helpers.ts

import ClassConstructor from './class-constructor';
import { Surrializable } from './surrializable';

export function isInstanceOf(thing: unknown, whitelist: ReadonlyArray<ClassConstructor>) {
  return whitelist.some(ctor => thing instanceof ctor);
}

const SURRIALIZABLE_FN_NAME: keyof Surrializable = 'surrialize';

export function isSurrializable(thing: unknown): thing is Surrializable {
  return thing && (typeof thing === 'object' || typeof thing === 'function') && typeof (thing as any)[SURRIALIZABLE_FN_NAME] === 'function';
}

function isEcmaScriptClass(constructor: ClassConstructor) {
  return constructor.toString().startsWith('class');
}

export function getParamList(constructor: ClassConstructor): string[] {
  const splitParams = (params: string) => params.split(',').map(param => param.trim());

  const constructorString = constructor.toString();
  if (isEcmaScriptClass(constructor)) {
    const parametersMatch = /constructor[^(]*\(([^)]*)\)/.exec(constructorString);
    if (parametersMatch) {
      return splitParams(parametersMatch[1]);
    } else {
      // Constructor is optional in an es6 class
      return [];
    }
  } else {
    const parametersMatch = /function[^(]*\(([^)]*)\)/.exec(constructorString);
    if (parametersMatch) {
      return splitParams(parametersMatch[1]);
    } else {
      throw new Error(`Constructor function "${constructor.name}" could not be serialized. Class was defined as: ${constructor.toString()}`);
    }
  }
}