'use client';

import { useState, useEffect } from 'react';
import { Button } from '@/components/ui/button';
import { Switch } from '@/components/ui/switch';
import { Download, Upload, Loader2, Sliders, ShieldAlert, FileArchive } from 'lucide-react';
import { createClient } from '@/lib/supabase/client';
import { useRouter } from 'next/navigation';

export default function SystemPage() {
  const [loading, setLoading] = useState(true);
  const [demoActive, setDemoActive] = useState(true);
  const [exporting, setExporting] = useState(false);
  const [importing, setImporting] = useState(false);
  const [statusMsg, setStatusMsg] = useState('');
  const [statusType, setStatusType] = useState<'success' | 'error' | 'info' | ''>('');
  const [selectedFile, setSelectedFile] = useState<File | null>(null);
  const router = useRouter();

  useEffect(() => {
    async function loadData() {
      try {
        const supabase = createClient();
        const { data: { user } } = await supabase.auth.getUser();
        if (!user) {
          router.push('/auth/login');
          return;
        }
        const state = localStorage.getItem('demo_banner_disabled') !== 'true';
        setDemoActive(state);
      } catch (e) {
        console.error(e);
      } finally {
        setLoading(false);
      }
    }
    loadData();
  }, [router]);

  const toggleDemo = (checked: boolean) => {
    setDemoActive(checked);
    localStorage.setItem('demo_banner_disabled', (!checked).toString());
    window.dispatchEvent(new Event('storage_demo_changed'));
  };

  const handleExport = async () => {
    setExporting(true);
    setStatusMsg('Export läuft...');
    setStatusType('info');
    try {
      const res = await fetch('/api/admin/db-backup');
      if (!res.ok) throw new Error('Export fehlgeschlagen');

      const blob = await res.blob();
      const url = window.URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = `webshop_backup_${new Date().toISOString().split('T')[0]}.zip`;
      document.body.appendChild(a);
      a.click();
      a.remove();
      window.URL.revokeObjectURL(url);
      setStatusMsg('Export erfolgreich abgeschlossen.');
      setStatusType('success');
    } catch (err: any) {
      console.error(err);
      setStatusMsg(`Fehler beim Export: ${err.message}`);
      setStatusType('error');
    } finally {
      setExporting(false);
    }
  };

  const handleImport = async () => {
    if (!selectedFile) return;
    if (!confirm('ACHTUNG: Dies löscht und überschreibt alle aktuellen Datenbankinhalte in dieser Instanz. Möchten Sie wirklich fortfahren?')) {
      return;
    }
    setImporting(true);
    setStatusMsg('Import läuft...');
    setStatusType('info');
    try {
      const formData = new FormData();
      formData.append('file', selectedFile);

      const res = await fetch('/api/admin/db-backup', {
        method: 'POST',
        body: formData,
      });

      const data = await res.json();
      if (!res.ok) throw new Error(data.error || 'Import fehlgeschlagen');

      setStatusMsg('Datenbank erfolgreich importiert!');
      setStatusType('success');
      setSelectedFile(null);
    } catch (err: any) {
      console.error(err);
      setStatusMsg(`Fehler beim Import: ${err.message}`);
      setStatusType('error');
    } finally {
      setImporting(false);
    }
  };

  if (loading) {
    return <div className="p-8 text-white flex justify-center items-center"><Loader2 className="w-8 h-8 animate-spin text-primary" /></div>;
  }

  return (
    <div className="p-6 max-w-5xl mx-auto space-y-6">
      <div>
        <h1 className="text-3xl font-extrabold tracking-tight text-white flex items-center gap-3">
          <Sliders className="w-8 h-8 text-amber-400" />
          System & Backup
        </h1>
        <p className="text-slate-400 text-xs mt-1">
          Verwaltung von System-Bannern, Datenbank-Sicherungen und Wiederherstellungen.
        </p>
      </div>

      {statusMsg && (
        <div className={`p-3.5 rounded-xl text-xs font-medium border ${
          statusType === 'success' ? 'bg-emerald-500/10 border-emerald-500/20 text-emerald-400' :
          statusType === 'error' ? 'bg-destructive/10 border-destructive/20 text-destructive' :
          'bg-sky-500/10 border-sky-500/20 text-sky-400'
        }`}>
          {statusMsg}
        </div>
      )}

