/*
 * Copyright 2015 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.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.util.ASTHelpers.hasAnnotation;
import static com.google.errorprone.util.ASTHelpers.streamSuperMethods;

import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.StandardTags;
import com.google.errorprone.ErrorProneFlags;
import com.google.errorprone.VisitorState;
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 javax.inject.Inject;
import javax.lang.model.element.Modifier;

/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
    summary = "method overrides method in supertype; expected @Override",
    severity = WARNING,
    tags = StandardTags.STYLE)
public class MissingOverride extends BugChecker implements MethodTreeMatcher {

  /** if true, don't warn on missing {@code @Override} annotations inside interfaces */
  private final boolean ignoreInterfaceOverrides;

  @Inject
  public MissingOverride(ErrorProneFlags flags) {
    this.ignoreInterfaceOverrides =
        flags.getBoolean("MissingOverride:IgnoreInterfaceOverrides").orElse(false);
  }

  @Override
  public Description matchMethod(MethodTree tree, VisitorState state) {
    var sym = ASTHelpers.getSymbol(tree);
    if (sym.isStatic()) {
      return NO_MATCH;
    }
    if (hasAnnotation(sym, Override.class, state)) {
      return NO_MATCH;
    }
    if (ignoreInterfaceOverrides && sym.enclClass().isInterface()) {
      return NO_MATCH;
    }
    return streamSuperMethods(sym, state.getTypes())
        .findFirst()
        .filter(unused -> ASTHelpers.getGeneratedBy(state).isEmpty())
        // to allow deprecated methods to be removed non-atomically, we permit overrides of
        // @Deprecated to skip the annotation
        .filter(override -> !hasAnnotation(override, Deprecated.class, state))
        .map(
            override ->
                buildDescription(tree)
                    .addFix(SuggestedFix.prefixWith(tree, "@Override "))
                    .setMessage(
                        String.format(
                            "%s %s method in %s; expected @Override",
                            sym.getSimpleName(),
                            override.enclClass().isInterface()
                                    || override.getModifiers().contains(Modifier.ABSTRACT)
                                ? "implements"
                                : "overrides",
                            override.enclClass().getSimpleName()))
                    .build())
        .orElse(NO_MATCH);
  }
}
