'use client';

import { useEffect } from 'react';
import { getHashTargetElement, normalizeHashFragment } from '../utils/same-page-hash-nav';
import { scrollElementIntoView } from '../utils/scroll-into-view';

/** ~1s at 60fps — long enough to outlast Radix accordion expand + SWR
 *  mount, short enough that a missed anchor doesn't hang the page. */
const MAX_POLL_FRAMES = 60;

export interface UseScrollToHashOptions {
  /** Pixels to subtract for sticky chrome. */
  headerOffset?: number;
}

/**
 * Scroll the page to `window.location.hash` once `readyDep` resolves
 * to a truthy value. Polls via rAF for ~1s so lazy-mounted rows (Radix
 * accordion, SWR fetch) have time to render. Re-runs on `readyDep`
 * reference change AND on `hashchange` (browser back/forward + the
 * synthetic event `navigateSamePageHash` dispatches).
 *
 * Skipped when `readyDep == null || readyDep === false`. Default
 * `true` makes the hook run on mount for pages whose target is in the
 * initial SSR render.
 */
export function useScrollToHash(readyDep: unknown = true, options?: UseScrollToHashOptions): void {
  const headerOffset = options?.headerOffset ?? 0;
  useEffect(() => {
    if (typeof window === 'undefined') return undefined;
    if (readyDep === null || readyDep === false) return undefined;
    let rafId: number | null = null;
    const cancelPoll = () => {
      if (rafId !== null) {
        cancelAnimationFrame(rafId);
        rafId = null;
      }
    };
    const tryScrollToHash = () => {
      // `normalizeHashFragment` heals a malformed multi-fragment hash
      // so `getElementById` resolves on deep-link entries that bypass
      // `navigateSamePageHash`'s own normalize.
      const hash = normalizeHashFragment(window.location.hash).slice(1);
      if (!hash) return;
      // Cancel any in-flight poll from a prior invocation so two
      // concurrent ticks can't both call scrollElementIntoView.
      cancelPoll();
      let frames = 0;
      const tick = () => {
        // Raw-then-decoded lookup — encoded fragments from href
        // composers must match the unencoded ids rows render.
        const el = getHashTargetElement(hash);
        if (el) {
          rafId = null;
          scrollElementIntoView(el, { headerOffset });
          return;
        }
        if (frames++ < MAX_POLL_FRAMES) {
          rafId = requestAnimationFrame(tick);
        } else {
          rafId = null;
        }
      };
      tick();
    };
    tryScrollToHash();
    window.addEventListener('hashchange', tryScrollToHash);
    return () => {
      window.removeEventListener('hashchange', tryScrollToHash);
      cancelPoll();
    };
  }, [readyDep, headerOffset]);
}