How to make a Rust Bradley APC and patrol helicopter kill announcer plugin

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

namespace Oxide.Plugins
{
    [Info("Boss Kill Announcer", "RustPluginGenerator", "1.0.0")]
    [Description("Announces who dealt the most damage to a Bradley APC or patrol helicopter and where it died.")]
    public class BossKillAnnouncer : RustPlugin
    {
        private const string PermAdmin = "bosskillannouncer.admin";

        private PluginConfig config;

        // entity net id -> (player id -> total damage)
        private readonly Dictionary<ulong, Dictionary<ulong, float>> damage = new Dictionary<ulong, Dictionary<ulong, float>>();

        private class PluginConfig
        {
            [JsonProperty("Announcements Enabled")]
            public bool AnnouncementsEnabled { get; set; } = true;

            [JsonProperty("Prefix")]
            public string Prefix { get; set; } = "[Boss]";

            [JsonProperty("Show Bradley")]
            public bool ShowBradley { get; set; } = true;

            [JsonProperty("Show Helicopter")]
            public bool ShowHelicopter { get; set; } = true;

            [JsonProperty("Grid In Messages")]
            public bool GridInMessages { get; set; } = 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>
            {
                ["Kill Message"] = "{0} {1} was destroyed by {2} (grid {3})",
                ["Status"] = "{0} announcements are {1}.",
                ["On"] = "enabled",
                ["Off"] = "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(PermAdmin, this);
        }

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

        private object OnEntityTakeDamage(BaseCombatEntity entity, HitInfo hitInfo)
        {
            if (entity == null || hitInfo == null || hitInfo.InitiatorPlayer == null) return null;
            if (!(entity is BradleyAPC) && !(entity is PatrolHelicopter)) return null;

            var attacker = hitInfo.InitiatorPlayer;
            if (attacker.IsNpc) return null;

            ulong entityId = entity.net.ID.Value;
            ulong playerId = attacker.userID;

            Dictionary<ulong, float> tally;
            if (!damage.TryGetValue(entityId, out tally))
            {
                tally = new Dictionary<ulong, float>();
                damage[entityId] = tally;
            }

            float amount;
            tally.TryGetValue(playerId, out amount);
            tally[playerId] = amount + hitInfo.damageTypes.Total();

            return null;
        }

        private void OnEntityDeath(BaseCombatEntity entity, HitInfo info)
        {
            if (entity == null) return;
            if (!(entity is BradleyAPC) && !(entity is PatrolHelicopter)) return;

            ulong entityId = entity.net.ID.Value;
            Dictionary<ulong, float> tally;
            if (!damage.TryGetValue(entityId, out tally))
            {
                return;
            }
            damage.Remove(entityId);

            ulong bestPlayer = 0;
            float bestDamage = 0f;
            foreach (var entry in tally)
            {
                if (entry.Value > bestDamage)
                {
                    bestDamage = entry.Value;
                    bestPlayer = entry.Key;
                }
            }

            if (bestPlayer == 0 || !config.AnnouncementsEnabled) return;

            bool isBradley = entity is BradleyAPC;
            if (isBradley && !config.ShowBradley) return;
            if (!isBradley && !config.ShowHelicopter) return;

            var killer = BasePlayer.FindAwakeOrSleeping(bestPlayer.ToString());
            string killerName = killer != null ? killer.displayName : bestPlayer.ToString();
            string bossName = isBradley ? "Bradley APC" : "Patrol Helicopter";
            string grid = config.GridInMessages ? GetGrid(entity.transform.position) : "?";

            Server.Broadcast(Msg("Kill Message", null, config.Prefix, bossName, killerName, grid));
        }

        [ChatCommand("bosskills")]
        private void CmdBossKills(BasePlayer player, string command, string[] args)
        {
            if (player == null) return;
            if (!permission.UserHasPermission(player.UserIDString, PermAdmin)) return;

            string state = config.AnnouncementsEnabled ? Msg("On", player.UserIDString) : Msg("Off", player.UserIDString);
            SendReply(player, Msg("Status", player.UserIDString, config.Prefix, state));
        }

        private static string GetGrid(Vector3 position)
        {
            float worldSize = ConVar.Server.worldsize;
            if (worldSize <= 0f) worldSize = 4000f;
            float half = worldSize * 0.5f;
            float cellSize = worldSize / 26.6f;

            int x = Mathf.FloorToInt((position.x + half) / cellSize);
            int z = Mathf.FloorToInt((position.z + half) / cellSize);

            char letter = (char)('A' + Mathf.Clamp(x, 0, 25));
            int number = Mathf.Clamp(z + 1, 1, 26);
            return letter.ToString() + number;
        }
    }
}