// dashboard/src/components/agent/useAutoScroll.ts
// 共享自动滚动 hook：检测是否贴底，仅在贴底时自动滚动
import { useState, useRef, useEffect, useCallback } from 'react';

interface UseAutoScrollReturn {
  chatEndRef: React.RefObject<HTMLDivElement | null>;
  scrollContainerRef: React.RefObject<HTMLDivElement | null>;
  shouldAutoScroll: boolean;
  setShouldAutoScroll: (v: boolean) => void;
  scrollToBottom: (behavior?: ScrollBehavior) => void;
  handleScroll: () => void;
}

export function useAutoScroll(deps: React.DependencyList): UseAutoScrollReturn {
  const chatEndRef = useRef<HTMLDivElement>(null);
  const scrollContainerRef = useRef<HTMLDivElement>(null);
  const [shouldAutoScroll, setShouldAutoScroll] = useState(true);

  const scrollToBottom = useCallback((behavior: ScrollBehavior = 'smooth') => {
    const el = scrollContainerRef.current;
    if (el) {
      el.scrollTo({
        top: el.scrollHeight,
        behavior,
      });
    }
  }, []);

  useEffect(() => {
    if (shouldAutoScroll) {
      scrollToBottom();
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, deps);

  const handleScroll = useCallback(() => {
    const el = scrollContainerRef.current;
    if (!el) return;
    const { scrollTop, scrollHeight, clientHeight } = el;
    setShouldAutoScroll(scrollHeight - scrollTop - clientHeight < 50);
  }, []);

  return {
    chatEndRef,
    scrollContainerRef,
    shouldAutoScroll,
    setShouldAutoScroll,
    scrollToBottom,
    handleScroll,
  };
}