How to make a Rust wipe raid cooldown plugin (block building damage after wipe)

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

namespace Oxide.Plugins
{
    [Info("Wipe Raid Cooldown", "RustPluginGenerator", "1.0.0")]
    [Description("Blocks player damage to structures for the configured number of hours after each new save.")]
    public class WipeRaidCooldown : RustPlugin
    {
        private class PluginConfig
        {
            [JsonProperty("Cooldown Hours")]
            public float CooldownHours = 12f;

            [JsonProperty("Notify Attacker")]
            public bool NotifyAttacker = true;

            [JsonProperty("Notify Interval Seconds")]
            public float NotifyIntervalSeconds = 60f;

            [JsonProperty("Save Timestamp")]
            public DateTime SaveTimestamp = DateTime.MinValue;
        }

        private const string PermUse = "wiperaidcooldown.use";

        private PluginConfig config;
        private readonly Dictionary<ulong, float> lastNotified = new Dictionary<ulong, float>();

        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>
            {
                ["CooldownActive"] = "Raiding is disabled for another {0}.",
                ["RaidingOpen"] = "Raiding is currently enabled.",
                ["NoPermission"] = "You do not have permission to use this command.",
                ["BlockedNotice"] = "Raiding is disabled for another {0} after the wipe."
            }, 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(PermUse, this);
        }

        private void OnNewSave(string strFilename)
        {
            config.SaveTimestamp = DateTime.UtcNow;
            SaveConfig();
        }

        private void Unload()
        {
            SaveConfig();
        }

        private bool IsCooldownActive()
        {
            if (config == null || config.SaveTimestamp == DateTime.MinValue) return false;
            return DateTime.UtcNow < config.SaveTimestamp.AddHours(config.CooldownHours);
        }

        private TimeSpan Remaining()
        {
            if (config == null || config.SaveTimestamp == DateTime.MinValue) return TimeSpan.Zero;
            TimeSpan span = config.SaveTimestamp.AddHours(config.CooldownHours) - DateTime.UtcNow;
            return span < TimeSpan.Zero ? TimeSpan.Zero : span;
        }

        private string FormatSpan(TimeSpan span)
        {
            int hours = (int)span.TotalHours;
            int minutes = span.Minutes;
            if (hours > 0) return string.Format("{0}h {1}m", hours, minutes);
            if (minutes > 0) return string.Format("{0}m", minutes);
            return string.Format("{0}s", Mathf.Max(1, span.Seconds));
        }

        private bool IsProtected(BaseEntity entity)
        {
            if (entity == null || entity.IsDestroyed) return false;
            if (entity is BuildingBlock) return true;
            if (entity is Door) return true;
            if (entity is StorageContainer) return true;
            if (entity is BuildingPrivlidge) return true;
            if (entity.GetBuildingPrivilege() != null) return true;
            return false;
        }

        private object HandleDamage(BaseCombatEntity entity, HitInfo hitInfo)
        {
            if (!IsCooldownActive()) return null;
            if (entity == null || hitInfo == null) return null;
            if (hitInfo.InitiatorPlayer == null) return null;
            if (!IsProtected(entity)) return null;

            ulong userId = hitInfo.InitiatorPlayer.userID.Get();
            if (config.NotifyAttacker)
            {
                float now = Time.realtimeSinceStartup;
                float last;
                if (!lastNotified.TryGetValue(userId, out last) || now - last >= config.NotifyIntervalSeconds)
                {
                    lastNotified[userId] = now;
                    string msg = Msg("BlockedNotice", hitInfo.InitiatorPlayer.UserIDString, FormatSpan(Remaining()));
                    hitInfo.InitiatorPlayer.ChatMessage(msg);
                }
            }

            hitInfo.damageTypes.ScaleAll(0f);
            return false;
        }

        private object OnEntityTakeDamage(BaseCombatEntity entity, HitInfo hitInfo)
        {
            return HandleDamage(entity, hitInfo);
        }

        private object OnEntityTakeDamage(BasePlayer player, HitInfo hitInfo)
        {
            return null;
        }

        [ChatCommand("raidcooldown")]
        private void CmdRaidCooldown(BasePlayer player, string command, string[] args)
        {
            if (player == null) return;
            if (!permission.UserHasPermission(player.UserIDString, PermUse))
            {
                player.ChatMessage(Msg("NoPermission", player.UserIDString));
                return;
            }

            if (IsCooldownActive())
                player.ChatMessage(Msg("CooldownActive", player.UserIDString, FormatSpan(Remaining())));
            else
                player.ChatMessage(Msg("RaidingOpen", player.UserIDString));
        }
    }
}