import { useEffect, useState } from "react";
import { useQueryClient } from "@tanstack/react-query";
import { getQueryStatusLabel } from "../utils/getQueryStatusLabel";

interface QueryStatusCounts {
  fresh: number;
  stale: number;
  fetching: number;
  paused: number;
  inactive: number;
}

/**
 * Tracks how many queries fall into each status bucket (fresh, stale, fetching, etc.). Uses
 * cache subscriptions to stay up to date without polling.
 */
function useQueryStatusCounts(): QueryStatusCounts {
  const queryClient = useQueryClient();
  const [counts, setCounts] = useState<QueryStatusCounts>({
    fresh: 0,
    stale: 0,
    fetching: 0,
    paused: 0,
    inactive: 0,
  });

  useEffect(() => {
    const updateCounts = () => {
      const allQueries = queryClient.getQueryCache().getAll();

      const newCounts = allQueries.reduce(
        (acc, query) => {
          const status = getQueryStatusLabel(query);
          acc[status as keyof QueryStatusCounts] =
            (acc[status as keyof QueryStatusCounts] || 0) + 1;
          return acc;
        },
        { fresh: 0, stale: 0, fetching: 0, paused: 0, inactive: 0 },
      );

      setTimeout(() => setCounts(newCounts), 0);
    };

    // Perform an initial update
    updateCounts();

    // Subscribe to the query cache to run updates on changes
    const unsubscribe = queryClient.getQueryCache().subscribe(updateCounts);

    // Cleanup the subscription when the component unmounts
    return () => unsubscribe();
  }, [queryClient]);

  return counts;
}

export default useQueryStatusCounts;

// Mutation status counts hook
interface MutationStatusCounts {
  pending: number;
  success: number;
  error: number;
  paused: number;
  idle: number;
}

/**
 * Companion hook for query status counts that groups mutations by status and pause state.
 */
export function useMutationStatusCounts(): MutationStatusCounts {
  const queryClient = useQueryClient();
  const [counts, setCounts] = useState<MutationStatusCounts>({
    pending: 0,
    success: 0,
    error: 0,
    paused: 0,
    idle: 0,
  });

  useEffect(() => {
    const updateCounts = () => {
      const allMutations = queryClient.getMutationCache().getAll();

      const newCounts = allMutations.reduce(
        (acc, mutation) => {
          const status = mutation.state.status;
          const isPaused = mutation.state.isPaused;

          if (isPaused) {
            acc.paused++;
          } else {
            switch (status) {
              case "idle":
                acc.idle++;
                break;
              case "pending":
                acc.pending++;
                break;
              case "success":
                acc.success++;
                break;
              case "error":
                acc.error++;
                break;
            }
          }
          return acc;
        },
        { pending: 0, success: 0, error: 0, paused: 0, idle: 0 },
      );

      setTimeout(() => setCounts(newCounts), 0);
    };

    // Perform an initial update
    updateCounts();

    // Subscribe to the mutation cache to run updates on changes
    const unsubscribe = queryClient.getMutationCache().subscribe(updateCounts);

    // Cleanup the subscription when the component unmounts
    return () => unsubscribe();
  }, [queryClient]);

  return counts;
}