app/ts/reception/classes.abuseprotectionmanager.ts

import * as plugins from '../plugins.js';

import { Reception } from './classes.reception.js';
import { AbuseWindow } from './classes.abusewindow.js';

export interface IAbuseProtectionConfig {
  maxAttempts: number;
  windowMillis: number;
  blockDurationMillis: number;
}

export class AbuseProtectionManager {
  public receptionRef: Reception;

  public get db() {
    return this.receptionRef.db.smartdataDb;
  }

  public CAbuseWindow = plugins.smartdata.setDefaultManagerForDoc(this, AbuseWindow);

  constructor(receptionRefArg: Reception) {
    this.receptionRef = receptionRefArg;
  }

  private normalizeIdentifier(identifierArg: string) {
    return identifierArg.trim().toLowerCase();
  }

  private hashIdentifier(identifierArg: string) {
    return plugins.smarthash.sha256FromStringSync(this.normalizeIdentifier(identifierArg));
  }

  private createWindowId(actionArg: string, identifierArg: string) {
    return plugins.smarthash.sha256FromStringSync(
      `${actionArg}:${this.hashIdentifier(identifierArg)}`
    );
  }

  private async getWindow(actionArg: string, identifierArg: string) {
    return this.CAbuseWindow.getInstance({
      id: this.createWindowId(actionArg, identifierArg),
    });
  }

  public async consumeAttempt(
    actionArg: string,
    identifierArg: string,
    configArg: IAbuseProtectionConfig,
    errorTextArg = 'Too many attempts. Please wait before trying again.'
  ) {
    const now = Date.now();
    let abuseWindow = await this.getWindow(actionArg, identifierArg);

    if (!abuseWindow) {
      abuseWindow = new AbuseWindow();
      abuseWindow.id = this.createWindowId(actionArg, identifierArg);
      abuseWindow.data.action = actionArg;
      abuseWindow.data.identifierHash = this.hashIdentifier(identifierArg);
      abuseWindow.data.createdAt = now;
    }

    if (abuseWindow.isBlocked(now)) {
      throw new plugins.typedrequest.TypedResponseError(errorTextArg);
    }

    if (abuseWindow.data.blockedUntil && abuseWindow.data.blockedUntil <= now) {
      abuseWindow.data.attemptCount = 0;
      abuseWindow.data.windowStartedAt = now;
      abuseWindow.data.blockedUntil = 0;
    }

    if (
      !abuseWindow.data.windowStartedAt ||
      abuseWindow.data.windowStartedAt + configArg.windowMillis <= now
    ) {
      abuseWindow.data.attemptCount = 0;
      abuseWindow.data.windowStartedAt = now;
    }

    abuseWindow.data.attemptCount += 1;
    abuseWindow.data.updatedAt = now;
    abuseWindow.data.validUntil = now + configArg.windowMillis;

    if (abuseWindow.data.attemptCount > configArg.maxAttempts) {
      abuseWindow.data.blockedUntil = now + configArg.blockDurationMillis;
      abuseWindow.data.validUntil = abuseWindow.data.blockedUntil;
      await abuseWindow.save();
      throw new plugins.typedrequest.TypedResponseError(errorTextArg);
    }

    await abuseWindow.save();
  }

  public async clearAttempts(actionArg: string, identifierArg: string) {
    const abuseWindow = await this.getWindow(actionArg, identifierArg);
    if (!abuseWindow) {
      return;
    }

    await abuseWindow.delete();
  }
}