updated });
  },
);

// ----------------------------------------------------------------------------
// MUSTERMIETVERTRAG GENERIEREN & DIGITAL UNTERSCHREIBEN
// ----------------------------------------------------------------------------

// Vermieter/Admin: Vertrags-Baukasten-Optionen speichern und daraus ein PDF
// erzeugen, das automatisch den Vertragsdokumenten angehängt wird. Eine
// bereits vorhandene Unterschrift bleibt unangetastet — wer die Klauseln
// nachträglich ändert, muss den Mieter erneut unterschreiben lassen (dafür
// separat der Sign-Endpunkt).
contractsRouter.post(
  '/contracts/:id/generate-document',
  requireAuth,
  requireRole('LANDLORD', 'ADMIN'),
  async (req: AuthedRequest, res: Response) => {
    const {
      wifiIncluded,
      furnished,
      utilityBillingModel,
      noticePeriodMonths,
      depositAmount,
      rentAdjustmentType,
      rentAdjustmentClause,
      landlordName,
      landlordAddress,
      propertyAddress,
    } = req.body || {};

    if (utilityBillingModel !== undefined && !UTILITY_MODELS.includes(utilityBillingModel)) {
      return res.status(400).json({ error: `Ungültiges Nebenkosten-Modell. Erlaubt: ${UTILITY_MODELS.join(', ')}` });
    }
    if (rentAdjustmentType !== undefined && !ADJUSTMENT_TYPES.includes(rentAdjustmentType)) {
      return res.status(400).json({ error: `Ungültige Mietanpassung. Erlaubt: ${ADJUSTMENT_TYPES.join(', ')}` });
    }

    const contract = await prisma.contract.update({
      where: { id: req.params.id },
      data: {
        wifiIncluded: typeof wifiIncluded === 'boolean' ? wifiIncluded : undefined,
        furnished: typeof furnished === 'boolean' ? furnished : undefined,
        utilityBillingModel: utilityBillingModel || undefined,
        noticePeriodMonths: Number.isFinite(Number(noticePeriodMonths)) ? Number(noticePeriodMonths) : undefined,
        depositAmount: Number.isFinite(Number(depositAmount)) ? Number(depositAmount) : undefined,
        rentAdjustmentType: rentAdjustmentType || undefined,
        rentAdjustmentClause: typeof rentAdjustmentClause === 'string' ? rentAdjustmentClause.trim() || null : undefined,
        landlordName: typeof landlordName === 'string' && landlordName.trim() ? landlordName.trim() : undefined,
        landlordAddress: typeof landlordAddress === 'string' ? landlordAddress.trim() || null : undefined,
        propertyAddress: typeof propertyAddress === 'string' ? propertyAddress.trim() || null : undefined,
      },
      include: { room: true, user: true },
    }).catch(() => null);

    if (!contract) return res.status(404).json({ error: 'Vertrag nicht gefunden' });

    const pdfBuffer = await generateContractPdf(contract);
    const dataUrl = `data:application/pdf;base64,${pdfBuffer.toString('base64')}`;

    const updated = await prisma.contract.update({
      where: { id: contract.id },
      data: { contractDocumentUrls: [...contract.contractDocumentUrls, dataUrl].slice(0, MAX_CONTRACT_DOCUMENTS) },
      select: CONTRACT_DOCUMENTS_SELECT,
    });
    res.status(200).json({ contract: updated });
  },
);

// Mieter (nur der eigene Vertrag) unterschreibt digital: Unterschrift-Bild
// wird gespeichert, ein finales PDF mit eingebetteter Unterschrift erzeugt
// und den Vertragsdokumenten angehängt.
contractsRouter.post('/contracts/:id/sign', requireAuth, async (req: AuthedRequest, res: Response) => {
  const contract = await prisma.contract.findUnique({ where: { id: req.params.id }, include: { room: true, user: true } });
  if (!contract) return res.status(404).json({ error: 'Vertrag nicht gefunden' });

  const isLandlord = req.user!.role === 'LANDLORD' || req.user!.role === 'ADMIN';
  if (!isLandlord && contract.userId !== req.user!.id) {
    return res.status(403).json({ error: 'Nur der eigene Vertrag kann unterschrieben werden' });
  }

  const { signatureDataUrl } = req.body || {};
  if (typeof signatureDataUrl !== 'string' || !/^data:image\/(png|jpeg);base64,/.test(signatureDataUrl)) {
    return res.status(400).json({ error: 'signatureDataUrl (PNG/JPEG Data-URL) ist erforderlich' });
  }

  const signedAt = new Date();
  const signedContract = { ...contract, tenantSignatureUrl: signatureDataUrl, signedAt };
  const pdfBuffer = await generateContractPdf(signedContract);
  const dataUrl = `data:application/pdf;base64,${pdfBuffer.toString('base64')}`;

  const updated = await prisma.contract.update({
    where: { id: contract.id },
    data: {
      tenantSignatureUrl: signatureDataUrl,
      signedAt,
      contractDocumentUrls: [...contract.contractDocumentUrls, dataUrl].slice(0, MAX_CONTRACT_DOCUMENTS),
    },
    select: CONTRACT_DOCUMENTS_SELECT,
  });
  res.status(200).json({ contract: updated });
});