tbd-station-14/Content.Shared/Projectiles/SharedProjectileSystem.cs

using System.Numerics;
using Content.Shared.CombatMode.Pacification;
using Content.Shared.Damage;
using Content.Shared.DoAfter;
using Content.Shared.Hands.EntitySystems;
using Content.Shared.Interaction;
using Content.Shared.Mobs.Components;
using Content.Shared.Throwing;
using Robust.Shared.Audio.Systems;
using Robust.Shared.Map;
using Robust.Shared.Network;
using Robust.Shared.Physics;
using Robust.Shared.Physics.Components;
using Robust.Shared.Physics.Dynamics;
using Robust.Shared.Physics.Events;
using Robust.Shared.Physics.Systems;
using Robust.Shared.Serialization;
using Robust.Shared.Utility;

namespace Content.Shared.Projectiles;

public abstract partial class SharedProjectileSystem : EntitySystem
{
    public const string ProjectileFixture = "projectile";

    [Dependency] private readonly INetManager _net = default!;
    [Dependency] private readonly SharedAudioSystem _audio = default!;
    [Dependency] private readonly SharedDoAfterSystem _doAfter = default!;
    [Dependency] private readonly SharedHandsSystem _hands = default!;
    [Dependency] private readonly SharedPhysicsSystem _physics = default!;
    [Dependency] private readonly SharedTransformSystem _transform = default!;

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

        SubscribeLocalEvent<ProjectileComponent, PreventCollideEvent>(PreventCollision);
        SubscribeLocalEvent<EmbeddableProjectileComponent, ProjectileHitEvent>(OnEmbedProjectileHit);
        SubscribeLocalEvent<EmbeddableProjectileComponent, ThrowDoHitEvent>(OnEmbedThrowDoHit);
        SubscribeLocalEvent<EmbeddableProjectileComponent, ActivateInWorldEvent>(OnEmbedActivate);
        SubscribeLocalEvent<EmbeddableProjectileComponent, RemoveEmbeddedProjectileEvent>(OnEmbedRemove);
        SubscribeLocalEvent<EmbeddableProjectileComponent, ComponentShutdown>(OnEmbeddableCompShutdown);

        SubscribeLocalEvent<EmbeddedContainerComponent, EntityTerminatingEvent>(OnEmbeddableTermination);
    }

    private void OnEmbedActivate(Entity<EmbeddableProjectileComponent> embeddable, ref ActivateInWorldEvent args)
    {
        // Unremovable embeddables moment
        if (embeddable.Comp.RemovalTime == null)
            return;

        if (args.Handled || !args.Complex || !TryComp<PhysicsComponent>(embeddable, out var physics) ||
            physics.BodyType != BodyType.Static)
            return;

        args.Handled = true;

        _doAfter.TryStartDoAfter(new DoAfterArgs(EntityManager,
            args.User,
            embeddable.Comp.RemovalTime.Value,
            new RemoveEmbeddedProjectileEvent(),
            eventTarget: embeddable,
            target: embeddable));
    }

    private void OnEmbedRemove(Entity<EmbeddableProjectileComponent> embeddable, ref RemoveEmbeddedProjectileEvent args)
    {
        // Whacky prediction issues.
        if (args.Cancelled || _net.IsClient)
            return;

        EmbedDetach(embeddable, embeddable.Comp, args.User);

        // try place it in the user's hand
        _hands.TryPickupAnyHand(args.User, embeddable);
    }

    private void OnEmbeddableCompShutdown(Entity<EmbeddableProjectileComponent> embeddable, ref ComponentShutdown arg)
    {
        EmbedDetach(embeddable, embeddable.Comp);
    }

    private void OnEmbedThrowDoHit(Entity<EmbeddableProjectileComponent> embeddable, ref ThrowDoHitEvent args)
    {
        if (!embeddable.Comp.EmbedOnThrow)
            return;

        EmbedAttach(embeddable, args.Target, null, embeddable.Comp);
    }

    private void OnEmbedProjectileHit(Entity<EmbeddableProjectileComponent> embeddable, ref ProjectileHitEvent args)
    {
        EmbedAttach(embeddable, args.Target, args.Shooter, embeddable.Comp);

        // Raise a specific event for projectiles.
        if (TryComp(embeddable, out ProjectileComponent? projectile))
        {
            var ev = new ProjectileEmbedEvent(projectile.Shooter!.Value, projectile.Weapon!.Value, args.Target);
            RaiseLocalEvent(embeddable, ref ev);
        }
    }

    private void EmbedAttach(EntityUid uid, EntityUid target, EntityUid? user, EmbeddableProjectileComponent component)
    {
        TryComp<PhysicsComponent>(uid, out var physics);
        _physics.SetLinearVelocity(uid, Vector2.Zero, body: physics);
        _physics.SetBodyType(uid, BodyType.Static, body: physics);
        var xform = Transform(uid);
        _transform.SetParent(uid, xform, target);

        if (component.Offset != Vector2.Zero)
        {
            var rotation = xform.LocalRotation;
            if (TryComp<ThrowingAngleComponent>(uid, out var throwingAngleComp))
                rotation += throwingAngleComp.Angle;
            _transform.SetLocalPosition(uid, xform.LocalPosition + rotation.RotateVec(component.Offset), xform);
        }