      <div className="grid grid-cols-1 md:grid-cols-2 gap-5">
        <div className="p-5 rounded-2xl bg-slate-900/60 border border-slate-800 flex flex-col justify-between space-y-4">
          <div className="space-y-3">
            <div className="w-10 h-10 rounded-xl bg-sky-500/10 border border-sky-500/20 text-sky-400 flex items-center justify-center">
              <Sliders className="w-5 h-5" />
            </div>
            <div>
              <h3 className="font-bold text-base text-white">System Banner</h3>
              <p className="text-xs text-slate-400 mt-1 leading-relaxed">
                Gelbe Demo-Warnmeldungen im gesamten Shop aktivieren oder stummschalten.
              </p>
            </div>
          </div>
          <div className="flex items-center justify-between pt-3 border-t border-slate-800/80">
            <span className="text-xs font-semibold text-slate-300">Banner aktiv</span>
            <Switch checked={demoActive} onCheckedChange={toggleDemo} />
          </div>
        </div>

        <div className="p-5 rounded-2xl bg-slate-900/60 border border-slate-800 flex flex-col justify-between space-y-4">
          <div className="space-y-3">
            <div className="w-10 h-10 rounded-xl bg-blue-500/10 border border-blue-500/20 text-blue-400 flex items-center justify-center">
              <Download className="w-5 h-5" />
            </div>
            <div>
              <h3 className="font-bold text-base text-white">DB Backup</h3>
              <p className="text-xs text-slate-400 mt-1 leading-relaxed">
                Lädt alle Produkte, Firmen, Lizenzen &amp; Einstellungen als ZIP-Archiv herunter.
              </p>
            </div>
          </div>
          <Button
            onClick={handleExport}
            disabled={exporting || importing}
            className="w-full bg-blue-600 hover:bg-blue-500 text-white rounded-xl h-10 text-xs font-bold"
          >
            {exporting ? (
              <><Loader2 className="w-4 h-4 mr-2 animate-spin" /> Export läuft...</>
            ) : (
              <><Download className="w-4 h-4 mr-2" /> ZIP Export</>
            )}
          </Button>
        </div>

        <div className="md:col-span-2 p-5 rounded-2xl bg-slate-900/60 border border-slate-800 space-y-4">
          <div className="space-y-3">
            <div className="flex items-center justify-between">
              <div className="w-10 h-10 rounded-xl bg-amber-500/10 border border-amber-500/20 text-amber-400 flex items-center justify-center">
                <Upload className="w-5 h-5" />
              </div>
              <span className="text-[10px] font-bold uppercase tracking-wider text-amber-400 bg-amber-500/10 px-2.5 py-1 rounded-full border border-amber-500/20 flex items-center gap-1">
                <ShieldAlert className="w-3 h-3" /> Überschreibt DB
              </span>
            </div>
            <div>
              <h3 className="font-bold text-base text-white">Daten Wiederherstellung</h3>
              <p className="text-xs text-slate-400 mt-1 leading-relaxed">
                Spielen Sie eine gesicherte ZIP-Sicherungsdatei ein. Warnung: Überschreibt aktuelle Datenbankinhalte.
              </p>
            </div>
          </div>

          <div className="grid sm:grid-cols-2 gap-3 pt-2">
            <div className="relative border border-dashed border-slate-700/80 rounded-xl p-3 hover:bg-slate-800/50 transition cursor-pointer flex items-center justify-center text-center">
              <input
                type="file"
                accept=".zip"
                onChange={(e) => setSelectedFile(e.target.files?.[0] || null)}
                disabled={exporting || importing}
                className="absolute inset-0 w-full h-full opacity-0 cursor-pointer disabled:cursor-not-allowed"
              />
              <span className="text-xs font-medium text-slate-300 truncate px-2 flex items-center gap-1.5">
                <FileArchive className="w-4 h-4 text-amber-400 shrink-0" />
                {selectedFile ? selectedFile.name : 'ZIP-Datei auswählen'}
              </span>
            </div>

            <Button
              onClick={handleImport}
              disabled={!selectedFile || exporting || importing}
              variant="outline"
              className="w-full border-amber-500/30 text-amber-300 hover:bg-amber-500/10 rounded-xl h-10 text-xs font-bold"
            >
              {importing ? (
                <><Loader2 className="w-4 h-4 mr-2 animate-spin" /> Importiert...</>
              ) : (
                <><Upload className="w-4 h-4 mr-2" /> ZIP Einspielen</>
              )}
            </Button>
          </div>
        </div>
      </div>
    </div>
  );
}