export type Index<T> = {[key: string]: T}
export type Option<T> = T | undefined;

export function map<A, B>(a: Option<A>, f: (a: A) => B): Option<B> {
  return a ? f(a) : undefined;
}

export function flatMap<A, B>(a: Option<A>, f: (a: A) => Option<B>): Option<B> {
  return a ? f(a) : undefined;
}

export function getOrElse<T>(t: Option<T>, _default: T): T {
  return t ? t : _default;
}

export function obfuscateString(rawString?: string): string | undefined {
  if (!rawString) return undefined;
  const stringLength = rawString.length;
  if (stringLength === 0) return '';
  else {
    const clearSize = Math.floor(0.3 * stringLength);
    const clear = rawString.substring(0, clearSize);
    const obfuscated = 'X'.repeat(stringLength - clearSize);
    return clear + obfuscated;
  }
}