tbd-station-14/Content.Server/Fluids/EntitySystems/SmokeSystem.cs

using System.Linq;
using Content.Server.Chemistry.Components;
using Content.Server.Chemistry.EntitySystems;
using Content.Server.Chemistry.ReactionEffects;
using Content.Server.Spreader;
using Content.Shared.Chemistry.Components;
using Content.Shared.Chemistry.Reaction;
using Content.Shared.FixedPoint;
using Content.Shared.Smoking;
using Robust.Server.GameObjects;
using Robust.Shared.Map;
using Robust.Shared.Prototypes;
using Robust.Shared.Random;
using Robust.Shared.Spawners;
using Robust.Shared.Timing;
using TimedDespawnComponent = Robust.Shared.Spawners.TimedDespawnComponent;

namespace Content.Server.Fluids.EntitySystems;

/// <summary>
/// Handles non-atmos solution entities similar to puddles.
/// </summary>
public sealed class SmokeSystem : EntitySystem
{
    // If I could do it all again this could probably use a lot more of puddles.
    [Dependency] private readonly IGameTiming _timing = default!;
    [Dependency] private readonly IMapManager _mapManager = default!;
    [Dependency] private readonly IPrototypeManager _prototype = default!;
    [Dependency] private readonly AppearanceSystem _appearance = default!;
    [Dependency] private readonly EntityLookupSystem _lookup = default!;
    [Dependency] private readonly SolutionContainerSystem _solutionSystem = default!;
    [Dependency] private readonly IRobustRandom _random = default!;

    /// <inheritdoc/>
    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<SmokeComponent, EntityUnpausedEvent>(OnSmokeUnpaused);
        SubscribeLocalEvent<SmokeComponent, ReactionAttemptEvent>(OnReactionAttempt);
        SubscribeLocalEvent<SmokeComponent, SpreadNeighborsEvent>(OnSmokeSpread);
    }

    private void OnSmokeSpread(EntityUid uid, SmokeComponent component, ref SpreadNeighborsEvent args)
    {
        if (component.SpreadAmount == 0
            || !_solutionSystem.TryGetSolution(uid, SmokeComponent.SolutionName, out var solution))
        {
            RemCompDeferred<ActiveEdgeSpreaderComponent>(uid);
            return;
        }

        var prototype = MetaData(uid).EntityPrototype;

        if (prototype == null)
        {
            RemCompDeferred<ActiveEdgeSpreaderComponent>(uid);
            return;
        }

        TryComp<TimedDespawnComponent>(uid, out var timer);
        _appearance.TryGetData(uid, SmokeVisuals.Color, out var color);

        // wtf is the logic behind any of this.
        var smokePerSpread = 1 + component.SpreadAmount / Math.Max(1, args.NeighborFreeTiles.Count);
        foreach (var neighbor in args.NeighborFreeTiles)
        {
            var coords = neighbor.Grid.GridTileToLocal(neighbor.Tile);
            var ent = Spawn(prototype.ID, coords);
            var neighborSmoke = EnsureComp<SmokeComponent>(ent);
            neighborSmoke.SpreadAmount = Math.Max(0, smokePerSpread - 2); // why - 2? who the fuck knows.
            component.SpreadAmount--;
            args.Updates--;

            // Listen this is the old behaviour iunno
            Start(ent, neighborSmoke, solution.Clone(), timer?.Lifetime ?? 10f);

            if (color != null)
                _appearance.SetData(ent, SmokeVisuals.Color, color);

            if (component.SpreadAmount == 0)
            {
                RemCompDeferred<ActiveEdgeSpreaderComponent>(uid);
                break;
            }

            if (args.Updates <= 0)
                break;
        }

        if (args.NeighborFreeTiles.Count > 0 || args.Neighbors.Count == 0 || component.SpreadAmount < 1)
            return;

        // We have no more neighbours to spread to. So instead we will randomly distribute our volume to neighbouring smoke tiles.

        var smokeQuery = GetEntityQuery<SmokeComponent>();

