Enable previously enabled data packs from world data

src/main/java/ml/unbreakinggold/datapackinstaller/mixin/EditWorldScreenMixin.java

@@ -6,12 +6,16 @@
 import net.minecraft.client.gui.screen.Screen;
 import net.minecraft.client.gui.screen.pack.PackScreen;
 import net.minecraft.client.gui.screen.world.EditWorldScreen;
+import net.minecraft.client.gui.screen.world.WorldCreator;
 import net.minecraft.client.gui.widget.ButtonWidget;
 import net.minecraft.client.gui.widget.DirectionalLayoutWidget;
+import net.minecraft.resource.DataConfiguration;
 import net.minecraft.resource.ResourcePackManager;
 import net.minecraft.resource.VanillaDataPackProvider;
 import net.minecraft.text.Text;
 import net.minecraft.world.level.storage.LevelStorage;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.jetbrains.annotations.Nullable;
 import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
@@ -21,11 +25,16 @@
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
+import java.io.IOException;
+
 @Mixin(EditWorldScreen.class)
 public class EditWorldScreenMixin extends Screen {
     @Shadow @Final private DirectionalLayoutWidget layout;
+    @Shadow @Final private LevelStorage.Session storageSession;
+    @Unique private final Logger LOGGER = LogManager.getLogger(EditWorldScreenMixin.class);
     @Unique private static final Text SELECT_DATAPACKS_TEXT = Text.translatable("dataPack.title");
     @Unique @Nullable private ResourcePackManager packManager;
+    @Unique @Nullable private DataConfiguration dataConfiguration;
 
     protected EditWorldScreenMixin(Text title) {
         super(title);
@@ -34,12 +43,26 @@ protected EditWorldScreenMixin(Text title) {
     @Inject(at = @At(value = "INVOKE", target = "Lnet/minecraft/client/gui/widget/EmptyWidget;<init>(II)V", ordinal = 1), method = "<init>")
     private void addButton(CallbackInfo info) {
         this.layout.add(ButtonWidget.builder(SELECT_DATAPACKS_TEXT, (button) -> {
+            try {
+                this.dataConfiguration = this.storageSession.getLevelSummary(this.storageSession.readLevelProperties()).getLevelInfo().getDataConfiguration();
+            } catch (IOException primaryException) {
+                LOGGER.warn("Failed to load world data from main level.dat. Attempting to load from fallback.", primaryException);
+
+                try {
+                    this.dataConfiguration = this.storageSession.getLevelSummary(this.storageSession.readOldLevelProperties()).getLevelInfo().getDataConfiguration();
+                } catch (IOException fallbackException) {
+                    LOGGER.error("Failed to load world data from fallback level.dat.", fallbackException);
+                }
+            }
+
             if (this.packManager == null) {
                 this.packManager = VanillaDataPackProvider.createManager(DatapackInstallerClient.MAIN_PATH, client.getSymlinkFinder());
                 this.packManager.scanPacks();
             }
 
-            this.client.setScreen(new PackScreen((ResourcePackManager) this.packManager, (resourcePackManager) -> {}, DatapackInstallerClient.MAIN_PATH, Text.translatable("dataPack.title")));
+            this.packManager.setEnabledProfiles(this.dataConfiguration.dataPacks().getEnabled());
+
+            this.client.setScreen(new PackScreen(this.packManager, (resourcePackManager) -> {}, DatapackInstallerClient.MAIN_PATH, Text.translatable("dataPack.title")));
         }).width(200).build());
 
         // Reduce spacing so vanilla buttons remain on screen.