gradle=7.1.1, gradle migrateMappings

remappedSrc/dan200/computercraft/shared/util/IDAssigner.java

@@ -0,0 +1,122 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2021. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.util;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.reflect.TypeToken;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.fabric.mixin.WorldSavePathAccess;
+import me.shedaniel.cloth.api.utils.v1.GameInstanceUtils;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.WorldSavePath;
+
+import java.io.File;
+import java.io.Reader;
+import java.io.Writer;
+import java.lang.ref.WeakReference;
+import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+
+public final class IDAssigner
+{
+    private static final WorldSavePath FOLDER = WorldSavePathAccess.createWorldSavePath( ComputerCraft.MOD_ID );
+    private static final Gson GSON = new GsonBuilder().setPrettyPrinting()
+        .create();
+    private static final Type ID_TOKEN = new TypeToken<Map<String, Integer>>()
+    {
+    }.getType();
+    private static Map<String, Integer> ids;
+    private static WeakReference<MinecraftServer> server;
+    private static Path idFile;
+
+    private IDAssigner()
+    {
+    }
+
+    public static synchronized int getNextId( String kind )
+    {
+        MinecraftServer currentServer = getCachedServer();
+        if( currentServer == null )
+        {
+            // The server has changed, refetch our ID map
+            if( GameInstanceUtils.getServer() != null )
+            {
+                server = new WeakReference<>( GameInstanceUtils.getServer() );
+
+                File dir = getDir();
+                dir.mkdirs();
+
+                // Load our ID file from disk
+                idFile = new File( dir, "ids.json" ).toPath();
+                if( Files.isRegularFile( idFile ) )
+                {
+                    try( Reader reader = Files.newBufferedReader( idFile, StandardCharsets.UTF_8 ) )
+                    {
+                        ids = GSON.fromJson( reader, ID_TOKEN );
+                    }
+                    catch( Exception e )
+                    {
+                        ComputerCraft.log.error( "Cannot load id file '" + idFile + "'", e );
+                        ids = new HashMap<>();
+                    }
+                }
+                else
+                {
+                    ids = new HashMap<>();
+                }
+            }
+        }
+
+        Integer existing = ids.get( kind );
+        int next = existing == null ? 0 : existing + 1;
+        ids.put( kind, next );
+
+        // We've changed the ID file, so save it back again.
+        try( Writer writer = Files.newBufferedWriter( idFile, StandardCharsets.UTF_8 ) )
+        {
+            GSON.toJson( ids, writer );
+        }
+        catch( Exception e )
+        {
+            ComputerCraft.log.error( "Cannot update ID file '" + idFile + "'", e );
+        }
+
+        return next;
+    }
+
+    private static MinecraftServer getCachedServer()
+    {
+        if( server == null )
+        {
+            return null;
+        }
+
+        MinecraftServer currentServer = server.get();
+        if( currentServer == null )
+        {
+            return null;
+        }
+
+        if( currentServer != GameInstanceUtils.getServer() )
+        {
+            return null;
+        }
+        return currentServer;
+    }
+
+    public static File getDir()
+    {
+        return GameInstanceUtils.getServer()
+            .getSavePath( FOLDER )
+            .toFile();
+    }
+}