OnTeamMemberInvite

using UnityEngine;
using System;
using System.Collections.Generic;
using Newtonsoft.Json;
using Oxide.Core;

namespace Oxide.Plugins
{
    [Info("Team Invite Guard", "RustPluginGenerator", "1.0.0")]
    [Description("Rate-limits and caps team invites on the server.")]
    public class TeamInviteGuard : RustPlugin
    {
        private const string PermBypass = "teaminviteguard.bypass";

        private class PluginConfig
        {
            [JsonProperty("Invite cooldown seconds")]
            public double CooldownSeconds = 30.0;

            [JsonProperty("Maximum team size")]
            public int MaxTeamSize = 8;
        }

        private PluginConfig config;
        private readonly Dictionary<ulong, double> lastInvites = new Dictionary<ulong, double>();

        protected override void LoadDefaultConfig() => config = new PluginConfig();

        protected override void LoadConfig()
        {
            base.LoadConfig();
            try
            {
                config = Config.ReadObject<PluginConfig>();
                if (config == null) throw new Exception();
            }
            catch
            {
                PrintWarning("Configuration file is invalid, using defaults");
                LoadDefaultConfig();
            }
            SaveConfig();
        }

        protected override void SaveConfig() => Config.WriteObject(config);

        protected override void LoadDefaultMessages()
        {
            lang.RegisterMessages(new Dictionary<string, string>
            {
                ["Cooldown"] = "You can invite another player in {0} seconds.",
                ["TeamFull"] = "Your team is full ({0} members).",
                ["Invited"] = "You invited {0} to your team."
            }, this);
        }

        private string Msg(string key, string userId = null, params object[] args) =>
            string.Format(lang.GetMessage(key, this, userId), args);

        private void Init()
        {
            permission.RegisterPermission(PermBypass, this);
        }

        private object OnTeamMemberInvite(RelationshipManager.PlayerTeam playerTeam, BasePlayer player, ulong inviteeId, bool isOfflineInvite)
        {
            if (playerTeam == null || player == null) return null;
            if (permission.UserHasPermission(player.UserIDString, PermBypass)) return null;

            ulong inviterId = player.userID.Get();
            double now = UnityEngine.Time.realtimeSinceStartup;
            double last;

            if (lastInvites.TryGetValue(inviterId, out last) && now - last < config.CooldownSeconds)
            {
                int wait = (int)Math.Ceiling(config.CooldownSeconds - (now - last));
                player.ChatMessage(Msg("Cooldown", player.UserIDString, wait));
                return true;
            }

            List<ulong> members = playerTeam.members;
            if (members != null && members.Count >= config.MaxTeamSize)
            {
                player.ChatMessage(Msg("TeamFull", player.UserIDString, members.Count));
                return true;
            }

            lastInvites[inviterId] = now;
            return null;
        }

        private void Unload()
        {
            lastInvites.Clear();
        }
    }
}