sorenabedi/artist-svelte

import { browser } from '$app/env';
import { readable } from 'svelte/store';
import Debounce from '../../helper/debounce';

type resizeHook = {
    width: number;
    height: number;
    scaleDirection?: 'down' | 'up';
    scaleFromEdge?: 'horizontal' | 'vertical' | 'both';
};

const multiplyObjectValues = (obj: { [key: string]: number }) =>
    Object.values(obj).reduce((a, b) => a * b);

const determineScaleFromEdge = (oldDimensions: resizeHook, newDimensions: resizeHook) => {
    switch (true) {
        case oldDimensions.height === newDimensions.height &&
            oldDimensions.width !== newDimensions.width:
            return 'horizontal';

        case oldDimensions.height !== newDimensions.height &&
            oldDimensions.width === newDimensions.width:
            return 'vertical';

        case oldDimensions.height !== newDimensions.height &&
            oldDimensions.width !== newDimensions.width:
            return 'both';
        default:
            return undefined;
    }
};

const currentWindowSize = (): { width: number; height: number } =>
    browser ? { width: window.innerWidth, height: window.innerHeight } : undefined;
export const store = readable<resizeHook>(currentWindowSize(), (set) => {
    let windowDimensions = currentWindowSize();

    /* istanbul ignore next */
    const setWindowDimensions = Debounce(() => {
        const currentWindowDimensions = currentWindowSize();
        const scaleDirection =
            multiplyObjectValues(windowDimensions) > multiplyObjectValues(currentWindowDimensions)
                ? 'down'
                : 'up';
        const scaleFromEdge: resizeHook['scaleFromEdge'] = determineScaleFromEdge(
            windowDimensions,
            currentWindowDimensions
        );
        if (
            Math.abs(
                multiplyObjectValues(windowDimensions) - multiplyObjectValues(currentWindowDimensions)
            ) > 1
        )
            windowDimensions = currentWindowDimensions;
        set({ ...currentWindowDimensions, scaleDirection, scaleFromEdge });
    }, 100);
    browser && window.addEventListener('resize', setWindowDimensions);

    return () => {
        if (browser) window.removeEventListener('resize', setWindowDimensions);
    };
});

export default store;