CatStation/Content.Shared/Guardian/GuardianSystem.cs

using Content.Shared.Actions;
using Content.Shared.Damage.Systems;
using Content.Shared.DoAfter;
using Content.Shared.Examine;
using Content.Shared.Gibbing;
using Content.Shared.Guardian.Components;
using Content.Shared.Hands.Components;
using Content.Shared.Hands.EntitySystems;
using Content.Shared.IdentityManagement;
using Content.Shared.Interaction;
using Content.Shared.Interaction.Events;
using Content.Shared.Mech.EntitySystems;
using Content.Shared.Mobs;
using Content.Shared.Popups;
using Robust.Shared.Audio.Systems;
using Robust.Shared.Containers;
using Robust.Shared.Player;
using Robust.Shared.Timing;
using Robust.Shared.Utility;

namespace Content.Shared.Guardian;

/// <summary>
/// A guardian has a host it's attached to that it fights for. A fighting spirit.
/// </summary>
public sealed partial class GuardianSystem : EntitySystem
{
    [Dependency] private DamageableSystem _damage = default!;
    [Dependency] private GibbingSystem _gibbing = default!;
    [Dependency] private IGameTiming _timing = default!;
    [Dependency] private SharedActionsSystem _action = default!;
    [Dependency] private SharedAudioSystem _audio = default!;
    [Dependency] private SharedContainerSystem _container = default!;
    [Dependency] private SharedDoAfterSystem _doAfter = default!;
    [Dependency] private SharedHandsSystem _hands = default!;
    [Dependency] private SharedPopupSystem _popup = default!;
    [Dependency] private SharedTransformSystem _transform = default!;

    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<GuardianCreatorComponent, UseInHandEvent>(OnCreatorUse);
        SubscribeLocalEvent<GuardianCreatorComponent, AfterInteractEvent>(OnCreatorInteract);
        SubscribeLocalEvent<GuardianCreatorComponent, ExaminedEvent>(OnCreatorExamine);
        SubscribeLocalEvent<GuardianCreatorComponent, GuardianCreatorDoAfterEvent>(OnDoAfter);

        SubscribeLocalEvent<GuardianComponent, ComponentShutdown>(OnGuardianShutdown);
        SubscribeLocalEvent<GuardianComponent, MoveEvent>(OnGuardianMove);
        SubscribeLocalEvent<GuardianComponent, DamageDealtEvent>(OnGuardianDamaged);
        SubscribeLocalEvent<GuardianComponent, PlayerAttachedEvent>(OnGuardianPlayerAttached);
        SubscribeLocalEvent<GuardianComponent, PlayerDetachedEvent>(OnGuardianPlayerDetached);

        SubscribeLocalEvent<GuardianHostComponent, ComponentInit>(OnHostInit);
        SubscribeLocalEvent<GuardianHostComponent, MoveEvent>(OnHostMove);
        SubscribeLocalEvent<GuardianHostComponent, MobStateChangedEvent>(OnHostStateChange);
        SubscribeLocalEvent<GuardianHostComponent, ComponentShutdown>(OnHostShutdown);

        SubscribeLocalEvent<GuardianHostComponent, GuardianToggleActionEvent>(OnPerformAction);

        SubscribeLocalEvent<GuardianComponent, AttackAttemptEvent>(OnGuardianAttackAttempt);

        SubscribeLocalEvent<GuardianHostComponent, MechPilotRelayedEvent<GettingAttackedAttemptEvent>>(OnPilotAttackAttempt);
    }

    private void OnGuardianShutdown(Entity<GuardianComponent> ent, ref ComponentShutdown args)
    {
        if (!TryComp<GuardianHostComponent>(ent, out var hostComponent))
            return;

        _container.Remove(ent.Owner, hostComponent.GuardianContainer);
        hostComponent.HostedGuardian = null;
        PredictedDel(hostComponent.ActionEntity);
        hostComponent.ActionEntity = null;
        ent.Comp.Host = null;

