OnUserConnected

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

namespace Oxide.Plugins
{
    [Info("Welcome Message", "RustPluginGenerator", "1.0.0")]
    [Description("Sends a configurable welcome message to players after they connect.")]
    public class WelcomeMessage : RustPlugin
    {
        private const string PermBypass = "welcomemessage.bypass";

        private PluginConfig config;
        private readonly Dictionary<string, Timer> pendingTimers = new Dictionary<string, Timer>();

        private class PluginConfig
        {
            [JsonProperty("Delay in seconds")]
            public float Delay = 3f;

            [JsonProperty("Send rules to console")]
            public bool SendRulesToConsole = true;
        }

        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>
            {
                ["Welcome"] = "Welcome to the server, {0}!",
                ["Rules"] = "Rules: no cheating, no griefing spawn areas, respect staff. Type /help for commands.",
                ["Discord"] = "Join our Discord: discord.gg/example"
            }, this);
        }

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

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

        private void OnUserConnected(IPlayer iplayer)
        {
            if (iplayer == null || string.IsNullOrEmpty(iplayer.Id)) return;
            if (permission.UserHasPermission(iplayer.Id, PermBypass)) return;

            var player = iplayer.Object as BasePlayer;
            if (player == null) return;

            string userId = player.UserIDString;
            if (pendingTimers.ContainsKey(userId)) return;

            pendingTimers[userId] = timer.Once(config.Delay <= 0f ? 0.1f : config.Delay, () =>
            {
                pendingTimers.Remove(userId);
                if (player == null || !player.IsConnected) return;

                player.ChatMessage(Msg("Welcome", userId, player.displayName));
                if (config.SendRulesToConsole)
                {
                    player.SendConsoleCommand("echo " + Msg("Rules", userId));
                    player.SendConsoleCommand("echo " + Msg("Discord", userId));
                }
            });
        }

        private void Unload()
        {
            foreach (var entry in pendingTimers)
            {
                entry.Value?.Destroy();
            }
            pendingTimers.Clear();
        }
    }
}