tbd-station-14/Content.Server/GameObjects/Components/Weapon/Ranged/Projectile/BallisticMagazineComponent.cs

using System;
using System.Collections.Generic;
using Content.Server.GameObjects.EntitySystems;
using Content.Server.Utility;
using Content.Shared.GameObjects.Components.Weapons.Ranged;
using Content.Shared.Interfaces;
using Robust.Server.GameObjects;
using Robust.Server.GameObjects.Components.Container;
using Robust.Server.Interfaces.GameObjects;
using Robust.Shared.GameObjects;
using Robust.Shared.Interfaces.GameObjects;
using Robust.Shared.Serialization;
using Robust.Shared.ViewVariables;

namespace Content.Server.GameObjects.Components.Weapon.Ranged.Projectile
{
    [RegisterComponent]
    public class BallisticMagazineComponent : Component, IMapInit, IAttackBy
    {
        public override string Name => "BallisticMagazine";

        // Stack of loaded bullets.
        [ViewVariables] private readonly Stack<IEntity> _loadedBullets = new Stack<IEntity>();
        private string _fillType;

        [ViewVariables] private Container _bulletContainer;
        [ViewVariables] private AppearanceComponent _appearance;

        private BallisticMagazineType _magazineType;
        private BallisticCaliber _caliber;
        private int _capacity;

        [ViewVariables] public string FillType => _fillType;
        [ViewVariables] public BallisticMagazineType MagazineType => _magazineType;
        [ViewVariables] public BallisticCaliber Caliber => _caliber;
        [ViewVariables] public int Capacity => _capacity;

        [ViewVariables] public int CountLoaded => _loadedBullets.Count + _availableSpawnCount;

        [ViewVariables] private int _availableSpawnCount;

        public event Action OnAmmoCountChanged;

        public override void ExposeData(ObjectSerializer serializer)
        {
            base.ExposeData(serializer);

            serializer.DataField(ref _magazineType, "magazine", BallisticMagazineType.Unspecified);
            serializer.DataField(ref _caliber, "caliber", BallisticCaliber.Unspecified);
            serializer.DataField(ref _fillType, "fill", null);
            serializer.DataField(ref _capacity, "capacity", 20);
            serializer.DataField(ref _availableSpawnCount, "availableSpawnCount", Capacity);
        }

        public override void Initialize()
        {
            base.Initialize();

            _appearance = Owner.GetComponent<AppearanceComponent>();
        }

        /// <inheritdoc />
        protected override void Startup()
        {
            base.Startup();

            _bulletContainer =
                ContainerManagerComponent.Ensure<Container>("magazine_bullet_container", Owner, out var existed);

            if (existed)
            {
                foreach (var entity in _bulletContainer.ContainedEntities)
                {
                    _loadedBullets.Push(entity);
                }
            }

            UpdateAppearance();

            OnAmmoCountChanged?.Invoke();
            _appearance.SetData(BallisticMagazineVisuals.AmmoCapacity, Capacity);
        }

        public void AddBullet(IEntity bullet)
        {
            if (!bullet.TryGetComponent(out BallisticBulletComponent component))
            {
                throw new ArgumentException("entity isn't a bullet.", nameof(bullet));
            }

            if (component.Caliber != Caliber)
            {
                throw new ArgumentException("entity is of the wrong caliber.", nameof(bullet));
            }

            if (CountLoaded >= Capacity)
            {
                throw new InvalidOperationException("Magazine is full.");
            }

            _bulletContainer.Insert(bullet);
            _loadedBullets.Push(bullet);
            UpdateAppearance();
            OnAmmoCountChanged?.Invoke();
        }

        public IEntity TakeBullet()
        {
            IEntity bullet;
            if (_loadedBullets.Count == 0)
            {
                if (_availableSpawnCount == 0)
                {
                    return null;
                }

