lbry-wunderbot/bot/modules/spam-detection.js

const authors = [];
let warned = [];
let banned = [];
let messagelog = [];
let hasPerms = require('../helpers.js').hasPerms;
let inPrivate = require('../helpers.js').inPrivate;
let hasExcludedSpamChannels = require('../helpers.js').hasExcludedSpamChannels;
let hasExcludedSpamUsers = require('../helpers.js').hasExcludedSpamUsers;

/**
 * Add simple spam protection to your discord server.
 * @param  {Bot} bot - The discord.js CLient/bot
 * @param  {object} options - Optional (Custom configuarion options)
 * @return {[type]}         [description]
 */

exports.custom = [
    "antiSpam"
]

exports.antiSpam = function(bot) {
  const warnBuffer = 5;
  const maxBuffer = 10;
  const interval = 2000;
  const warningMessage = ", Stop spamming or you will be banned! This is your warning!";
  const banMessage = "has been banned for spamming!";
  const maxDuplicatesWarning = 5;
  const maxDuplicatesBan = 10;
   
   
    bot.on('message', msg => {
	if(!inPrivate(msg) && hasPerms(msg) || hasExcludedSpamChannels(msg) || hasExcludedSpamUsers(msg)) {
		return
	}
    if(msg.author.id != bot.user.id){
      var now = Math.floor(Date.now());
      authors.push({
        "time": now,
        "author": msg.author.id
      });
      messagelog.push({
        "message": msg.content,
        "author": msg.author.id
      });

      // Check how many times the same message has been sent.
      var msgMatch = 0;
      for (var i = 0; i < messagelog.length; i++) {
        if (messagelog[i].message == msg.content && (messagelog[i].author == msg.author.id) && (msg.author.id !== bot.user.id)) {
          msgMatch++;
        }
      }
      // Check matched count
      if (msgMatch == maxDuplicatesWarning && !warned.includes(msg.author.id)) {
        warn(msg, msg.author.id);
      }
      if (msgMatch == maxDuplicatesBan && !banned.includes(msg.author.id)) {
        ban(msg, msg.author.id);
      }

      matched = 0;

      for (var i = 0; i < authors.length; i++) {
        if (authors[i].time > now - interval) {
          matched++;
          if (matched == warnBuffer && !warned.includes(msg.author.id)) {
            warn(msg, msg.author.id);
          }
          else if (matched == maxBuffer) {
            if (!banned.includes(msg.author.id)) {
              ban(msg, msg.author.id);
            }
          }
        }
        else if (authors[i].time < now - interval) {
          authors.splice(i);
          warned.splice(warned.indexOf(authors[i]));
          banned.splice(warned.indexOf(authors[i]));
        }
        if (messagelog.length >= 200) {
          messagelog.shift();
        }
      }
    }
  });

  /**
   * Warn a user
   * @param  {Object} msg
   * @param  {string} userid userid
   */
  function warn(msg, userid) {
    warned.push(msg.author.id);
    msg.channel.send(msg.author + " " + warningMessage);
  }

  /**
   * Ban a user by the user id
   * @param  {Object} msg
   * @param  {string} userid userid
   * @return {boolean} True or False
   */
  function ban(msg, userid) {
    for (var i = 0; i < messagelog.length; i++) {
      if (messagelog[i].author == msg.author.id) {
        messagelog.splice(i);

      }
    }

    banned.push(msg.author.id);

    var user = msg.channel.guild.members.find(member => member.user.id === msg.author.id);
    if (user) {
      user.ban().then((member) => {
        msg.channel.send(msg.author + " " +banMessage);
        return true;
     }).catch(() => {
        msg.channel.send("insufficient permission to kick " + msg.author + " for spamming.");
        return false;
     });
    }
  }
	}