OnMapMarkerRemove

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

namespace Oxide.Plugins
{
    [Info("Marker Guard", "RustPluginGenerator", "1.0.0")]
    [Description("Prevents players from removing map markers tagged as protected.")]
    public class MarkerGuard : RustPlugin
    {
        private const string PermBypass = "markerguard.bypass";

        private PluginConfig config;

        private class PluginConfig
        {
            [JsonProperty("Protected name prefix")]
            public string ProtectedPrefix = "[PIN]";

            [JsonProperty("Allow admins to remove protected markers")]
            public bool AllowAdminRemove = 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>
            {
                ["Protected"] = "This marker is pinned and cannot be removed from the map.",
                ["NoPrefix"] = "The protected prefix in the config is empty; marker protection is disabled."
            }, 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(PermBypass, this);
            if (string.IsNullOrEmpty(config.ProtectedPrefix))
                PrintWarning(Msg("NoPrefix"));
        }

        private object OnMapMarkerRemove(BasePlayer player, List<MapNote> pointsOfInterest, int index)
        {
            if (player == null || pointsOfInterest == null) return null;
            if (index < 0 || index >= pointsOfInterest.Count) return null;
            if (string.IsNullOrEmpty(config.ProtectedPrefix)) return null;

            var note = pointsOfInterest[index];
            if (note == null) return null;

            var text = GetNoteText(note);
            if (string.IsNullOrEmpty(text)) return null;
            if (!text.StartsWith(config.ProtectedPrefix, StringComparison.OrdinalIgnoreCase)) return null;

            if (config.AllowAdminRemove && (player.IsAdmin || permission.UserHasPermission(player.UserIDString, PermBypass)))
                return null;

            player.ChatMessage(Msg("Protected", player.UserIDString));
            return false;
        }

        // The marker label is carried on the ProtoBuf MapNote as the "label" string field.
        private static string GetNoteText(MapNote note)
        {
            return note != null ? note.label : null;
        }
    }
}