import axios, { AxiosInstance } from "axios";
import { APIOptions } from "./APIOptions";
import { AccessTokenResponse } from "./AccessTokenResponse";
import * as moment from "moment";
import { APIResponse } from "./APIResponse";

// tslint:disable: no-console

export class SwychAxiosInstance {
  private accessToken: string;
  private expiresAt: moment.Moment;
  private axiosInstance: AxiosInstance;

  private constructor(
    private options: APIOptions,
    private getAccessToken: () => Promise<APIResponse<AccessTokenResponse>>
  ) {}

  public static async newInstance(
    options: APIOptions,
    getAccessToken: () => Promise<APIResponse<AccessTokenResponse>>
  ) {
    const instance = new SwychAxiosInstance(options, getAccessToken);
    await instance.initialize();
    return instance;
  }

  public getAxiosInstance(): AxiosInstance {
    return this.axiosInstance;
  }

  private async initialize() {
    await this.setAccessToken();

    this.axiosInstance = axios.create({
      baseURL: `${this.options.baseUrl}`,
      // timeout: 1000,
      headers: {
        "Swych-Access-Token": this.accessToken
      }
    });

    this.axiosInstance.interceptors.request.use(async config => {
      config = await this.checkAccessToken(config);
      return config;
    });
  }

  private async checkAccessToken(config) {
    const expiryCheck = moment().add(60, "seconds");
    if (expiryCheck.isAfter(this.expiresAt)) {
      console.log("checkAccessToken: modifying axios instance");
      await this.initialize();
      config.headers["Swych-Access-Token"] = this.accessToken;
    }

    return config;
  }

  private async setAccessToken(): Promise<void> {
    const res = await this.getAccessToken();

    const { response: accessTokenResponse } = res;
    // console.log(`setAccessToken: ${JSON.stringify(accessTokenResponse)}`)

    const { accessToken, expiresAt } = accessTokenResponse;

    this.accessToken = accessToken;
    this.expiresAt = moment(new Date(`${expiresAt}Z`));
  }
}