/*
 * Copyright 2016 The Error Prone Authors.
 *
 * 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;

import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;

import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.CompilationUnitTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.CompilationUnitTree;

/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
    summary = "Declaring types inside package-info.java files is very bad form",
    severity = ERROR)
public class PackageInfo extends BugChecker implements CompilationUnitTreeMatcher {
  @Override
  public Description matchCompilationUnit(CompilationUnitTree tree, VisitorState state) {
    if (tree.getSourceFile() == null) {
      return NO_MATCH;
    }
    String name = ASTHelpers.getFileName(tree);
    int idx = name.lastIndexOf('/');
    if (idx != -1) {
      name = name.substring(idx + 1);
    }
    if (!name.equals("package-info.java")) {
      return NO_MATCH;
    }
    if (tree.getTypeDecls().isEmpty()) {
      return NO_MATCH;
    }
    return describeMatch(tree.getTypeDecls().getFirst());
  }
}