        Dirty(ent);
        Dirty(ent, hostComponent);
    }

    private void OnPerformAction(Entity<GuardianHostComponent> ent, ref GuardianToggleActionEvent args)
    {
        if (args.Handled)
            return;

        if (_container.IsEntityInContainer(ent.Owner))
        {
            _popup.PopupEntity(Loc.GetString("guardian-inside-container"), ent.Owner, ent.Owner);
            return;
        }

        if (ent.Comp.HostedGuardian != null)
            ToggleGuardian(ent);

        args.Handled = true;
    }

    private void OnGuardianPlayerDetached(Entity<GuardianComponent> ent, ref PlayerDetachedEvent args)
    {
        if (!TryComp<GuardianHostComponent>(ent.Comp.Host, out var hostComponent) ||
            TerminatingOrDeleted(ent.Owner))
        {
            PredictedQueueDel(ent.Owner);
            ent.Comp.Host = null;
            Dirty(ent);
            return;
        }

        RetractGuardian((ent.Comp.Host.Value, hostComponent), (ent.Owner, ent.Comp));
    }

    private void OnGuardianPlayerAttached(Entity<GuardianComponent> ent, ref PlayerAttachedEvent args)
    {
        var host = ent.Comp.Host;
        if (!HasComp<GuardianHostComponent>(host))
        {
            PredictedQueueDel(ent.Owner);
            ent.Comp.Host = null;
            Dirty(ent);
            return;
        }

        _popup.PopupEntity(Loc.GetString("guardian-available"), host.Value, host.Value);
    }

    private void OnHostInit(Entity<GuardianHostComponent> ent, ref ComponentInit args)
    {
        ent.Comp.GuardianContainer = _container.EnsureContainer<ContainerSlot>(ent.Owner, "GuardianContainer");
        _action.AddAction(ent.Owner, ref ent.Comp.ActionEntity, ent.Comp.Action);
    }

    private void OnHostShutdown(Entity<GuardianHostComponent> ent, ref ComponentShutdown args)
    {
        if (ent.Comp.HostedGuardian is not { } guardian)
            return;

        // Ensure held items are dropped before deleting guardian.
        if (HasComp<HandsComponent>(guardian))
            _gibbing.Gib(ent.Comp.HostedGuardian.Value);

        PredictedQueueDel(guardian);
        ent.Comp.HostedGuardian = null;
        PredictedDel(ent.Comp.ActionEntity);
        ent.Comp.ActionEntity = null;
        Dirty(ent);
    }

    private void OnGuardianAttackAttempt(Entity<GuardianComponent> ent, ref AttackAttemptEvent args)
    {
        if (args.Cancelled || args.Target != ent.Comp.Host)
            return;

        _popup.PopupCursor(Loc.GetString("guardian-attack-host"), ent.Owner, PopupType.LargeCaution);
        args.Cancel();
    }

    private void OnPilotAttackAttempt(Entity<GuardianHostComponent> ent,
        ref MechPilotRelayedEvent<GettingAttackedAttemptEvent> args)
    {
        if (args.Args.Cancelled)
            return;

        _popup.PopupCursor(Loc.GetString("guardian-attack-host"),
            args.Args.Attacker,
            PopupType.LargeCaution);
        args.Args.Cancelled = true;
    }

    private void ToggleGuardian(Entity<GuardianHostComponent> ent)
    {
        if (!TryComp<GuardianComponent>(ent.Comp.HostedGuardian, out var guardianComponent))
            return;

        if (guardianComponent.GuardianLoose)
            RetractGuardian(ent, (ent.Comp.HostedGuardian.Value, guardianComponent));
        else
            ReleaseGuardian(ent, (ent.Comp.HostedGuardian.Value, guardianComponent));
    }

