@sendbird/uikit-react/chunks/bundle-DZ3gQWc4.js

Sendbird UIKit for React: A feature-rich and customizable chat UI kit with messaging, channel management, and user authentication.

import { S as SCROLL_BUFFER } from './bundle-CqLLOVG5.js';
import { u as useThrottleCallback } from './bundle-CMi8r50C.js';
import { a as isAboutSame } from './bundle-DFni3Lhf.js';
import { usePreservedCallback } from '@sendbird/uikit-tools';

var DELAY = 100;
function calcScrollBottom(scrollHeight, scrollTop) {
    return scrollHeight - scrollTop;
}
function useHandleOnScrollCallback(_a) {
    var hasMore = _a.hasMore, hasNext = _a.hasNext, onScroll = _a.onScroll, scrollRef = _a.scrollRef, setShowScrollDownButton = _a.setShowScrollDownButton;
    var scrollCb = usePreservedCallback(function () {
        var element = scrollRef === null || scrollRef === void 0 ? void 0 : scrollRef.current;
        if (element == null)
            return;
        var scrollTop = element.scrollTop, scrollHeight = element.scrollHeight, clientHeight = element.clientHeight;
        // https://sendbird.atlassian.net/browse/SBISSUE-11759
        // the edge case where channel is inside a page that already has scroll
        // scrollintoView will move the whole page, which we dont want
        var scrollBottom = calcScrollBottom(scrollHeight, scrollTop);
        // even if there is more to fetch or not,
        // we still have to show the scroll to bottom button
        if (typeof setShowScrollDownButton === 'function') {
            setShowScrollDownButton(scrollHeight > scrollTop + clientHeight + 1);
        }
        // Load previous messages
        // 1. check if hasMore(hasPrevious) and reached to top
        // 2. load previous messages (onScroll)
        // 3. maintain scroll position (sets the scroll position to the bottom of the new messages)
        if (hasMore && isAboutSame(scrollTop, 0, SCROLL_BUFFER)) {
            onScroll(function () {
                var messagesAreAddedToView = element.scrollHeight > scrollHeight;
                if (messagesAreAddedToView)
                    element.scrollTop = element.scrollHeight - scrollBottom;
            });
        }
        // Load next messages
        // 1. check if hasNext and reached to bottom
        // 2. load next messages (onScroll)
        // 3. maintain scroll position (sets the scroll position to the top of the new messages)
        if (hasNext && isAboutSame(clientHeight + scrollTop, scrollHeight, SCROLL_BUFFER)) {
            onScroll(function () {
                var messagesAreAddedToView = element.scrollHeight > scrollHeight;
                if (messagesAreAddedToView)
                    element.scrollTop = scrollTop;
            });
        }
    });
    return useThrottleCallback(scrollCb, DELAY, { trailing: true });
}

export { useHandleOnScrollCallback as u };
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