import { context } from '../context';

export interface IChannelPolicy {
  /**
   * The rate at which interstitial ads should be shown.
   * A value of 1 means always bypass interstitials call, while a value of 0 means always forbid calling interstitials.
   * A value between 0 and 1 means the interstitial call will be bypassed with a probability of `rate`.
   */
  interstitialRate?: number;
}

interface HttpClient {
  get<T>(url: string, options?: { query?: Record<string, string> }): Promise<T>;
}

export class ChannelPolicy {
  private configs: Record<string, IChannelPolicy> | null = null;
  private firstRun = true;

  constructor(readonly httpClient: HttpClient) {
    this.init();
  }

  private async init() {
    try {
      this.configs = await this.httpClient.get<Record<string, IChannelPolicy>>(
        '/api/fe-configs/js-sdk/ads-channel-config'
      );
    } catch (error) {
      // no-op
    }
  }

  /**
   * Should bypass calling interstitial based on the channel policy.
   * @returns
   */
  shouldBypassCallingInterstitial() {
    let result;
    if (!this.configs) {
      this.init();
      result = !this.firstRun; // If configs are not loaded yet, should forbid calling interstitial on first run.
    } else {
      const channel = context.channel ?? '';
      const policy: IChannelPolicy | undefined = this.configs[channel];
      const rate = policy?.interstitialRate ?? 1;
      result = Math.random() < rate; // Bypass interstitial calling with the given rate.
    }
    this.firstRun = false;
    return result;
  }
}