From 33f59fd7edb89cddcbf9f4f691f462906106d967 Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flo@geekplace.eu>
Date: Tue, 2 Mar 2021 21:40:52 +0100
Subject: [PATCH] [xdata] Ensure that hidden FROM_TYPE field is first

---
 .../smackx/xdata/packet/DataForm.java         | 27 +++++++++++++++++++
 .../smackx/xdata/packet/DataFormTest.java     | 10 +++++++
 2 files changed, 37 insertions(+)

diff --git a/smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/packet/DataForm.java b/smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/packet/DataForm.java
index 37a37741a..9ab354d57 100644
--- a/smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/packet/DataForm.java
+++ b/smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/packet/DataForm.java
@@ -100,6 +100,9 @@ public final class DataForm implements ExtensionElement {
         instructions = CollectionUtil.cloneAndSeal(builder.instructions);
         reportedData = builder.reportedData;
         items = CollectionUtil.cloneAndSeal(builder.items);
+
+        builder.orderFields();
+
         fields = CollectionUtil.cloneAndSeal(builder.fields);
         fieldsMap = CollectionUtil.cloneAndSeal(builder.fieldsMap);
         extensionElements = CollectionUtil.cloneAndSeal(builder.extensionElements);
@@ -382,6 +385,30 @@ public final class DataForm implements ExtensionElement {
             extensionElements = CollectionUtil.newListWith(dataForm.getExtensionElements());
         }
 
+        private void orderFields() {
+            Iterator<FormField> it = fields.iterator();
+            if (!it.hasNext()) {
+                return;
+            }
+
+            FormField hiddenFormTypeField = it.next().asHiddenFormTypeFieldIfPossible();
+            if (hiddenFormTypeField != null) {
+                // The hidden FROM_TYPE field is already in first position, nothing to do.
+                return;
+            }
+
+            while (it.hasNext()) {
+                hiddenFormTypeField = it.next().asHiddenFormTypeFieldIfPossible();
+                if (hiddenFormTypeField != null) {
+                    // Remove the hidden FORM_TYPE field that is not on first position.
+                    it.remove();
+                    // And insert it again at first position.
+                    fields.add(0, hiddenFormTypeField);
+                    break;
+                }
+            }
+        }
+
         /**
          * Deprecated do not use.
          *
diff --git a/smack-extensions/src/test/java/org/jivesoftware/smackx/xdata/packet/DataFormTest.java b/smack-extensions/src/test/java/org/jivesoftware/smackx/xdata/packet/DataFormTest.java
index 726be55d6..3f9e6feb3 100644
--- a/smack-extensions/src/test/java/org/jivesoftware/smackx/xdata/packet/DataFormTest.java
+++ b/smack-extensions/src/test/java/org/jivesoftware/smackx/xdata/packet/DataFormTest.java
@@ -153,4 +153,14 @@ public class DataFormTest extends SmackTestSuite {
         DataForm df = pr.parse(PacketParserUtils.getParserFor(formWithFixedField));
         assertEquals(Type.fixed, df.getFields().get(0).getType());
     }
+
+    @Test
+    public void testReorderHiddenFormTypeFieldAtFirstPosition() {
+        DataForm dataForm = DataForm.builder()
+            .addField(FormField.textSingleBuilder("foo1").setValue("bar").build())
+            .addField(FormField.textSingleBuilder("foo2").setValue("baz").build())
+            .setFormType("my-form-type")
+            .build();
+        assertNotNull(dataForm.getFields().get(0).asHiddenFormTypeFieldIfPossible());
+    }
 }