OnItemStacked

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

namespace Oxide.Plugins
{
    [Info("Stack Announcer", "RustPluginGenerator", "1.0.0")]
    [Description("Announces when a player merges a watched resource into a large stack")]
    public class StackAnnouncer : RustPlugin
    {
        private const string PermNotify = "stackannouncer.notify";

        private class PluginConfig
        {
            [JsonProperty("Watched shortnames")]
            public List<string> Shortnames = new List<string> { "sulfur", "scrap" };

            [JsonProperty("Notify at stack amount")]
            public int Threshold = 1000;

            [JsonProperty("Per player cooldown in seconds")]
            public float Cooldown = 30f;
        }

        private PluginConfig config;
        private readonly Dictionary<ulong, float> lastNotify = new Dictionary<ulong, float>();

        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>
            {
                ["LargeStack"] = "You now hold {0} {1} in one stack.",
                ["Notify"] = "{0} merged a stack of {1} {2}."
            }, 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(PermNotify, this);
        }

        private void OnItemStacked(Item stack, Item item, ItemContainer container, int amount)
        {
            if (stack?.info == null || container == null) return;
            if (!config.Shortnames.Contains(stack.info.shortname)) return;

            int total = stack.amount;
            if (total < config.Threshold) return;

            BasePlayer owner = item?.GetOwnerPlayer() ?? container.playerOwner;
            if (owner == null || owner.IsNpc) return;

            float now = UnityEngine.Time.realtimeSinceStartup;
            float last;
            if (lastNotify.TryGetValue(owner.userID, out last) && now - last < config.Cooldown) return;
            lastNotify[owner.userID] = now;

            string display = stack.info.displayName.english;
            owner.ChatMessage(Msg("LargeStack", owner.UserIDString, total, display));

            foreach (BasePlayer admin in BasePlayer.activePlayerList)
            {
                if (admin == owner || !admin.IsAdmin) continue;
                if (!permission.UserHasPermission(admin.UserIDString, PermNotify)) continue;
                admin.ChatMessage(Msg("Notify", admin.UserIDString, owner.displayName, total, display));
            }
        }

        private void Unload()
        {
            lastNotify.Clear();
        }
    }
}