ArachnaeSwarm/Source/ArachnaeSwarm/PowerArmor/ARA_PowerArmor.cs

using RimWorld;
using UnityEngine;
using Verse;
using System.Collections.Generic;

namespace ArachnaeSwarm
{
    public interface IStructurePoints
    {
        float StructurePoints { get; }
        float StructurePointsMax { get; }
        float StructurePointsPercent { get; }
        string Label { get; }
    }

    public class PowerArmorExtension : DefModExtension
    {
        public ThingDef buildingDef;
        public float structurePointsMax = 500f;
    }

    [StaticConstructorOnStartup]
    public class ARA_PowerArmor : Apparel, IStructurePoints
    {
        #region Properties
        private PowerArmorExtension ext;
        public PowerArmorExtension Ext => ext ??= def.GetModExtension<PowerArmorExtension>();
        public override string Label => base.Label;

        private float structurePoints = -1f;
        public float StructurePointsMax => Ext?.structurePointsMax ?? 500f;
        
        public float StructurePoints
        {
            get
            {
                if (structurePoints < 0)
                {
                    structurePoints = StructurePointsMax;
                }
                return structurePoints;
            }
            set
            {
                structurePoints = Mathf.Clamp(value, 0, StructurePointsMax);
            }
        }

        public float StructurePointsPercent => StructurePoints / StructurePointsMax;
        
        public Building sourceBuilding;
        #endregion

        #region Data
        public override void ExposeData()
        {
            base.ExposeData();
            Scribe_Values.Look(ref structurePoints, "structurePoints", -1f);
            Scribe_References.Look(ref sourceBuilding, "sourceBuilding");
        }
        #endregion

        #region Gizmo
        public override IEnumerable<Gizmo> GetWornGizmos()
        {
            foreach (var gizmo in base.GetWornGizmos())
            {
                yield return gizmo;
            }
            yield return new Gizmo_StructurePanel(this);
        }
        #endregion

        #region State-Switching
        public override void Notify_Unequipped(Pawn pawn)
        {
            base.Notify_Unequipped(pawn);

            ThingDef buildingToSpawn = sourceBuilding?.def ?? Ext?.buildingDef;

            if (buildingToSpawn == null)
            {
                Log.Error($"[ArachnaeSwarm] Power Armor {this.def.defName} unequipped, but has no buildingDef defined in its PowerArmorExtension or a source building.");
                return;
            }

            Building building = (Building)ThingMaker.MakeThing(buildingToSpawn);
            building.HitPoints = Mathf.RoundToInt(this.StructurePoints);
            GenPlace.TryPlaceThing(building, pawn.Position, pawn.Map, ThingPlaceMode.Near);
        }
        #endregion

        #region Damage Handling - THE FINAL, CORRECT IMPLEMENTATION
        public override bool CheckPreAbsorbDamage(DamageInfo dinfo)
        {
            if (this.Wearer == null || !dinfo.Def.harmsHealth || dinfo.Amount <= 0.001f)
            {
                return false;
            }

            float finalDamage = GetPostArmorDamage(ref dinfo);

            if (finalDamage > 0)
            {
                this.StructurePoints -= finalDamage;
                EffecterDefOf.DamageDiminished_Metal.SpawnAttached(this.Wearer, this.Wearer.Map, 1f);

                if (this.StructurePoints <= 0)
                {
                    Messages.Message("PowerArmorBroken".Translate(this.Label, this.Wearer.LabelShort), this, MessageTypeDefOf.NegativeEvent);
                    this.Destroy(DestroyMode.KillFinalize);
                }
            }
            else
            {
                EffecterDefOf.Deflect_Metal_Bullet.SpawnAttached(this.Wearer, this.Wearer.Map, 1f);
            }
            
            // By returning true, we tell the game the damage has been fully handled and should not proceed to the pawn.
            return true;
        }

        private float GetPostArmorDamage(ref DamageInfo dinfo)
        {
            float amount = dinfo.Amount;
            if (dinfo.Def.armorCategory != null)
            {
                StatDef armorRatingStat = dinfo.Def.armorCategory.armorRatingStat;
                float armorRating = this.GetStatValue(armorRatingStat);
                
                float armorPenetration = dinfo.ArmorPenetrationInt;
                float num = Mathf.Max(armorRating - armorPenetration, 0f);
                float value = Rand.Value;
                float num2 = num * 0.5f;
                float num3 = num;
                if (value < num2)
                {
                    amount = 0f;
                }
                else if (value < num3)
                {
                    amount = GenMath.RoundRandom(amount / 2f);
                    if (dinfo.Def.armorCategory == DamageArmorCategoryDefOf.Sharp)
                    {
                        dinfo.Def = DamageDefOf.Blunt;
                    }
                }
            }
            return amount;
        }
        #endregion
    }
}