CanEquipItem

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

namespace Oxide.Plugins
{
    [Info("Belt Weapon Lock", "RustPluginGenerator", "1.0.0")]
    [Description("Blocks equipping restricted items into belt or wear slots without a permission")]
    public class BeltWeaponLock : RustPlugin
    {
        private const string PermUse = "beltweaponlock.use";

        private PluginConfig config;
        private readonly Dictionary<string, float> lastNotice = new Dictionary<string, float>();

        private class PluginConfig
        {
            [JsonProperty("Block wear slot equips too")]
            public bool BlockWearSlots { get; set; } = false;

            [JsonProperty("Blocked item shortnames")]
            public List<string> BlockedShortnames { get; set; } = new List<string>
            {
                "rifle.ak",
                "rifle.lr300",
                "lmg.m249",
                "smg.thompson"
            };
        }

        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>
            {
                ["Blocked"] = "You are not allowed to equip {0}.",
                ["BlockedNoPerm"] = "You need the '{0}' permission to equip this item."
            }, this);
        }

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

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

        private object CanEquipItem(PlayerInventory playerInventory, Item item, int targetSlot, BasePlayer player)
        {
            if (item?.info == null || player == null)
                return null;

            if (item.info.shortname == null)
                return null;

            if (!config.BlockedShortnames.Contains(item.info.shortname))
                return null;

            if (permission.UserHasPermission(player.UserIDString, PermUse))
                return null;

            NotifyPlayer(player, item);
            return false;
        }

        private void NotifyPlayer(BasePlayer player, Item item)
        {
            if (!player.IsConnected)
                return;

            float now = UnityEngine.Time.realtimeSinceStartup;
            float last;
            if (lastNotice.TryGetValue(player.UserIDString, out last) && now - last < 5f)
                return;

            lastNotice[player.UserIDString] = now;

            string name = item.info.displayName?.english ?? item.info.shortname;
            player.ChatMessage(Msg("Blocked", player.UserIDString, name));
        }

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