import { Ellipsis, Upload } from 'lucide-react';
import { Suspense, useEffect, useState } from 'react';
import { Link, NavLink, Outlet, useLocation, useNavigate } from 'react-router';
import { toast } from 'sonner';
import { useReviewCount } from '@/lib/data';
import { queueFiles } from '@/lib/pendingFiles';
import { useConfig, useCurrentUser } from '@/lib/session';
import { cn } from '@/lib/utils';
import { APP_VERSION } from '@/lib/version';
import { LogoMark, VersionTag } from './brand';
import { IdeaButton } from './IdeaDialog';
import { NAV, SETTINGS_NAV, type NavItem } from './nav';
import { Button } from './ui/button';
import { Skeleton, Tip } from './ui/misc';
import { UserMenu } from './UserMenu';

function pageTitle(pathname: string): string {
  if (pathname === '/') return 'Home';
  if (pathname.startsWith('/settings')) return 'Settings';
  if (pathname.startsWith('/more')) return 'More';
  if (pathname.startsWith('/import')) return 'Import';
  return NAV.find((n) => n.to !== '/' && pathname.startsWith(n.to))?.label ?? 'Spendlight';
}

function CountBadge({ count, className }: { count: number | undefined; className?: string }) {
  if (!count) return null;
  return (
    <span className={cn('tabular flex h-5 min-w-5 items-center justify-center rounded-full bg-primary px-1.5 text-[11px] font-semibold text-primary-foreground', className)}>
      {count > 999 ? '999+' : count}
    </span>
  );
}

function SideLink({ item, badge }: { item: NavItem; badge?: number }) {
  const Icon = item.icon;
  return (
    <NavLink
      to={item.to}
      end={item.to === '/'}
      title={item.label}
      className={({ isActive }) =>
        cn(
          'flex h-11 items-center gap-3 rounded-xl px-3 text-[14px] font-medium text-muted-foreground transition-colors hover:bg-muted hover:text-foreground md:justify-center lg:justify-start',
          isActive && 'bg-accent text-accent-foreground hover:bg-accent hover:text-accent-foreground',
        )
      }
    >
      <span className="relative">
        <Icon className="size-[19px] shrink-0" strokeWidth={1.9} />
        <CountBadge count={badge} className="absolute -right-2.5 -top-2 h-4 min-w-4 px-1 text-[10px] lg:hidden" />
      </span>
      <span className="flex-1 md:sr-only lg:not-sr-only">{item.label}</span>
      <CountBadge count={badge} className="hidden lg:flex" />
    </NavLink>
  );
}

function Sidebar() {
  const { data: toReview } = useReviewCount();
  return (
    <aside className="fixed inset-y-0 left-0 z-40 hidden flex-col border-r bg-card/70 backdrop-blur-xl md:flex md:w-[84px] lg:w-64">
      <Link to="/" className="flex h-16 items-center gap-2.5 px-6 md:justify-center lg:justify-start" aria-label="Spendlight home">
        <LogoMark />
        <span className="hidden text-[17px] font-semibold tracking-tight lg:inline">Spendlight</span>
      </Link>
      <nav className="flex flex-1 flex-col gap-1 px-3 py-2" aria-label="Main">
        {NAV.map((item) => (
          <SideLink key={item.to} item={item} badge={item.to === '/review' ? toReview : undefined} />
        ))}
      </nav>
      <div className="px-3 pb-4">
        <SideLink item={SETTINGS_NAV} />
        <div className="mt-3 px-3 md:text-center lg:text-left">
          <VersionTag />
        </div>
      </div>
    </aside>
  );
}

function PhoneTabBar() {
  const { pathname } = useLocation();
  const { data: toReview } = useReviewCount();
  const inMore = pathname.startsWith('/more') || pathname.startsWith('/settings') || pathname.startsWith('/import') || NAV.some((n) => !n.phone && pathname.startsWith(n.to));
  const tab = 'flex flex-col items-center gap-1 pt-2 pb-1 text-[11px] font-medium text-muted-foreground transition-colors';
  return (
    <nav className="fixed inset-x-0 bottom-0 z-40 border-t bg-card/85 pb-safe backdrop-blur-xl md:hidden" aria-label="Main">
      <div className="mx-auto grid max-w-md grid-cols-5">
        {NAV.filter((n) => n.phone).map(({ to, label, icon: Icon }) => (
          <NavLink key={to} to={to} end={to === '/'} className={({ isActive }) => cn(tab, isActive && 'text-primary')}>
            <span className="relative">
              <Icon className="size-[22px]" strokeWidth={1.9} />
              {to === '/review' ? <CountBadge count={toReview} className="absolute -right-3 -top-1.5 h-4 min-w-4 px-1 text-[10px]" /> : null}
            </span>
            {label}
          </NavLink>
        ))}
        <NavLink to="/more" className={cn(tab, inMore && 'text-primary')}>
          <Ellipsis className="size-[22px]" strokeWidth={1.9} />
          More
        </NavLink>
      </div>
    </nav>
  );
}

