import { TObject } from ".";
import { dlog } from "./dlog";
export namespace dcache {
  /*
    https://www.sitepoint.com/implementing-memoization-in-javascript/
    function pow(a, b) {
    return a ** b;
    }

    // creates the memoized version
    pow = memoize(pow);

    pow(3, 5); // creates the index "[3,5]" and returns 243
    */
  // make sure you have used await
  export function memoizeAsync(func: Function, timeoutms?: number, customKey?: string) {
    const cache: TObject = {};
    return async function memoized(...args: any) {
      const key = customKey || JSON.stringify(args);
      if (!cache[key]) {
        cache[key] = await func(...args);
        if (timeoutms) {
          setTimeout(() => {
            cache[key] = undefined;
          }, timeoutms);
        }
      } else {
        dlog.d("perf:avoid call as cache founds");
      }
      return cache[key];
    };
  }

  // just call
  export function memoize(func: Function, timeoutms?: number, customKey?: string) {
    const cache: TObject = {};
    return function memoized(...args: any) {
      const key = customKey || JSON.stringify(args);
      if (!cache[key]) {
        cache[key] = func(...args);
        if (timeoutms) {
          setTimeout(() => {
            cache[key] = undefined;
          }, timeoutms);
        }
      } else {
        dlog.d("perf:avoid call as cache founds");
      }
      return cache[key];
    };
  }

  export function ensureOneCallAsync(func: Function): (...args: any) => Promise<any> {
    const cache: TObject = {};
    return async function memoized(...args: any) {
      const key = JSON.stringify(args);
      if (!cache[key]) {
        cache[key] = true;
        try {
          await func(...args);
          cache[key] = false;
        } catch (e) {
          cache[key] = false;
          throw e;
        }
      } else {
        dlog.d("perf:avoid call as other ongoing");
      }
    };
  }
}


// test