Add GT_MetaTileEntity_CubicMultiBlockBase and a few minor changes

1. add ofCoil() IStructureElement to standardise how to add a homogeneous set of coils to the structure definition
2. Changed newMetaEntity's return type back to IMetaTileEntity to prevent addons crying out
3. Initialize mExtendedFacing to ensure rendering code don't step on null

2 files changed, 113 insertions, 7 deletions

diff --git a/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_CubicMultiBlockBase.java b/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_CubicMultiBlockBase.java
new file mode 100644
index 0000000000..ef53c1bca2
--- /dev/null
+++ b/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_CubicMultiBlockBase.java
@@ -0,0 +1,111 @@
+package gregtech.api.metatileentity.implementations;
+
+import com.gtnewhorizon.structurelib.structure.IStructureDefinition;
+import com.gtnewhorizon.structurelib.structure.IStructureElement;
+import com.gtnewhorizon.structurelib.structure.StructureDefinition;
+import gregtech.api.interfaces.tileentity.IGregTechTileEntity;
+import net.minecraft.item.ItemStack;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import static com.gtnewhorizon.structurelib.structure.StructureUtility.ofChain;
+import static com.gtnewhorizon.structurelib.structure.StructureUtility.onElementPass;
+import static com.gtnewhorizon.structurelib.structure.StructureUtility.transpose;
+import static gregtech.api.util.GT_StructureUtility.ofHatchAdder;
+
+/**
+ * A simple 3x3x3 hollow cubic multiblock, that can be arbitrarily rotated, made of a single type of machine casing and accepts hatches everywhere.
+ * Controller will be placed in front center of the structure.
+ * <p>
+ * Note: You cannot use different casing for the same Class. Make a new subclass for it.
+ * <p>
+ * Implementation tips:
+ * 1. To restrict hatches, override {@link #addDynamoToMachineList(IGregTechTileEntity, int)} and its cousins instead of overriding the whole
+ * {@link #getStructureDefinition()} or change {@link #checkHatches(IGregTechTileEntity, ItemStack)}. The former is a total overkill, while the later cannot
+ * stop the structure check early.
+ * 2. To limit rotation, override {@link #getInitialAlignmentLimits()}
+ *
+ * @param <T>
+ */
+public abstract class GT_MetaTileEntity_CubicMultiBlockBase<T extends GT_MetaTileEntity_CubicMultiBlockBase<T>> extends GT_MetaTileEntity_EnhancedMultiBlockBase<T> {
+	protected static final String STRUCTURE_PIECE_MAIN = "main";
+	private static final ConcurrentMap<Integer, IStructureDefinition<?>> STRUCTURE_DEFINITIONS = new ConcurrentHashMap<>();
+	private int mCasingAmount = 0;
+
+	protected GT_MetaTileEntity_CubicMultiBlockBase(int aID, String aName, String aNameRegional) {
+		super(aID, aName, aNameRegional);
+	}
+
+	protected GT_MetaTileEntity_CubicMultiBlockBase(String aName) {
+		super(aName);
+	}
+
+
+	private static IStructureDefinition<? extends GT_MetaTileEntity_CubicMultiBlockBase<?>> createStructure(GT_MetaTileEntity_CubicMultiBlockBase<?> aTile) {
+		return StructureDefinition.<GT_MetaTileEntity_CubicMultiBlockBase<?>>builder()
+				.addShape(STRUCTURE_PIECE_MAIN, transpose(new String[][]{
+						{"hhh", "hhh", "hhh"},
+						{"h-h", "hhh", "hhh"},
+						{"hhh", "hhh", "hhh"},
+				}))
+				.addElement('h', ofChain(
+						ofHatchAdder(GT_MetaTileEntity_CubicMultiBlockBase::addToMachineList, aTile.getHatchTextureIndex(), 1),
+						onElementPass(
+								GT_MetaTileEntity_CubicMultiBlockBase::onCorrectCasingAdded,
+								aTile.getCasingElement()
+						)
+				))
+				.build();
+	}
+
+	/**
+	 * Create a simple 3x3x3 hollow cubic structure made of a single type of machine casing and accepts hatches everywhere.