    /// <summary>
    /// Adds the guardian host component to the user and spawns the guardian inside said component.
    /// </summary>
    private void OnCreatorUse(Entity<GuardianCreatorComponent> ent, ref UseInHandEvent args)
    {
        if (args.Handled)
            return;

        args.Handled = true;
        UseCreator(args.User, args.User, ent);
    }

    private void OnCreatorInteract(Entity<GuardianCreatorComponent> ent, ref AfterInteractEvent args)
    {
        if (args.Handled || args.Target == null || !args.CanReach)
            return;

        args.Handled = true;
        UseCreator(args.User, args.Target.Value, ent);
    }

    private void UseCreator(EntityUid user, EntityUid target, Entity<GuardianCreatorComponent> ent)
    {
        if (ent.Comp.Used)
        {
            _popup.PopupEntity(Loc.GetString(ent.Comp.EmptyPopup), user, user);

            return;
        }

        // Can only inject things with the component...
        if (!HasComp<CanHostGuardianComponent>(target))
        {
            var msg = Loc.GetString("guardian-activator-invalid-target",
                ("entity", Identity.Entity(target, EntityManager, user)));
            _popup.PopupEntity(msg, user, user);
            return;
        }

        // If user is already a host don't duplicate.
        if (HasComp<GuardianHostComponent>(target))
        {
            _popup.PopupEntity(Loc.GetString("guardian-already-present-invalid-creation"), user, user);
            return;
        }

        _doAfter.TryStartDoAfter(new DoAfterArgs(EntityManager,
            user,
            ent.Comp.InjectionDelay,
            new GuardianCreatorDoAfterEvent(),
            ent,
            target: target,
            used: ent)
        {
            BreakOnMove = true,
            NeedHand = true,
            BreakOnHandChange = true
        });
    }

    private void OnDoAfter(Entity<GuardianCreatorComponent> ent, ref GuardianCreatorDoAfterEvent args)
    {
        if (args.Handled || args.Args.Target == null || args.Cancelled || ent.Comp.Deleted || ent.Comp.Used)
            return;

        if (!_hands.IsHolding(args.Args.User, ent.Owner) || HasComp<GuardianHostComponent>(args.Args.Target))
            return;

        var hostXform = Transform(args.Args.Target.Value);
        var host = EnsureComp<GuardianHostComponent>(args.Args.Target.Value);

        // Use map position so it's not inadvertently parented to the host + if it's in a container it spawns outside I guess.
        var guardian = PredictedSpawnAtPosition(ent.Comp.GuardianProto,
            _transform.GetMoverCoordinates(args.Args.Target.Value, xform: hostXform));
        _container.Insert(guardian, host.GuardianContainer);
        host.HostedGuardian = guardian;

        if (TryComp<GuardianComponent>(guardian, out var guardianComp))
        {
            guardianComp.Host = args.Args.Target.Value;
            _audio.PlayPredicted(ent.Comp.UsedSound,
                ent.Owner,
                args.Args.Target);
            _popup.PopupEntity(Loc.GetString(ent.Comp.GuardianHauntedPopup),
                args.Args.Target.Value,
                args.Args.Target.Value);
            // Exhaust the activator
            ent.Comp.Used = true;
        }
        else
        {
            Log.Error($"Tried to spawn a guardian that doesn't have {nameof(GuardianComponent)}");
            PredictedDel(guardian);
        }

        Dirty(ent);
        args.Handled = true;
    }

    /// <summary>
    /// Triggers when the host receives damage which puts the host in either critical or killed state.
    /// </summary>
    private void OnHostStateChange(Entity<GuardianHostComponent> ent, ref MobStateChangedEvent args)
    {
        if (ent.Comp.HostedGuardian == null ||
            !TryComp<GuardianComponent>(ent.Comp.HostedGuardian, out var guardianComp))
            return;

        if (args.NewMobState == MobState.Critical)
        {
            _popup.PopupEntity(Loc.GetString(ent.Comp.GuardianHostCritWarn),
                ent.Comp.HostedGuardian.Value,
                ent.Comp.HostedGuardian.Value);
            _audio.PlayPredicted(guardianComp.CriticalSound, ent.Comp.HostedGuardian.Value, args.Target);
        }
        else if (args.NewMobState == MobState.Dead)
        {
            _audio.PlayPredicted(guardianComp.DeathSound, ent.Owner, args.Target);
            RemComp<GuardianHostComponent>(ent.Owner);
        }
    }

    /// <summary>
    /// Handles guardian receiving damage and splitting it with the host according to his defense percent.
    /// </summary>
    private void OnGuardianDamaged(Entity<GuardianComponent> ent, ref DamageDealtEvent args)
    {
        if (_timing.ApplyingState)
            return;

        if (args.Damage == null! || ent.Comp.Host == null || ent.Comp.DamageShare == 0)
            return;

