import request, { Agent } from "superagent";
import prefix from "superagent-prefix";

export function customErrorHandler(err: Error): request.Response {
  // optional chaining doesn't work in repos that don't use node-ts yet.
  const errMsg = (err as any) && (err as any).response && (err as any).response.text? (err as any).response.text: err.message;
  throw new Error(errMsg);
}

export abstract class BaseCaller {
  /**
   * Makes the request after prefixing the apiUrl to the request path
   * https://visionmedia.github.io/superagent/#get-requests
   */
  protected agent: Agent;
  /**
   * base API url
   */
  protected apiUrl: string;

  /**
   * Used in case we use the default token used at the time this class was initialized
   */
  private authTokenString: string | undefined;

  /**
   * In case the caller decides to pass a function to use to get the authToken
   */
  private authTokenFunction: (() => string) | undefined;

  protected useBearerToken = true;

  /**
   * Used in case we pass a function to resolve the authToken at realTime
   * By default, this simply returns the passed authToken
   */
   protected getAuthToken = (): string => {
    if (this.authTokenString !== undefined) {
      if(this.useBearerToken) {
        if(!this.authTokenString.startsWith("Bearer ")){
          return `Bearer ${this.authTokenString}`
        }
      }
      return `${this.authTokenString}`;
    } else if (this.authTokenFunction !== undefined) {
      return this.authTokenFunction();
    } else {
      console.log(`Error from BaseCaller: no auth token set`);
      return "";
    }
  }

  /**
   * Used for callers where the only option is to use API token
   * Can be used in the Caller code instead of calling callerInstance.setUseBearerToken(false) in the implementation file
   * which would set the Bearer option globally for this callerInstance
   */
   protected getApiToken = (): string => {
    if (this.authTokenString !== undefined) {
      return `${this.authTokenString}`;
    } else {
      console.log(`Error from BaseCaller: no auth token set`);
      return "";
    }
  }

  private setAuthToken(authToken: string | (() => string)) {
    if(typeof authToken === "string") {
      this.authTokenString = authToken;
    } else {
      this.authTokenFunction = authToken;
    }
  }

  /**
   * authToken accepts either a string or a function.
   */
  constructor(apiUrl: string, authToken?: string | (() => string), useBearerToken?: boolean) {
    this.apiUrl = apiUrl;
    if(authToken !== undefined) {
      this.setAuthToken(authToken);
    }
    if(useBearerToken !== undefined) {
      this.setUseBearerToken(useBearerToken);
    }
    this.agent = request.agent().use(prefix(apiUrl));
    /**
     * !IMPORTANT: DO NOT ADD ERROR HANDLING. API ALWAYS RETURNS RESPONSES AND ERRORS.
     */
      /*.on("error", (err) => {
        console.log(`Error while making request. Status: ${err.status}, Text: ${err.response?.text}`);
        throw err;
      });*/
  }

  public setUseBearerToken(value = true): void {
    this.useBearerToken = value;
  }

  /**
   * @example
   * return new ExampleCaller(this.apiUrl, token);
   */
  abstract withToken(token: string): BaseCaller
}