Refactor Carpet's sticky blocks code (#1505)

refactor sticky blocks code

src/main/java/carpet/mixins/PistonStructureResolver_customStickyMixin.java

@@ -0,0 +1,94 @@
+package carpet.mixins;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.Redirect;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+import org.spongepowered.asm.mixin.injection.callback.LocalCapture;
+
+import carpet.fakes.BlockBehaviourInterface;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.piston.PistonStructureResolver;
+import net.minecraft.world.level.block.state.BlockState;
+
+@Mixin(PistonStructureResolver.class)
+public class PistonStructureResolver_customStickyMixin {
+
+    @Shadow @Final private Level level;
+    @Shadow @Final private Direction pushDirection;
+
+    @Inject(
+        method = "isSticky",
+        cancellable = true,
+        at = @At(
+            value = "HEAD"
+        )
+    )
+    private static void isSticky(BlockState state, CallbackInfoReturnable<Boolean> cir) {
+        cir.setReturnValue(((BlockBehaviourInterface)state.getBlock()).isSticky(state));
+    }
+
+    // fields that are needed because @Redirects cannot capture locals
+    private BlockPos pos_addBlockLine;
+    private BlockPos behindPos_addBlockLine;
+
+    @Inject(
+        method = "addBlockLine",
+        locals = LocalCapture.CAPTURE_FAILHARD,
+        at = @At(
+            value = "INVOKE",
+            ordinal = 1,
+            target = "Lnet/minecraft/world/level/Level;getBlockState(Lnet/minecraft/core/BlockPos;)Lnet/minecraft/world/level/block/state/BlockState;"
+        )
+    )
+    private void captureBlockLinePositions(BlockPos pos, Direction fromDir, CallbackInfoReturnable<Boolean> cir, BlockState state, int dst, BlockPos behindPos) {
+        pos_addBlockLine = behindPos.relative(pushDirection);
+        behindPos_addBlockLine = behindPos;
+    }
+
+    @Redirect(
+        method = "addBlockLine",
+        at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/world/level/block/piston/PistonStructureResolver;canStickToEachOther(Lnet/minecraft/world/level/block/state/BlockState;Lnet/minecraft/world/level/block/state/BlockState;)Z"
+        )
+    )
+    private boolean onAddBlockLineCanStickToEachOther(BlockState state, BlockState behindState) {
+        return ((BlockBehaviourInterface)state.getBlock()).isStickyToNeighbor(level, pos_addBlockLine, state, behindPos_addBlockLine, behindState, pushDirection.getOpposite(), pushDirection);
+    }
+
+    // fields that are needed because @Redirects cannot capture locals
+    private Direction dir_addBranchingBlocks;
+    private BlockPos neighborPos_addBranchingBlocks;
+
+    @Inject(
+        method = "addBranchingBlocks",
+        locals = LocalCapture.CAPTURE_FAILHARD,
+        at = @At(
+            value = "INVOKE",
+            ordinal = 1,
+            target = "Lnet/minecraft/world/level/Level;getBlockState(Lnet/minecraft/core/BlockPos;)Lnet/minecraft/world/level/block/state/BlockState;"
+        )
+    )
+    private void captureNeighborPositions(BlockPos pos, CallbackInfoReturnable<Boolean> cir, BlockState state, Direction[] dirs, int i, int j, Direction dir, BlockPos neighborPos) {
+        dir_addBranchingBlocks = dir;
+        neighborPos_addBranchingBlocks = neighborPos;
+    }
+
+    @Redirect(
+        method = "addBranchingBlocks",
+        at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/world/level/block/piston/PistonStructureResolver;canStickToEachOther(Lnet/minecraft/world/level/block/state/BlockState;Lnet/minecraft/world/level/block/state/BlockState;)Z"
+        )
+    )
+    private boolean onAddBranchingBlocksCanStickToEachOther(BlockState neighborState, BlockState state, BlockPos pos) {
+        return ((BlockBehaviourInterface)state.getBlock()).isStickyToNeighbor(level, pos, state, neighborPos_addBranchingBlocks, neighborState, dir_addBranchingBlocks, pushDirection);
+    }
+}