tbd-station-14/Content.Shared/GameObjects/Components/Movement/SlipperyComponent.cs

#nullable enable
using System;
using System.Collections.Generic;
using System.Linq;
using Content.Shared.Audio;
using Content.Shared.GameObjects.Components.Mobs;
using Content.Shared.GameObjects.EntitySystems.EffectBlocker;
using Content.Shared.Interfaces;
using Robust.Shared.Audio;
using Robust.Shared.Containers;
using Robust.Shared.GameObjects;
using Robust.Shared.IoC;
using Robust.Shared.Maths;
using Robust.Shared.Physics;
using Robust.Shared.Physics.Collision;
using Robust.Shared.Physics.Dynamics;
using Robust.Shared.Player;
using Robust.Shared.Players;
using Robust.Shared.Serialization;
using Robust.Shared.Serialization.Manager.Attributes;
using Robust.Shared.ViewVariables;

namespace Content.Shared.GameObjects.Components.Movement
{
    [RegisterComponent]
    public class SlipperyComponent : Component, IStartCollide
    {
        [Dependency] private IModuleManager _moduleManager = default!;

        public sealed override string Name => "Slippery";
        public override uint? NetID => ContentNetIDs.SLIP;

        private float _paralyzeTime = 3f;
        private float _intersectPercentage = 0.3f;
        private float _requiredSlipSpeed = 0.1f;
        private float _launchForwardsMultiplier = 1f;
        private bool _slippery = true;
        private string _slipSound = "/Audio/Effects/slip.ogg";

        /// <summary>
        ///     List of entities that are currently colliding with the entity.
        /// </summary>
        private readonly HashSet<EntityUid> _colliding = new();

        /// <summary>
        ///     The list of entities that have been slipped by this component, which shouldn't be slipped again.
        /// </summary>
        private readonly HashSet<EntityUid> _slipped = new();

        /// <summary>
        ///     Path to the sound to be played when a mob slips.
        /// </summary>
        [ViewVariables]
        [DataField("slipSound")]
        public string SlipSound
        {
            get => _slipSound;
            set
            {
                if (value == _slipSound)
                    return;

                _slipSound = value;
                Dirty();
            }
        }

        /// <summary>
        ///     How many seconds the mob will be paralyzed for.
        /// </summary>
        [ViewVariables(VVAccess.ReadWrite)]
        [DataField("paralyzeTime")]
        public float ParalyzeTime
        {
            get => _paralyzeTime;
            set
            {
                if (MathHelper.CloseTo(_paralyzeTime, value)) return;

                _paralyzeTime = value;
                Dirty();
            }
        }

        /// <summary>
        ///     Percentage of shape intersection for a slip to occur.
        /// </summary>
        [ViewVariables(VVAccess.ReadWrite)]
        [DataField("intersectPercentage")]
        public float IntersectPercentage
        {
            get => _intersectPercentage;
            set
            {
                if (MathHelper.CloseTo(_intersectPercentage, value)) return;

                _intersectPercentage = value;
                Dirty();
            }
        }

        /// <summary>
        ///     Entities will only be slipped if their speed exceeds this limit.
        /// </summary>
        [ViewVariables(VVAccess.ReadWrite)]
        [DataField("requiredSlipSpeed")]
        public float RequiredSlipSpeed
        {
            get => _requiredSlipSpeed;
            set
            {
                if (MathHelper.CloseTo(_requiredSlipSpeed, value)) return;

                _requiredSlipSpeed = value;
                Dirty();
            }
        }

        /// <summary>
        ///     The entity's speed will be multiplied by this to slip it forwards.
        /// </summary>
        [ViewVariables(VVAccess.ReadWrite)]
        [DataField("launchForwardsMultiplier")]
        public float LaunchForwardsMultiplier
        {
            get => _launchForwardsMultiplier;
            set
            {
                if (MathHelper.CloseTo(_launchForwardsMultiplier, value)) return;

                _launchForwardsMultiplier = value;
                Dirty();
            }
        }

        /// <summary>
        ///     Whether or not this component will try to slip entities.
        /// </summary>
        [ViewVariables(VVAccess.ReadWrite)]
        [DataField("slippery")]
        public bool Slippery
        {
            get => _slippery;
            set
            {
                if (_slippery == value) return;

