import * as React from 'react';
import { mergeCallbacks, slot, useAnimationFrame, useMergedRefs, useIsomorphicLayoutEffect, getIntrinsicElementProps } from '@fluentui/react-utilities';
import { useDrawerContext_unstable } from '../../contexts/drawerContext';
/**
 * @internal
 *
 * Get the current scroll state of the DrawerBody.
 *
 * @param element - HTMLElement to check scroll state of
 */ const getScrollState = ({ scrollTop, scrollHeight, clientHeight })=>{
    if (scrollHeight <= clientHeight) {
        return 'none';
    }
    if (scrollTop === 0) {
        return 'top';
    }
    if (scrollTop + clientHeight === scrollHeight) {
        return 'bottom';
    }
    return 'middle';
};
/**
 * Create the state required to render DrawerBody.
 *
 * The returned state can be modified with hooks such as useDrawerBodyStyles_unstable,
 * before being passed to renderDrawerBody_unstable.
 *
 * @param props - props from this instance of DrawerBody
 * @param ref - reference to root HTMLElement of DrawerBody
 */ export const useDrawerBody_unstable = (props, ref)=>{
    const { setScrollState } = useDrawerContext_unstable();
    const scrollRef = React.useRef(null);
    const [setAnimationFrame, cancelAnimationFrame] = useAnimationFrame();
    const updateScrollState = React.useCallback(()=>{
        if (!scrollRef.current) {
            return;
        }
        setScrollState(getScrollState(scrollRef.current));
    }, [
        setScrollState
    ]);
    const onScroll = React.useCallback(()=>{
        cancelAnimationFrame();
        setAnimationFrame(()=>updateScrollState());
    }, [
        cancelAnimationFrame,
        setAnimationFrame,
        updateScrollState
    ]);
    useIsomorphicLayoutEffect(()=>{
        cancelAnimationFrame();
        setAnimationFrame(()=>updateScrollState());
        /* update scroll state when children changes */ return ()=>cancelAnimationFrame();
    }, [
        props.children,
        cancelAnimationFrame,
        updateScrollState,
        setAnimationFrame
    ]);
    useIsomorphicLayoutEffect(()=>{
        cancelAnimationFrame();
        setAnimationFrame(()=>updateScrollState());
        return ()=>cancelAnimationFrame();
    }, [
        cancelAnimationFrame,
        updateScrollState,
        setAnimationFrame
    ]);
    return {
        components: {
            root: 'div'
        },
        root: slot.always(getIntrinsicElementProps('div', {
            // FIXME:
            // `ref` is wrongly assigned to be `HTMLElement` instead of `HTMLDivElement`
            // but since it would be a breaking change to fix it, we are casting ref to it's proper type
            ref: useMergedRefs(ref, scrollRef),
            ...props,
            onScroll: mergeCallbacks(props.onScroll, onScroll)
        }), {
            elementType: 'div'
        })
    };
};