import {
  type AnyRouter,
  Outlet,
  useRouter,
  useRouterState,
  useParams as useTanstackParams,
} from "@tanstack/react-router";
import type { AnchorHTMLAttributes, MouseEvent, ReactNode } from "react";
import { createContext, forwardRef, useCallback, useContext } from "react";

// Keep URL search values as strings while the console's existing links move to TanStack Router.
export function parseUrlSearch(value: string): Record<string, string | string[]> {
  const result: Record<string, string | string[]> = Object.create(null);
  for (const [key, part] of new URLSearchParams(value)) {
    const previous = result[key];
    result[key] = previous === undefined ? part : [...(Array.isArray(previous) ? previous : [previous]), part];
  }
  return result;
}

export function stringifyUrlSearch(search: Record<string, unknown>): string {
  const params = new URLSearchParams();
  for (const [key, value] of Object.entries(search)) {
    if (value == null) continue;
    for (const part of Array.isArray(value) ? value : [value]) params.append(key, String(part));
  }
  const value = params.toString();
  return value ? `?${value}` : "";
}

export type Location = {
  pathname: string;
  search: string;
  hash: string;
  state: unknown;
  key: string;
};
const TestLocation = createContext<Location | null>(null);
let navigationSequence = 0;

declare module "@tanstack/react-router" {
  interface HistoryState {
    __umtNavigationKey?: string;
  }
}

export function useLocation(): Location {
  const testLocation = useContext(TestLocation);
  // The test provider is fixed for a render tree; production always uses RouterProvider.
  if (testLocation) return testLocation;
  // biome-ignore lint/correctness/useHookAtTopLevel: provider branch is stable for the component lifetime
  const location = useRouterState({ select: (state) => state.location });
  return {
    pathname: location.pathname,
    search: location.searchStr,
    hash: location.hash ? (location.hash.startsWith("#") ? location.hash : `#${location.hash}`) : "",
    state: location.state,
    key: location.state.__TSR_key ?? location.href,
  };
}

type To = string | { pathname?: string; search?: string; hash?: string };
type NavigationOptions = { replace?: boolean; state?: unknown; preventScrollReset?: boolean };

export function navigateTo(router: AnyRouter, target: URL, options: NavigationOptions = {}) {
  return router.navigate({
    to: target.pathname,
    search: parseUrlSearch(target.search),
    hash: target.hash.slice(1),
    replace: options.replace,
    resetScroll: !options.preventScrollReset,
    // 显式导航即使地址和业务 state 相同，也要更新 key，让设置搜索能再次定位同一字段。
    state: {
      ...((options.state ?? {}) as Record<string, unknown>),
      __umtNavigationKey: `${Date.now()}:${++navigationSequence}`,
    },
  });
}

export function resolveTo(to: To, current: Pick<Location, "pathname" | "search" | "hash">): string {
  if (typeof to === "string") {
    if (to.startsWith("?") || to.startsWith("#"))
      return `${current.pathname}${to.startsWith("#") ? current.search : ""}${to}`;
    return to;
  }
  return `${to.pathname ?? current.pathname}${to.search ?? ""}${to.hash ?? ""}`;
}

export function useNavigate() {
  const router = useRouter({ warn: false });
  const { pathname, search, hash } = useLocation();
  return useCallback(
    (to: To | number, options: NavigationOptions = {}) => {
      if (typeof to === "number") {
        router?.history.go(to);
        return;
      }
      const target = new URL(resolveTo(to, { pathname, search, hash }), window.location.origin);
      if (target.origin !== window.location.origin) {
        window.location.assign(target.href);
        return;
      }
      if (!router) return;
      void navigateTo(router, target, options);
    },
    [router, pathname, search, hash],
  );
}

type SearchInput = URLSearchParams | Record<string, string>;
export function useSearchParams(): [
  URLSearchParams,
  (next: SearchInput | ((current: URLSearchParams) => SearchInput), options?: NavigationOptions) => void,
] {
  const location = useLocation();
  const navigate = useNavigate();
  const set = useCallback(
    (next: SearchInput | ((current: URLSearchParams) => SearchInput), options?: NavigationOptions) => {
      const value = typeof next === "function" ? next(new URLSearchParams(location.search)) : next;
      const params = value instanceof URLSearchParams ? value : new URLSearchParams(value);
      navigate({ search: params.toString() ? `?${params}` : "" }, options);
    },
    [location.search, navigate],
  );
  return [new URLSearchParams(location.search), set];
}

export function useParams<T extends Record<string, string | undefined> = Record<string, string | undefined>>(): T {
  const testLocation = useContext(TestLocation);
  if (testLocation) return {} as T;
  // biome-ignore lint/correctness/useHookAtTopLevel: provider branch is stable for the component lifetime
  return useTanstackParams({ strict: false } as never) as T;
}

export type LinkProps = Omit<AnchorHTMLAttributes<HTMLAnchorElement>, "href"> & {
  to: To;
  replace?: boolean;
  state?: unknown;
  preventScrollReset?: boolean;
};

export const Link = forwardRef<HTMLAnchorElement, LinkProps>(function Link(
  { to, replace, state, preventScrollReset, onClick, target, children, ...props },
  ref,
) {
  const location = useLocation();
  const navigate = useNavigate();
  const href = resolveTo(to, location);
  const click = (event: MouseEvent<HTMLAnchorElement>) => {
    onClick?.(event);
    if (
      event.defaultPrevented ||
      event.button !== 0 ||
      event.metaKey ||
      event.ctrlKey ||
      event.shiftKey ||
      event.altKey ||
      target === "_blank" ||
      props.download
    )
      return;
    const url = new URL(href, window.location.origin);
    if (url.origin !== window.location.origin) return;
    event.preventDefault();
    navigate(href, { replace, state, preventScrollReset });
  };
  return (
    <a {...props} ref={ref} href={href} target={target} onClick={click}>
      {children}
    </a>
  );
});

export function redirect(to: string): Response {
  return new Response(null, { status: 302, headers: { Location: to } });
}

export { Outlet };

// Existing component tests mount only a memory navigation context.
export function MemoryRouter({ children, initialEntries }: { children?: ReactNode; initialEntries?: string[] }) {
  const url = new URL(initialEntries?.[0] ?? "/", "http://localhost");
  const location: Location = { pathname: url.pathname, search: url.search, hash: url.hash, state: null, key: "test" };
  return <TestLocation value={location}>{children}</TestLocation>;
}