/**
 * NotificationItem — single notification row inside the dropdown.
 *
 * Props:
 *   notification: NotificationItem
 *   onMarkRead: (id: string) => void
 */

import React from 'react';
import clsx from 'clsx';
import {
  Info,
  Mail,
  CheckSquare,
  Calendar,
  AlertCircle,
  User,
  FileText,
  Bell,
  type LucideIcon,
} from 'lucide-react';
import type { NotificationItem as NotificationItemType } from '@/api/notifications';

// ── helpers ──

/**
 * Returns a German relative-time string like "vor 5 Min" or "vor 2 Stunden".
 * Falls back to "gerade eben" for < 1 min and an absolute date for > 7 days.
 */
function relativeTime(isoDate: string | null | undefined): string {
  if (!isoDate) return '';
  const now = Date.now();
  const then = new Date(isoDate).getTime();
  if (Number.isNaN(then)) return '';
  const diffMs = now - then;
  if (diffMs < 0) return 'gerade eben';
  const diffMin = Math.floor(diffMs / 60000);
  if (diffMin < 1) return 'gerade eben';
  if (diffMin < 60) return `vor ${diffMin} Min`;
  const diffHrs = Math.floor(diffMin / 60);
  if (diffHrs < 24) return `vor ${diffHrs} Std`;
  const diffDays = Math.floor(diffHrs / 24);
  if (diffDays < 7) return `vor ${diffDays} ${diffDays === 1 ? 'Tag' : 'Tagen'}`;
  // > 7 days: show absolute date
  return new Date(isoDate).toLocaleDateString('de-DE', {
    day: '2-digit',
    month: '2-digit',
    year: 'numeric',
  });
}

/** Map notification type → lucide icon. */
const typeIconMap: Record<string, LucideIcon> = {
  info: Info,
  email: Mail,
  mail: Mail,
  task: CheckSquare,
  calendar: Calendar,
  event: Calendar,
  alert: AlertCircle,
  warning: AlertCircle,
  error: AlertCircle,
  contact: User,
  user: User,
  document: FileText,
  file: FileText,
};

function getIconForType(type: string): LucideIcon {
  return typeIconMap[type] ?? Bell;
}

// ── component ──

export interface NotificationItemProps {
  notification: NotificationItemType;
  onMarkRead: (id: string) => void;
}

export function NotificationItem({ notification, onMarkRead }: NotificationItemProps) {
  const isUnread = notification.read_at == null;
  const Icon = getIconForType(notification.type);

  const handleClick = () => {
    if (isUnread) {
      onMarkRead(notification.id);
    }
  };

  return (
    <button
      onClick={handleClick}
      className={clsx(
        'w-full text-left flex items-start gap-3 px-3 py-2.5 hover:bg-secondary-50 transition-colors cursor-pointer',
        'border-b border-secondary-100 last:border-b-0 min-h-touch focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500',
        isUnread && 'bg-primary-50/40',
      )}
      role="menuitem"
      aria-label={notification.title}
    >
      {/* Icon */}
      <span
        className={clsx(
          'flex-shrink-0 mt-0.5 w-8 h-8 rounded-full flex items-center justify-center',
          isUnread ? 'bg-primary-100 text-primary-600' : 'bg-secondary-100 text-secondary-500',
        )}
        aria-hidden="true"
      >
        <Icon className="w-4 h-4" strokeWidth={2} />
      </span>

      {/* Content */}
      <div className="flex-1 min-w-0">
        <div className="flex items-center gap-2">
          <p
            className={clsx(
              'text-sm truncate',
              isUnread ? 'font-semibold text-secondary-900' : 'font-medium text-secondary-700',
            )}
          >
            {notification.title}
          </p>
          {isUnread && (
            <span
              className="flex-shrink-0 w-2 h-2 rounded-full bg-primary-500"
              aria-label="ungelesen"
              title="ungelesen"
            />
          )}
        </div>
        {notification.body && (
          <p className="text-xs text-secondary-500 truncate mt-0.5">
            {notification.body}
          </p>
        )}
        {notification.created_at && (
          <p className="text-xs text-secondary-400 mt-1">
            {relativeTime(notification.created_at)}
          </p>
        )}
      </div>
    </button>
  );
}