/** When the server is running a newer version than these screens, offer a reload. */
function UpdateNotice() {
  const { data } = useConfig();
  useEffect(() => {
    if (!data || data.version === 'dev' || APP_VERSION === 'dev' || data.version === APP_VERSION) return;
    toast('A new version of Spendlight is ready', {
      id: 'update',
      description: `Version ${data.version}`,
      duration: Infinity,
      action: { label: 'Reload', onClick: () => window.location.reload() },
    });
  }, [data]);
  return null;
}

export function PageSkeleton() {
  return (
    <div className="grid gap-4">
      <Skeleton className="h-8 w-48" />
      <Skeleton className="h-40 w-full rounded-2xl" />
      <Skeleton className="h-28 w-full rounded-2xl" />
    </div>
  );
}

/** Drop statement files anywhere on a big screen to start importing them. */
function useFileDrop(enabled: boolean) {
  const navigate = useNavigate();
  const [over, setOver] = useState(false);
  useEffect(() => {
    if (!enabled) return;
    let depth = 0;
    const hasFiles = (e: DragEvent) => !!e.dataTransfer?.types.includes('Files');
    const enter = (e: DragEvent) => {
      if (!hasFiles(e)) return;
      depth++;
      setOver(true);
    };
    const leave = (e: DragEvent) => {
      if (!hasFiles(e)) return;
      depth = Math.max(0, depth - 1);
      if (!depth) setOver(false);
    };
    const overHandler = (e: DragEvent) => {
      if (hasFiles(e)) e.preventDefault();
    };
    const drop = (e: DragEvent) => {
      if (!hasFiles(e)) return;
      e.preventDefault();
      depth = 0;
      setOver(false);
      const files = [...(e.dataTransfer?.files ?? [])];
      if (files.length && !window.location.pathname.startsWith('/import')) {
        queueFiles(files);
        navigate('/import');
      }
    };
    window.addEventListener('dragenter', enter);
    window.addEventListener('dragleave', leave);
    window.addEventListener('dragover', overHandler);
    window.addEventListener('drop', drop);
    return () => {
      window.removeEventListener('dragenter', enter);
      window.removeEventListener('dragleave', leave);
      window.removeEventListener('dragover', overHandler);
      window.removeEventListener('drop', drop);
    };
  }, [enabled, navigate]);
  return over;
}

export function AppShell() {
  const { data: config } = useConfig();
  const me = useCurrentUser();
  const { pathname } = useLocation();
  const dropping = useFileDrop(me.access === 'full' && !pathname.startsWith('/import'));

  useEffect(() => {
    window.scrollTo(0, 0);
  }, [pathname]);

  return (
    <div className="min-h-dvh">
      <Sidebar />
      <div className="md:pl-[84px] lg:pl-64">
        <header className="sticky top-0 z-30 border-b bg-background/80 pt-safe backdrop-blur-xl">
          <div className="mx-auto flex h-14 max-w-6xl items-center gap-2 px-4 sm:px-6 lg:px-8">
            <Link to="/" className="mr-1 md:hidden" aria-label="Spendlight home">
              <LogoMark className="size-7" />
            </Link>
            <h1 className="flex-1 truncate text-[17px] font-semibold tracking-tight">{pageTitle(pathname)}</h1>
            {me.access === 'full' ? (
              <Tip label="Import statements">
                <Button variant="ghost" size="icon" asChild aria-label="Import statements">
                  <Link to="/import">
                    <Upload />
                  </Link>
                </Button>
              </Tip>
            ) : null}
            {config?.ideasEnabled ? <IdeaButton /> : null}
            <UserMenu />
          </div>
        </header>
        <main className="mx-auto max-w-6xl px-4 pb-32 pt-5 sm:px-6 md:pb-14 md:pt-8 lg:px-8">
          <Suspense fallback={<PageSkeleton />}>
            <Outlet />
          </Suspense>
        </main>
      </div>
      <PhoneTabBar />
      <UpdateNotice />
      {dropping ? (
        <div className="pointer-events-none fixed inset-0 z-[60] flex items-center justify-center bg-night/50 p-8 backdrop-blur-sm">
          <div className="flex flex-col items-center rounded-3xl border-2 border-dashed border-white/50 px-16 py-12 text-center text-white">
            <Upload className="mb-3 size-10" strokeWidth={1.6} />
            <p className="text-xl font-semibold">Drop to import</p>
            <p className="mt-1 text-white/75">Statements from any of your banks</p>
          </div>
        </div>
      ) : null}
    </div>
  );
}