RocketChat/Rocket.Chat

import { useMutableCallback } from '@rocket.chat/fuselage-hooks';
import type { Block, LayoutBlock } from '@rocket.chat/ui-kit';
import { useReducer } from 'react';

type LayoutBlockWithElement = Extract<LayoutBlock, { element: unknown }>;
type LayoutBlockWithElements = Extract<LayoutBlock, { elements: readonly unknown[] }>;
type ElementFromLayoutBlock = LayoutBlockWithElement['element'] | LayoutBlockWithElements['elements'][number];

const hasElementInBlock = (block: LayoutBlock): block is LayoutBlockWithElement => 'element' in block;
const hasElementsInBlock = (block: LayoutBlock): block is LayoutBlockWithElements => 'elements' in block;
const hasInitialValueAndActionId = (
    element: ElementFromLayoutBlock,
): element is Extract<ElementFromLayoutBlock, { actionId: string }> & { initialValue: unknown } =>
    'initialValue' in element && 'actionId' in element && typeof element.actionId === 'string' && !!element?.initialValue;

const extractValue = (element: ElementFromLayoutBlock, obj: Record<string, { value: unknown; blockId?: string }>, blockId?: string) => {
    if (hasInitialValueAndActionId(element)) {
        obj[element.actionId] = { value: element.initialValue, blockId };
    }
};

const reduceBlocks = (obj: Record<string, { value: unknown; blockId?: string }>, block: LayoutBlock) => {
    if (hasElementInBlock(block)) {
        extractValue(block.element, obj, block.blockId);
    }
    if (hasElementsInBlock(block)) {
        for (const element of block.elements) {
            extractValue(element, obj, block.blockId);
        }
    }

    return obj;
};

export const useValues = (blocks: Block[]) => {
    const reducer = useMutableCallback((values, { actionId, payload }) => ({
        ...values,
        [actionId]: payload,
    }));

    const initializer = useMutableCallback((blocks: LayoutBlock[]) => {
        const obj: Record<string, { value: unknown; blockId?: string }> = {};

        return blocks.reduce(reduceBlocks, obj);
    });

    return useReducer(reducer, blocks, initializer);
};