spaghiajoeojo / express-beans

import { ExpressBean } from '@/ExpressBeansTypes';

function isABean(singletonClass: any) {

  return !!singletonClass._beanUUID && !!singletonClass._instance && !!singletonClass._className;

}

function getSingleton<T>(singletonClass: T): T {

  if (!singletonClass) {

    throw new Error('Please specify the type of Bean. Example: @InjectBean(BeanClass)');

  }

  if (!hasName(singletonClass)) {

    throw new Error(`Cannot get instance for ${JSON.stringify(singletonClass)}: it is not an ExpressBean`);

  }

  if (!isABean(singletonClass)) {

    const className = (singletonClass as any).name;

    throw new Error(`Cannot get instance from ${className}. Make sure that ${className} has @Bean as class decorator`);

  }

  const bean = singletonClass as unknown as ExpressBean;

  return bean._instance;

}

/**

 * Gets singleton instance by its static property

 * @decorator

 * @param singletonClass

 */

export function InjectBean<T>(singletonClass: NonNullable<T>) {

  return (_value: unknown, context: ClassFieldDecoratorContext) => () => {

    const singletonInstance = getSingleton(singletonClass);

    const className = (singletonInstance as unknown as ExpressBean)._className;

    logger.debug(`initializing ${String(context.name)} with instance of bean ${className}`);

    return singletonInstance as any;

  };

}