function getEnvironmentVariable<T = undefined>(
	key: string,
	defaultValue: T,
	formatter?: (data: string) => T,
): T {
	const value = process.env[key];

	if (value === undefined) return defaultValue;
	if (formatter) return formatter(value);
	return value as T;
}

function getEnvironmentVariableOrThrow<T = undefined>(
	key: string,
	formatter?: (data: string) => T,
): T {
	const value = process.env[key];

	if (value === undefined)
		throw new Error(`Missing environment variable: ${key}`);
	if (formatter) return formatter(value);
	return value as T;
}

const PORT = getEnvironmentVariableOrThrow<number>("PORT", (data) =>
	Number.parseInt(data, 10),
);
const HMR_PORT = getEnvironmentVariableOrThrow<number>("HMR_PORT", (data) =>
	Number.parseInt(data, 10),
);
const BASE_URL = getEnvironmentVariable<string>(
	"BASE_URL",
	`http://localhost:${PORT}`,
);
const NODE_ENV = getEnvironmentVariable<string>("NODE_ENV", "development");

export const config = {
	PORT,
	HMR_PORT,
	BASE_URL,
	NODE_ENV,
};