Implement Smart Enter Processor for the last function call argument being a lambda

Fixes #KT-6785

idea/src/org/jetbrains/kotlin/idea/editor/KotlinSmartEnterHandler.kt

@@ -54,7 +54,9 @@ class KotlinSmartEnterHandler: SmartEnterProcessorWithFixers() {
                 KotlinTryBodyFixer(),
                 KotlinCatchParameterFixer(),
                 KotlinCatchBodyFixer(),
-                KotlinFinallyBodyFixer()
+                KotlinFinallyBodyFixer(),
+
+                KotlinLastLambdaParameterFixer()
         )
 
         addEnterProcessors(KotlinPlainEnterProcessor())

idea/src/org/jetbrains/kotlin/idea/editor/fixers/KotlinLastLambdaParameterFixer.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.idea.editor.fixers
+
+import com.intellij.lang.SmartEnterProcessorWithFixers
+import com.intellij.openapi.editor.Editor
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.editor.KotlinSmartEnterHandler
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.psiUtil.endOffset
+import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
+import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
+
+class KotlinLastLambdaParameterFixer : SmartEnterProcessorWithFixers.Fixer<KotlinSmartEnterHandler>() {
+    override fun apply(editor: Editor, processor: KotlinSmartEnterHandler, element: PsiElement) {
+        if (element !is KtCallExpression) return
+
+        val bindingContext = element.analyze(BodyResolveMode.PARTIAL)
+        val resolvedCall = element.getResolvedCall(bindingContext) ?: return
+
+        val valueParameters = resolvedCall.candidateDescriptor.valueParameters
+
+        if (resolvedCall.valueArguments.size == valueParameters.size - 1) {
+            val type = valueParameters.last().type
+            if (KotlinBuiltIns.isExactFunctionOrExtensionFunctionType(type)) {
+                val doc = editor.document
+
+                var offset = element.endOffset
+                if (element.valueArgumentList?.rightParenthesis == null) {
+                    doc.insertString(offset, ")")
+                    offset++
+                }
+
+                var arity = type.constructor.parameters.size - 1
+                if (KotlinBuiltIns.isExactExtensionFunctionType(type)) arity--
+
+                if (arity <= 1) {
+                    doc.insertString(offset, "{\n}")
+                } else {
+                    val params = (1..arity).map { "x$it" }.joinToString(", ")
+                    doc.insertString(offset, "{ $params ->\n}")
+                }
+            }
+        }
+    }
+}