                _slippery = value;
                Dirty();
            }
        }

        private bool TrySlip(IPhysBody ourBody, IPhysBody otherBody)
        {
            if (!Slippery
                || Owner.IsInContainer()
                ||  _slipped.Contains(otherBody.Owner.Uid)
                ||  !otherBody.Owner.TryGetComponent(out SharedStunnableComponent? stun))
            {
                return false;
            }

            if (otherBody.LinearVelocity.Length < RequiredSlipSpeed || stun.KnockedDown)
            {
                return false;
            }

            var percentage = otherBody.GetWorldAABB().IntersectPercentage(ourBody.GetWorldAABB());

            if (percentage < IntersectPercentage)
            {
                return false;
            }

            if (!EffectBlockerSystem.CanSlip(otherBody.Owner))
            {
                return false;
            }

            otherBody.LinearVelocity *= LaunchForwardsMultiplier;

            stun.Paralyze(5);
            _slipped.Add(otherBody.Owner.Uid);
            Dirty();

            if (!string.IsNullOrEmpty(SlipSound) && _moduleManager.IsServerModule)
            {
                SoundSystem.Play(Filter.Broadcast(), SlipSound, Owner, AudioHelpers.WithVariation(0.2f));
            }

            return true;
        }

        void IStartCollide.CollideWith(Fixture _, Fixture otherFixture, in Manifold manifold)
        {
            _colliding.Add(otherFixture.Body.Owner.Uid);
        }

        public void Update()
        {
            if (!Slippery)
                return;

            var physics = Owner.GetComponent<IPhysBody>();

            foreach (var uid in _colliding.ToArray())
            {
                if (!uid.IsValid() || !Owner.EntityManager.EntityExists(uid))
                {
                    _colliding.Remove(uid);
                    _slipped.Remove(uid);
                    Dirty();
                    continue;
                }

                var entity = Owner.EntityManager.GetEntity(uid);
                var otherPhysics = entity.GetComponent<IPhysBody>();

                if (!physics.GetWorldAABB().Intersects(otherPhysics.GetWorldAABB()))
                {
                    _colliding.Remove(uid);
                    _slipped.Remove(uid);
                    Dirty();
                    continue;
                }

                if (!_slipped.Contains(uid))
                    TrySlip(physics, otherPhysics);
            }
        }

        public override ComponentState GetComponentState(ICommonSession player)
        {
            return new SlipperyComponentState(ParalyzeTime, IntersectPercentage, RequiredSlipSpeed, LaunchForwardsMultiplier, Slippery, SlipSound, _slipped.ToArray());
        }

        public override void HandleComponentState(ComponentState? curState, ComponentState? nextState)
        {
            if (curState is not SlipperyComponentState state) return;

            _slippery = state.Slippery;
            _intersectPercentage = state.IntersectPercentage;
            _paralyzeTime = state.ParalyzeTime;
            _requiredSlipSpeed = state.RequiredSlipSpeed;
            _launchForwardsMultiplier = state.LaunchForwardsMultiplier;
            _slipSound = state.SlipSound;
            _slipped.Clear();

            foreach (var slipped in state.Slipped)
            {
                _slipped.Add(slipped);
            }
        }
    }

    [Serializable, NetSerializable]
    public class SlipperyComponentState : ComponentState
    {
        public float ParalyzeTime { get; }
        public float IntersectPercentage { get; }
        public float RequiredSlipSpeed { get; }
        public float LaunchForwardsMultiplier { get; }
        public bool Slippery { get; }
        public string SlipSound { get; }
        public readonly EntityUid[] Slipped;

        public SlipperyComponentState(float paralyzeTime, float intersectPercentage, float requiredSlipSpeed, float launchForwardsMultiplier, bool slippery, string slipSound, EntityUid[] slipped) : base(ContentNetIDs.SLIP)
        {
            ParalyzeTime = paralyzeTime;
            IntersectPercentage = intersectPercentage;
            RequiredSlipSpeed = requiredSlipSpeed;
            LaunchForwardsMultiplier = launchForwardsMultiplier;
            Slippery = slippery;
            SlipSound = slipSound;
            Slipped = slipped;
        }
    }
}