import { Link, useLocation } from 'react-router-dom';

import { Icon } from './Icon';

interface NavRailItem {
  to: string;
  icon: string;
  label: string;
  badge?: number;
}

const TOP_ITEMS: NavRailItem[] = [
  { to: '/messages', icon: 'chat_bubble', label: '消息' },
  { to: '/contacts', icon: 'contacts', label: '通讯录' },
  { to: '/favorites', icon: 'inventory_2', label: '收藏' },
  { to: '/files', icon: 'folder', label: '文件助手' },
];

const BOTTOM_ITEMS: NavRailItem[] = [
  { to: '/calls', icon: 'phone', label: '通话记录' },
  { to: '/settings', icon: 'settings', label: '设置' },
];

/** `/files` is `<Navigate to="/messages/slf" replace />` (App.tsx) -- the real URL right after
 *  clicking "文件助手" is `/messages/slf`, which a plain (non-`end`) NavLink match makes "消息"
 *  light up for (a same-topicId prefix match) while "文件助手" itself (`to: '/files'`, a path that
 *  no longer exists once redirected) never matches at all. Overriding both items' active state off
 *  the real pathname instead of trusting NavLink's own prefix match fixes both sides of the mix-up. */
function isNavItemActive(to: string, pathname: string): boolean {
  if (to === '/files') return pathname === '/messages/slf';
  if (to === '/messages') return pathname.startsWith('/messages') && pathname !== '/messages/slf';
  return pathname === to || pathname.startsWith(`${to}/`);
}

function NavRailButton({ item }: { item: NavRailItem }) {
  const location = useLocation();
  const isActive = isNavItemActive(item.to, location.pathname);
  return (
    // Plain Link, not NavLink -- NavLink computes its OWN `aria-current` from ITS OWN prefix-match
    // logic unconditionally (confirmed by reading react-router's source: passing an `aria-current`
    // prop only changes the STRING used, not whether it's applied at all, which stays gated on
    // NavLink's internal isActive). That's exactly `/files`'s own problem above -- NavLink's naive
    // match would light up "消息" for `/messages/slf`, not "文件助手" -- so a second, independent
    // aria-current computation fighting the same override this file already needed for `className`
    // is a real, verifiable a11y bug (screen readers and sighted highlighting would disagree on
    // which icon is current). Driving both off the one already-correct `isActive` avoids that
    // entirely.
    <Link
      to={item.to}
      title={item.label}
      aria-label={item.label}
      aria-current={isActive ? 'page' : undefined}
      className={`relative grid h-11 w-11 place-items-center rounded-[10px] no-underline ${
        isActive ? 'bg-accent-soft-bg text-accent' : 'text-text-secondary'
      }`}
    >
      <Icon name={item.icon} className="!text-2xl" />
      {item.badge ? (
        <b className="absolute top-1 right-0.5 grid h-4 min-w-4 place-items-center rounded-full bg-unread px-1 text-[10px] leading-none font-medium text-white">
          {item.badge}
        </b>
      ) : null}
    </Link>
  );
}

/** Persistent 64px icon rail, visible at >=640px (see App.tsx for the <640 bottom-tab fallback). */
export function NavRail({ selfInitial = '我', unreadMessages = 0 }: { selfInitial?: string; unreadMessages?: number }) {
  return (
    <nav className="flex h-full w-16 flex-none flex-col items-center border-r border-[#e6e9ee] bg-surface-rail pb-3 pt-3.5">
      <div className="mb-[22px] grid h-[38px] w-[38px] place-items-center rounded-[10px] bg-accent text-base font-semibold text-white">
        {selfInitial}
      </div>
      <div className="flex flex-1 flex-col items-center gap-1.5">
        {TOP_ITEMS.map((item) => (
          <NavRailButton key={item.to} item={item.to === '/messages' ? { ...item, badge: unreadMessages } : item} />
        ))}
      </div>
      <div className="flex flex-col items-center gap-1.5">
        {BOTTOM_ITEMS.map((item) => (
          <NavRailButton key={item.to} item={item} />
        ))}
      </div>
    </nav>
  );
}