interface IStringMap { [key: string]: string }

export default class Env {

    public static get(key: string) {
        return process.env[key]
    }
    public static getAs<T>(key: string, mapper: (val: string) => T): T | undefined {
        const val = this.get(key)
        return val ? mapper(val) : undefined
    }

    public static orElse(key: string, fallback: string) {
        return this.get(key) || fallback
    }

    public static orFail(key: string) {
        const val = this.get(key)
        if (val) {
            return val
        }
        throw Error(`Required config key: ${key}`)
    }

    public static map(map: IStringMap) {
        const res = {} as IStringMap
        for (const [key, val] of Object.entries(map)) {
            res[key] = this.get(val)
        }
        return res
    }

}