tbd-station-14/Content.Server/Body/Systems/LungSystem.cs

using Content.Server.Atmos.Components;
using Content.Server.Atmos.EntitySystems;
using Content.Server.Body.Components;
using Content.Server.Chemistry.Containers.EntitySystems;
using Content.Shared.Atmos;
using Content.Shared.Clothing;
using Content.Shared.Inventory.Events;

namespace Content.Server.Body.Systems;

public sealed class LungSystem : EntitySystem
{
    [Dependency] private readonly AtmosphereSystem _atmos = default!;
    [Dependency] private readonly InternalsSystem _internals = default!;
    [Dependency] private readonly SolutionContainerSystem _solutionContainerSystem = default!;
    [Dependency] private readonly AtmosphereSystem _atmosphereSystem = default!;

    public static string LungSolutionName = "Lung";

    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<LungComponent, ComponentInit>(OnComponentInit);
        SubscribeLocalEvent<BreathToolComponent, GotEquippedEvent>(OnGotEquipped);
        SubscribeLocalEvent<BreathToolComponent, GotUnequippedEvent>(OnGotUnequipped);
        SubscribeLocalEvent<BreathToolComponent, ItemMaskToggledEvent>(OnMaskToggled);
    }

    private void OnGotUnequipped(Entity<BreathToolComponent> ent, ref GotUnequippedEvent args)
    {
        _atmosphereSystem.DisconnectInternals(ent);
    }

    private void OnGotEquipped(Entity<BreathToolComponent> ent, ref GotEquippedEvent args)
    {
        if ((args.SlotFlags & ent.Comp.AllowedSlots) == 0)
        {
            return;
        }

        ent.Comp.IsFunctional = true;

        if (TryComp(args.Equipee, out InternalsComponent? internals))
        {
            ent.Comp.ConnectedInternalsEntity = args.Equipee;
            _internals.ConnectBreathTool((args.Equipee, internals), ent);
        }
    }

    private void OnComponentInit(Entity<LungComponent> entity, ref ComponentInit args)
    {
        var solution = _solutionContainerSystem.EnsureSolution(entity.Owner, entity.Comp.SolutionName);
        solution.MaxVolume = 100.0f;
        solution.CanReact = false; // No dexalin lungs
    }

    private void OnMaskToggled(Entity<BreathToolComponent> ent, ref ItemMaskToggledEvent args)
    {
        if (args.IsToggled || args.IsEquip)
        {
            _atmos.DisconnectInternals(ent.Comp);
        }
        else
        {
            ent.Comp.IsFunctional = true;

            if (TryComp(args.Wearer, out InternalsComponent? internals))
            {
                ent.Comp.ConnectedInternalsEntity = args.Wearer;
                _internals.ConnectBreathTool((args.Wearer, internals), ent);
            }
        }
    }

    public void GasToReagent(EntityUid uid, LungComponent lung)
    {
        if (!_solutionContainerSystem.ResolveSolution(uid, lung.SolutionName, ref lung.Solution, out var solution))
            return;

        foreach (var gas in Enum.GetValues<Gas>())
        {
            var i = (int) gas;
            var moles = lung.Air[i];
            if (moles <= 0)
                continue;
            var reagent = _atmosphereSystem.GasReagents[i];
            if (reagent is null) continue;

            var amount = moles * Atmospherics.BreathMolesToReagentMultiplier;
            solution.AddReagent(reagent, amount);

            // We don't remove the gas from the lung mix,
            // that's the responsibility of whatever gas is being metabolized.
            // Most things will just want to exhale again.
        }

        _solutionContainerSystem.UpdateChemicals(lung.Solution.Value);
    }
}