'use client';

import { useState } from 'react';
import { t } from '@/lib/i18n';

type Row = { name: string; email: string; company: string; status: string };
type Preview = { total: number; valid: number; errors: { row: number; message: string }[]; duplicatesInFile: number[]; sample: Row[] };
type Committed = { imported: number; updated: number; errors: { row: number; message: string }[]; duplicatesInFile: number[] };

const SAMPLE = 'name,email,company,status\nJane Doe,jane@example.com,Acme,lead\nBad Row,not-an-email,Globex,active';

export function ImportWizard({ canImport }: { canImport: boolean }) {
  const [csv, setCsv] = useState('');
  const [preview, setPreview] = useState<Preview | null>(null);
  const [committed, setCommitted] = useState<Committed | null>(null);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);

  async function post(commit: boolean) {
    setBusy(true);
    setError(null);
    try {
      const res = await fetch('/api/admin/import/customers', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ csv, commit }),
      });
      const data = (await res.json().catch(() => ({}))) as Record<string, unknown>;
      if (!res.ok) {
        setError((data.error as string) || t('common.error'));
        return;
      }
      if (commit) {
        setPreview(null);
        setCommitted(data as unknown as Committed);
      } else {
        setCommitted(null);
        setPreview(data as unknown as Preview);
      }
    } finally {
      setBusy(false);
    }
  }

  async function onFile(event: React.ChangeEvent<HTMLInputElement>) {
    const file = event.target.files?.[0];
    if (file) setCsv(await file.text());
  }

  if (!canImport) {
    return (
      <div className="space-y-4">
        <h1 className="text-2xl font-bold">{t('admin.importTitle')}</h1>
        <p className="muted text-sm">{t('admin.readOnly')}</p>
      </div>
    );
  }

  return (
    <div className="space-y-6">
      <header className="flex flex-wrap items-center justify-between gap-3">
        <h1 className="text-2xl font-bold">{t('admin.importTitle')}</h1>
        <a className="btn-secondary" href="/api/admin/export/customers" download>
          {t('admin.export')}
        </a>
      </header>
      <p className="muted text-sm">{t('admin.importHint')}</p>

      <div className="card space-y-3">
        <label className="block text-sm">
          {t('admin.chooseFile')}
          <input type="file" accept=".csv,text/csv" className="mt-1 block text-sm" onChange={onFile} />
        </label>
        <label className="block text-sm">
          CSV
          <textarea
            className="input mt-1 min-h-40 font-mono"
            value={csv}
            onChange={(e) => setCsv(e.target.value)}
            placeholder={SAMPLE}
          />
        </label>
        <div className="flex flex-wrap gap-2">
          <button type="button" className="btn-secondary" disabled={busy || !csv.trim()} onClick={() => post(false)}>
            {t('admin.preview')}
          </button>
          <button
            type="button"
            className="btn-primary"
            disabled={busy || !preview || preview.valid === 0}
            onClick={() => post(true)}
          >
            {busy ? t('admin.importing') : t('admin.commit', { count: preview?.valid ?? 0 })}
          </button>
        </div>
        {error && <p className="text-sm text-red-600">{error}</p>}
      </div>

      {committed && (
        <div className="card">
          <p className="text-sm font-medium">
            {t('admin.imported', { imported: committed.imported, updated: committed.updated })}
          </p>
          {committed.errors.length > 0 && <RowErrors errors={committed.errors} />}
        </div>
      )}

      {preview && (
        <div className="card space-y-4">
          <p className="text-sm">
            {t('admin.previewResult', {
              total: preview.total,
              valid: preview.valid,
              errors: preview.errors.length,
              duplicates: preview.duplicatesInFile.length,
            })}
          </p>
          <div>
            <h2 className="mb-2 text-sm font-semibold">{t('admin.sample')}</h2>
            {preview.sample.length === 0 ? (
              <p className="muted text-sm">{t('admin.empty')}</p>
            ) : (
              <div className="overflow-x-auto rounded-xl border" style={{ borderColor: 'var(--border)' }}>
                <table className="w-full text-sm">
                  <thead className="muted text-left text-xs uppercase">
                    <tr>
                      <th className="px-4 py-2">{t('admin.name')}</th>
                      <th className="px-4 py-2">{t('admin.email')}</th>
                      <th className="px-4 py-2">{t('admin.company')}</th>
                      <th className="px-4 py-2">{t('admin.status')}</th>
                    </tr>
                  </thead>
                  <tbody>
                    {preview.sample.map((r) => (
                      <tr key={r.email} className="border-t" style={{ borderColor: 'var(--border)' }}>
                        <td className="px-4 py-2">{r.name}</td>
                        <td className="px-4 py-2">{r.email}</td>
                        <td className="px-4 py-2">{r.company || t('admin.none')}</td>
                        <td className="px-4 py-2">{t(`admin.${r.status}`)}</td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              </div>
            )}
          </div>
          <div>
            <h2 className="mb-2 text-sm font-semibold">{t('admin.perRowErrors')}</h2>
            {preview.errors.length === 0 ? (
              <p className="muted text-sm">{t('admin.noErrors')}</p>
            ) : (
              <RowErrors errors={preview.errors} />
            )}
          </div>
        </div>
      )}
    </div>
  );
}

function RowErrors({ errors }: { errors: { row: number; message: string }[] }) {
  return (
    <div className="overflow-x-auto rounded-xl border" style={{ borderColor: 'var(--border)' }}>
      <table className="w-full text-sm">
        <thead className="muted text-left text-xs uppercase">
          <tr>
            <th className="px-4 py-2">{t('admin.row')}</th>
            <th className="px-4 py-2">{t('admin.message')}</th>
          </tr>
        </thead>
        <tbody>
          {errors.map((e) => (
            <tr key={`${e.row}-${e.message}`} className="border-t" style={{ borderColor: 'var(--border)' }}>
              <td className="px-4 py-2">{e.row}</td>
              <td className="px-4 py-2 text-red-600">{e.message}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
}