Add safeguard for importing fils from incorrect files

This is based on ibans saved in baka and filenames. Therefore, this
isn't bulletproof. We need to inspect formats and see what metadata is
available for a 90% solution. The current solution at least works for
DKB2

src/main/java/link/biosmarcel/baka/view/PaymentsView.java

@@ -38,6 +38,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.function.BiFunction;
+import java.util.stream.Collectors;
 
 public class PaymentsView extends BakaTab {
     private final TableView<PaymentFX> table;
@@ -197,6 +198,10 @@ private void importHandler(final Account account, final BiFunction<Account, File
             return;
         }
 
+        if (account.iban != null && !account.iban.isBlank() && safeguardIncorrectlyImportedFile(account, files)) {
+            return;
+        }
+
         // Since it's assumed we can only pick files from one directory, we use the next best parent dir we can find.
         final String dir = files.getFirst().getParent();
         state.data.convenienceState.lastImportPath = dir;
@@ -209,12 +214,41 @@ private void importHandler(final Account account, final BiFunction<Account, File
         final var newPayments = files.stream()
                 .flatMap(file -> importer.apply(account, file).stream())
                 // Since the files usually have consistent order, we sort, as adding together two files contents may
-                // produces an incorrect order.
+                // produce an incorrect order.
                 .sorted(Comparator.comparing(payment -> payment.bookingDate))
                 .toList();
         createPayments(newPayments);
     }
 
+    private boolean safeguardIncorrectlyImportedFile(Account account, List<File> files) {
+        final var potentiallyWrongImports = new ArrayList<String>();
+        for (final var file : files) {
+            for (final var otherAccount : state.data.accounts) {
+                if (account.equals(otherAccount) || otherAccount.iban == null || otherAccount.iban.isBlank()) {
+                    continue;
+                }
+
+                if (file.getName().toLowerCase().contains(otherAccount.iban.toLowerCase())) {
+                    potentiallyWrongImports.add(file.getName());
+                }
+            }
+        }
+
+        if (!potentiallyWrongImports.isEmpty()) {
+            final var safetyCheck = new Alert(Alert.AlertType.CONFIRMATION);
+            safetyCheck.setTitle("Import into '%s'".formatted(account.name));
+            safetyCheck.setHeaderText("Potentially importing into incorrect account");
+            safetyCheck.setContentText(
+                    "Are you sure you want to import the following files into account '%s (%s)':\n\n%s"
+                            .formatted(account.name, account.iban, String.join("\n", potentiallyWrongImports)));
+            safetyCheck.initOwner(getTabPane().getScene().getWindow());
+            safetyCheck.getDialogPane().setPrefWidth(600);
+            final var choice = safetyCheck.showAndWait();
+            return choice.isEmpty() || choice.get().getButtonData() != ButtonBar.ButtonData.YES;
+        }
+        return false;
+    }
+
     private void createPayments(final Collection<Payment> newPayments) {
         // We simply append, preventing to restore everything (hopefully). We also won't depend on the sorting by
         // accident later on.