import { logger } from "../logger/logger";
import { BaseProvider } from "./BaseProvider";

// https://advancedweb.hu/how-to-add-timeout-to-a-promise-in-javascript/
const promiseTimeout = (prom: Promise<any>, time: number) =>
  Promise.race([
    prom,
    new Promise((_r, reject) =>
      setTimeout(() => reject("Promise timed out"), time)
    ),
  ]);

export interface ConstructorOptions {
  timeoutDuration?: number;
}
const DEFAULT_TIMEOUT_DURATION = 8000;

export class FallthroughProvider extends BaseProvider {
  // index of current trusted rpc url
  /**
   * @ignore
   */
  private rpcUrlCounter = 0;
  private readonly timeoutDuration: number;
  /**
   * @ignore
   */
  public selectRpcUrl(): string {
    return this._rpcUrls[this.rpcUrlCounter];
  }

  constructor(rpcUrls: string[], options: ConstructorOptions = {}) {
    if (!Array.isArray(rpcUrls)) {
      logger.throwError("Array required", { rpcUrls });
    }
    if (rpcUrls.length <= 1) {
      logger.throwError("More than one rpcUrl is required", { rpcUrls });
    }
    super(rpcUrls);
    this.timeoutDuration = options.timeoutDuration || DEFAULT_TIMEOUT_DURATION;
  }

  /**
   * @ignore
   */
  public post = (body: Record<string, unknown>): Promise<any> => {
    // while failing post, add to rpcUrlCounter and post again
    const genesisCount = this.rpcUrlCounter;

    const recursivePostRetry = (): Promise<any> => {
      // Times out request
      const genesisRpcUrl = this.selectRpcUrl();
      const res = promiseTimeout(this._post(body), this.timeoutDuration).catch(
        (e) => {
          if (genesisRpcUrl === this.selectRpcUrl()) {
            this.rpcUrlCounter =
              (this.rpcUrlCounter + 1) % this._rpcUrls.length;
          }
          if (this.rpcUrlCounter === genesisCount) {
            throw e;
          }
          return recursivePostRetry();
        }
      );
      return res;
    };
    return recursivePostRetry();
  };
}