node-haxball/examples/plugins/balanceTeams.js

The most powerful and lightweight API that allows you to develop your original Haxball(www.haxball.com) host, client, and standalone applications both on node.js and browser environments and also includes every possible hack and functionality that you can

module.exports = function(API){
  const { OperationType, VariableType, ConnectionState, AllowFlags, Direction, CollisionFlags, CameraFollow, BackgroundType, GamePlayState, BanEntryType, Callback, Utils, Room, Replay, Query, Library, RoomConfig, Plugin, Renderer, Errors, Language, EventFactory, Impl } = API;

  Object.setPrototypeOf(this, Plugin.prototype);
  Plugin.call(this, "balanceTeams", true, { // "balanceTeams" is plugin's name, "true" means "activated just after initialization". Every plugin should have a unique name.
    version: "0.1",
    author: "abc",
    description: `This plugin balances the player counts of teams automatically whenever a player joins/leaves the room or changes team.`,
    allowFlags: AllowFlags.CreateRoom | AllowFlags.JoinRoom // We allow this plugin to be activated on both CreateRoom and JoinRoom.
  });

  var teams = [[], [], []], playerTeams = {}, that = this;

  this.finalize = function(){
    teams = null;
    playerTeams = null;
  };

  var balanceTeams = function(){
    // count players for each team
    var specCount = teams[0].length, redCount = teams[1].length, blueCount = teams[2].length;

    // if there is a spectator
    if (specCount>0){

      // if red team has more players, add the player to blue team
      if (redCount>blueCount)
        that.room.setPlayerTeam(teams[0][0], 2);
      
      // if blue team has more players, add the player to red team
      else if (blueCount>redCount)
        that.room.setPlayerTeam(teams[0][0], 1);
      
      // if player counts are equal for both teams, add the player to a random team
      else
        that.room.setPlayerTeam(teams[0][0], 1+Math.floor(Math.random()*2));
    }

    // if there is no spectator
    else{

      // if red team has more than 1 extra player than blue team, move the last red player to blue
      if (redCount>blueCount+1)
        that.room.setPlayerTeam(teams[1][teams[1].length-1], 2);

      // if blue team has more than 1 extra player than red team, move the last blue player to red
      else if (blueCount>redCount+1)
        that.room.setPlayerTeam(teams[2][teams[2].length-1], 1);
    }
  };

  this.onPlayerJoin = function(playerObj, customData){
    // get player's id
    var id = playerObj.id;
    
    // add the new player to spectators
    teams[0].push(id);

    // update player's team
    playerTeams[id] = 0;

    // balance teeams
    balanceTeams();
  };

  this.onPluginActiveChange = function(plugin, customData){
    if (plugin.name!=that.name)
      return;
    if (that.active)
      balanceTeams();
  };

  this.onPlayerLeave = function(playerObj, reason, isBanned, byId, customData){
    // get player's id
    var id = playerObj.id;

    // remove player from his/her team
    var currentTeam = teams[playerTeams[id]], idx = currentTeam?.findIndex((x)=>(x==id));
    if (idx>=0)
      currentTeam.splice(idx, 1);
    delete playerTeams[id];

    // balance teams
    balanceTeams();
  };

  this.onPlayerTeamChange = function(id, teamId, byId, customData){
    // remove player from his/her old team
    var currentTeam = teams[playerTeams[id]], idx = currentTeam?.findIndex((x)=>(x==id));
    if (idx>=0)
      currentTeam.splice(idx, 1);

    // add player to his/her new team
    teams[teamId].push(id);

    // update player's team
    playerTeams[id] = teamId;

    // balance teams
    balanceTeams();
  };
};