'use client';

import { useState, useEffect, useCallback } from 'react';
import { useRouter } from 'next/navigation';
import { createClient } from '@/lib/supabase/client';
import Header from '@/components/Header';
import QRCode from 'qrcode';
import { Wasserzaehler } from '@/types';

const BASE_URL = process.env.NEXT_PUBLIC_BASE_URL || 'https://gemeindeportal.vercel.app';

interface QRData {
  zaehler: Wasserzaehler;
  dataUrl: string;
}

export default function AdminQRCodesPage() {
  const router = useRouter();
  const supabase = createClient();

  const [loading, setLoading] = useState(true);
  const [qrItems, setQrItems] = useState<QRData[]>([]);
  const [error, setError] = useState('');

  const loadAndGenerate = useCallback(async () => {
    try {
      const { data: { user } } = await supabase.auth.getUser();
      if (!user) {
        router.push('/admin/login');
        return;
      }

      const { data, error: fetchError } = await supabase
        .from('wasserzaehler')
        .select('*')
        .order('kundennummer', { ascending: true });

      if (fetchError) {
        setError('Fehler beim Laden der Wasserzähler.');
        setLoading(false);
        return;
      }

      const zaehlerList: Wasserzaehler[] = data || [];

      const items: QRData[] = await Promise.all(
        zaehlerList.map(async (z) => {
          const url = `${BASE_URL}/wasserzaehler?token=${z.access_token}`;
          const dataUrl = await QRCode.toDataURL(url, {
            width: 300,
            margin: 2,
            errorCorrectionLevel: 'M',
          });
          return { zaehler: z, dataUrl };
        })
      );

      setQrItems(items);
    } catch {
      setError('Unerwarteter Fehler.');
    } finally {
      setLoading(false);
    }
  }, [supabase, router]);

  useEffect(() => {
    loadAndGenerate();
  }, [loadAndGenerate]);

  if (loading) {
    return (
      <div className="min-h-screen flex flex-col bg-bg">
        <Header back={{ href: '/admin/dashboard', label: 'Dashboard' }} />
        <main className="flex-1 max-w-4xl mx-auto px-4 py-6 w-full">
          <div className="space-y-4">
            <div className="skeleton h-8 w-64" />
            <div className="skeleton h-4 w-48" />
            <div className="skeleton h-96 w-full" />
          </div>
        </main>
      </div>
    );
  }

  if (error) {
    return (
      <div className="min-h-screen flex flex-col bg-bg">
        <Header back={{ href: '/admin/dashboard', label: 'Dashboard' }} />
        <main className="flex-1 flex items-center justify-center px-4">
          <div className="bg-white rounded-2xl border border-border p-8 max-w-sm w-full text-center">
            <p className="text-danger">{error}</p>
          </div>
        </main>
      </div>
    );
  }

  return (
    <div className="min-h-screen flex flex-col bg-bg">
      {/* Screen-only header */}
      <div className="print:hidden">
        <Header back={{ href: '/admin/dashboard', label: 'Dashboard' }} />

        {/* Admin Bar */}
        <div className="bg-white border-b border-border">
          <div className="max-w-4xl mx-auto px-4 py-3 flex items-center justify-between">
            <div>
              <h2 className="text-lg font-bold text-primary">QR-Codes — Wasserzähler</h2>
              <p className="text-sm text-text-muted">
                {qrItems.length} Zähler — je 1 Seite pro Kunde beim Drucken
              </p>
            </div>
            <div className="flex gap-2">
              <a
                href="/api/zaehler-qrcodes-excel"
                className="border border-border bg-white px-4 py-2.5 rounded-xl text-sm font-semibold hover:bg-bg active:scale-[0.98] transition-all flex items-center gap-2"
              >
                <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 10v6m0 0l-3-3m3 3l3-3m2 8H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z" />
                </svg>
                Excel Download
              </a>
              <button
                onClick={() => window.print()}
                className="bg-accent text-white px-5 py-2.5 rounded-xl text-sm font-semibold hover:bg-accent-light active:scale-[0.98] transition-all flex items-center gap-2"
              >
                <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 17h2a2 2 0 002-2v-4a2 2 0 00-2-2H5a2 2 0 00-2 2v4a2 2 0 002 2h2m2 4h6a2 2 0 002-2v-4a2 2 0 00-2-2H9a2 2 0 00-2 2v4a2 2 0 002 2zm8-12V5a2 2 0 00-2-2H9a2 2 0 00-2 2v4h10z" />
                </svg>
                Drucken (Strg+P)
              </button>
            </div>
          </div>
        </div>
      </div>