        _random.Shuffle(args.Neighbors);
        foreach (var neighbor in args.Neighbors)
        {
            if (!smokeQuery.TryGetComponent(neighbor, out var smoke))
                continue;

            smoke.SpreadAmount++;
            args.Updates--;
            component.SpreadAmount--;
            EnsureComp<ActiveEdgeSpreaderComponent>(neighbor);

            if (component.SpreadAmount == 0)
            {
                RemCompDeferred<ActiveEdgeSpreaderComponent>(uid);
                break;
            }
        }
    }

    private void OnReactionAttempt(EntityUid uid, SmokeComponent component, ReactionAttemptEvent args)
    {
        if (args.Solution.Name != SmokeComponent.SolutionName)
            return;

        // Prevent smoke/foam fork bombs (smoke creating more smoke).
        foreach (var effect in args.Reaction.Effects)
        {
            if (effect is AreaReactionEffect)
            {
                args.Cancel();
                return;
            }
        }
    }

    private void OnSmokeUnpaused(EntityUid uid, SmokeComponent component, ref EntityUnpausedEvent args)
    {
        component.NextReact += args.PausedTime;
    }

    /// <inheritdoc/>
    public override void Update(float frameTime)
    {
        base.Update(frameTime);
        var query = EntityQueryEnumerator<SmokeComponent>();
        var curTime = _timing.CurTime;

        while (query.MoveNext(out var uid, out var smoke))
        {
            if (smoke.NextReact > curTime)
                continue;

            smoke.NextReact += TimeSpan.FromSeconds(1.5);

            SmokeReact(uid, 1f, smoke);
        }
    }

    /// <summary>
    /// Does the relevant smoke reactions for an entity for the specified exposure duration.
    /// </summary>
    public void SmokeReact(EntityUid uid, float frameTime, SmokeComponent? component = null, TransformComponent? xform = null)
    {
        if (!Resolve(uid, ref component, ref xform))
            return;

        if (!_solutionSystem.TryGetSolution(uid, SmokeComponent.SolutionName, out var solution) ||
            solution.Contents.Count == 0)
        {
            return;
        }

        if (!_mapManager.TryGetGrid(xform.GridUid, out var mapGrid))
            return;

        var tile = mapGrid.GetTileRef(xform.Coordinates.ToVector2i(EntityManager, _mapManager));

        var solutionFraction = 1 / Math.Floor(frameTime);
        var ents = _lookup.GetEntitiesIntersecting(tile, 0f, flags: LookupFlags.Uncontained).ToArray();

        foreach (var reagentQuantity in solution.Contents.ToArray())
        {
            if (reagentQuantity.Quantity == FixedPoint2.Zero)
                continue;

            // NOOP, react with entities on the tile or whatever.
        }

        foreach (var entity in ents)
        {
            if (entity == uid)
                continue;

            ReactWithEntity(entity, solution, solutionFraction);
        }

        UpdateVisuals(uid);
    }

    private void UpdateVisuals(EntityUid uid)
    {
        if (TryComp(uid, out AppearanceComponent? appearance) &&
            _solutionSystem.TryGetSolution(uid, SmokeComponent.SolutionName, out var solution))
        {
            var color = solution.GetColor(_prototype);
            _appearance.SetData(uid, SmokeVisuals.Color, color, appearance);
        }
    }

    private void ReactWithEntity(EntityUid entity, Solution solution, double solutionFraction)
    {
        // NOOP due to people complaining constantly.
        return;
    }

    /// <summary>
    /// Sets up a smoke component for spreading.
    /// </summary>
    public void Start(EntityUid uid, SmokeComponent component, Solution solution, float duration)
    {
        TryAddSolution(uid, component, solution);
        EnsureComp<ActiveEdgeSpreaderComponent>(uid);
        var timer = EnsureComp<TimedDespawnComponent>(uid);
        timer.Lifetime = duration;
    }

    /// <summary>
    /// Adds the specified solution to the relevant smoke solution.
    /// </summary>
    public void TryAddSolution(EntityUid uid, SmokeComponent component, Solution solution)
    {
        if (solution.Volume == FixedPoint2.Zero)
            return;

        if (!_solutionSystem.TryGetSolution(uid, SmokeComponent.SolutionName, out var solutionArea))
            return;

        var addSolution =
            solution.SplitSolution(FixedPoint2.Min(solution.Volume, solutionArea.AvailableVolume));

        _solutionSystem.TryAddSolution(uid, solutionArea, addSolution);

        UpdateVisuals(uid);
    }
}