        _audio.PlayPredicted(component.Sound, uid, null);
        component.EmbeddedIntoUid = target;
        var ev = new EmbedEvent(user, target);
        RaiseLocalEvent(uid, ref ev);
        Dirty(uid, component);

        EnsureComp<EmbeddedContainerComponent>(target, out var embeddedContainer);

        //Assert that this entity not embed
        DebugTools.AssertEqual(embeddedContainer.EmbeddedObjects.Contains(uid), false);

        embeddedContainer.EmbeddedObjects.Add(uid);
    }

    public void EmbedDetach(EntityUid uid, EmbeddableProjectileComponent? component, EntityUid? user = null)
    {
        if (!Resolve(uid, ref component))
            return;

        if (component.EmbeddedIntoUid is not null)
        {
            if (TryComp<EmbeddedContainerComponent>(component.EmbeddedIntoUid.Value, out var embeddedContainer))
            {
                embeddedContainer.EmbeddedObjects.Remove(uid);
                Dirty(component.EmbeddedIntoUid.Value, embeddedContainer);
                if (embeddedContainer.EmbeddedObjects.Count == 0)
                    RemCompDeferred<EmbeddedContainerComponent>(component.EmbeddedIntoUid.Value);
            }
        }

        if (component.DeleteOnRemove && _net.IsServer)
        {
            QueueDel(uid);
            return;
        }

        var xform = Transform(uid);
        if (TerminatingOrDeleted(xform.GridUid) && TerminatingOrDeleted(xform.MapUid))
            return;
        TryComp<PhysicsComponent>(uid, out var physics);
        _physics.SetBodyType(uid, BodyType.Dynamic, body: physics, xform: xform);
        _transform.AttachToGridOrMap(uid, xform);
        component.EmbeddedIntoUid = null;
        Dirty(uid, component);

        // Reset whether the projectile has damaged anything if it successfully was removed
        if (TryComp<ProjectileComponent>(uid, out var projectile))
        {
            projectile.Shooter = null;
            projectile.Weapon = null;
            projectile.ProjectileSpent = false;

            Dirty(uid, projectile);
        }

        if (user != null)
        {
            // Land it just coz uhhh yeah
            var landEv = new LandEvent(user, true);
            RaiseLocalEvent(uid, ref landEv);
        }

        _physics.WakeBody(uid, body: physics);
    }

    private void OnEmbeddableTermination(Entity<EmbeddedContainerComponent> container, ref EntityTerminatingEvent args)
    {
        DetachAllEmbedded(container);
    }

    public void DetachAllEmbedded(Entity<EmbeddedContainerComponent> container)
    {
        foreach (var embedded in container.Comp.EmbeddedObjects)
        {
            if (!TryComp<EmbeddableProjectileComponent>(embedded, out var embeddedComp))
                continue;

            EmbedDetach(embedded, embeddedComp);
        }
    }

    private void PreventCollision(EntityUid uid, ProjectileComponent component, ref PreventCollideEvent args)
    {
        if (component.IgnoreShooter && (args.OtherEntity == component.Shooter || args.OtherEntity == component.Weapon))
        {
            args.Cancelled = true;
        }
    }

    public void SetShooter(EntityUid id, ProjectileComponent component, EntityUid shooterId)
    {
        if (component.Shooter == shooterId)
            return;

        component.Shooter = shooterId;
        Dirty(id, component);
    }

    [Serializable, NetSerializable]
    private sealed partial class RemoveEmbeddedProjectileEvent : DoAfterEvent
    {
        public override DoAfterEvent Clone() => this;
    }
}

[Serializable, NetSerializable]
public sealed class ImpactEffectEvent : EntityEventArgs
{
    public string Prototype;
    public NetCoordinates Coordinates;

    public ImpactEffectEvent(string prototype, NetCoordinates coordinates)
    {
        Prototype = prototype;
        Coordinates = coordinates;
    }
}

/// <summary>
/// Raised when an entity is just about to be hit with a projectile but can reflect it
/// </summary>
[ByRefEvent]
public record struct ProjectileReflectAttemptEvent(EntityUid ProjUid, ProjectileComponent Component, bool Cancelled);

/// <summary>
/// Raised when a projectile hits an entity
/// </summary>
[ByRefEvent]
public record struct ProjectileHitEvent(DamageSpecifier Damage, EntityUid Target, EntityUid? Shooter = null);