Preserve W3I map name in synthesized headers

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/languageserver/ProjectConfigBuilder.java

@@ -107,7 +107,7 @@ public static MapRequest.CompilationResult apply(WurstProjectConfigData projectC
         w3I.write(result.w3i);
 
         // Apply map header (this is cheap, so we always do it)
-        applyMapHeader(projectConfig, targetMap, w3I.getPlayers().size());
+        applyMapHeader(projectConfig, targetMap, w3I.getPlayers().size(), w3I.getMapName());
 
         // Update the manifest with new config hash (must open writable to insert)
         try (MpqEditor mpq = MpqEditorFactory.getEditor(Optional.of(targetMap), false)) {
@@ -357,7 +357,7 @@ private static void setVolatilePlayerConfig(WurstProjectBuildPlayer wplayer, W3I
     }
 
     private static void applyMapHeader(WurstProjectConfigData projectConfig, File targetMap,
-                                       int existingPlayerCount) throws IOException {
+                                       int existingPlayerCount, String existingMapName) throws IOException {
         boolean shouldWrite = false;
         WurstProjectBuildMapData buildMapData = projectConfig.buildMapData();
         if (buildMapData.players().isEmpty() && StringUtils.isBlank(buildMapData.name())) {
@@ -378,6 +378,9 @@ private static void applyMapHeader(WurstProjectConfigData projectConfig, File ta
         } else if (hasNoMapHeader) {
             mapHeader.setMaxPlayersCount(existingPlayerCount);
         }
+        if (hasNoMapHeader && StringUtils.isBlank(buildMapData.name())) {
+            mapHeader.setMapName(existingMapName);
+        }
         if (StringUtils.isNotBlank(buildMapData.name())) {
             mapHeader.setMapName(buildMapData.name());
             shouldWrite = true;

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/WurstBuildConfigTests.java

@@ -2,6 +2,7 @@
 
 import org.wurstscript.projectconfig.WurstProjectConfigData;
 import org.wurstscript.projectconfig.WurstProjectBuildMapData;
+import org.wurstscript.projectconfig.WurstProjectBuildPlayer;
 import de.peeeq.wurstio.languageserver.WFile;
 import de.peeeq.wurstio.languageserver.ProjectConfigBuilder;
 import de.peeeq.wurstio.languageserver.WurstBuildConfig;
@@ -13,6 +14,7 @@
 
 import java.io.File;
 import java.lang.reflect.Method;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
@@ -236,7 +238,7 @@ public void mapHeaderConfigAcceptsAnArchiveWithoutAnHm3wPrefix() throws Exceptio
         Files.write(mapWithoutHeader, original);
 
         Method applyMapHeader = ProjectConfigBuilder.class.getDeclaredMethod(
-            "applyMapHeader", WurstProjectConfigData.class, File.class, int.class
+            "applyMapHeader", WurstProjectConfigData.class, File.class, int.class, String.class
         );
         applyMapHeader.setAccessible(true);
 
@@ -250,7 +252,8 @@ public void mapHeaderConfigAcceptsAnArchiveWithoutAnHm3wPrefix() throws Exceptio
                 null
             ),
             mapWithoutHeader.toFile(),
-            3
+            3,
+            "Existing map"
         );
 
         assertEquals(Files.readAllBytes(mapWithoutHeader)[0], (byte) 'H');
@@ -269,14 +272,52 @@ public void mapHeaderConfigDoesNotReadAnArchiveWhenNothingNeedsChanging() throws
         Files.write(mapWithoutHeader, original);
 
         Method applyMapHeader = ProjectConfigBuilder.class.getDeclaredMethod(
-            "applyMapHeader", WurstProjectConfigData.class, File.class, int.class
+            "applyMapHeader", WurstProjectConfigData.class, File.class, int.class, String.class
         );
         applyMapHeader.setAccessible(true);
-        applyMapHeader.invoke(null, WurstProjectConfigData.empty(), mapWithoutHeader.toFile(), 0);
+        applyMapHeader.invoke(null, WurstProjectConfigData.empty(), mapWithoutHeader.toFile(), 0, null);
 
         assertEquals(Files.readAllBytes(mapWithoutHeader), original);
     }
 
+    @Test
+    public void mapHeaderConfigPreservesExistingMapNameWhenOnlyPlayersChange() throws Exception {
+        Path mapWithoutHeader = Files.createTempFile("wurst-map-without-header-name", ".w3x");
+        byte[] original = new byte[1024];
+        original[0] = 'M';
+        original[1] = 'P';
+        original[2] = 'Q';
+        original[3] = 0x1a;
+        Files.write(mapWithoutHeader, original);
+
+        Method applyMapHeader = ProjectConfigBuilder.class.getDeclaredMethod(
+            "applyMapHeader", WurstProjectConfigData.class, File.class, int.class, String.class
+        );
+        applyMapHeader.setAccessible(true);
+
+        applyMapHeader.invoke(
+            null,
+            new WurstProjectConfigData(
+                "Test",
+                List.of(),
+                new WurstProjectBuildMapData(
+                    "", null, null, null, null,
+                    List.of(new WurstProjectBuildPlayer(0, null, null, null, null)),
+                    List.of()
+                ),
+                null,
+                null
+            ),
+            mapWithoutHeader.toFile(),
+            4,
+            "Existing map"
+        );
+
+        byte[] result = Files.readAllBytes(mapWithoutHeader);
+        assertEquals(MapHeader.ofFile(mapWithoutHeader.toFile()).getMaxPlayersCount(), 1);
+        assertTrue(new String(result, StandardCharsets.UTF_8).contains("Existing map"));
+    }
+
     private static String calculateProjectConfigHash(File buildDir) throws Exception {
         Method method = ProjectConfigBuilder.class.getDeclaredMethod(
             "calculateProjectConfigHash",