How to make a Rust horse spawn plugin (Oxide/Carbon cooldown)

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

namespace Oxide.Plugins
{
    [Info("Horse Spawn", "RustPluginGenerator", "1.0.0")]
    [Description("Spawns a ridable horse next to the player with a permission-gated cooldown.")]
    public class HorseSpawn : RustPlugin
    {
        private const string PermSpawn = "horsespawn.spawn";
        private const string DataFileName = "HorseSpawn";

        private PluginConfig config;
        private StoredData data;
        private readonly Dictionary<string, float> cooldowns = new Dictionary<string, float>();

        private class PluginConfig
        {
            [JsonProperty("Horse Prefab")]
            public string HorsePrefab = "assets/rust.ai/agents/horse/horse.prefab";

            [JsonProperty("Cooldown Seconds")]
            public float CooldownSeconds = 300f;

            [JsonProperty("Allow In Building Blocked")]
            public bool AllowInBuildingBlocked = false;

            [JsonProperty("Spawn Offset")]
            public float SpawnOffset = 1.5f;

            [JsonProperty("Announce Cooldown")]
            public bool AnnounceCooldown = true;
        }

        private class StoredData
        {
            [JsonProperty("Horses")]
            public Dictionary<string, ulong> Horses = new Dictionary<string, ulong>();
        }

        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>
            {
                ["Spawned"] = "Your horse has been spawned.",
                ["SpawnFailed"] = "The horse could not be spawned. Contact an admin.",
                ["Cooldown"] = "You can spawn another horse in {0} seconds.",
                ["BuildingBlocked"] = "You cannot spawn a horse in a building blocked zone.",
                ["NoPermission"] = "You do not have permission to spawn a horse.",
                ["Removed"] = "Your previous horse was removed and a new one spawned.",
                ["CooldownsCleared"] = "All horse cooldowns were cleared."
            }, this);
        }

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

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

        private void OnServerInitialized()
        {
            data = Interface.Oxide.DataFileSystem.ReadObject<StoredData>(DataFileName);
            if (data == null || data.Horses == null) data = new StoredData();
        }

        private void Unload()
        {
            SaveData();
        }

        private void SaveData()
        {
            if (data != null) Interface.Oxide.DataFileSystem.WriteObject(DataFileName, data);
        }

        [ChatCommand("horse")]
        private void CmdHorse(BasePlayer player, string command, string[] args)
        {
            if (player == null) return;

            if (!permission.UserHasPermission(player.UserIDString, PermSpawn))
            {
                player.ChatMessage(Msg("NoPermission", player.UserIDString));
                return;
            }

            string id = player.UserIDString;
            float readyAt;
            if (cooldowns.TryGetValue(id, out readyAt))
            {
                if (readyAt <= Time.realtimeSinceStartup)
                {
                    cooldowns.Remove(id);
                }
                else if (config.AnnounceCooldown)
                {
                    player.ChatMessage(Msg("Cooldown", id, Mathf.CeilToInt(readyAt - Time.realtimeSinceStartup)));
                    return;
                }
            }

            if (!SpawnHorse(player)) return;

            cooldowns[id] = Time.realtimeSinceStartup + Mathf.Max(0f, config.CooldownSeconds);
        }

        private bool SpawnHorse(BasePlayer player)
        {
            string id = player.UserIDString;

            if (!config.AllowInBuildingBlocked && player.IsBuildingBlocked())
            {
                player.ChatMessage(Msg("BuildingBlocked", id));
                return false;
            }

            bool replaced = RemoveStoredHorse(id);

            Vector3 forward = player.eyes.HeadForward();
            Vector3 pos = player.transform.position + forward * config.SpawnOffset;
            Quaternion rot = Quaternion.LookRotation(new Vector3(forward.x, 0f, forward.z));

            BaseEntity horse = GameManager.server.CreateEntity(config.HorsePrefab, pos, rot);
            if (horse == null)
            {
                player.ChatMessage(Msg("SpawnFailed", id));
                return false;
            }

            horse.Spawn();
            data.Horses[id] = horse.net.ID.Value;
            SaveData();

            player.ChatMessage(Msg(replaced ? "Removed" : "Spawned", id));
            return true;
        }

        private bool RemoveStoredHorse(string userId)
        {
            ulong entityId;
            if (!data.Horses.TryGetValue(userId, out entityId)) return false;

            data.Horses.Remove(userId);

            foreach (BaseNetworkable networkable in BaseNetworkable.serverEntities)
            {
                if (networkable == null || networkable.net == null) continue;
                if (networkable.net.ID.Value != entityId) continue;

                networkable.Kill();
                return true;
            }

            return false;
        }

        private object OnEntityKill(BaseNetworkable entity)
        {
            if (entity == null || entity.net == null || data == null || data.Horses == null) return null;

            ulong entityId = entity.net.ID.Value;
            string matchedKey = null;

            foreach (KeyValuePair<string, ulong> pair in data.Horses)
            {
                if (pair.Value != entityId) continue;
                matchedKey = pair.Key;
                break;
            }

            if (matchedKey == null) return null;

            data.Horses.Remove(matchedKey);
            SaveData();
            return null;
        }

        [ConsoleCommand("horsespawn.clearcooldowns")]
        private void CcmdClearCooldowns(ConsoleSystem.Arg arg)
        {
            BasePlayer player = arg.Player();
            if (player != null && !permission.UserHasPermission(player.UserIDString, PermSpawn))
            {
                arg.ReplyWith(Msg("NoPermission", player.UserIDString));
                return;
            }

            cooldowns.Clear();
            arg.ReplyWith(Msg("CooldownsCleared"));
        }
    }
}