"Lift return / assignment": do not suggest for too long expressions

idea/src/org/jetbrains/kotlin/idea/inspections/LiftReturnOrAssignmentInspection.kt

@@ -20,6 +20,7 @@ import com.intellij.codeInspection.*
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.BranchedFoldingUtils
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.lineCount
 import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.psi.KtIfExpression
 import org.jetbrains.kotlin.psi.KtVisitorVoid
@@ -31,6 +32,7 @@ class LiftReturnOrAssignmentInspection : AbstractKotlinInspection() {
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession) =
             object : KtVisitorVoid() {
                 private fun visitIfOrWhen(expression: KtExpression, keyword: PsiElement) {
+                    if (expression.lineCount() > LINES_LIMIT) return
                     val returnNumber = BranchedFoldingUtils.getFoldableReturnNumber(expression)
                     if (returnNumber > 0) {
                         holder.registerProblem(
@@ -84,4 +86,8 @@ class LiftReturnOrAssignmentInspection : AbstractKotlinInspection() {
             BranchedFoldingUtils.foldToAssignment(descriptor.psiElement.getParentOfType(true)!!)
         }
     }
+
+    companion object {
+        private val LINES_LIMIT = 15
+    }
 }

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/IfThenUtils.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.idea.intentions.branchedTransformations
 
 import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.fileEditor.FileDocumentManager
 import com.intellij.psi.search.LocalSearchScope
 import com.intellij.psi.search.searches.ReferencesSearch
 import org.jetbrains.kotlin.KtNodeTypes
@@ -254,3 +255,12 @@ private fun KtExpression.insertSafeCalls(factory: KtPsiFactory): KtExpression {
     replaced.receiverExpression.let { it.replace(it.insertSafeCalls(factory)) }
     return replaced
 }
+
+// Returns -1 if cannot obtain a document
+internal fun KtExpression.lineCount(): Int {
+    val file = containingFile?.virtualFile ?: return -1
+    val document = FileDocumentManager.getInstance().getDocument(file) ?: return -1
+    return document.getLineNumber(textRange.endOffset) - document.getLineNumber(textRange.startOffset) + 1
+}
+
+internal fun KtExpression.isOneLiner(): Boolean = lineCount() == 1

idea/testData/inspectionsLocal/liftOut/ifToReturn/ifVeryLong.kt

@@ -0,0 +1,33 @@
+// PROBLEM: none
+
+fun println(s: String) {}
+
+fun test(n: Int): String {
+    <caret>if (n == 1) {
+        println("123")
+        println("456")
+        println("789")
+        println("123")
+        println("456")
+        println("789")
+        return "one"
+    }
+    else if (n == 2) {
+        println("123")
+        println("456")
+        println("789")
+        println("123")
+        println("456")
+        println("789")
+        return "two"
+    }
+    else {
+        println("123")
+        println("456")
+        println("789")
+        println("123")
+        println("456")
+        println("789")
+        return "three"
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -529,6 +529,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("ifVeryLong.kt")
+            public void testIfVeryLong() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/liftOut/ifToReturn/ifVeryLong.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("innerIfTransformed.kt")
             public void testInnerIfTransformed() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/liftOut/ifToReturn/innerIfTransformed.kt");