spaghiajoeojo / express-beans

import { createHash } from 'node:crypto';

import { Cache } from '@/ExpressBeansTypes';

import { logger, registeredMethods } from '@/core';

type BeanFunction = (...args: any) => any

type CacheEntry = {

  data: ReturnType<BeanFunction>,

  expiration: number,

}

const createKey = (obj: any) => createHash('sha224')

  .update(JSON.stringify(obj))

  .digest('hex');

const getCachedData = (cache: Map<string, CacheEntry>, key: string) => {

  const cached = cache.get(key);

  if (!cached) {

    throw new Error(`Key ${key} not found in cache`);

  }

  if (cached.expiration < Date.now()) {

    cache.delete(key);

    throw new Error(`Key ${key} expired in cache`);

  }

  return cached;

};

/**

 * Caches the result of a method

 * @param options {Cache}

 * @decorator

 */

export function Cached<This>(

  options: Cache = { duration: 60_000, type: 'memory' },

) {

  return (

    method: BeanFunction,

    context: ClassMethodDecoratorContext<This, BeanFunction>,

  ) => {

    logger.debug(`Initializing cache for method ${String(context.name)}`);

    const cache = new Map<string, CacheEntry>();

    return (...args: any) => {

      const key = createKey(args);

      let result;

      try {

        result = getCachedData(cache, key);

        logger.debug(`Returning cached data for ${key}`);

      } catch (error) {

        logger.debug(error);

        const computed = method.bind(registeredMethods.get(method))(...args);

        cache.set(key, {

          data: computed,

          expiration: Date.now() + options.duration,

        });

        return computed;

      }

      logger.debug(result);

      return result.data;

    };

  };

}