                _availableSpawnCount -= 1;
                bullet = Owner.EntityManager.SpawnEntity(FillType, Owner.Transform.GridPosition);
            }
            else
            {
                bullet = _loadedBullets.Pop();
                _bulletContainer.Remove(bullet);
            }

            UpdateAppearance();
            OnAmmoCountChanged?.Invoke();
            return bullet;
        }

        // TODO: Allow putting individual casings into mag (also box)
        AmmoMagTransferPopupMessage CanTransferFrom(IEntity source)
        {
            // Currently the below duplicates box but at some stage these will likely differ
            if (source.TryGetComponent(out BallisticMagazineComponent magazineComponent))
            {
                if (magazineComponent.Caliber != Caliber)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "Wrong caliber");
                }

                if (CountLoaded == Capacity)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "Already full");
                }

                if (magazineComponent.CountLoaded == 0)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "No ammo to transfer");
                }

                return new AmmoMagTransferPopupMessage(result: true, message: "");
            }

            // If box
            if (source.TryGetComponent(out AmmoBoxComponent boxComponent))
            {
                if (boxComponent.Caliber != Caliber)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "Wrong caliber");
                }

                if (CountLoaded == Capacity)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "Already full");
                }

                if (boxComponent.CountLeft == 0)
                {
                    return new AmmoMagTransferPopupMessage(result: false, message: "No ammo to transfer");
                }

                return new AmmoMagTransferPopupMessage(result: true, message: "");
            }

            return new AmmoMagTransferPopupMessage(result: false, message: "");
        }

        // TODO: Potentially abstract out to reduce duplicate structs
        private struct AmmoMagTransferPopupMessage
        {
            public readonly bool Result;
            public readonly string Message;

            public AmmoMagTransferPopupMessage(bool result, string message)
            {
                Result = result;
                Message = message;
            }
        }

        bool IAttackBy.AttackBy(AttackByEventArgs eventArgs)
        {
            var ammoMagTransfer = CanTransferFrom(eventArgs.AttackWith);
            if (ammoMagTransfer.Result) {
                IEntity bullet;
                if (eventArgs.AttackWith.TryGetComponent(out BallisticMagazineComponent magazineComponent))
                {
                    int fillCount = Math.Min(magazineComponent.CountLoaded, Capacity - CountLoaded);
                    for (int i = 0; i < fillCount; i++)
                    {
                        bullet = magazineComponent.TakeBullet();
                        AddBullet(bullet);
                    }
                    eventArgs.User.PopupMessage(eventArgs.User, $"Transferred {fillCount} rounds");
                    return true;
                }
                if (eventArgs.AttackWith.TryGetComponent(out AmmoBoxComponent boxComponent))
                {
                    int fillCount = Math.Min(boxComponent.CountLeft, Capacity - CountLoaded);
                    for (int i = 0; i < fillCount; i++)
                    {
                        bullet = boxComponent.TakeBullet();
                        AddBullet(bullet);
                    }
                    eventArgs.User.PopupMessage(eventArgs.User, $"Transferred {fillCount} rounds");
                    return true;
                }
            }
            else
            {
                eventArgs.User.PopupMessage(eventArgs.User, ammoMagTransfer.Message);
            }

            return false;
        }

        private void UpdateAppearance()
        {
            _appearance.SetData(BallisticMagazineVisuals.AmmoLeft, CountLoaded);
        }

        public void MapInit()
        {
            _availableSpawnCount = Capacity;
        }
    }

    public enum BallisticMagazineType
    {
        Unspecified = 0,

        // .32
        A32,

        // .357
        A357,

        // .44
        A44,

        // .45mm
        A45mm,

        // .50 cal
        A50,

        // 5.56mm
        A556mm,

        // 6.5mm
        A65mm,

        // 7.62mm
        A762mm,
        Maxim,

        // 9mm
        A9mm,
        A9mmSMG,
        A9mmTopMounted,

        // 10mm
        A10mm,
        A10mmSMG,

        // 20mm
        A20mm,

        // 24mm
        A24mm,

        // 12g
        A12g,
    }
}