immich/web/src/lib/stores/download.ts

import { writable, derived } from 'svelte/store';

export const downloadAssets = writable<Record<string, number>>({});

export const isDownloading = derived(downloadAssets, ($downloadAssets) => {
	if (Object.keys($downloadAssets).length == 0) {
		return false;
	}

	return true;
});

const update = (key: string, value: number | null) => {
	downloadAssets.update((state) => {
		const newState = { ...state };
		if (value === null) {
			delete newState[key];
		} else {
			newState[key] = value;
		}
		return newState;
	});
};

export const clearDownload = (key: string) => update(key, null);
export const updateDownload = (key: string, value: number) => update(key, value);