(sideload) Fix sideloading of explicitly selected stackexchange files

Fix a bug where sideloading stackexchange files by explicitly selecting the 7z file would fail, since the 7z file would be passed along to the converter rather than the path to the pre-converted .db file.

code/services-core/executor-service/src/main/java/nu/marginalia/actor/task/ConvertActor.java

@@ -198,13 +198,16 @@ public class ConvertActor extends RecordActorPrototype {
 
                 // Convert stackexchange data to sqlite database
                 // (we can't use a Predigest- step here because the conversion is too complicated)
-                StackExchangeSideloadHelper.convertStackexchangeData(sourcePath);
+                var preprocessedPath = StackExchangeSideloadHelper.convertStackexchangeData(sourcePath);
+
+                if (preprocessedPath.isEmpty())
+                    yield new Error("Failed to convert stackexchange 7z file to sqlite database");
 
                 // Pre-send convert request
 
                 yield new ConvertWait(
                         processedArea.id(),
-                        mqConverterOutbox.sendAsync(ConvertRequest.forStackexchange(sourcePath, processedArea.id()))
+                        mqConverterOutbox.sendAsync(ConvertRequest.forStackexchange(preprocessedPath.get(), processedArea.id()))
                 );
             }
             case ConvertWait(FileStorageId destFid, long msgId) -> {

code/services-core/executor-service/src/main/java/nu/marginalia/sideload/StackExchangeSideloadHelper.java

@@ -19,33 +19,46 @@ public class StackExchangeSideloadHelper {
      *  The function is idempotent, so it is safe to call it multiple times on the same path
      *  (it will not re-convert files that have already been successfully converted)
      * */
-    public static void convertStackexchangeData(Path sourcePath) {
+    public static Optional<Path> convertStackexchangeData(Path sourcePath) {
         if (Files.isDirectory(sourcePath)) {
             try (var contents = Files.list(sourcePath)) {
                 contents.filter(Files::isRegularFile)
                         .parallel()
                         .forEach(StackExchangeSideloadHelper::convertSingleStackexchangeFile);
+
+                // If we process a directory, then the converter step will find the .db files automatically
+                return Optional.of(sourcePath);
             } catch (IOException ex) {
                 logger.warn("Failed to convert stackexchange 7z file to sqlite database", ex);
             }
         } else if (Files.isRegularFile(sourcePath)) {
-            convertSingleStackexchangeFile(sourcePath);
+            // If we process a single file, then we need to alter the input path to the converted file's name
+            return convertSingleStackexchangeFile(sourcePath);
         }
+
+        return Optional.empty();
     }
 
-    private static void convertSingleStackexchangeFile(Path sourcePath) {
+    /** Converts a single stackexchange 7z file to a sqlite database.
+     *  The function is idempotent, so it is safe to call it multiple times on the same file
+     *  (it will not re-convert files that have already been successfully converted)
+     *
+     * @return The path to the converted sqlite database, or an empty optional if the conversion failed
+     * */
+    private static Optional<Path> convertSingleStackexchangeFile(Path sourcePath) {
         String fileName = sourcePath.toFile().getName();
 
-        if (fileName.endsWith(".db")) return;
+        if (fileName.endsWith(".db")) return Optional.of(sourcePath);
-        if (!fileName.endsWith(".7z")) return;
+        if (!fileName.endsWith(".7z")) return Optional.empty();
 
         Optional<String> domain = getStackexchangeDomainFromFilename(fileName);
         if (domain.isEmpty())
-            return;
+            return Optional.empty();
 
         try {
             Path destPath = getStackexchangeDbPath(sourcePath);
-            if (Files.exists(destPath)) return;
+            if (Files.exists(destPath))
+                return Optional.of(destPath);
 
             Path tempFile = Files.createTempFile(destPath.getParent(), "processed", "db.tmp");
             try {
@@ -53,6 +66,8 @@ public class StackExchangeSideloadHelper {
                 StackExchangePostsDb.create(domain.get(), tempFile, sourcePath);
                 logger.info("Finished converting stackexchange 7z file {} to sqlite database", sourcePath);
                 Files.move(tempFile, destPath, StandardCopyOption.REPLACE_EXISTING);
+
+                return Optional.of(destPath);
             } catch (Exception e) {
                 logger.error("Failed to convert stackexchange 7z file to sqlite database", e);
                 Files.deleteIfExists(tempFile);
@@ -61,6 +76,7 @@ public class StackExchangeSideloadHelper {
         } catch (IOException ex) {
             logger.warn("Failed to convert stackexchange 7z file to sqlite database", ex);
         }
+        return Optional.empty();
     }
 
     private static Path getStackexchangeDbPath(Path sourcePath) throws IOException {