How to make a Rust no fall damage plugin (permission based)

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

namespace Oxide.Plugins
{
    [Info("No Fall Damage", "RustPluginGenerator", "1.0.0")]
    [Description("Removes or scales fall damage for players, optionally gated by permission.")]
    public class NoFallDamage : RustPlugin
    {
        private const string PermUse = "nofalldamage.use";
        private const string PermToggle = "nofalldamage.toggle";

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

        private class PluginConfig
        {
            [JsonProperty("Enabled")]
            public bool Enabled { get; set; } = true;

            [JsonProperty("Require Permission")]
            public bool RequirePermission { get; set; } = true;

            [JsonProperty("Fall Multiplier")]
            public float FallMultiplier { get; set; } = 0f;

            [JsonProperty("Show Chat Notice")]
            public bool ShowNotice { get; set; } = true;

            [JsonProperty("Notice Cooldown")]
            public float NoticeCooldown { get; set; } = 15f;
        }

        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>
            {
                ["FallBlocked"] = "Fall damage cancelled.",
                ["FallReduced"] = "Fall damage reduced.",
                ["ToggledOn"] = "Fall damage protection enabled.",
                ["ToggledOff"] = "Fall damage protection disabled.",
                ["NoPermission"] = "You do not have permission to use this command."
            }, 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);
            permission.RegisterPermission(PermToggle, this);
        }

        [ChatCommand("nofall.toggle")]
        private void CmdToggle(BasePlayer player, string command, string[] args)
        {
            if (player == null || !permission.UserHasPermission(player.UserIDString, PermToggle))
            {
                if (player != null) SendReply(player, Msg("NoPermission", player.UserIDString));
                return;
            }

            config.Enabled = !config.Enabled;
            SaveConfig();
            SendReply(player, Msg(config.Enabled ? "ToggledOn" : "ToggledOff", player.UserIDString));
        }

        private object OnEntityTakeDamage(BasePlayer player, HitInfo hitInfo)
        {
            if (player == null || hitInfo == null || hitInfo.damageTypes == null) return null;
            if (!config.Enabled || player.IsNpc) return null;
            if (config.RequirePermission && !permission.UserHasPermission(player.UserIDString, PermUse)) return null;

            if (hitInfo.damageTypes.GetMajorityDamageType() != Rust.DamageType.Fall) return null;

            float fallDamage = hitInfo.damageTypes.Get(Rust.DamageType.Fall);
            if (fallDamage <= 0f) return null;

            float multiplier = Mathf.Clamp(config.FallMultiplier, 0f, 1f);
            hitInfo.damageTypes.Scale(Rust.DamageType.Fall, multiplier);

            if (config.ShowNotice) Notify(player, multiplier <= 0f ? "FallBlocked" : "FallReduced");

            // Fully cancelled fall damage: kill the remaining zero-value hit.
            if (multiplier <= 0f && hitInfo.damageTypes.Total() <= 0f) return false;

            return null;
        }

        private void Notify(BasePlayer player, string key)
        {
            float now = UnityEngine.Time.realtimeSinceStartup;
            float last;
            if (lastNotice.TryGetValue(player.userID, out last) && now - last < config.NoticeCooldown) return;

            lastNotice[player.userID] = now;
            SendReply(player, Msg(key, player.UserIDString));
        }

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