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import { useEffect, useRef, useState } from "react";
interface UseAutoScrollOptions {
offset?: number;
bottomThreshold?: number;
}
export function useAutoScroll({ offset = 250, bottomThreshold = 10 }: UseAutoScrollOptions = {}) {
const [shouldAutoScroll, setShouldAutoScroll] = useState(true);
const scrollRef = useRef<HTMLDivElement>(null);
const bottomRef = useRef<HTMLDivElement>(null);
const scrollToBottom = (behavior: ScrollBehavior = "smooth") => {
if (bottomRef.current && shouldAutoScroll) {
const parent = scrollRef.current;
if (!parent) return;
// Calculate the scroll position accounting for the offset
const targetScrollTop = bottomRef.current.offsetTop - parent.clientHeight + offset;
parent.scrollTo({ top: targetScrollTop, behavior });
}
};
const handleScroll = () => {
if (!scrollRef.current || !bottomRef.current) return;
const { scrollTop, clientHeight } = scrollRef.current;
const targetScrollTop = bottomRef.current.offsetTop - clientHeight + offset;
// Consider the user at the bottom if they're within the threshold of the target scroll position
const isAtBottom = Math.abs(targetScrollTop - scrollTop) < bottomThreshold;
if (shouldAutoScroll !== isAtBottom) {
setShouldAutoScroll(isAtBottom);
}
};
useEffect(() => {
const scrollElement = scrollRef.current;
if (!scrollElement) return;
const handleTouchStart = () => {
setShouldAutoScroll(false);
};
scrollElement.addEventListener("touchstart", handleTouchStart);
scrollElement.addEventListener("scroll", handleScroll);
return () => {
scrollElement.removeEventListener("touchstart", handleTouchStart);
scrollElement.removeEventListener("scroll", handleScroll);
};
}, []);
return {
scrollRef,
bottomRef,
shouldAutoScroll,
scrollToBottom,
setShouldAutoScroll
};
}
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