How to make a Rust default item skins plugin (skin per crafted item)

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

namespace Oxide.Plugins
{
    [Info("DefaultSkins", "RustPluginGenerator", "1.0.0")]
    [Description("Lets players save a default skin per item shortname and applies it to crafted items.")]
    public class DefaultSkins : RustPlugin
    {
        private const string PermUse = "defaultskins.use";

        private class StoredData
        {
            [JsonProperty("Skins")]
            public Dictionary<string, Dictionary<string, ulong>> Skins = new Dictionary<string, Dictionary<string, ulong>>();
        }

        private StoredData data;

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

        private void OnServerInitialized()
        {
            LoadData();
        }

        private void Unload()
        {
            SaveData();
        }

        private void LoadData()
        {
            try
            {
                data = Interface.Oxide.DataFileSystem.ReadObject<StoredData>("DefaultSkins");
            }
            catch
            {
                PrintWarning("DefaultSkins data file was unreadable, starting empty");
                data = null;
            }

            if (data == null)
                data = new StoredData();

            if (data.Skins == null)
                data.Skins = new Dictionary<string, Dictionary<string, ulong>>();
        }

        private void SaveData()
        {
            if (data != null)
                Interface.Oxide.DataFileSystem.WriteObject("DefaultSkins", data);
        }

        [ChatCommand("skin")]
        private void CmdSkin(BasePlayer player, string command, string[] args)
        {
            if (player == null)
                return;

            if (!permission.UserHasPermission(player.UserIDString, PermUse))
            {
                player.ChatMessage(Msg("NoPermission", player.UserIDString));
                return;
            }

            if (args == null || args.Length == 0)
            {
                player.ChatMessage(Msg("Usage", player.UserIDString));
                return;
            }

            if (args.Length == 1 && args[0].Equals("list", StringComparison.OrdinalIgnoreCase))
            {
                ListSkins(player);
                return;
            }

            if (args.Length < 2)
            {
                player.ChatMessage(Msg("Usage", player.UserIDString));
                return;
            }

            string shortname = args[0].ToLowerInvariant();
            var definition = ItemManager.FindItemDefinition(shortname);
            if (definition == null)
            {
                player.ChatMessage(Msg("InvalidItem", player.UserIDString, shortname));
                return;
            }

            ulong skinId;
            if (!ulong.TryParse(args[1], out skinId))
            {
                player.ChatMessage(Msg("InvalidSkin", player.UserIDString, args[1]));
                return;
            }

            if (!data.Skins.TryGetValue(player.UserIDString, out var entries))
            {
                entries = new Dictionary<string, ulong>();
                data.Skins[player.UserIDString] = entries;
            }

            if (skinId == 0)
            {
                if (entries.Remove(shortname))
                {
                    player.ChatMessage(Msg("SkinCleared", player.UserIDString, definition.displayName.english));
                    SaveData();
                }
                else
                {
                    player.ChatMessage(Msg("NoEntry", player.UserIDString, definition.displayName.english));
                }
                return;
            }

            entries[shortname] = skinId;
            SaveData();
            player.ChatMessage(Msg("SkinSet", player.UserIDString, definition.displayName.english, skinId.ToString()));
        }

        private void ListSkins(BasePlayer player)
        {
            if (!data.Skins.TryGetValue(player.UserIDString, out var entries) || entries.Count == 0)
            {
                player.ChatMessage(Msg("ListEmpty", player.UserIDString));
                return;
            }

            var lines = new List<string>();
            foreach (var kvp in entries)
            {
                var definition = ItemManager.FindItemDefinition(kvp.Key);
                string name = definition != null ? definition.displayName.english : kvp.Key;
                lines.Add(string.Format("{0} = {1}", name, kvp.Value));
            }

            player.ChatMessage(Msg("SkinList", player.UserIDString, string.Join(", ", lines)));
        }

        private void OnItemCraftFinished(ItemCraftTask task, Item item, ItemCrafter itemCrafter)
        {
            if (item == null || item.info == null || itemCrafter == null)
                return;

            BasePlayer owner = itemCrafter.owner;
            if (owner == null || owner.IsNpc)
                return;

            if (!data.Skins.TryGetValue(owner.UserIDString, out var entries) || entries.Count == 0)
                return;

            if (!entries.TryGetValue(item.info.shortname, out ulong skinId) || skinId == 0)
                return;

            if (item.skin == skinId)
                return;

            item.skin = skinId;
            item.MarkDirty();
        }

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

        protected override void LoadDefaultMessages()
        {
            lang.RegisterMessages(new Dictionary<string, string>
            {
                ["Usage"] = "Usage: /skin <shortname> <skinid> to set a default skin, /skin <shortname> 0 to clear it, /skin list to view saved skins.",
                ["NoPermission"] = "You do not have permission to use default skins.",
                ["InvalidItem"] = "Unknown item shortname: {0}",
                ["InvalidSkin"] = "Skin ID must be a whole number: {0}",
                ["SkinSet"] = "Default skin for {0} is now {1}. Newly crafted items will use it.",
                ["SkinCleared"] = "Default skin for {0} cleared.",
                ["NoEntry"] = "You had no default skin saved for {0}.",
                ["ListEmpty"] = "You have no default skins saved.",
                ["SkinList"] = "Your default skins: {0}"
            }, this);
        }
    }
}