ForgottenWawiTech/Content/NPCs/OriginalNeptune/Neptune.cs

using Terraria;
using Terraria.ID;
using Terraria.ModLoader;
using Microsoft.Xna.Framework;
using Terraria.Chat;
using Terraria.Localization;
using Terraria.GameContent.ItemDropRules;
using ForgottenWawiTech.Content.Items.TreasureBags;

namespace ForgottenWawiTech.Content.NPCs.OriginalNeptune
{
    [AutoloadBossHead]
    public class Neptune : ModNPC
    {
        public override void SetStaticDefaults()
        {
            // DisplayName.SetDefault("Original Neptune");
            Main.npcFrameCount[NPC.type] = 1;
        }

        public override void SetDefaults()
        {
            NPC.width = 40;
            NPC.height = 40;
            NPC.damage = 1786;
            NPC.defense = 290;
            NPC.lifeMax = 1000000;
            NPC.HitSound = SoundID.NPCHit1;
            NPC.DeathSound = SoundID.NPCDeath1;
            NPC.knockBackResist = 0f;
            NPC.boss = true;
            NPC.aiStyle = -1;
            NPC.value = Item.buyPrice(0, 1, 0, 0);
        }

        public override void AI()
        {
            // Phased boss AI: at 50% HP spawn Raccoon. Neptune becomes invulnerable and does not attack
            // until Raccoon is defeated, then move to Phase 2.

            NPC.TargetClosest(false);
            Player target = Main.player[NPC.target];
            if (!target.active || target.dead)
            {
                NPC.timeLeft = 300;
                return;
            }

            int phase = (int)NPC.ai[0]; // 0 = phase 1 (initial), 1 = waiting for raccoon, 2 = phase 2
            int flags = (int)NPC.ai[1]; // bitflags: bit0 = raccoon spawned

            // Phase 0: before Raccoon summoned
            if (phase == 0)
            {
                // If at or below 50% life and raccoon hasn't been spawned, spawn it and enter waiting state
                if (NPC.life <= NPC.lifeMax / 2 && (flags & 1) == 0)
                {
                    flags |= 1;
                    NPC.ai[1] = flags;

                    // Make Neptune invulnerable and enter waiting phase
                    NPC.dontTakeDamage = true;
                    NPC.ai[0] = 1;
                    NPC.netUpdate = true;

                    string announce = "A mischievous raccoon scurries into the battlefield!";
                }

                // Simple approach movement when not waiting
                if (NPC.ai[0] == 0)
                {
                    Vector2 dir = (target.Center - NPC.Center);
                    if (dir.Length() > 8f)
                    {
                        dir.Normalize();
                        NPC.velocity = Vector2.Lerp(NPC.velocity, dir * 3f, 0.02f);
                    }
                }
            }
            // Phase 1: waiting for Raccoon to be defeated
            else if (phase == 1)
            {
                bool raccoonAlive = false;
                int raccoonType = ModContent.NPCType<Raccoon>();
                for (int i = 0; i < Main.maxNPCs; i++)
                {
                    NPC check = Main.npc[i];
                    if (check.active && check.type == raccoonType)
                    {
                        raccoonAlive = true;
                        break;
                    }
                }

                // Stay invulnerable and idle until raccoon is gone
                if (!raccoonAlive)
                {
                    NPC.dontTakeDamage = false;
                    NPC.ai[0] = 2; // enter Phase 2
                    NPC.netUpdate = true;
                }
                else
                {
                    // idle drift while waiting
                    NPC.velocity *= 0.98f;
                }
            }
            // Phase 2+: normal behaviour (placeholder movement)
            else
            {
                Vector2 dir = (target.Center - NPC.Center);
                if (dir.Length() > 8f)
                {
                    dir.Normalize();
                    NPC.velocity = Vector2.Lerp(NPC.velocity, dir * 4f, 0.02f);
                }
                NPC.spriteDirection = NPC.direction = (target.Center.X < NPC.Center.X) ? -1 : 1;
            }
        }

        public override void OnKill()
        {
/*             // Spawn NeptuneNPC when killed
            if (Main.netMode != NetmodeID.MultiplayerClient)
            {
                NPC.NewNPC(NPC.GetSource_Death(), (int)NPC.Center.X, (int)NPC.Center.Y, ModContent.NPCType<NeptuneNPC>());
            }
            else
            {
                NetMessage.SendData(MessageID.SpawnNPC, number: ModContent.NPCType<NeptuneNPC>(), number2: NPC.whoAmI);
            } */
            // Set a world flag or similar to indicate Neptune has been defeated
            WorldDefeatedBosses.Neptune = true;
            // Immediate sync of world flags
            WorldDefeatedBosses.Sync(ModContent.GetInstance<ForgottenWawiTech>());
        }

        public override void ModifyNPCLoot(NPCLoot npcLoot)
        {
            npcLoot.Add(ItemDropRule.BossBag(ModContent.ItemType<NeptuneBossBag>()));
        }
    }
}