/*
 * 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;

import static com.google.errorprone.BugPattern.Category.INJECT;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.bugpatterns.inject.ElementPredicates.isFirstConstructorOfMultiInjectedClass;
import static com.google.errorprone.matchers.InjectMatchers.IS_APPLICATION_OF_GUICE_INJECT;
import static com.google.errorprone.matchers.InjectMatchers.IS_APPLICATION_OF_JAVAX_INJECT;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.util.ASTHelpers.getSymbol;

import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker;
import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.AnnotationTree;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.Tree;

/**
 * Matches classes that have two or more constructors annotated with @Inject.
 *
 * @author sgoldfeder@google.com (Steven Goldfeder)
 */
@BugPattern(
  name = "MoreThanOneInjectableConstructor",
  summary =
      "This class has more than one @Inject-annotated constructor. Please remove the @Inject"
          + " annotation from all but one of them.",
  explanation =
      "Injection frameworks may use `@Inject` to determine how to construct an object"
          + " in the absence of other instructions. Annotating `@Inject` on a constructor tells"
          + " the injection framework to use that constructor. However, if multiple `@Inject`"
          + " constructors exist, injection frameworks can't reliably choose between them.",
  category = INJECT,
  severity = ERROR,
  altNames = {"inject-constructors", "InjectMultipleAtInjectConstructors"}
)
public class MoreThanOneInjectableConstructor extends BugChecker implements AnnotationTreeMatcher {

  private static final Matcher<AnnotationTree> IS_EITHER_INJECT =
      anyOf(IS_APPLICATION_OF_GUICE_INJECT, IS_APPLICATION_OF_JAVAX_INJECT);

  @Override
  public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
    if (IS_EITHER_INJECT.matches(tree, state)) {
      Tree injectedMember = state.getPath().getParentPath().getParentPath().getLeaf();
      if (isFirstConstructorOfMultiInjectedClass(getSymbol(injectedMember))) {
        return describeMatch(ASTHelpers.findEnclosingNode(state.getPath(), ClassTree.class));
      }
    }
    return Description.NO_MATCH;
  }

}