Fallback to ViaVersion to convert block state (#515)

* Fallback to ViaVersion to convert block state

* Use ViaVersion 3.0.0-SNAPSHOT

* Detect versions better; change logic for getting blocks

bootstrap/bukkit/pom.xml

@@ -23,6 +23,12 @@
             <version>1.14-R0.1-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>us.myles</groupId>
+            <artifactId>viaversion</artifactId>
+            <version>3.0.0-SNAPSHOT</version>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
     <build>
         <finalName>${outputName}-Bukkit</finalName>

bootstrap/bukkit/src/main/java/org/geysermc/platform/bukkit/GeyserBukkitPlugin.java

@@ -35,6 +35,7 @@ import org.geysermc.connector.network.translators.world.WorldManager;
 import org.geysermc.platform.bukkit.command.GeyserBukkitCommandExecutor;
 import org.geysermc.platform.bukkit.command.GeyserBukkitCommandManager;
 import org.geysermc.platform.bukkit.world.GeyserBukkitWorldManager;
+import us.myles.ViaVersion.api.Via;
 
 import java.util.UUID;
 
@@ -73,7 +74,24 @@ public class GeyserBukkitPlugin extends JavaPlugin implements GeyserBootstrap {
         this.connector = GeyserConnector.start(PlatformType.BUKKIT, this);
 
         this.geyserCommandManager = new GeyserBukkitCommandManager(this, connector);
-        this.geyserWorldManager = new GeyserBukkitWorldManager();
+
+        boolean isViaVersion = false;
+        // Used to determine if Block.getBlockData() is present.
+        boolean isLegacy = !isCompatible(Bukkit.getServer().getVersion(), "1.13.0");
+        if (isLegacy)
+            geyserLogger.debug("Legacy version of Minecraft (1.12.2 or older) detected.");
+
+        if (Bukkit.getPluginManager().getPlugin("ViaVersion") != null) {
+            // TODO: Update when ViaVersion updates
+            // API changes between 2.2.3 and 3.0.0-SNAPSHOT require this check
+            if (!Via.getAPI().getVersion().equals("3.0.0-SNAPSHOT") && isLegacy) {
+                geyserLogger.info("ViaVersion detected but not ViaVersion-ABSTRACTION. Please update your ViaVersion plugin for compatibility with Geyser.");
+            } else {
+                isViaVersion = true;
+            }
+        }
+
+        this.geyserWorldManager = new GeyserBukkitWorldManager(isLegacy, isViaVersion);
 
         this.getCommand("geyser").setExecutor(new GeyserBukkitCommandExecutor(connector));
     }
@@ -102,4 +120,38 @@ public class GeyserBukkitPlugin extends JavaPlugin implements GeyserBootstrap {
     public WorldManager getWorldManager() {
         return this.geyserWorldManager;
     }
+
+    public boolean isCompatible(String version, String whichVersion) {
+        int[] currentVersion = parseVersion(version);
+        int[] otherVersion = parseVersion(whichVersion);
+        int length = Math.max(currentVersion.length, otherVersion.length);
+        for (int index = 0; index < length; index = index + 1) {
+            int self = (index < currentVersion.length) ? currentVersion[index] : 0;
+            int other = (index < otherVersion.length) ? otherVersion[index] : 0;
+
+            if (self != other) {
+                return (self - other) > 0;
+            }
+        }
+        return true;
+    }
+
+    private int[] parseVersion(String versionParam) {
+        versionParam = (versionParam == null) ? "" : versionParam;
+        if (versionParam.contains("(MC: ")) {
+            versionParam = versionParam.split("\\(MC: ")[1];
+            versionParam = versionParam.split("\\)")[0];
+        }
+        String[] stringArray = versionParam.split("[_.-]");
+        int[] temp = new int[stringArray.length];
+        for (int index = 0; index <= (stringArray.length - 1); index = index + 1) {
+            String t = stringArray[index].replaceAll("\\D", "");
+            try {
+                temp[index] = Integer.parseInt(t);
+            } catch(NumberFormatException ex) {
+                temp[index] = 0;
+            }
+        }
+        return temp;
+    }
 }

bootstrap/bukkit/src/main/java/org/geysermc/platform/bukkit/world/GeyserBukkitWorldManager.java

@@ -28,18 +28,43 @@ package org.geysermc.platform.bukkit.world;
 
 import com.github.steveice10.mc.protocol.data.game.world.block.BlockState;
 
+import lombok.AllArgsConstructor;
 import org.bukkit.Bukkit;
+import org.bukkit.block.Block;
 import org.geysermc.connector.network.session.GeyserSession;
 import org.geysermc.connector.network.translators.world.WorldManager;
 import org.geysermc.connector.network.translators.world.block.BlockTranslator;
+import us.myles.ViaVersion.protocols.protocol1_13_1to1_13.Protocol1_13_1To1_13;
+import us.myles.ViaVersion.protocols.protocol1_15to1_14_4.data.MappingData;
 
+@AllArgsConstructor
 public class GeyserBukkitWorldManager extends WorldManager {
 
+    private final boolean isLegacy;
+    // You need ViaVersion to connect to an older server with Geyser.
+    // However, we still check for ViaVersion in case there's some other way that gets Geyser on a pre-1.13 Bukkit server
+    private final boolean isViaVersion;
+
     @Override
+    @SuppressWarnings("deprecation")
     public BlockState getBlockAt(GeyserSession session, int x, int y, int z) {
         if (session.getPlayerEntity() == null) {
             return BlockTranslator.AIR;
         }
+        if (isLegacy) {
+            if (isViaVersion) {
+                Block block = Bukkit.getPlayer(session.getPlayerEntity().getUsername()).getWorld().getBlockAt(x, y, z);
+                // Black magic that gets the old block state ID
+                int oldBlockId = (block.getType().getId() << 4) | (block.getData() & 0xF);
+                // Convert block state from old version -> 1.13 -> 1.13.1 -> 1.14 -> 1.15
+                int thirteenBlockId = us.myles.ViaVersion.protocols.protocol1_13to1_12_2.data.MappingData.blockMappings.getNewId(oldBlockId);
+                int thirteenPointOneBlockId = Protocol1_13_1To1_13.getNewBlockStateId(thirteenBlockId);
+                int fourteenBlockId = us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data.MappingData.blockStateMappings.getNewId(thirteenPointOneBlockId);
+                return new BlockState(MappingData.blockStateMappings.getNewId(fourteenBlockId));
+            } else {
+                return BlockTranslator.AIR;
+            }
+        }
         return BlockTranslator.getJavaIdBlockMap().get(Bukkit.getPlayer(session.getPlayerEntity().getUsername()).getWorld().getBlockAt(x, y, z).getBlockData().getAsString());
     }
 }

bootstrap/bukkit/src/main/resources/plugin.yml

@@ -3,6 +3,7 @@ name: ${outputName}-Bukkit
 author: ${project.organization.name}
 website: ${project.organization.url}
 version: ${project.version}
+softdepend: ["ViaVersion"]
 commands:
   geyser:
     description: The main command for Geyser.

pom.xml

@@ -67,6 +67,10 @@
                 <enabled>true</enabled>
             </snapshots>
         </repository>
+        <repository>
+            <id>viaversion-repo</id>
+            <url>https://repo.viaversion.com</url>
+        </repository>
     </repositories>
 
     <distributionManagement>