Simpler Map unzip - delete old & simple unzip (#12773)

Updates map extraction algorithm to the following:
  -  on startup, or immediately following map download: detect '.zip' file in 'downloadedMaps' folder
  -  determine target folder for extraction (strip '-master' suffix if present)
  -  delete target folder
  -  unzip the zip file to the target folder

The above is simpler notably because we just 'unzip'. Before the algorithm would check the case whether the extracted contents is a single folder, or if the zip contained all the map files in an exploded format. With this update, it does not matter, we just unzip into a destination folder.

The delete is unfortunate but required. Existing maps will potentially have this format: `[map-name]/*`, rather than something like `[map-name]/[map-name-mastter]/*`. Because of this mismatch, if we just extract, then we would wind up with duplicate map files.

game-app/game-core/src/main/java/games/strategy/engine/framework/map/file/system/loader/ZippedMapsExtractor.java

@@ -19,7 +19,6 @@
 import org.triplea.io.ZipExtractor;
 import org.triplea.io.ZipExtractor.FileSystemException;
 import org.triplea.io.ZipExtractor.ZipReadException;
-import org.triplea.java.collections.CollectionUtils;
 import org.triplea.map.description.file.MapDescriptionYaml;
 
 /**
@@ -125,68 +124,34 @@ public static Optional<Path> unzipMap(final Path mapZip) {
         mapZip.getFileName().toString().endsWith(".zip"), mapZip.toAbsolutePath());
 
     try {
-      return unzipMapThrowing(mapZip);
-    } catch (final IOException e) {
-      log.warn("Error extracting file: {}, {}", mapZip.toAbsolutePath() + ", " + e.getMessage(), e);
-      return Optional.empty();
-    }
-  }
-
-  // unzip map
-  // if previous folder exists then back it up
-  private static Optional<Path> unzipMapThrowing(final Path mapZip) throws IOException {
-    // extraction target is important, it is the folder path we seek to create with
-    // extracted map contents.
-    final Path mapsFolder = ClientFileSystemHelper.getUserMapsFolder();
-    final Path extractionTarget =
-        mapsFolder.resolve(computeExtractionFolderName(mapZip.getFileName().toString()));
-
-    if (!GameRunner.headless() && Files.exists(extractionTarget)) {
+      // extraction target is important, it is the folder path we seek to create with
+      // extracted map contents.
+      final Path mapsFolder = ClientFileSystemHelper.getUserMapsFolder();
+      final Path extractionTarget =
+          mapsFolder.resolve(computeExtractionFolderName(mapZip.getFileName().toString()));
       log.info(
-          "Skipping extraction of: {}, extraction target already exists: {}",
+          "Extracting map zip: {} -> {}",
           mapZip.toAbsolutePath(),
           extractionTarget.toAbsolutePath());
-      return Optional.empty();
-    }
-
-    // if this is a bot, then we are updating the map - delete the old folder and extract a new.
-    if (GameRunner.headless() && Files.exists(extractionTarget)) {
-      log.info("Deleting old map folder: " + extractionTarget.toAbsolutePath());
       FileUtils.deleteDirectory(extractionTarget);
-    }
+      ZipExtractor.unzipFile(mapZip, extractionTarget);
 
-    log.info(
-        "Extracting map zip: {} -> {}", mapZip.toAbsolutePath(), extractionTarget.toAbsolutePath());
-
-    // extract to a temp folder.
-    //    If the temp folder then contains a single folder:
-    //       -> move that single folder to extraction target and remove the temp folder
-    //    If the temp folder contains many files:
-    //       -> rename the temp folder to extraction target
-    final Path tempFolder = Files.createTempDirectory(mapsFolder, "map-unzip");
-    ZipExtractor.unzipFile(mapZip, tempFolder);
-    final Collection<Path> files = FileUtils.listFiles(tempFolder);
-    if (files.size() == 1 && Files.isDirectory(CollectionUtils.getAny(files))) {
-      // temp folder contains a folder that contains all the map files
-      Files.move(CollectionUtils.getAny(files), extractionTarget);
-      Files.delete(tempFolder);
-    } else {
-      // temp folder contains all the map files. Rename the temp folder
-      Files.move(tempFolder, extractionTarget);
-    }
-
-    // delete old properties file if they exists
-    final Path propertiesFile =
-        mapZip.resolveSibling(mapZip.getFileName().toString() + ".properties");
-    if (Files.exists(propertiesFile)) {
-      FileUtils.delete(propertiesFile);
-    }
+      // delete old properties file if they exists
+      final Path propertiesFile =
+          mapZip.resolveSibling(mapZip.getFileName().toString() + ".properties");
+      if (Files.exists(propertiesFile)) {
+        FileUtils.delete(propertiesFile);
+      }
 
-    final boolean successfullyExtracted = Files.exists(extractionTarget);
-    if (successfullyExtracted) {
-      Files.delete(mapZip);
-      return Optional.of(extractionTarget);
-    } else {
+      final boolean successfullyExtracted = Files.exists(extractionTarget);
+      if (successfullyExtracted) {
+        Files.delete(mapZip);
+        return Optional.of(extractionTarget);
+      } else {
+        return Optional.empty();
+      }
+    } catch (final IOException e) {
+      log.warn("Error extracting file: {}, {}", mapZip.toAbsolutePath(), e.getMessage(), e);
       return Optional.empty();
     }
   }