Unload

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

namespace Oxide.Plugins
{
    [Info("Supply Drop Announcer", "RustPluginGenerator", "1.0.0")]
    [Description("Announces the next timed supply drop and shows a countdown panel to all players")]
    public class SupplyDropAnnouncer : RustPlugin
    {
        private const string PanelName = "SupplyDropAnnouncer.Panel";
        private const string PermAdmin = "supplydropannouncer.admin";

        private PluginConfig config;
        private Timer dropTimer;
        private Timer panelTimer;
        private float nextDropAt;

        private class PluginConfig
        {
            [JsonProperty("Interval between drops (seconds)")]
            public float IntervalSeconds = 900f;

            [JsonProperty("Required online players")]
            public int RequiredPlayers = 3;

            [JsonProperty("Spawn a real airdrop when the timer ends")]
            public bool SpawnAirdrop = 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>
            {
                ["NextDrop"] = "Next supply drop in {0}.",
                ["DropNow"] = "A supply drop is on its way.",
                ["NotEnough"] = "Not enough players online for a scheduled drop.",
                ["Panel"] = "Supply drop in {0}",
                ["Reloaded"] = "Supply Drop Announcer reset its timers."
            }, 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(PermAdmin, this);
        }

        private void OnServerInitialized()
        {
            ScheduleDrop();
            panelTimer = timer.Every(1f, UpdatePanels);
        }

        private void ScheduleDrop()
        {
            nextDropAt = UnityEngine.Time.realtimeSinceStartup + config.IntervalSeconds;

            if (dropTimer != null) dropTimer.Destroy();
            dropTimer = timer.Once(config.IntervalSeconds, OnDropTimerElapsed);
        }

        private void OnDropTimerElapsed()
        {
            if (BasePlayer.activePlayerList.Count >= config.RequiredPlayers)
            {
                if (config.SpawnAirdrop) SpawnFallingAirdrop();
                Server.Broadcast(Msg("DropNow"));
            }

            ScheduleDrop();
        }

        private void SpawnFallingAirdrop()
        {
            var prefab = "assets/prefabs/npc/cargo plane/cargo_plane.prefab";
            var entity = GameManager.server.CreateEntity(prefab, new Vector3(0f, 200f, 0f), Quaternion.identity);
            entity?.Spawn();
        }

        private void UpdatePanels()
        {
            int remaining = Mathf.Max(0, Mathf.CeilToInt(nextDropAt - UnityEngine.Time.realtimeSinceStartup));
            string text = Msg("Panel", null, FormatTime(remaining));

            foreach (var player in BasePlayer.activePlayerList)
            {
                if (player == null || !player.IsConnected) continue;

                CuiHelper.DestroyUi(player, PanelName);
                var container = new CuiElementContainer();
                container.Add(new CuiPanel
                {
                    Image = { Color = "0.05 0.05 0.05 0.6" },
                    RectTransform = { AnchorMin = "0.42 0.92", AnchorMax = "0.58 0.955" }
                }, "Hud", PanelName);
                container.Add(new CuiLabel
                {
                    Text = { Text = text, FontSize = 13, Align = TextAnchor.MiddleCenter, Color = "0.9 0.9 0.9 1" },
                    RectTransform = { AnchorMin = "0 0", AnchorMax = "1 1" }
                }, PanelName);
                CuiHelper.AddUi(player, container);
            }
        }

        private static string FormatTime(int seconds)
        {
            return string.Format("{0:00}:{1:00}", seconds / 60, seconds % 60);
        }

        private void Unload()
        {
            if (dropTimer != null) { dropTimer.Destroy(); dropTimer = null; }
            if (panelTimer != null) { panelTimer.Destroy(); panelTimer = null; }

            foreach (var player in BasePlayer.activePlayerList)
            {
                if (player == null) continue;
                CuiHelper.DestroyUi(player, PanelName);
            }
        }
    }
}