Invert if condition intention: don't remove line breaks

#KT-30900 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/InvertIfConditionIntention.kt

@@ -17,7 +17,10 @@
 package org.jetbrains.kotlin.idea.intentions
 
 import com.intellij.openapi.editor.Editor
+import com.intellij.psi.PsiComment
 import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiWhiteSpace
+import com.intellij.psi.util.PsiTreeUtil
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
 import org.jetbrains.kotlin.idea.core.moveCaret
 import org.jetbrains.kotlin.idea.core.replaced
@@ -45,7 +48,10 @@ class InvertIfConditionIntention : SelfTargetingIntention<KtIfExpression>(KtIfEx
         else
             PsiChildRange.singleElement(element)
         val commentSaver = CommentSaver(commentSavingRange)
-
+        if (rBrace != null) {
+            element.nextEolCommentOnSameLine()?.delete()
+        }
+        
         val newCondition = element.condition!!.negate()
 
         val newIf = handleSpecialCases(element, newCondition) ?: handleStandardCase(element, newCondition)
@@ -90,18 +96,17 @@ class InvertIfConditionIntention : SelfTargetingIntention<KtIfExpression>(KtIfEx
         else
             thenBranch
 
-        var thenSpace = " "
-        var elseSpace = " "
-        if (ifExpression.condition?.getLineNumber(false) != thenBranch.getLineNumber()
-            || ifExpression.elseKeyword?.getLineNumber() != elseBranch.getLineNumber()
-        ) {
-            if (newThen !is KtBlockExpression) thenSpace = "\n"
-            if (newElse !is KtBlockExpression) elseSpace = "\n"
-        }
+        val conditionLineNumber = ifExpression.condition?.getLineNumber(false)
+        val thenBranchLineNumber = thenBranch.getLineNumber(false)
+        val elseKeywordLineNumber = ifExpression.elseKeyword?.getLineNumber()
+        val afterCondition = if (newThen !is KtBlockExpression && elseKeywordLineNumber != elseBranch.getLineNumber(false)) "\n" else ""
+        val beforeElse = if (newThen !is KtBlockExpression && conditionLineNumber != elseKeywordLineNumber) "\n" else " "
+        val afterElse = if (newElse !is KtBlockExpression && conditionLineNumber != thenBranchLineNumber) "\n" else " "
+
         val newIf = if (newElse == null) {
-            psiFactory.createExpressionByPattern("if ($0)$thenSpace$1", newCondition, newThen)
+            psiFactory.createExpressionByPattern("if ($0)$afterCondition$1", newCondition, newThen)
         } else {
-            psiFactory.createExpressionByPattern("if ($0)$thenSpace$1${thenSpace}else$elseSpace$2", newCondition, newThen, newElse)
+            psiFactory.createExpressionByPattern("if ($0)$afterCondition$1${beforeElse}else$afterElse$2", newCondition, newThen, newElse)
         } as KtIfExpression
 
         return ifExpression.replaced(newIf)
@@ -249,4 +254,11 @@ class InvertIfConditionIntention : SelfTargetingIntention<KtIfExpression>(KtIfEx
     private fun parentBlockRBrace(element: KtIfExpression): PsiElement? {
         return (element.parent as? KtBlockExpression)?.rBrace
     }
+
+    private fun KtIfExpression.nextEolCommentOnSameLine(): PsiElement? {
+        val lastLineNumber = getLineNumber(false)
+        return siblings(withItself = false)
+            .takeWhile { it.getLineNumber() == lastLineNumber }
+            .firstOrNull { it is PsiComment && it.node.elementType == KtTokens.EOL_COMMENT }
+    }
 }

idea/testData/intentions/invertIfCondition/notBlock4.kt

@@ -0,0 +1,6 @@
+fun foo(b: Boolean) {
+    <caret>if (b) bar(1) // comment1
+    else bar(2) // comment2
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock4.kt.after

@@ -0,0 +1,6 @@
+fun foo(b: Boolean) {
+    if (!b) bar(2) // comment2
+    else bar(1) // comment1
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock5.kt

@@ -0,0 +1,7 @@
+fun foo(b: Boolean) {
+    <caret>if (b)
+        bar(1) // comment1
+    else bar(2) // comment2
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock5.kt.after

@@ -0,0 +1,7 @@
+fun foo(b: Boolean) {
+    if (!b) bar(2) // comment2
+    else
+        bar(1) // comment1
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock6.kt

@@ -0,0 +1,7 @@
+fun foo(b: Boolean) {
+    <caret>if (b) bar(1) // comment1
+    else 
+        bar(2) // comment2
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock6.kt.after

@@ -0,0 +1,7 @@
+fun foo(b: Boolean) {
+    if (!b)
+        bar(2) // comment2
+    else bar(1) // comment1
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock7.kt

@@ -0,0 +1,8 @@
+fun foo() {
+    <caret>if (true) bar(1)
+    else {
+        bar(2)
+    }
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock7.kt.after

@@ -0,0 +1,7 @@
+fun foo() {
+    if (false) {
+        bar(2)
+    } else bar(1)
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock8.kt

@@ -0,0 +1,7 @@
+fun foo() {
+    <caret>if (true) {
+        bar(1)
+    } else bar(2)
+}
+
+fun bar(i: Int) {}

idea/testData/intentions/invertIfCondition/notBlock8.kt.after

@@ -0,0 +1,8 @@
+fun foo() {
+    if (false) bar(2)
+    else {
+        bar(1)
+    }
+}
+
+fun bar(i: Int) {}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -10509,6 +10509,31 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             runTest("idea/testData/intentions/invertIfCondition/notBlock3.kt");
         }
 
+        @TestMetadata("notBlock4.kt")
+        public void testNotBlock4() throws Exception {
+            runTest("idea/testData/intentions/invertIfCondition/notBlock4.kt");
+        }
+
+        @TestMetadata("notBlock5.kt")
+        public void testNotBlock5() throws Exception {
+            runTest("idea/testData/intentions/invertIfCondition/notBlock5.kt");
+        }
+
+        @TestMetadata("notBlock6.kt")
+        public void testNotBlock6() throws Exception {
+            runTest("idea/testData/intentions/invertIfCondition/notBlock6.kt");
+        }
+
+        @TestMetadata("notBlock7.kt")
+        public void testNotBlock7() throws Exception {
+            runTest("idea/testData/intentions/invertIfCondition/notBlock7.kt");
+        }
+
+        @TestMetadata("notBlock8.kt")
+        public void testNotBlock8() throws Exception {
+            runTest("idea/testData/intentions/invertIfCondition/notBlock8.kt");
+        }
+
         @TestMetadata("notIn.kt")
         public void testNotIn() throws Exception {
             runTest("idea/testData/intentions/invertIfCondition/notIn.kt");