How to make a Rust craft speed plugin (Oxide/Carbon multipliers)

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

namespace Oxide.Plugins
{
    [Info("Craft Speed", "RustPluginGenerator", "1.0.0")]
    [Description("Speeds up player crafting with a global multiplier and per-permission multipliers.")]
    public class CraftSpeed : RustPlugin
    {
        private const string PermUse = "craftspeed.use";

        private PluginConfig config;

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

            [JsonProperty("Permission multipliers")]
            public Dictionary<string, float> PermissionMultipliers = new Dictionary<string, float>
            {
                ["craftspeed.vip"] = 2.0f,
                ["craftspeed.elite"] = 3.0f
            };
        }

        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>
            {
                ["Speed"] = "Your current craft speed multiplier is {0}x.",
                ["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);
            if (config.PermissionMultipliers != null)
            {
                foreach (var key in config.PermissionMultipliers.Keys)
                {
                    if (!permission.PermissionExists(key) && !string.IsNullOrEmpty(key))
                    {
                        permission.RegisterPermission(key, this);
                    }
                }
            }
        }

        private object OnItemCraft(ItemCraftTask itemCraftTask, BasePlayer owner, Item fromTempBlueprint)
        {
            if (itemCraftTask == null || owner == null || itemCraftTask.blueprint == null) return null;

            float multiplier = GetMultiplier(owner);
            if (multiplier <= 1f) return null;

            // The craft duration is stored on the blueprint (time in seconds); shorten it proportionally.
            float duration = itemCraftTask.blueprint.time;
            if (duration <= 1f) return null;

            float scaled = duration / multiplier;
            // keep at least one second so the task never completes instantly
            if (scaled < 1f) scaled = 1f;

            itemCraftTask.blueprint.time = scaled;
            return null;
        }

        private float GetMultiplier(BasePlayer player)
        {
            float best = config.GlobalMultiplier;
            if (config.PermissionMultipliers == null) return best;

            foreach (var entry in config.PermissionMultipliers)
            {
                if (string.IsNullOrEmpty(entry.Key)) continue;
                if (!permission.UserHasPermission(player.UserIDString, entry.Key)) continue;
                if (entry.Value > best) best = entry.Value;
            }
            return best;
        }

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

            float multiplier = GetMultiplier(player);
            SendReply(player, Msg("Speed", player.UserIDString, multiplier.ToString("0.##")));
        }
    }
}