Fix composter inventory when using 'Useful Hoppers'

src/main/java/skyblock/mixin/ComposterBlockMixin.java

@@ -5,9 +5,15 @@
 import net.minecraft.block.Blocks;
 import net.minecraft.block.ComposterBlock;
 import net.minecraft.entity.ItemEntity;
+import net.minecraft.inventory.SidedInventory;
+import net.minecraft.inventory.SimpleInventory;
+import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.Direction;
 import net.minecraft.world.World;
+import net.minecraft.world.WorldAccess;
+import org.jetbrains.annotations.Nullable;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -22,24 +28,81 @@
 @Mixin(ComposterBlock.class)
 public class ComposterBlockMixin {
     // Maybe this should have Gravel, Mycelium, Podzol etc
-    private final static List<Block> possibleSurfaceDrops = new ArrayList<>(Arrays.asList(Blocks.SAND, Blocks.RED_SAND, Blocks.DIRT));
+    private static final List<Block> possibleSurfaceDrops = new ArrayList<>(Arrays.asList(Blocks.SAND, Blocks.RED_SAND, Blocks.DIRT));
+
+    private static Item getComposterDrop(WorldAccess world, BlockPos pos) {
+        Block dropBlock = Blocks.DIRT;
+
+        Block surfaceBlock = world.getBiome(pos).getGenerationSettings().getSurfaceConfig().getTopMaterial().getBlock();
+        if (possibleSurfaceDrops.contains(surfaceBlock)) {
+            dropBlock = surfaceBlock;
+        }
+
+        return dropBlock.asItem();
+    }
+
+    // Provides a simple, single-item inventory for the full composter. Used in place of the private subclass
+    private static class FullComposterInventory extends SimpleInventory implements SidedInventory {
+        private final BlockState state;
+        private final WorldAccess world;
+        private final BlockPos pos;
+        private boolean dirty;
+
+        public FullComposterInventory(BlockState state, WorldAccess world, BlockPos pos) {
+            super(new ItemStack(getComposterDrop(world, pos)));
+            this.state = state;
+            this.world = world;
+            this.pos = pos;
+        }
+
+        public int getMaxCountPerStack() {
+            return 1;
+        }
+
+        public int[] getAvailableSlots(Direction side) {
+            return side == Direction.DOWN ? new int[]{0} : new int[0];
+        }
+
+        public boolean canInsert(int slot, ItemStack stack, @Nullable Direction dir) {
+            return false;
+        }
+
+        public boolean canExtract(int slot, ItemStack stack, Direction dir) {
+            return !this.dirty && dir == Direction.DOWN && stack.getItem() == getComposterDrop(world, pos);
+        }
+
+        public void markDirty() {
+            emptyComposter(this.state, this.world, this.pos);
+            this.dirty = true;
+        }
+    }
+
+    private static void emptyComposter(BlockState state, WorldAccess world, BlockPos pos) {
+        BlockState blockState = state.with(ComposterBlock.LEVEL, 0);
+        world.setBlockState(pos, blockState, 3);
+    }
+
 
     @Inject(method = "emptyFullComposter", locals = LocalCapture.CAPTURE_FAILSOFT, at=@At(
-            value = "INVOKE",
-            target = "Lnet/minecraft/entity/ItemEntity;setToDefaultPickupDelay()V",
-            shift = At.Shift.BEFORE
+        value = "INVOKE",
+        target = "Lnet/minecraft/entity/ItemEntity;setToDefaultPickupDelay()V",
+        shift = At.Shift.BEFORE
     ))
     @SuppressWarnings("unused")
     private static void setComposterOutput(BlockState arg0, World world, BlockPos pos, CallbackInfoReturnable<BlockState> cir, float f, double d, double e, double g, ItemEntity dropItemEntity) {
         if (SkyBlockSettings.usefulComposters) {
-            Block dropBlock = Blocks.DIRT;
-
-            Block surfaceBlock = world.getBiome(pos).getGenerationSettings().getSurfaceConfig().getTopMaterial().getBlock();
-            if (possibleSurfaceDrops.contains(surfaceBlock)) {
-                dropBlock = surfaceBlock;
-            }
+            dropItemEntity.setStack(new ItemStack(getComposterDrop(world, pos)));
+        }
+    }
 
-            dropItemEntity.setStack(new ItemStack(dropBlock));
+    @Inject(method = "getInventory", locals = LocalCapture.CAPTURE_FAILSOFT, cancellable = true, at=@At(
+            value = "RETURN",
+            ordinal = 0
+    ))
+    @SuppressWarnings("unused")
+    private void setInventory(BlockState state, WorldAccess world, BlockPos pos, CallbackInfoReturnable<SidedInventory> cir) {
+        if (SkyBlockSettings.usefulComposters) {
+            cir.setReturnValue(new FullComposterInventory(state, world, pos));
         }
     }
 }