wwdpublic/Content.Shared/Psionics/Abilities/PsionicInvisibility/PsionicInvisibleContactsSystem.cs

using Content.Shared.Stealth;
using Content.Shared.Stealth.Components;
using Content.Shared.Whitelist;
using Robust.Shared.Physics.Events;
using Robust.Shared.Physics.Systems;

namespace Content.Shared.Psionics;

/// <summary>
/// Allows an entity to become psionically invisible when touching certain entities.
/// </summary>
public sealed class PsionicInvisibleContactsSystem : EntitySystem
{
    [Dependency] private readonly SharedStealthSystem _stealth = default!;
    [Dependency] private readonly EntityWhitelistSystem _whitelistSystem = default!;

    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<PsionicInvisibleContactsComponent, StartCollideEvent>(OnEntityEnter);
        SubscribeLocalEvent<PsionicInvisibleContactsComponent, EndCollideEvent>(OnEntityExit);

        UpdatesAfter.Add(typeof(SharedPhysicsSystem));
    }

    private void OnEntityEnter(EntityUid uid, PsionicInvisibleContactsComponent component, ref StartCollideEvent args)
    {
        var otherUid = args.OtherEntity;
        var ourEntity = args.OurEntity;

        if (_whitelistSystem.IsWhitelistFail(component.Whitelist, otherUid))
            return;

        // This will go up twice per web hit, since webs also have a flammable fixture.
        // It goes down twice per web exit, so everything's fine.
        ++component.Stages;

        if (HasComp<PsionicallyInvisibleComponent>(ourEntity))
            return;

        EnsureComp<PsionicallyInvisibleComponent>(ourEntity);
        var stealth = EnsureComp<StealthComponent>(ourEntity);
        _stealth.SetVisibility(ourEntity, 0.66f, stealth);
    }

    private void OnEntityExit(EntityUid uid, PsionicInvisibleContactsComponent component, ref EndCollideEvent args)
    {
        var otherUid = args.OtherEntity;
        var ourEntity = args.OurEntity;

        if (_whitelistSystem.IsWhitelistFail(component.Whitelist, otherUid))
            return;

        if (!HasComp<PsionicallyInvisibleComponent>(ourEntity))
            return;

        if (--component.Stages > 0)
            return;

        RemComp<PsionicallyInvisibleComponent>(ourEntity);
        var stealth = EnsureComp<StealthComponent>(ourEntity);
        // Just to be sure...
        _stealth.SetVisibility(ourEntity, 1f, stealth);

        RemComp<StealthComponent>(ourEntity);
    }
}