guava inspection: conversion for FluentIterable.last (IDEA-160221)

java/typeMigration/src/com/intellij/refactoring/typeMigration/rules/guava/GuavaFluentIterableConversionRule.java

@@ -229,6 +229,24 @@ public class GuavaFluentIterableConversionRule extends BaseGuavaTypeConversionRu
       };
       needSpecifyType = false;
     }
+    else if (methodName.equals("last")) {
+      descriptorBase = new TypeConversionDescriptor("$it$.last()", null) {
+        @Override
+        public PsiExpression replace(PsiExpression expression, TypeEvaluator evaluator) {
+          final JavaCodeStyleManager codeStyleManager = JavaCodeStyleManager.getInstance(expression.getProject());
+          String varA = suggestName("a", codeStyleManager, expression);
+          String varB = suggestName("b", codeStyleManager, expression);
+          setReplaceByString("$it$.reduce((" + varA + ", " + varB + ") -> " + varB + ")");
+          return super.replace(expression, evaluator);
+        }
+
+        private  String suggestName(String baseName, JavaCodeStyleManager codeStyleManager, PsiElement place) {
+          final SuggestedNameInfo suggestedNameInfo = codeStyleManager
+            .suggestVariableName(VariableKind.LOCAL_VARIABLE, baseName, null, null, false);
+          return codeStyleManager.suggestUniqueVariableName(suggestedNameInfo, place, false).names[0];
+        }
+      };
+    }
     else {
       final TypeConversionDescriptorFactory base = DESCRIPTORS_MAP.get(methodName);
       if (base != null) {

java/typeMigration/test/com/intellij/codeInsight/inspections/GuavaInspectionTest.java

@@ -289,6 +289,10 @@ public class GuavaInspectionTest extends JavaCodeInsightFixtureTestCase {
     doTest();
   }
 
+  public void testFluentIterableLast() {
+    doTest();
+  }
+
   private void doTestNoQuickFixes(Class<? extends PsiElement>... highlightedElements) {
     myFixture.configureByFile(getTestName(true) + ".java");
 

java/typeMigration/testData/inspections/guava/fluentIterableLast.java

@@ -0,0 +1,11 @@
+import com.google.common.base.Optional;
+import com.google.common.collect.FluentIterable;
+
+import java.util.ArrayList;
+
+public class LastMigration {
+
+  void m(ArrayList<String> ss, String a, String b) {
+    Optional<String> last = FluentIterable.fr<caret>om(ss).last();
+  }
+}

java/typeMigration/testData/inspections/guava/fluentIterableLast_after.java

@@ -0,0 +1,9 @@
+import java.util.ArrayList;
+import java.util.Optional;
+
+public class LastMigration {
+
+  void m(ArrayList<String> ss, String a, String b) {
+    Optional<String> last = ss.stream().reduce((a1, b1) -> b1);
+  }
+}