OnEngineStatsRefresh

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

namespace Oxide.Plugins
{
    [Info("Engine Stat Locker", "RustPluginGenerator", "1.0.0")]
    [Description("Forces modular car engine performance to peak values by skipping the vanilla stat recalculation.")]
    public class EngineStatLocker : RustPlugin
    {
        private const string PermUse = "enginestatlocker.toggle";

        private PluginConfig config;

        private class PluginConfig
        {
            [JsonProperty("Peak performance locked")]
            public bool PeakLocked { get; set; } = true;

            [JsonProperty("Performance fraction when locked")]
            public float Fraction { get; set; } = 1f;
        }

        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>
            {
                ["ToggleOn"] = "Engine stat lock enabled: performance set to {0}.",
                ["ToggleOff"] = "Engine stat lock disabled: vanilla engine calculation restored.",
                ["NoPermission"] = "You do not have permission to use this command."
            }, this);
        }

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

        private object OnEngineStatsRefresh(VehicleModuleEngine vehicleModuleEngine, Rust.Modular.EngineStorage engineStorage)
        {
            if (!config.PeakLocked || vehicleModuleEngine == null || engineStorage == null) return null;
            if (engineStorage.inventory == null || engineStorage.inventory.itemList.Count == 0) return null;

            var fraction = UnityEngine.Mathf.Clamp01(config.Fraction);
            vehicleModuleEngine.IsUsable = true;
            vehicleModuleEngine.PerformanceFractionAcceleration = fraction;
            vehicleModuleEngine.PerformanceFractionTopSpeed = fraction;

            // Non-null return tells Oxide the work is done, so vanilla keeps our numbers.
            return true;
        }

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

            config.PeakLocked = !config.PeakLocked;
            SaveConfig();
            player.ChatMessage(Msg(config.PeakLocked ? "ToggleOn" : "ToggleOff", player.UserIDString, config.Fraction));
        }

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