      {/* Preview on screen / Print pages */}
      <main className="flex-1 max-w-4xl mx-auto px-4 py-5 w-full print:max-w-none print:p-0 print:m-0">
        {qrItems.length === 0 ? (
          <div className="bg-white rounded-2xl border border-border p-12 text-center print:hidden">
            <p className="text-text-muted">Keine Wasserzähler gefunden. Bitte zuerst das Import-Script ausführen.</p>
            <code className="block mt-2 text-xs bg-bg p-2 rounded-lg">
              npx tsx scripts/import-zaehler.ts zaehlerablesen_2025.xlsx
            </code>
          </div>
        ) : (
          <div className="space-y-6 print:space-y-0">
            {qrItems.map((item, index) => (
              <div
                key={item.zaehler.id}
                className="bg-white rounded-2xl border border-border p-8 print:rounded-none print:border-0 print:p-0 print:break-after-page"
              >
                <div className="flex flex-col items-center justify-center print:min-h-screen print:py-16">
                  {/* Gemeinde Header */}
                  <div className="text-center mb-8 print:mb-12">
                    <h1 className="text-xl font-bold text-primary print:text-2xl">
                      Gemeindeamt Weißkirchen an der Traun
                    </h1>
                    <p className="text-text-muted text-sm mt-1 print:text-base">
                      Wasserzähler-Ablesung {new Date().getFullYear()}
                    </p>
                  </div>

                  {/* QR Code */}
                  <div className="mb-6 print:mb-10">
                    {/* eslint-disable-next-line @next/next/no-img-element */}
                    <img
                      src={item.dataUrl}
                      alt={`QR-Code für Kundennr. ${item.zaehler.kundennummer}`}
                      className="w-48 h-48 print:w-64 print:h-64"
                    />
                  </div>

                  {/* Info */}
                  <div className="text-center space-y-2 print:space-y-3">
                    <div>
                      <span className="text-xs text-text-muted uppercase tracking-wider print:text-sm">Kundennummer</span>
                      <div className="text-2xl font-bold font-mono tracking-wider print:text-3xl">
                        {item.zaehler.kundennummer}
                      </div>
                    </div>
                    <div>
                      <span className="text-xs text-text-muted uppercase tracking-wider print:text-sm">Zählernummer</span>
                      <div className="text-lg font-semibold font-mono print:text-xl">
                        {item.zaehler.zaehlernummer}
                      </div>
                    </div>
                  </div>

                  {/* Instructions */}
                  <div className="mt-8 p-4 bg-bg rounded-xl max-w-sm text-center print:mt-12 print:bg-gray-50 print:max-w-md print:p-6">
                    <p className="text-sm text-text-muted print:text-base">
                      Scannen Sie den QR-Code mit Ihrem Smartphone um Ihren aktuellen Zählerstand zu melden.
                    </p>
                  </div>

                  {/* Screen-only badge */}
                  <div className="mt-4 text-xs text-text-muted print:hidden">
                    Seite {index + 1} von {qrItems.length}
                  </div>
                </div>
              </div>
            ))}
          </div>
        )}
      </main>

      {/* Print Styles */}
      <style jsx global>{`
        @media print {
          body {
            margin: 0 !important;
            padding: 0 !important;
            -webkit-print-color-adjust: exact;
            print-color-adjust: exact;
          }
          .print\\:hidden {
            display: none !important;
          }
          .print\\:break-after-page {
            break-after: page;
          }
          .print\\:min-h-screen {
            min-height: 100vh;
          }
        }
      `}</style>
    </div>
  );
}