import { useState } from 'react';
import { useMutation } from '@tanstack/react-query';
import { useTranslation } from 'react-i18next';

import { enableTotp, setupTotp } from '@/api/auth';
import { ErrorNotice } from '@/components/ui/ErrorNotice';
import { Field } from '@/components/ui/Field';
import { Button, Card } from '@/components/ui/primitives';

/**
 * Включение двухфакторной аутентификации: setup → секрет (и QR) → код →
 * одноразовые коды восстановления, которые показываются ровно один раз.
 */
export function TwoFactorSection({
  enabled,
  onEnabled,
}: {
  enabled: boolean;
  onEnabled: () => void;
}) {
  const { t } = useTranslation();
  const [secret, setSecret] = useState<string | null>(null);
  const [otpauthUrl, setOtpauthUrl] = useState('');
  const [qrPng, setQrPng] = useState('');
  const [code, setCode] = useState('');
  const [recoveryCodes, setRecoveryCodes] = useState<string[] | null>(null);
  const [qrFailed, setQrFailed] = useState(false);
  const [copied, setCopied] = useState(false);

  const setup = useMutation({
    mutationFn: () => setupTotp(),
    onSuccess: (payload) => {
      setSecret(payload.secret);
      setOtpauthUrl(payload.otpauth_url);
      setQrPng(payload.qr_png ?? '');
      setRecoveryCodes(null);
      setQrFailed(false);
    },
  });

  const enable = useMutation({
    mutationFn: () => enableTotp(code.trim()),
    onSuccess: (codes) => {
      setRecoveryCodes(codes);
      setSecret(null);
      setCode('');
      onEnabled();
    },
  });

  const copyRecovery = (): void => {
    if (recoveryCodes === null) {
      return;
    }
    void navigator.clipboard?.writeText(recoveryCodes.join('\n'));
    setCopied(true);
  };

  return (
    <Card>
      <div className="flex items-start justify-between gap-4">
        <div>
          <h2 className="text-lg font-semibold">{t('settings.security.twoFactorTitle')}</h2>
          <p className="mt-1 text-sm text-fg-muted">
            {t(
              enabled
                ? 'settings.security.twoFactorEnabled'
                : 'settings.security.twoFactorDisabled',
            )}
          </p>
        </div>
        {enabled || secret !== null ? null : (
          <Button disabled={setup.isPending} onClick={() => setup.mutate()}>
            {t('settings.security.twoFactorEnable')}
          </Button>
        )}
      </div>

      {setup.isError ? <ErrorNotice className="mt-3" error={setup.error} /> : null}

      {secret !== null ? (
        <div className="mt-4 flex flex-col gap-3 rounded-[var(--radius-md)] border border-border/60 bg-surface-2/60 p-3">
          <p className="text-sm text-fg-muted">{t('settings.security.twoFactorSetupHint')}</p>

          <div className="flex flex-wrap items-start gap-4">
            {qrFailed || qrPng === '' ? (
              <p className="text-xs text-fg-muted">
                {t('settings.security.twoFactorQrUnavailable')}
              </p>
            ) : (
              <img
                src={qrPng}
                alt={t('settings.security.twoFactorQrAlt')}
                width={160}
                height={160}
                className="rounded-[var(--radius-sm)] bg-white p-1"
                onError={() => setQrFailed(true)}
              />
            )}
            <dl className="text-sm">
              <dt className="text-fg-muted">{t('settings.security.twoFactorSecret')}</dt>
              <dd className="mt-1 font-mono text-xs break-all" data-testid="totp-secret">
                {secret}
              </dd>
              <dt className="mt-3 text-fg-muted">{t('settings.security.twoFactorUri')}</dt>
              <dd className="mt-1 font-mono text-xs break-all">{otpauthUrl}</dd>
            </dl>
          </div>

          <form
            className="flex flex-col gap-3"
            onSubmit={(event) => {
              event.preventDefault();
              if (code.trim() !== '') {
                enable.mutate();
              }
            }}
          >
            <Field
              label={t('settings.security.twoFactorCode')}
              name="totp_code"
              inputMode="numeric"
              autoComplete="one-time-code"
              pattern="[0-9]*"
              maxLength={8}
              value={code}
              onChange={(event) => setCode(event.target.value)}
              required
            />
            {enable.isError ? <ErrorNotice error={enable.error} /> : null}
            <div className="flex justify-end">
              <Button type="submit" disabled={enable.isPending || code.trim() === ''}>
                {t(enable.isPending ? 'common.saving' : 'settings.security.twoFactorConfirm')}
              </Button>
            </div>
          </form>
        </div>
      ) : null}

      {recoveryCodes !== null ? (
        <div className="mt-4 rounded-[var(--radius-md)] border border-success/50 bg-success/10 p-3">
          <p className="text-sm text-success" role="status">
            {t('settings.security.twoFactorEnabledDone')}
          </p>
          <h3 className="mt-2 text-sm font-semibold">{t('settings.security.recoveryTitle')}</h3>
          <p className="text-xs text-fg-muted">{t('settings.security.recoveryHint')}</p>
          <ul
            className="mt-2 grid grid-cols-2 gap-1 font-mono text-xs"
            data-testid="recovery-codes"
          >
            {/* Коды вида `a8eh-pshp-t8st` не обрезаем: переносим по символам. */}
            {recoveryCodes.map((recoveryCode) => (
              <li key={recoveryCode} className="min-w-0 break-all">
                {recoveryCode}
              </li>
            ))}
          </ul>
          <div className="mt-3 flex items-center gap-3">
            <Button variant="ghost" onClick={copyRecovery}>
              {t(copied ? 'common.copied' : 'settings.security.recoveryCopyAll')}
            </Button>
          </div>
        </div>
      ) : null}
    </Card>
  );
}