directus/api/src/utils/get-config-from-env.ts

import camelcase from 'camelcase';
import { set } from 'lodash-es';
import { getEnv } from '../env.js';

export function getConfigFromEnv(
	prefix: string,
	omitPrefix?: string | string[],
	type: 'camelcase' | 'underscore' = 'camelcase'
): Record<string, any> {
	const env = getEnv();

	const config: any = {};

	for (const [key, value] of Object.entries(env)) {
		if (key.toLowerCase().startsWith(prefix.toLowerCase()) === false) continue;

		if (omitPrefix) {
			let matches = false;

			if (Array.isArray(omitPrefix)) {
				matches = omitPrefix.some((prefix) => key.toLowerCase().startsWith(prefix.toLowerCase()));
			} else {
				matches = key.toLowerCase().startsWith(omitPrefix.toLowerCase());
			}

			if (matches) continue;
		}

		if (key.includes('__')) {
			const path = key
				.split('__')
				.map((key, index) => (index === 0 ? transform(transform(key.slice(prefix.length))) : transform(key)));
			set(config, path.join('.'), value);
		} else {
			config[transform(key.slice(prefix.length))] = value;
		}
	}

	return config;

	function transform(key: string): string {
		if (type === 'camelcase') {
			return camelcase(key, { locale: false });
		} else if (type === 'underscore') {
			return key.toLowerCase();
		}

		return key;
	}
}