"use client";

import { useMemo } from "react";
import { useQueries, useQuery } from "@tanstack/react-query";
import type { StatsManifest, VideoStat } from "../lib/stats";
import { readerFor } from "../lib/archive/readers";

export type StatsState = {
  manifest: StatsManifest | null;
  stats: VideoStat[];
  loadedPages: number;
  pageCount: number;
  ready: boolean;
  error: Error | null;
};

export function useStatsManifest(origin = "") {
  return useQuery<StatsManifest>({
    queryKey: ["stats-manifest", origin],
    queryFn: () => readerFor(origin).readStatsManifest(),
  });
}

// Mirrors summariesCache.useSummaries: load the manifest, then fan out the
// byte-capped page files via react-query and concatenate them.
export function useStats(origin = ""): StatsState {
  const manifestQuery = useStatsManifest(origin);
  const manifest = manifestQuery.data ?? null;
  const pageCount = manifest?.pageCount ?? 0;

  const pageQueries = useQueries({
    queries: Array.from({ length: pageCount }, (_, i) => ({
      queryKey: ["stats-page", origin, i],
      queryFn: () => readerFor(origin).readStatsPage(i),
      enabled: pageCount > 0,
    })),
  });

  const loadedPages = pageQueries.filter((q) => q.data).length;
  const ready = pageCount > 0 && loadedPages === pageCount;

  const stats = useMemo<VideoStat[]>(() => {
    if (loadedPages === 0) return [];
    const out: VideoStat[] = [];
    for (const q of pageQueries) if (q.data) out.push(...q.data);
    return out;
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [loadedPages, ready]);

  const error =
    manifestQuery.error instanceof Error
      ? manifestQuery.error
      : ((pageQueries.find((q) => q.error)?.error as Error | undefined) ?? null);

  return { manifest, stats, loadedPages, pageCount, ready, error };
}