+	 * <p>
+	 * The created definition contains a single piece named {@link #STRUCTURE_PIECE_MAIN}.
+	 */
+	@Override
+	@SuppressWarnings("unchecked")
+	public IStructureDefinition<T> getStructureDefinition() {
+		return (IStructureDefinition<T>) STRUCTURE_DEFINITIONS.computeIfAbsent(getBaseMetaTileEntity().getMetaTileID(), o -> createStructure(this));
+	}
+
+	@Override
+	public void construct(ItemStack aStack, boolean aHintsOnly) {
+		buildPiece(STRUCTURE_PIECE_MAIN, aStack, aHintsOnly, 1, 1, 0);
+	}
+
+	@Override
+	public boolean checkMachine(IGregTechTileEntity aBaseMetaTileEntity, ItemStack aStack) {
+		mCasingAmount = 0;
+		return checkPiece(STRUCTURE_PIECE_MAIN, 1, 1, 0) &&
+				mCasingAmount > getRequiredCasingCount() &&
+				checkHatches(aBaseMetaTileEntity, aStack);
+	}
+
+	/**
+	 * Called by {@link #checkMachine(IGregTechTileEntity, ItemStack)} to check if all required hatches are present.
+	 * <p>
+	 * Default implementation requires EXACTLY ONE maintenance hatch to be present, and ignore all other conditions.
+	 *
+	 * @param aBaseMetaTileEntity the tile entity of self
+	 * @param aStack              The item stack inside the controller
+	 * @return true if the test passes, false otherwise
+	 */
+	protected boolean checkHatches(IGregTechTileEntity aBaseMetaTileEntity, ItemStack aStack) {
+		return mMaintenanceHatches.size() == 1;
+	}
+
+	protected abstract IStructureElement<GT_MetaTileEntity_CubicMultiBlockBase<?>> getCasingElement();
+
+	/**
+	 * The hatch's texture index.
+	 */
+	protected abstract int getHatchTextureIndex();
+
+	protected abstract int getRequiredCasingCount();
+
+	protected void onCorrectCasingAdded() {
+		mCasingAmount++;
+	}
+}
diff --git a/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_EnhancedMultiBlockBase.java b/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_EnhancedMultiBlockBase.java
index c3d41664b7..89d2ce765e 100644
--- a/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_EnhancedMultiBlockBase.java
+++ b/src/main/java/gregtech/api/metatileentity/implementations/GT_MetaTileEntity_EnhancedMultiBlockBase.java
@@ -30,17 +30,15 @@ import java.util.concurrent.atomic.AtomicReferenceArray;
  */
 public abstract class GT_MetaTileEntity_EnhancedMultiBlockBase<T extends GT_MetaTileEntity_EnhancedMultiBlockBase<T>> extends GT_MetaTileEntity_MultiBlockBase implements IAlignment, IConstructable {
 	private static final AtomicReferenceArray<GT_Multiblock_Tooltip_Builder> tooltips = new AtomicReferenceArray<>(GregTech_API.METATILEENTITIES.length);
-	private ExtendedFacing mExtendedFacing;
-	private final IAlignmentLimits mLimits;
+	private ExtendedFacing mExtendedFacing = ExtendedFacing.DEFAULT;
+	private final IAlignmentLimits mLimits = getInitialAlignmentLimits();
 
 	protected GT_MetaTileEntity_EnhancedMultiBlockBase(int aID, String aName, String aNameRegional) {
 		super(aID, aName, aNameRegional);
-		mLimits = getInitialAlignmentLimits();
 	}
 
 	protected GT_MetaTileEntity_EnhancedMultiBlockBase(String aName) {
 		super(aName);
-		mLimits = getInitialAlignmentLimits();
 	}
 
 	@Override
@@ -128,9 +126,6 @@ public abstract class GT_MetaTileEntity_EnhancedMultiBlockBase<T extends GT_Meta
 				Flip.byIndex(aNBT.getByte("mFlip")));
 	}
 
-	@Override
-	public abstract GT_MetaTileEntity_EnhancedMultiBlockBase<T> newMetaEntity(IGregTechTileEntity aTileEntity);
-
 	@SuppressWarnings("unchecked")
 	private IStructureDefinition<GT_MetaTileEntity_EnhancedMultiBlockBase<T>> getCastedStructureDefinition() {
 		return (IStructureDefinition<GT_MetaTileEntity_EnhancedMultiBlockBase<T>>) getStructureDefinition();