/*
 * Copyright 2000-2014 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 com.siyeh.ig.classlayout;

import com.intellij.codeInsight.AnnotationUtil;
import com.intellij.codeInsight.intention.AddAnnotationPsiFix;
import com.intellij.psi.*;
import com.intellij.psi.util.MethodSignature;
import com.intellij.psi.util.PsiUtil;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.DelegatingFix;
import com.siyeh.ig.InspectionGadgetsFix;
import org.jetbrains.annotations.Nls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.List;

/**
 * @author Bas Leijdekkers
 */
public class InterfaceMayBeAnnotatedFunctionalInspection extends BaseInspection {
  @Nls
  @NotNull
  @Override
  public String getDisplayName() {
    return InspectionGadgetsBundle.message("interface.may.be.annotated.functional.display.name");
  }

  @NotNull
  @Override
  protected String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message("interface.may.be.annotated.functional.problem.descriptor");
  }

  @Nullable
  @Override
  protected InspectionGadgetsFix buildFix(Object... infos) {
    final PsiClass aClass = (PsiClass)infos[0];
    return new DelegatingFix(new AddAnnotationPsiFix(CommonClassNames.JAVA_LANG_FUNCTIONAL_INTERFACE, aClass, PsiNameValuePair.EMPTY_ARRAY));

  }

  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new InterfaceMayBeAnnotatedFunctionalVisitor();
  }

  private static class InterfaceMayBeAnnotatedFunctionalVisitor extends BaseInspectionVisitor {

    @Override
    public void visitClass(PsiClass aClass) {
      if (!PsiUtil.isLanguageLevel8OrHigher(aClass)) {
        return;
      }
      super.visitClass(aClass);
      if (!aClass.isInterface() || AnnotationUtil.isAnnotated(aClass, "java.lang.FunctionalInterface", false)) {
        return;
      }
      if (LambdaHighlightingUtil.checkInterfaceFunctional(aClass) != null) {
        return;
      }
      final List<HierarchicalMethodSignature> candidates = LambdaUtil.findFunctionCandidates(aClass);
      if (candidates == null || candidates.size() != 1) {
        return;
      }
      final MethodSignature signature = candidates.get(0);
      if (signature.getTypeParameters().length > 0) {
        return;
      }
      registerClassError(aClass, aClass);
    }
  }
}