5 files changed, 154 insertions, 0 deletions
diff --git a/src/main/java/com/notnite/gloppers/mixin/HopperBlockEntityMixin.java b/src/main/java/com/notnite/gloppers/mixin/HopperBlockEntityMixin.java
new file mode 100644
index 0000000..78468ac
--- /dev/null
+++ b/src/main/java/com/notnite/gloppers/mixin/HopperBlockEntityMixin.java
@@ -0,0 +1,65 @@
+package com.notnite.gloppers.mixin;
+
+import com.notnite.gloppers.Gloppers;
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+import net.minecraft.block.entity.Hopper;
+import net.minecraft.block.entity.HopperBlockEntity;
+import net.minecraft.inventory.Inventory;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.math.Direction;
+import org.spongepowered.asm.mixin.Mixin;
+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;
+
+@Environment(EnvType.SERVER)
+@Mixin(HopperBlockEntity.class)
+public class HopperBlockEntityMixin {
+    private static int dirtySlotState = 0;
+
+    // We can't decrement the item stack before it gets passed to transfer, because we may not be allowed to transfer,
+    // eating an item. We know removeStack will get called immediately before transfer, so while it's messy, we can use
+    // a static variable to keep track of what slot we're removing from.
+    @Redirect(
+        method = "insert",
+        at = @At(value = "INVOKE", target = "Lnet/minecraft/inventory/Inventory;removeStack(II)Lnet/minecraft/item/ItemStack;")
+    )
+    private static ItemStack insert$gloppersRemoveStack(Inventory instance, int slot, int amount) {
+        dirtySlotState = slot;
+        return instance.getStack(slot);
+    }
+
+    // This works by mixing into the call of HopperBlockEntity::transfer and returning a stubbed item stack if it's not
+    // allowed to transfer. I wanted to instead insert a continue statement into the for loop, but I couldn't figure out
+    // a good way to do that.
+    @Redirect(
+        method = "insert",
+        at = @At(value = "INVOKE", target = "Lnet/minecraft/block/entity/HopperBlockEntity;transfer(Lnet/minecraft/inventory/Inventory;Lnet/minecraft/inventory/Inventory;Lnet/minecraft/item/ItemStack;Lnet/minecraft/util/math/Direction;)Lnet/minecraft/item/ItemStack;")
+    )
+    private static ItemStack insert$gloppersTransfer(
+        Inventory from, Inventory to, ItemStack stack, Direction side
+    ) {
+        if (!Gloppers.INSTANCE.canTransfer(to, stack)) {
+            // The return value of this is only used to check if it's empty, and if so, returns that it succeeded.
+            // We can just return the item stack we were given, as we didn't remove from it.
+            return stack;
+        }
+
+        // Make sure to remove the item here, because we didn't in the actual call.
+        return HopperBlockEntity.transfer(from, to, from.removeStack(dirtySlotState, 1), side);
+    }
+
+    // This handles the case where a hopper extracts from a hopper above it (such as two anvils facing forward, stacked
+    // on top of one another).
+    @Inject(
+        method = "extract(Lnet/minecraft/block/entity/Hopper;Lnet/minecraft/inventory/Inventory;ILnet/minecraft/util/math/Direction;)Z",
+        at = @At("HEAD"),
+        cancellable = true
+    )
+    private static void extract(Hopper hopper, Inventory inventory, int slot, Direction side, CallbackInfoReturnable<Boolean> cir) {
+        var item = inventory.getStack(slot);
+        if (!Gloppers.INSTANCE.canTransfer(hopper, item)) cir.setReturnValue(false);
+    }
+}
diff --git a/src/main/kotlin/com/notnite/gloppers/Gloppers.kt b/src/main/kotlin/com/notnite/gloppers/Gloppers.kt
new file mode 100644
index 0000000..bdea779
--- /dev/null
+++ b/src/main/kotlin/com/notnite/gloppers/Gloppers.kt
@@ -0,0 +1,41 @@
+package com.notnite.gloppers
+
+import net.fabricmc.api.DedicatedServerModInitializer
+import net.minecraft.block.entity.HopperBlockEntity
+import net.minecraft.inventory.Inventory
+import net.minecraft.item.ItemStack
+
+object Gloppers : DedicatedServerModInitializer {
+    override fun onInitializeServer() {}
+
+    private fun matchesGlob(glob: String, str: String): Boolean {
+        val regex = glob
+            .replace(".", "\\.")
+            .replace("*", ".*")
+            .replace("?", ".")
+        return str.matches(regex.toRegex())
+    }
+
+    fun canTransfer(to: Inventory, stack: ItemStack): Boolean {
+        if (to is HopperBlockEntity) {
+            val hopperName = to.name.copyContentOnly().string
+            val itemName = stack.registryEntry.key.get().value.path
+
+            if (hopperName.startsWith("!")) {
+                val globs = hopperName.substring(1).split(",")
+                for (glob in globs) {
+                    if (matchesGlob(glob, itemName)) {
+                        // Glob matched, transfer
+                        return true
+                    }
+                }
+
+                // No globs matched, so don't transfer
+                return false
+            }
+        }
+
+        // Doesn't have a glob, so transfer
+        return true
+    }
+}
diff --git a/src/main/resources/assets/gloppers/icon.png b/src/main/resources/assets/gloppers/icon.png
new file mode 100644
index 0000000..25b7fb6
--- /dev/null
+++ b/src/main/resources/assets/gloppers/icon.png
diff --git a/src/main/resources/fabric.mod.json b/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..7599de5
--- /dev/null
+++ b/src/main/resources/fabric.mod.json
@@ -0,0 +1,37 @@
+{
+  "schemaVersion": 1,
+  "id": "gloppers",
+  "version": "${version}",
+  "name": "Gloppers!",
+  "description": "Filter your hoppers by renaming them with glob patterns.",
+  "authors": [
+    "NotNite"
+  ],
+  "contact": {
+    "sources": "https://github.com/NotNite/gloppers"
+  },
+  "license": "MIT",
+  "icon": "assets/gloppers/icon.png",
+  "environment": "server",
+  "entrypoints": {
+    "server": [
+      {
+        "value": "com.notnite.gloppers.Gloppers",
+        "adapter": "kotlin"
+      }
+    ]
+  },
+  "mixins": [
+    {
+      "environment": "server",
+      "config": "gloppers.mixins.json"
+    }
+  ],
+  "depends": {
+    "fabricloader": ">=0.14.19",
+    "minecraft": "~1.20",
+    "java": ">=17",
+    "fabric-api": "*",
+    "fabric-language-kotlin": ">=1.8.22"
+  }
+}
diff --git a/src/main/resources/gloppers.mixins.json b/src/main/resources/gloppers.mixins.json
new file mode 100644
index 0000000..6ddce8d
--- /dev/null
+++ b/src/main/resources/gloppers.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": true,
+  "package": "com.notnite.gloppers.mixin",
+  "compatibilityLevel": "JAVA_17",
+  "server": [
+    "HopperBlockEntityMixin"
+  ],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}