OnInventoryItemFind

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

namespace Oxide.Plugins
{
    [Info("Inventory Find Override", "RustPluginGenerator", "1.0.0")]
    [Description("Substitutes a configured item when a player's inventory is searched for it by definition id.")]
    public class InventoryFindOverride : RustPlugin
    {
        private const string PermUse = "inventoryfindoverride.use";

        private PluginConfig config;

        private ulong overrideUserId;

        public class PluginConfig
        {
            [JsonProperty("Item shortname to substitute")]
            public string Shortname = "scrap";
        }

        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);

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

        private void Unload()
        {
            overrideUserId = 0UL;
        }

        private void OnServerInitialized()
        {
            if (ItemManager.FindItemDefinition(config.Shortname) == null)
            {
                PrintWarning($"Item shortname '{config.Shortname}' was not found; the override will never match.");
            }
        }

        private object OnInventoryItemFind(PlayerInventory playerInventory, int id)
        {
            if (playerInventory == null || overrideUserId == 0UL) return null;

            BasePlayer player = playerInventory.containerMain?.playerOwner;
            if (player == null || player.userID.Get() != overrideUserId) return null;

            ItemDefinition definition = ItemManager.FindItemDefinition(config.Shortname);
            if (definition == null || definition.itemid != id) return null;

            foreach (Item item in playerInventory.containerMain.itemList)
            {
                if (item == null || item.info == null) continue;
                if (item.info.itemid == id) return item;
            }

            return null;
        }

        [ChatCommand("findoverride")]
        private void CmdFindOverride(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 (overrideUserId == player.userID.Get())
            {
                overrideUserId = 0UL;
                player.ChatMessage("Inventory find override disabled.");
                return;
            }

            overrideUserId = player.userID.Get();
            player.ChatMessage($"Inventory find override enabled for '{config.Shortname}' lookups on your inventory.");
        }
    }
}