// app/(app)/users/UsersCsvImportButton.tsx
'use client';

import { useRef, useState } from 'react';
import { useRouter } from 'next/navigation';
import Button from '@/components/ui/Button';

type SimpleGroup = {
  id: string;
  name: string;
};

type Props = {
  groups: SimpleGroup[];
};

export default function UsersCsvImportButton({ groups }: Props) {
  const router = useRouter();
  const fileInputRef = useRef<HTMLInputElement | null>(null);

  const [importing, setImporting] = useState(false);
  const [importError, setImportError] = useState<string | null>(null);
  const [importSummary, setImportSummary] = useState<string | null>(null);

  // Hilfsfunktion: Gruppe sicherstellen (existiert oder neu anlegen)
  async function ensureGroupId(
    name: string,
    cache: Map<string, string>,
  ): Promise<string | null> {
    const trimmed = name.trim();
    if (!trimmed) return null;

    const cached = cache.get(trimmed);
    if (cached) return cached;

    const res = await fetch('/api/user-groups', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ name: trimmed }),
    });

    if (!res.ok) {
      const data = await res.json().catch(() => null);
      console.error('Fehler beim Anlegen der Gruppe', res.status, data);
      return null;
    }

    const data = await res.json();
    const id = data.id as string;
    cache.set(trimmed, id);
    return id;
  }

  async function handleImportCsv(
    e: React.ChangeEvent<HTMLInputElement>,
  ): Promise<void> {
    const file = e.target.files?.[0];
    if (!file) return;

    setImporting(true);
    setImportError(null);
    setImportSummary(null);

    try {
      const text = await file.text();

      // Gruppen-Cache (Name -> ID), Start mit bestehenden Gruppen
      const groupCache = new Map<string, string>();
      for (const g of groups) {
        groupCache.set(g.name.trim(), g.id);
      }

      let createdCount = 0;
      let skippedCount = 0;

      const lines = text
        .split(/\r?\n/)
        .map((l) => l.trim())
        .filter((l) => l.length > 0);

      for (let index = 0; index < lines.length; index++) {
        const line = lines[index];

        // ⬅️ Erste Zeile immer ignorieren (Header)
        if (index === 0) {
          continue;
        }

        // Format: NwKennung;Nachname;Vorname;Arbeitsname;Gruppe
        const parts = line.split(';');
        if (parts.length < 4) {
          console.warn('Zeile übersprungen (falsches Format):', line);
          skippedCount++;
          continue;
        }

        const [
          nwkennungRaw,
          lastNameRaw,
          firstNameRaw,
          arbeitsnameRaw,
          groupRaw,
        ] = parts;

        const nwkennung = (nwkennungRaw ?? '').trim().toLowerCase();
        const lastName = (lastNameRaw ?? '').trim();
        const firstName = (firstNameRaw ?? '').trim();
        const arbeitsname = (arbeitsnameRaw ?? '').trim();
        const groupName = (groupRaw ?? '').trim();

        // NwKennung + Name + Arbeitsname als Pflichtfelder
        if (!nwkennung || !lastName || !firstName || !arbeitsname) {
          console.warn(
            'Zeile übersprungen (Pflichtfelder leer):',
            line,
          );
          skippedCount++;
          continue;
        }

        let groupId: string | null = null;
        if (groupName) {
          groupId = await ensureGroupId(groupName, groupCache);
          if (!groupId) {
            console.warn(
              'Zeile übersprungen (Gruppe konnte nicht angelegt werden):',
              line,
            );
            skippedCount++;
            continue;
          }
        }

        const res = await fetch('/api/users', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({
            nwkennung,       // ⬅ NEU
            arbeitsname,
            firstName,
            lastName,
            groupId,
          }),
        });

        if (!res.ok) {
          const data = await res.json().catch(() => null);
          console.error(
            'Fehler beim Anlegen der Person aus CSV:',
            res.status,
            data,
            'Zeile:',
            line,
          );
          skippedCount++;
          continue;
        }

        createdCount++;
      }

      setImportSummary(
        `Import abgeschlossen: ${createdCount} Personen importiert, ${skippedCount} Zeilen übersprungen.`,
      );
      router.refresh();
    } catch (err: any) {
      console.error('Fehler beim CSV-Import', err);
      setImportError(
        err instanceof Error
          ? err.message
          : 'Fehler beim CSV-Import.',
      );
    } finally {
      setImporting(false);
      if (e.target) {
        e.target.value = '';
      }
    }
  }

  return (
    <div className="flex flex-col items-stretch gap-1">
      <Button
        type="button"
        variant="soft"
        tone="indigo"
        size="lg"
        disabled={importing}
        onClick={() => fileInputRef.current?.click()}
      >
        {importing ? 'Importiere …' : 'Import aus CSV'}
      </Button>

      <input
        ref={fileInputRef}
        type="file"
        accept=".csv,text/csv"
        className="hidden"
        onChange={handleImportCsv}
      />

      {importSummary && (
        <p className="text-[11px] text-gray-600 dark:text-gray-300">
          {importSummary}
        </p>
      )}
      {importError && (
        <p className="text-[11px] text-red-600 dark:text-red-400">
          {importError}
        </p>
      )}
    </div>
  );
}