Layering for atmospheric pipes (#36124)

Co-authored-by: ArtisticRoomba <145879011+ArtisticRoomba@users.noreply.github.com>
Co-authored-by: Kevin Zheng <kevinz5000@gmail.com>

Content.Shared/Atmos/Components/AtmosPipeLayersComponent.cs

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+using Content.Shared.Atmos.EntitySystems;
+using Content.Shared.DoAfter;
+using Content.Shared.Tools;
+using Robust.Shared.GameStates;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Atmos.Components;
+
+/// <summary>
+/// Contains layer data for atmos pipes. Layers allow multiple atmos pipes with the
+/// same orientation to be anchored to the same tile without their contents mixing.
+/// </summary>
+[RegisterComponent, NetworkedComponent, AutoGenerateComponentState]
+[Access(typeof(SharedAtmosPipeLayersSystem))]
+public sealed partial class AtmosPipeLayersComponent : Component
+{
+    /// <summary>
+    /// The number of pipe layers this entity supports.
+    /// Must be equal to or less than the number of values
+    /// in <see cref="AtmosPipeLayer"/>.
+    /// </summary>
+    [DataField]
+    public byte NumberOfPipeLayers = 3;
+
+    /// <summary>
+    /// Determines which layer the pipe is currently assigned.
+    /// Only pipes on the same layer can connect with each other.
+    /// </summary>
+    [DataField("pipeLayer"), AutoNetworkedField]
+    [ViewVariables(VVAccess.ReadOnly)]
+    public AtmosPipeLayer CurrentPipeLayer = AtmosPipeLayer.Primary;
+
+    /// <summary>
+    /// The RSI paths that the entity will use to update its sprite when its pipe layer changes;
+    /// if empty, the entity sprite will not update when it pipe layer changes.
+    /// If you want to set specific sprite layers to update when the pipe layer changes, use
+    /// <see cref="SpriteLayersRsiPaths"/> instead.
+    /// </summary>
+    /// <remarks>
+    /// If the dictionary is not empty there should be an entry for each atmos pipe layer.
+    /// </remarks>
+    [DataField]
+    public Dictionary<AtmosPipeLayer, string> SpriteRsiPaths = new();
+
+    /// <summary>
+    /// Used to update specific sprite layers when the entity's pipe layer changes.
+    /// The dictionary key is the name of the sprite layer to be updated, and its value is
+    /// a second dictionary which contains the RSI paths indexed by pipe layer.
+    /// If you want to change the default RSI path used by the entity, use
+    /// <see cref="SpriteRsiPaths"/> instead.
+    /// </summary>
+    /// <remarks>
+    /// If an dictionary is not empty there should be an entry for each pipe layer.
+    /// </remarks>
+    [DataField]
+    public Dictionary<string, Dictionary<AtmosPipeLayer, string>> SpriteLayersRsiPaths = new();
+
+    /// <summary>
+    /// Entity prototypes that will be used to replace the current one when using
+    /// position dependent entity placement via AlignAtmosPipeLayers.
+    /// </summary>
+    /// <remarks>
+    /// If the dictionary is not empty there should be an entry for each atmos pipe layer.
+    /// </remarks>
+    [DataField]
+    public Dictionary<AtmosPipeLayer, EntProtoId> AlternativePrototypes = new();
+
+    /// <summary>
+    /// The pipe layers of this entity cannot be changed when this value is true.
+    /// </summary>
+    [DataField]
+    public bool PipeLayersLocked;
+
+    /// <summary>
+    /// Tool quality required to cause a pipe to change layers
+    /// </summary>
+    [DataField]
+    public ProtoId<ToolQualityPrototype> Tool = "Screwing";
+
+    /// <summary>
+    /// The base delay to use for changing layers.
+    /// </summary>
+    [DataField]
+    public float Delay = 1f;
+}
+
+/// <summary>
+/// Raised when a player attempts to cycle a pipe to its next layer
+/// </summary>
+[Serializable, NetSerializable]
+public sealed partial class TrySetNextPipeLayerCompletedEvent : SimpleDoAfterEvent;
+
+/// <summary>
+/// Raised when a player attempts to set a pipe a specified layer
+/// </summary>
+[Serializable, NetSerializable]
+public sealed partial class TrySettingPipeLayerCompletedEvent : SimpleDoAfterEvent
+{
+    public AtmosPipeLayer PipeLayer;
+
+    public TrySettingPipeLayerCompletedEvent(AtmosPipeLayer pipeLayer)
+    {
+        PipeLayer = pipeLayer;
+    }
+}
+
+[Serializable, NetSerializable]
+public enum AtmosPipeLayerVisuals
+{
+    Sprite,
+    SpriteLayers,
+    DrawDepth,
+}
+
+[Serializable, NetSerializable]
+public enum AtmosPipeLayer
+{
+    Primary,
+    Secondary,
+    Tertiary,
+}