OnRfFrequencyChange

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

namespace Oxide.Plugins
{
    [Info("RfFrequencyGuard", "RustPluginGenerator", "1.0.0")]
    [Description("Blocks players from tuning RF entities to protected frequencies unless permitted.")]
    public class RfFrequencyGuard : RustPlugin
    {
        private const string PermBypass = "rffrequencyguard.bypass";

        private PluginConfig config;

        public class PluginConfig
        {
            [JsonProperty("Protected frequency ranges (min / max)")]
            public List<Range> ProtectedRanges = new List<Range>
            {
                new Range { Min = 9000, Max = 9100 }
            };

            [JsonProperty("Notify player when change is blocked")]
            public bool NotifyPlayer = true;
        }

        public class Range
        {
            [JsonProperty("Min")]
            public int Min;

            [JsonProperty("Max")]
            public int Max;
        }

        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"] = "The frequency {0} is reserved and cannot be set by players.",
                ["NoRanges"] = "No protected frequency ranges are configured."
            }, 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(PermBypass, this);
            if (config.ProtectedRanges == null || config.ProtectedRanges.Count == 0)
                PrintWarning(Msg("NoRanges"));
        }

        private object OnRfFrequencyChange(BaseEntity entity, int frequency, BasePlayer player)
        {
            if (entity == null) return null;
            if (player == null) return null;
            if (permission.UserHasPermission(player.UserIDString, PermBypass)) return null;

            foreach (Range range in config.ProtectedRanges)
            {
                if (range == null) continue;
                if (frequency < range.Min || frequency > range.Max) continue;

                if (config.NotifyPlayer)
                    player.ChatMessage(Msg("Blocked", player.UserIDString, frequency));
                return false;
            }

            return null;
        }
    }
}