Fix UnfoldProperties recipe for 4 space indent (#6447)

* Fix UnfoldProperties recipe for 4 space indent

* Do not change the default fallback indentation to four

---------

Co-authored-by: Tim te Beek <tim@moderne.io>

Author: der-eismann

rewrite-yaml/src/main/java/org/openrewrite/yaml/MergeDuplicateSectionsVisitor.java

@@ -37,7 +37,12 @@ public Yaml.Document visitDocument(Yaml.Document document, P p) {
         Yaml.Document d = super.visitDocument(document, p);
         String newRootComments = getCursor().getMessage("NEW_ROOT_COMMENTS", "");
         if (!newRootComments.isEmpty()) {
-            d = d.withPrefix(d.getPrefix() + newRootComments);
+            // Clean up extra leading newlines when adding root comments
+            String cleanComments = newRootComments;
+            if (cleanComments.startsWith("\n") && d.getPrefix().isEmpty()) {
+                cleanComments = cleanComments.substring(1);
+            }
+            d = d.withPrefix(d.getPrefix() + cleanComments);
         }
         return d;
     }

rewrite-yaml/src/main/java/org/openrewrite/yaml/UnfoldProperties.java

@@ -19,6 +19,7 @@
 import lombok.Value;
 import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
+import org.openrewrite.yaml.search.FindIndentYamlVisitor;
 import org.openrewrite.yaml.tree.Yaml;
 
 import java.util.ArrayList;
@@ -71,8 +72,11 @@ public String getDescription() {
     public TreeVisitor<?, ExecutionContext> getVisitor() {
         List<JsonPathMatcher> exclusionMatchers = exclusions.stream().map(JsonPathMatcher::new).collect(toList());
         return new YamlIsoVisitor<ExecutionContext>() {
+            private final FindIndentYamlVisitor<ExecutionContext> findIndent = new FindIndentYamlVisitor<>();
+
             @Override
             public Yaml.Document visitDocument(Yaml.Document document, ExecutionContext ctx) {
+                findIndent.visit(document, ctx);
                 Yaml.Document doc = super.visitDocument(document, ctx);
                 doAfterVisit(new MergeDuplicateSectionsVisitor<>(doc));
                 return doc;
@@ -106,7 +110,10 @@ public Yaml.Mapping.Entry visitMappingEntry(Yaml.Mapping.Entry e, ExecutionConte
                                 if (!hasLineBreak(entry.getPrefix()) && hasLineBreak(newEntry.getPrefix())) {
                                     newEntry = newEntry.withPrefix(substringOfAfterFirstLineBreak(entry.getPrefix()));
                                 } else if (identLevel == 0 && hasLineBreak(newEntry.getPrefix())) {
-                                    identLevel = 2; // autFormat indents the entire block by 2 spaces though it is a root level entry -> shift by 2 later
+                                    // Use the detected indentation from the document, defaulting to 2 if none detected
+                                    int mostCommonIndent = findIndent.getMostCommonIndent();
+                                    // autoFormat indents the entire block by detected spaces though it is a root level entry -> shift by detected amount later
+                                    identLevel = 0 < mostCommonIndent ? mostCommonIndent : 2;
                                 }
                                 doAfterVisit(new ShiftFormatLeftVisitor<>(newEntry, identLevel));
                             }

rewrite-yaml/src/test/java/org/openrewrite/yaml/UnfoldPropertiesTest.java

@@ -472,4 +472,58 @@ void applyToWithExclusion() {
           )
         );
     }
+
+    @Test
+    void unfoldSpringPropertiesTwoSpace() {
+        rewriteRun(
+          yaml(
+            """
+            spring:
+              datasource:
+                url: jdbc:postgresql://localhost/test
+
+            spring.servlet.encoding.charset: UTF-8
+            spring.servlet.encoding.enabled: true
+            spring.servlet.encoding.force: true
+            """,
+            """
+            spring:
+              datasource:
+                url: jdbc:postgresql://localhost/test
+              servlet:
+                encoding:
+                  charset: UTF-8
+                  enabled: true
+                  force: true
+              """
+          )
+        );
+    }
+
+    @Test
+    void unfoldSpringPropertiesFourSpace() {
+        rewriteRun(
+          yaml(
+            """
+            spring:
+                datasource:
+                    url: jdbc:postgresql://localhost/test
+
+            spring.servlet.encoding.charset: UTF-8
+            spring.servlet.encoding.enabled: true
+            spring.servlet.encoding.force: true
+            """,
+            """
+            spring:
+                datasource:
+                    url: jdbc:postgresql://localhost/test
+                servlet:
+                    encoding:
+                        charset: UTF-8
+                        enabled: true
+                        force: true
+              """
+          )
+        );
+    }
 }