import { useQuery, type QueryClient } from "@tanstack/react-query";
import type { Company } from "@paperclipai/shared";
import { authApi } from "./auth";
import { companiesApi } from "./companies";
import { ApiError } from "./client";
import { queryKeys } from "../lib/queryKeys";

export type CompanyListResult = { companies: Company[]; unauthorized: boolean };

// Single source of truth for the company-list query. Every consumer reads the
// same cache entry, so they must agree on the shape — returning a bare
// `Company[]` from one and this wrapped object from another silently corrupts
// the entry and crashes whichever reads the other's shape.
//
// The entry is keyed by account. Callers therefore cannot ask for "the company
// list" without saying whose, which is the point: the previous design let a
// list fetched for one account answer a question about another, and every
// consumer had to defend against that individually.
export function companyListQueryOptions(userId: string | null) {
  return {
    queryKey: queryKeys.companies.list(userId),
    queryFn: async (): Promise<CompanyListResult> => {
      // Request coalescing keys on the path alone, so it would happily answer a
      // fetch for this account with a `/companies` request issued under the
      // previous one — putting the wrong account's list in an account-keyed
      // entry. Coalescing has nothing to offer here anyway: React Query already
      // dedupes concurrent fetches within a key, and *across* keys the accounts
      // differ by construction, which is exactly when sharing is wrong.
      companiesApi.detachInflightList();
      try {
        return { companies: await companiesApi.list(), unauthorized: false };
      } catch (err) {
        if (err instanceof ApiError && (err.status === 401 || err.status === 403)) {
          return { companies: [], unauthorized: true };
        }
        throw err;
      }
    },
    retry: false,
  } as const;
}

const sessionQueryOptions = {
  queryKey: queryKeys.auth.session,
  queryFn: () => authApi.getSession(),
  retry: false,
} as const;

/**
 * The signed-in account, as the cache currently understands it.
 *
 * `settled` means the session query *answered*, not merely that it stopped
 * being pending. The distinction is the whole point of this helper. `null` is a
 * real answer — `authApi.getSession` returns it for a 401, meaning "signed out"
 * — but a session request that *failed* answers nothing, and it throws rather
 * than returning null. Treating that failure as `null` would key an account's
 * list to `anonymous` while the request still carried their cookie, writing a
 * credentialed response into the entry every signed-out reader trusts. Which is
 * the original bug, rebuilt for anonymous.
 *
 * So: settled on success only. A failed session lookup leaves the list unfetched
 * until the query recovers, which it does on the next refetch.
 */
export function useAccountIdentity(): { userId: string | null; settled: boolean } {
  const { data: session, isSuccess } = useQuery(sessionQueryOptions);
  return { userId: session?.user.id ?? null, settled: isSuccess };
}

/**
 * Observe the company list for the account signed in now.
 *
 * Pass `enabled: false` to hold for a caller's own reasons; the session gate is
 * applied on top of it either way.
 */
export function useCompanyListQuery(
  options: { enabled?: boolean; staleTime?: number; retry?: number | boolean } = {},
) {
  const { userId, settled } = useAccountIdentity();
  const query = useQuery<CompanyListResult>({
    ...companyListQueryOptions(userId),
    ...options,
    enabled: settled && (options.enabled ?? true),
  });

  // While the account is unknown this query is disabled, and a disabled query
  // reports `isLoading: false` with `data: undefined` — which consumers default
  // to an empty list and read as "asked, and owns nothing". That is the
  // destructive reading: `shouldClearStoredCompanySelection` would throw away
  // the customer's stored company on every cold boot, before the session had
  // even landed.
  //
  // Waiting for the account is part of getting the list, so it is reported as
  // part of getting the list. Consumers gate on these two, and both must mean
  // "no answer yet" for the whole window in which there is no answer.
  const waitingForAccount = !settled && (options.enabled ?? true);
  return {
    ...query,
    isLoading: query.isLoading || waitingForAccount,
    isFetching: query.isFetching || waitingForAccount,
  };
}

/**
 * Resolve the account identity for an imperative path, fetching the session if
 * the cache has no answer yet.
 *
 * Not `getQueryData` with a `?? null` fallback: an empty or errored session
 * entry would read as "signed out" and key an authenticated response to
 * `anonymous`. There is no safe default here — the identity is either known or
 * must be obtained, and if it cannot be obtained the caller must fail rather
 * than guess.
 */
export async function resolveAccountUserId(queryClient: QueryClient): Promise<string | null> {
  const state = queryClient.getQueryState<Awaited<ReturnType<typeof authApi.getSession>>>(
    queryKeys.auth.session,
  );
  // `isInvalidated` matters as much as `status` here. Invalidation is how the
  // app says "this is the previous account's answer" — InviteLanding invalidates
  // the session immediately after a sign-in and resolves an identity in the next
  // breath. The entry is still `success`, still holding the *old* user, until a
  // refetch lands; trusting it would key the new account's list to the old
  // account's id, which is the misattribution this whole file exists to prevent.
  if (state?.status === "success" && !state.isInvalidated) {
    return state.data?.user.id ?? null;
  }
  const session = await queryClient.fetchQuery({ ...sessionQueryOptions, staleTime: 0 });
  return session?.user.id ?? null;
}

/** Fetch the company list for the account signed in now, ignoring what is cached. */
export async function fetchCompanyListForCurrentAccount(
  queryClient: QueryClient,
): Promise<CompanyListResult> {
  const userId = await resolveAccountUserId(queryClient);
  return queryClient.fetchQuery({
    ...companyListQueryOptions(userId),
    staleTime: 0,
  });
}