How to make a Rust PvP damage multiplier plugin (global, per-weapon, headshot)

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

namespace Oxide.Plugins
{
    [Info("PvP Damage Multiplier", "RustPluginGenerator", "1.0.0")]
    [Description("Scales player versus player damage with a global multiplier, per-weapon overrides and a headshot multiplier.")]
    public class PvPDamageMultiplier : RustPlugin
    {
        private const string PermUse = "pvpdamagemultiplier.use";

        private PluginConfig config;

        private class PluginConfig
        {
            [JsonProperty("Global multiplier")]
            public float GlobalMultiplier = 1.0f;

            [JsonProperty("Headshot multiplier")]
            public float HeadshotMultiplier = 1.0f;

            [JsonProperty("Minimum damage scale")]
            public float MinDamageScale = 0.1f;

            [JsonProperty("Maximum damage scale")]
            public float MaxDamageScale = 5.0f;

            [JsonProperty("Weapon multipliers (shortname)")]
            public Dictionary<string, float> WeaponMultipliers = new Dictionary<string, float>
            {
                ["rifle.ak"] = 1.0f,
                ["smg.2"] = 1.0f,
                ["shotgun.pump"] = 1.0f
            };
        }

        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>
            {
                ["Status"] = "PvP damage: global {0}x, headshot {1}x, {2} weapon overrides.",
                ["NoPermission"] = "You do not have permission to use this command."
            }, this);
        }

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

        private void Unload()
        {
            SaveConfig();
        }

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

        private object OnEntityTakeDamage(BasePlayer player, HitInfo hitInfo)
        {
            if (player == null || hitInfo == null || hitInfo.damageTypes == null) return null;
            if (player.IsNpc) return null;

            BasePlayer attacker = hitInfo.InitiatorPlayer;
            if (attacker == null || attacker.IsNpc || attacker == player) return null;

            float scale = config.GlobalMultiplier;

            AttackEntity weapon = hitInfo.Weapon;
            if (weapon != null && !string.IsNullOrEmpty(weapon.ShortPrefabName))
            {
                float overrideScale;
                if (config.WeaponMultipliers != null && config.WeaponMultipliers.TryGetValue(weapon.ShortPrefabName, out overrideScale))
                {
                    scale = overrideScale;
                }
            }

            if (hitInfo.isHeadshot) scale *= config.HeadshotMultiplier;

            scale = Mathf.Clamp(scale, config.MinDamageScale, config.MaxDamageScale);

            hitInfo.damageTypes.ScaleAll(scale);
            return null;
        }

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

            int overrides = config.WeaponMultipliers != null ? config.WeaponMultipliers.Count : 0;
            player.ChatMessage(Msg("Status", player.UserIDString, config.GlobalMultiplier, config.HeadshotMultiplier, overrides));
        }
    }
}