import { Emitter } from "@noya-app/emitter";
import { uuid } from "@noya-app/noya-utils";

export type EvalRequest = {
  id: string;
  code: string;
};

export type EvalResponse =
  | {
      id: string;
      type: "error";
      error: string;
    }
  | {
      id: string;
      type: "result";
      result: string;
    };

export type SafeEval = (code: string) => unknown;

export class EvalManager {
  constructor(options: { safeEval?: SafeEval }) {
    this.safeEval = options.safeEval;
  }

  safeEval?: SafeEval;
  requestEmitter = new Emitter<[EvalRequest]>();
  responseEmitter = new Emitter<[EvalResponse]>();

  _evalRequests = new Map<string, Promise<unknown>>();

  async evaluate(code: string) {
    if (this.safeEval) {
      return this.safeEval(code);
    }

    const id = uuid();
    const promise = new Promise<EvalResponse>((resolve, reject) => {
      this.responseEmitter.addListener((response) => {
        if (response.id === id) {
          if (response.type === "error") {
            reject(new Error(response.error));
          } else {
            try {
              resolve(JSON.parse(response.result as string));
            } catch (error) {
              reject(error);
            }
          }
        }
      });
    });
    this._evalRequests.set(id, promise);
    this.requestEmitter.emit({ id, code });
    const result = await promise;
    this._evalRequests.delete(id);
    return result;
  }
}