/* Admin Settings with Database Import / Export functionality */
'use client';

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

export default function AdminSettings() {
  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 [loading, setLoading] = useState(true);
  const router = useRouter();

  useEffect(() => {
    async function checkAccess() {
      const supabase = createClient();
      const { data: { user } } = await supabase.auth.getUser();
      if (!user) {
        router.push('/auth/login');
        return;
      }
      const { data: userData } = await supabase
        .from('users')
        .select('role')
        .eq('id', user.id)
        .single();
      if (!userData || userData.role === 'verwaltung') {
        router.push('/admin');
      } else {
        const state = localStorage.getItem('demo_banner_disabled') !== 'true';
        setDemoActive(state);
        setLoading(false);
      }
    }
    checkAccess();
  }, [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-4xl mx-auto text-slate-900 dark:text-white space-y-8">
      {/* Page Header */}
      <div>
        <h1 className="text-3xl font-extrabold tracking-tight">Admin Einstellungen</h1>
        <p className="text-slate-500 dark:text-slate-400 text-sm mt-1">
          Verwalten Sie globale Shopeinstellungen.
        </p>
      </div>

      {/* Allgemeine Einstellungen */}
      <div className="p-5 bg-white dark:bg-slate-900/50 rounded-xl border border-slate-200 dark:border-white/10 shadow-sm space-y-4">
        <h2 className="text-lg font-bold flex items-center gap-2">
          Allgemeine Einstellungen
        </h2>
        <div className="flex items-center justify-between p-4 bg-slate-50 dark:bg-white/5 rounded-lg border border-slate-100 dark:border-white/5">
          <div>
            <p className="font-medium text-sm text-slate-900 dark:text-white">Demo-Warnmeldungen</p>
            <p className="text-xs text-slate-500 dark:text-slate-400">Schaltet gelbe Banner ein oder aus.</p>
          </div>
          <Switch checked={demoActive} onCheckedChange={toggleDemo} />
        </div>
      </div>

      {/* Datenimport & -export */}
      <div className="p-5 bg-white dark:bg-slate-900/50 rounded-xl border border-slate-200 dark:border-white/10 shadow-sm space-y-6">
        <div>
          <h2 className="text-lg font-bold flex items-center gap-2">
            <Database className="w-5 h-5 text-primary" />
            Datenimport & -export
          </h2>
          <p className="text-slate-500 dark:text-slate-400 text-xs mt-1">
            Sichern Sie Ihre gesamte Instanz oder stellen Sie Daten wieder her.
          </p>
        </div>

        {statusMsg && (
          <div className={`p-4 rounded-lg text-sm border ${
            statusType === 'success' ? 'bg-green-500/10 border-green-500/20 text-green-600 dark:text-green-400' :
            statusType === 'error' ? 'bg-destructive/10 border-destructive/20 text-destructive' :
            'bg-blue-500/10 border-blue-500/20 text-blue-600 dark:text-blue-400'
          }`}>
            {statusMsg}
          </div>
        )}

        <div className="grid md:grid-cols-2 gap-6">
          {/* Export Card */}
          <div className="p-5 bg-slate-50 dark:bg-white/5 border border-slate-100 dark:border-white/5 rounded-xl flex flex-col justify-between space-y-4">
            <div className="space-y-2">
              <h3 className="font-bold text-sm flex items-center gap-2 text-slate-800 dark:text-white">
                <Download className="w-4 h-4 text-primary" />
                Daten exportieren
              </h3>
              <p className="text-xs text-slate-500 dark:text-slate-400 leading-relaxed">
                Lädt alle Kategorien, Produkte, Module, Firmen, Endkunden, Bestellungen und SMTP-Einstellungen als ZIP-Datei herunter.
              </p>
            </div>
            <Button 
              onClick={handleExport} 
              disabled={exporting || importing}
              className="w-full bg-primary hover:bg-primary/90 text-white"
            >
              {exporting ? (
                <><Loader2 className="w-4 h-4 mr-2 animate-spin" /> Export läuft...</>
              ) : (
                <><Download className="w-4 h-4 mr-2" /> ZIP-Backup herunterladen</>
              )}
            </Button>
          </div>

          {/* Import Card */}
          <div className="p-5 bg-slate-50 dark:bg-white/5 border border-slate-100 dark:border-white/5 rounded-xl flex flex-col justify-between space-y-4">
            <div className="space-y-2">
              <h3 className="font-bold text-sm flex items-center gap-2 text-slate-800 dark:text-white">
                <Upload className="w-4 h-4 text-amber-500" />
                Daten importieren
              </h3>
              <div className="flex items-start gap-2 bg-amber-500/10 border border-amber-500/20 p-2.5 rounded-lg text-amber-600 dark:text-amber-400 text-[11px] leading-snug">
                <AlertTriangle className="w-4 h-4 shrink-0 mt-0.5" />
                <span>
                  <strong>Warnung:</strong> Der Import überschreibt alle Daten dieser Instanz unwiderruflich!
                </span>
              </div>
            </div>

            <div className="space-y-3">
              <div className="relative border border-dashed border-slate-200 dark:border-white/10 rounded-lg p-3 hover:bg-slate-100/50 dark:hover:bg-white/5 transition">
                <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"
                />
                <div className="text-center text-xs text-slate-500 dark:text-slate-400">
                  {selectedFile ? (
                    <span className="text-primary font-semibold">{selectedFile.name}</span>
                  ) : (
                    "ZIP-Datei auswählen oder hierher ziehen"
                  )}
                </div>
              </div>

              <Button 
                onClick={handleImport} 
                disabled={!selectedFile || exporting || importing}
                variant="secondary"
                className="w-full border border-slate-200 dark:border-white/10"
              >
                {importing ? (
                  <><Loader2 className="w-4 h-4 mr-2 animate-spin" /> Import läuft...</>
                ) : (
                  <><Upload className="w-4 h-4 mr-2" /> ZIP-Backup einspielen</>
                )}
              </Button>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}