How to make a Rust furnace smelting speed plugin (Oxide/Carbon)

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

namespace Oxide.Plugins
{
    [Info("FurnaceSmeltSpeed", "RustPluginGenerator", "1.0.0")]
    [Description("Multiplies furnace and refinery smelt cycles per tick with per-oven config multipliers.")]
    public class FurnaceSmeltSpeed : RustPlugin
    {
        private const string PermUse = "furnacesmeltspeed.use";

        private PluginConfig config;
        private readonly Dictionary<ulong, int> pendingCycles = new Dictionary<ulong, int>();
        private readonly HashSet<ulong> processing = new HashSet<ulong>();

        private class PluginConfig
        {
            [JsonProperty("Multipliers by oven prefab")]
            public Dictionary<string, float> Multipliers = new Dictionary<string, float>
            {
                ["furnace"] = 4f,
                ["furnace.large"] = 2f,
                ["furnace.static"] = 1f,
                ["refinery_small_deployed"] = 2f,
                ["electricfurnace.deployed"] = 4f
            };

            [JsonProperty("Default multiplier for unlisted ovens")]
            public float DefaultMultiplier = 1f;

            [JsonProperty("Max extra cycles scheduled per cook tick")]
            public int MaxExtraCyclesPerTick = 10;
        }

        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>
            {
                ["NoConfig"] = "No oven multipliers are configured.",
                ["Line"] = "{0}: x{1}",
                ["Default"] = "default: x{0}"
            }, 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 object OnOvenCook(BaseOven oven, Item item)
        {
            if (oven == null || item == null || item.info == null || oven.IsDestroyed) return null;
            if (!oven.IsOn()) return null;

            ulong id = oven.net.ID.Value;
            if (processing.Contains(id) || pendingCycles.ContainsKey(id)) return null;

            float multiplier = GetMultiplier(oven.ShortPrefabName);
            if (multiplier <= 1f) return null;

            int extra = (int)Math.Floor(multiplier) - 1;
            if (extra <= 0) return null;
            if (extra > config.MaxExtraCyclesPerTick) extra = config.MaxExtraCyclesPerTick;

            int itemId = item.info.itemid;
            ulong skin = item.skin;

            pendingCycles[id] = extra;
            processing.Add(id);

            NextTick(() =>
            {
                int remaining;
                if (!pendingCycles.TryGetValue(id, out remaining)) remaining = 0;
                pendingCycles.Remove(id);
                processing.Remove(id);

                if (oven == null || oven.IsDestroyed || !oven.IsOn()) return;
                if (remaining <= 0) return;

                for (int i = 0; i < remaining; i++)
                {
                    if (oven == null || oven.IsDestroyed || !oven.IsOn()) break;
                    Item fresh = ItemManager.CreateByItemID(itemId, 1, skin);
                    if (fresh == null) break;
                    processing.Add(id);
                    try
                    {
                        Interface.CallHook("OnOvenCook", oven, fresh);
                    }
                    finally
                    {
                        processing.Remove(id);
                        fresh.Remove();
                    }
                }
            });

            return null;
        }

        private float GetMultiplier(string shortPrefabName)
        {
            if (string.IsNullOrEmpty(shortPrefabName)) return config.DefaultMultiplier;
            string key = shortPrefabName.ToLowerInvariant();

            foreach (var entry in config.Multipliers)
            {
                if (entry.Key != null && entry.Key.ToLowerInvariant() == key)
                    return entry.Value;
            }

            return config.DefaultMultiplier;
        }

        [ChatCommand("smeltspeed")]
        private void CmdSmeltSpeed(BasePlayer player, string command, string[] args)
        {
            if (player == null) return;
            if (!permission.UserHasPermission(player.UserIDString, PermUse))
            {
                player.ChatMessage("You do not have permission to use this command.");
                return;
            }

            if (config.Multipliers.Count == 0)
            {
                player.ChatMessage(Msg("NoConfig", player.UserIDString));
                return;
            }

            foreach (var entry in config.Multipliers)
                player.ChatMessage(Msg("Line", player.UserIDString, entry.Key, entry.Value));

            player.ChatMessage(Msg("Default", player.UserIDString, config.DefaultMultiplier));
        }

        private void Unload()
        {
            pendingCycles.Clear();
            processing.Clear();
        }
    }
}