/*
 * Copyright 2013 Google Inc. All Rights Reserved.
 *
 * 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.google.errorprone.bugpatterns.inject.guice;

import static com.google.errorprone.BugPattern.Category.GUICE;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.InjectMatchers.GUICE_INJECT_ANNOTATION;
import static com.google.errorprone.matchers.InjectMatchers.JAVAX_INJECT_ANNOTATION;
import static com.google.errorprone.matchers.InjectMatchers.hasInjectAnnotation;

import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker;
import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.MethodTree;
import com.sun.tools.javac.code.Symbol.MethodSymbol;

/**
 * This checker matches methods that 1) are not themselves annotated with @Inject (neither
 * javax.inject.Inject nor com.google.inject.Inject) 2) descend from a method that is annotated
 * with @com.google.inject.Inject
 *
 * @author sgoldfeder@google.com (Steven Goldfeder)
 */
@BugPattern(
  name = "OverridesGuiceInjectableMethod",
  summary =
      "This method is not annotated with @Inject, but it overrides a "
          + "method that is annotated with @com.google.inject.Inject. Guice will inject this "
          + "method, and it is recommended to annotate it explicitly.",
  explanation =
      "Unlike with `@javax.inject.Inject`, if a method overrides a method annotated with "
          + "`@com.google.inject.Inject`, Guice will inject it even if it itself is not annotated. "
          + "This differs from the behavior of methods that override `@javax.inject.Inject` "
          + "methods since according to the JSR-330 spec, a method that overrides a method "
          + "annotated with `@javax.inject.Inject` will not be injected unless it iself is "
          + "annotated with `@Inject`. Because of this difference, it is recommended that you "
          + "annotate this method explicitly.",
  category = GUICE,
  severity = WARNING
)
public class OverridesGuiceInjectableMethod extends BugChecker implements MethodTreeMatcher {

  @Override
  public Description matchMethod(MethodTree methodTree, VisitorState state) {
    // if method is itself annotated with @Inject or it has no ancestor methods, return NO_MATCH;
    if (!hasInjectAnnotation().matches(methodTree, state)) {
      MethodSymbol method = ASTHelpers.getSymbol(methodTree);
      for (MethodSymbol superMethod : ASTHelpers.findSuperMethods(method, state.getTypes())) {
        if (ASTHelpers.hasAnnotation(superMethod, GUICE_INJECT_ANNOTATION, state)) {
          return buildDescription(methodTree)
              .addFix(
                  SuggestedFix.builder()
                      .addImport(JAVAX_INJECT_ANNOTATION)
                      .prefixWith(methodTree, "@Inject\n")
                      .build())
              .setMessage(
                  String.format(
                      "This method is not annotated with @Inject, but overrides the method in %s "
                          + "that is annotated with @com.google.inject.Inject. Guice will inject "
                          + "this method, and it is recommended to annotate it explicitly.",
                      ASTHelpers.enclosingClass(superMethod).getQualifiedName()))
              .build();
        }
      }
    }
    return Description.NO_MATCH;
  }
}