4 files changed, 26 insertions, 18 deletions

diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/Gui.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/Gui.java
index 05146d4a..21120b8a 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/Gui.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/Gui.java
@@ -147,6 +147,7 @@ public class Gui {
 
         private void setupUi() {
                 this.jarFileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
+                this.jarFileChooser.setMultiSelectionEnabled(true);
 
                 this.exportSourceFileChooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
                 this.exportSourceFileChooser.setAcceptAllFileFilterUsed(false);
diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/GuiController.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/GuiController.java
index ad10abfc..ece11b00 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/GuiController.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/GuiController.java
@@ -23,6 +23,7 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import javax.swing.JOptionPane;
@@ -119,20 +120,27 @@ public class GuiController implements ClientPacketHandler {
                 return project != null && project.getMapper().isDirty();
         }
 
-        public CompletableFuture<Void> openJar(final Path jarPath) {
+        public CompletableFuture<Void> openJar(final List<Path> jarPaths) {
                 this.gui.onStartOpenJar();
 
                 return ProgressDialog.runOffThread(gui.getFrame(), progress -> {
-                        project = enigma.openJar(jarPath, new ClasspathClassProvider(), progress);
+                        project = enigma.openJars(jarPaths, new ClasspathClassProvider(), progress);
                         indexTreeBuilder = new IndexTreeBuilder(project.getJarIndex());
                         chp = new ClassHandleProvider(project, UiConfig.getDecompiler().service);
                         SwingUtilities.invokeLater(() -> {
-                                gui.onFinishOpenJar(jarPath.getFileName().toString());
+                                gui.onFinishOpenJar(getFileNames(jarPaths));
                                 refreshClasses();
                         });
                 });
         }
 
+        private static String getFileNames(List<Path> jarPaths) {
+                return jarPaths.stream()
+                                .map(Path::getFileName)
+                                .map(Object::toString)
+                                .collect(Collectors.joining(", "));
+        }
+
         public void closeJar() {
                 this.chp.destroy();
                 this.chp = null;
@@ -241,17 +249,15 @@ public class GuiController implements ClientPacketHandler {
         }
 
         public void reloadAll() {
-                Path jarPath = this.project.getJarPath();
+                List<Path> jarPaths = this.project.getJarPaths();
                 MappingFormat loadedMappingFormat = this.loadedMappingFormat;
                 Path loadedMappingPath = this.loadedMappingPath;
 
-                if (jarPath != null) {
-                        this.closeJar();
-                        CompletableFuture<Void> f = this.openJar(jarPath);
+                this.closeJar();
+                CompletableFuture<Void> f = this.openJar(jarPaths);
 
-                        if (loadedMappingFormat != null && loadedMappingPath != null) {
-                                f.whenComplete((v, t) -> this.openMappings(loadedMappingFormat, loadedMappingPath));
-                        }
+                if (loadedMappingFormat != null && loadedMappingPath != null) {
+                        f.whenComplete((v, t) -> this.openMappings(loadedMappingFormat, loadedMappingPath));
                 }
         }
 
diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/Main.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/Main.java
index 213a5fea..43b16cd9 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/Main.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/Main.java
@@ -38,7 +38,7 @@ public class Main {
         public static void main(String[] args) throws IOException {
                 OptionParser parser = new OptionParser();
 
-                OptionSpec<Path> jar = parser.accepts("jar", "Jar file to open at startup").withRequiredArg().withValuesConvertedBy(PathConverter.INSTANCE);
+                OptionSpec<Path> jar = parser.accepts("jar", "Jar file to open at startup; if there are multiple jars, the order must be the same between all collab session members").withRequiredArg().withValuesConvertedBy(PathConverter.INSTANCE);
 
                 OptionSpec<Path> mappings = parser.accepts("mappings", "Mappings file to open at startup").withRequiredArg().withValuesConvertedBy(PathConverter.INSTANCE);
 
@@ -137,8 +137,8 @@ public class Main {
                         }
 
                         if (options.has(jar)) {
-                                Path jarPath = options.valueOf(jar);
-                                controller.openJar(jarPath).whenComplete((v, t) -> {
+                                List<Path> jarPaths = options.valuesOf(jar);
+                                controller.openJar(jarPaths).whenComplete((v, t) -> {
                                         if (options.has(mappings)) {
                                                 Path mappingsPath = options.valueOf(mappings);
 
diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
index d7054f78..78050bb3 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
@@ -7,6 +7,7 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -235,15 +236,15 @@ public class MenuBar {
                         return;
                 }
 
-                File file = d.getSelectedFile();
+                File[] files = d.getSelectedFiles();
 
                 // checks if the file name is not empty
-                if (file != null) {
-                        Path path = file.toPath();
+                if (files.length >= 1) {
+                        List<Path> paths = Arrays.stream(files).map(File::toPath).toList();
 
                         // checks if the file name corresponds to an existing file
-                        if (Files.exists(path)) {
-                                this.gui.getController().openJar(path);
+                        if (paths.stream().allMatch(Files::exists)) {
+                                this.gui.getController().openJar(paths);
                         }
 
                         UiConfig.setLastSelectedDir(d.getCurrentDirectory().getAbsolutePath());