        _damage.ChangeDamage(
            ent.Comp.Host.Value,
            args.Damage * ent.Comp.DamageShare,
            origin: args.Origin,
            ignoreResistances: true,
            interruptsDoAfters: false);
        _popup.PopupEntity(Loc.GetString(ent.Comp.GuardianDamagePopup), ent.Comp.Host.Value, ent.Comp.Host.Value);
    }

    /// <summary>
    /// Triggers while trying to examine an activator to see if it's used.
    /// </summary>
    private void OnCreatorExamine(Entity<GuardianCreatorComponent> ent, ref ExaminedEvent args)
    {
        if (!ent.Comp.Used)
            return;

        args.PushMarkup(Loc.GetString(ent.Comp.EmptyExamine));
    }

    /// <summary>
    /// Called every time the host moves, to make sure the host and the guardian are not too far away from each other.
    /// </summary>
    private void OnHostMove(Entity<GuardianHostComponent> ent, ref MoveEvent args)
    {
        if (!TryComp<GuardianComponent>(ent.Comp.HostedGuardian, out var guardianComponent) ||
            !guardianComponent.GuardianLoose)
        {
            return;
        }

        CheckGuardianMove(ent.Owner, ent.Comp.HostedGuardian.Value);
    }

    /// <summary>
    /// Called every time the guardian moves: makes sure it's not out of it's allowed distance.
    /// </summary>
    private void OnGuardianMove(Entity<GuardianComponent> ent, ref MoveEvent args)
    {
        if (!ent.Comp.GuardianLoose)
            return;

        if (ent.Comp.Host == null)
            return;

        CheckGuardianMove(ent.Comp.Host.Value, ent.Owner);
    }

    /// <summary>
    /// Retract the guardian if either the host or the guardian move away from each other.
    /// </summary>
    private void CheckGuardianMove(
        Entity<GuardianHostComponent?> host,
        Entity<GuardianComponent?> guardian,
        TransformComponent? hostXform = null,
        TransformComponent? guardianXform = null)
    {
        if (TerminatingOrDeleted(guardian.Owner) || TerminatingOrDeleted(host.Owner))
            return;

        if (!Resolve(host.Owner, ref host.Comp, ref hostXform) ||
            !Resolve(guardian.Owner, ref guardian.Comp, ref guardianXform))
        {
            return;
        }

        if (!guardian.Comp.GuardianLoose)
            return;

        if (!_transform.InRange(guardianXform.Coordinates, hostXform.Coordinates, guardian.Comp.DistanceAllowed))
            RetractGuardian((host.Owner, host.Comp), guardian);
    }

    private void ReleaseGuardian(Entity<GuardianHostComponent> host, Entity<GuardianComponent> guardian)
    {
        _audio.PlayPredicted(host.Comp.ReleaseSound, guardian, host);
        if (guardian.Comp.GuardianLoose)
        {
            DebugTools.Assert(!host.Comp.GuardianContainer.Contains(guardian));
            return;
        }

        DebugTools.Assert(host.Comp.GuardianContainer.Contains(guardian));
        _container.Remove(guardian.Owner, host.Comp.GuardianContainer);
        DebugTools.Assert(!host.Comp.GuardianContainer.Contains(guardian));

        guardian.Comp.GuardianLoose = true;
        Dirty(host);
        Dirty(guardian);
    }

    private void RetractGuardian(Entity<GuardianHostComponent> host, Entity<GuardianComponent?> guardian)
    {
        if (_timing.ApplyingState)
            return;

        if (!Resolve(guardian, ref guardian.Comp))
            return;

        if (!guardian.Comp.GuardianLoose)
        {
            DebugTools.Assert(host.Comp.GuardianContainer.Contains(guardian));
            return;
        }

        _container.Insert(guardian.Owner, host.Comp.GuardianContainer);
        _popup.PopupEntity(Loc.GetString(host.Comp.GuardianHostRecall), host.Owner, host.Owner);
        guardian.Comp.GuardianLoose = false;

        Dirty(host);
        Dirty(guardian);
    }
}