@uimkit/uikit-react/dist/cjs/components/UIMessageList/hooks/useMessageListScrollManager.js

<img style="width:64px" src="https://mgmt.uimkit.chat/media/img/avatar.png"/>

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var React = require('react');
require('../../../types/models.js');
require('../../../types/events.js');
require('../../../context/TranslationContext.js');
var UIKitContext = require('../../../context/UIKitContext.js');
require('../../../context/ComponentContext.js');
require('../../../context/ChatActionContext.js');
require('../../../context/MessageInputContext.js');
require('../../../context/UIMessageContext.js');
require('../../../context/ChatStateContext.js');

function useMessageListScrollManager(params) {
    var onScrollBy = params.onScrollBy, scrollContainerMeasures = params.scrollContainerMeasures, scrolledUpThreshold = params.scrolledUpThreshold, scrollToBottom = params.scrollToBottom, showNewMessages = params.showNewMessages;
    var activeProfile = UIKitContext.useUIKit('useMessageListScrollManager').activeProfile;
    var measures = React.useRef({
        offsetHeight: 0,
        scrollHeight: 0,
    });
    var messages = React.useRef();
    var scrollTop = React.useRef(0);
    React.useEffect(function () {
        var _a;
        var prevMeasures = measures.current;
        var prevMessages = messages.current;
        var newMessages = params.messages;
        var lastNewMessage = (_a = newMessages[newMessages.length - 1]) !== null && _a !== void 0 ? _a : {};
        var lastPrevMessage = prevMessages === null || prevMessages === void 0 ? void 0 : prevMessages[prevMessages.length - 1];
        var newMeasures = scrollContainerMeasures();
        var wasAtBottom = prevMeasures.scrollHeight - prevMeasures.offsetHeight - scrollTop.current <
            scrolledUpThreshold;
        if (typeof prevMessages !== 'undefined') {
            if (prevMessages.length < newMessages.length) {
                // messages added to the top
                if ((lastPrevMessage === null || lastPrevMessage === void 0 ? void 0 : lastPrevMessage.id) === lastNewMessage.id) {
                    var listHeightDelta = newMeasures.scrollHeight - prevMeasures.scrollHeight;
                    if (scrollTop.current === 0) {
                        onScrollBy(listHeightDelta);
                    }
                }
                // messages added to the bottom
                else {
                    var lastMessageIsFromCurrentUser = lastNewMessage.from === activeProfile.id;
                    if (lastMessageIsFromCurrentUser || wasAtBottom) {
                        scrollToBottom();
                    }
                    else {
                        showNewMessages();
                    }
                }
            }
        }
        messages.current = newMessages;
        measures.current = newMeasures;
    }, [measures, messages, params.messages]);
    return function (scrollTopValue) {
        scrollTop.current = scrollTopValue;
    };
}

exports.useMessageListScrollManager = useMessageListScrollManager;
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