library-ts/node/users/requirements/security/NotTooManyRequests.ts

import { FastifyReply, FastifyRequest } from "fastify";
import { RequestRequirement } from "../RequestRequirement";
import { UserManagementServer } from "../../UserManagementServer";
import { MapList } from "../../../../browser/tools/MapList";
import { DateHelper } from "../../../../browser/date/DateHelper";
import { Duration } from "../../../../browser/date/Duration";
import { DateMath } from "../../../../browser/date/DateMath";
import { Message } from "../../../../browser/messages/Message";


export class NotTooManyRequests extends RequestRequirement
{  
  _trackedIPs = new Map<string,number[]>();
  _maxRequests = 50;
  _duration = Duration.fromMinutes( 2 );
  
  _watchList = new Set<string>();
  _blockList = new Map<string,number>()
  _blockDuration = Duration.fromHours( 4 );

  async handle( request:FastifyRequest, reply:FastifyReply ):Promise<Message[]>
  {
    if ( this._blockList.has( request.ip ) )
    {
      let blockTime = this._blockList.get( request.ip );
      
      if ( ! DateMath.isExpired( new Date( blockTime +  this._blockDuration ) ) )
      {
        return this.sendError( "User blocked" ); 
      } 
    }

    let valid = this.updateIP( request.ip );

    if ( ! valid )
    {
      return this.sendError( "Too many requests" );
    }

    return this.giveOK();
  }

  async updateIP( ip:string ):Promise<boolean>
  {
    MapList.add( this._trackedIPs, ip, DateHelper.nowMS() );
    MapList.shiftToSize( this._trackedIPs, ip, this._maxRequests );

    let lastRelevantDate  = DateMath.addSeconds( DateHelper.now(), -this._duration );

    let timeStamps = this._trackedIPs.get( ip );
    let filteredStamps = timeStamps.filter( ts => DateMath.isAfter( lastRelevantDate, new Date( ts ) ) );
    

    if ( filteredStamps.length < this._maxRequests )
    {
      this._trackedIPs.set( ip, filteredStamps );
      return Promise.resolve( true );
    }

    this._trackedIPs.delete( ip );

    if ( this._watchList.has( ip ) )
    {
      this._blockList.set( ip, DateHelper.nowMS() );
      this._watchList.delete( ip );
    }
    else
    {
      this._watchList.add( ip );
    }

    return Promise.resolve( false );
    
  }


}