java/java.hints/src/org/netbeans/modules/java/hints/bugs/Unused.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.netbeans.modules.java.hints.bugs;

import com.sun.source.tree.Tree.Kind;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import javax.lang.model.element.ElementKind;
import org.netbeans.modules.java.editor.base.semantic.UnusedDetector;
import org.netbeans.modules.java.editor.base.semantic.UnusedDetector.UnusedDescription;
import org.netbeans.spi.editor.hints.ErrorDescription;
import org.netbeans.spi.editor.hints.Fix;
import org.netbeans.spi.java.hints.ErrorDescriptionFactory;
import org.netbeans.spi.java.hints.Hint;
import org.netbeans.spi.java.hints.HintContext;
import org.netbeans.spi.java.hints.JavaFixUtilities;
import org.netbeans.spi.java.hints.TriggerTreeKind;
import org.openide.util.NbBundle.Messages;

/**
 *
 * @author lahvac
 */
@Hint(displayName = "#DN_org.netbeans.modules.java.hints.bugs.Unused", description = "#DESC_org.netbeans.modules.java.hints.bugs.Unused", category="bugs", options=Hint.Options.QUERY, suppressWarnings="unused")
@Messages({
    "DN_org.netbeans.modules.java.hints.bugs.Unused=Unused Element",
    "DESC_org.netbeans.modules.java.hints.bugs.Unused=Detects and reports unused variables, methods and classes"
})
public class Unused {

    @TriggerTreeKind(Kind.COMPILATION_UNIT)
    public static List<ErrorDescription> unused(HintContext ctx) {
        List<UnusedDescription> unused = UnusedDetector.findUnused(ctx.getInfo(), () -> ctx.isCanceled());
        List<ErrorDescription> result = new ArrayList<>(unused.size());
        for (UnusedDescription ud : unused) {
            if (ctx.isCanceled()) {
                break;
            }
            ErrorDescription err = convertUnused(ctx, ud);
            if (err != null) {
                result.add(err);
            }
        }
        return result;
    }

    @Messages({
        "# {0} - variable name",
        "ERR_NeitherReadOrWritten=Variable {0} is neither read or written to",
        "# {0} - variable name",
        "ERR_NotWritten=Variable {0} is never written to",
        "# {0} - variable name",
        "ERR_NotRead=Variable {0} is never read",
        "# {0} - element name",
        "ERR_NotUsed={0} is never used",
        "ERR_NotUsedConstructor=Constructor is never used",
        "# {0} - element name",
        "FIX_RemoveUsedElement=Remove unused \"{0}\"",
        "FIX_RemoveUsedConstructor=Remove unused constructor",
    })
    private static ErrorDescription convertUnused(HintContext ctx, UnusedDescription ud) {
        //TODO: switch expression candidate!
        String name = ud.unusedElement.getSimpleName().toString();
        String message;
        Fix fix = null;
        switch (ud.reason) {
            case NOT_WRITTEN_READ: message = Bundle.ERR_NeitherReadOrWritten(name);
                fix = JavaFixUtilities.removeFromParent(ctx, Bundle.FIX_RemoveUsedElement(name), ud.unusedElementPath);
                break;
            case NOT_WRITTEN: message = Bundle.ERR_NotWritten(name);
                break;
            case NOT_READ: message = Bundle.ERR_NotRead(name);
                fix = JavaFixUtilities.safelyRemoveFromParent(ctx, Bundle.FIX_RemoveUsedElement(name), ud.unusedElementPath);
                break;
            case NOT_USED:
                if (ud.unusedElement.getKind() == ElementKind.CONSTRUCTOR) {
                    message = Bundle.ERR_NotUsedConstructor();
                    fix = JavaFixUtilities.removeFromParent(ctx, Bundle.FIX_RemoveUsedConstructor(), ud.unusedElementPath);
                } else {
                    message = Bundle.ERR_NotUsed(name);
                    fix = JavaFixUtilities.removeFromParent(ctx, Bundle.FIX_RemoveUsedElement(name), ud.unusedElementPath);
                }
                break;
            default:
                throw new IllegalStateException("Unknown unused type: " + ud.reason);
        }
        return fix != null ? ErrorDescriptionFactory.forName(ctx, ud.unusedElementPath, message, fix)
                           : ErrorDescriptionFactory.forName(ctx, ud.unusedElementPath, message);
    }
}