/*
 * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package crules;

import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.sun.source.util.JavacTask;
import com.sun.source.util.TaskEvent.Kind;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.tree.TreeScanner;

import static com.sun.tools.javac.code.Flags.ENUM;
import static com.sun.tools.javac.code.Flags.FINAL;
import static com.sun.tools.javac.code.Flags.STATIC;
import static com.sun.tools.javac.code.Flags.SYNTHETIC;
import static com.sun.tools.javac.code.Kinds.Kind.*;

/**This analyzer guards against non-final static fields.*/
public class MutableFieldsAnalyzer extends AbstractCodingRulesAnalyzer {

    public MutableFieldsAnalyzer(JavacTask task) {
        super(task);
        treeVisitor = new MutableFieldsVisitor();
        eventKind = Kind.ANALYZE;
    }

    private boolean ignoreField(String className, String field) {
        Set<String> fieldsToIgnore = classFieldsToIgnoreMap.get(className);
        return (fieldsToIgnore) != null && fieldsToIgnore.contains(field);
    }

    class MutableFieldsVisitor extends TreeScanner {

        @Override
        public void visitVarDef(JCVariableDecl tree) {
            boolean isJavacPack = tree.sym.outermostClass().fullname.toString()
                    .contains(packageToCheck);
            if (isJavacPack &&
                (tree.sym.flags() & SYNTHETIC) == 0 &&
                tree.sym.owner.kind == TYP) {
                if (!ignoreField(tree.sym.owner.flatName().toString(),
                        tree.getName().toString())) {
                    boolean enumClass = (tree.sym.owner.flags() & ENUM) != 0;
                    boolean nonFinalStaticEnumField =
                            (tree.sym.flags() & (ENUM | FINAL)) == 0;
                    boolean nonFinalStaticField =
                            (tree.sym.flags() & STATIC) != 0 &&
                            (tree.sym.flags() & FINAL) == 0;
                    if (enumClass ? nonFinalStaticEnumField : nonFinalStaticField) {
                        messages.error(tree, "crules.err.var.must.be.final", tree);
                    }
                }
            }
            super.visitVarDef(tree);
        }

    }

    private static final String packageToCheck = "com.sun.tools.javac";

    private static final Map<String, Set<String>> classFieldsToIgnoreMap =
                new HashMap<>();

    private static void ignoreFields(String className, String... fieldNames) {
        classFieldsToIgnoreMap.put(className, new HashSet<>(Arrays.asList(fieldNames)));
    };

    static {
        ignoreFields("com.sun.tools.javac.util.JCDiagnostic", "fragmentFormatter");
        ignoreFields("com.sun.tools.javac.util.JavacMessages", "defaultBundle", "defaultMessages");
        ignoreFields("com.sun.tools.javac.file.JRTIndex", "sharedInstance");
        ignoreFields("com.sun.tools.javac.main.JavaCompiler", "versionRB");
        ignoreFields("com.sun.tools.javac.code.Type", "moreInfo");
        ignoreFields("com.sun.tools.javac.util.SharedNameTable", "freelist");
        ignoreFields("com.sun.tools.javac.util.Log", "useRawMessages");
        ignoreFields("com.sun.tools.javac.util.JDK9Wrappers$ModuleFinder",
                "moduleFinderClass", "ofMethod");
        ignoreFields("com.sun.tools.javac.util.JDK9Wrappers$Configuration",
                "configurationClass", "resolveRequiresAndUsesMethod");
        ignoreFields("com.sun.tools.javac.util.JDK9Wrappers$Layer",
                "layerClass", "bootMethod", "defineModulesWithOneLoaderMethod", "configurationMethod");
        ignoreFields("com.sun.tools.javac.util.JDK9Wrappers$ServiceLoaderHelper",
                "loadMethod");
        ignoreFields("com.sun.tools.javac.util.JDK9Wrappers$VMHelper",
                "vmClass", "getRuntimeArgumentsMethod");
        ignoreFields("com.sun.tools.javac.util.ModuleHelper",
                "addExportsMethod", "getUnnamedModuleMethod", "getModuleMethod");
    }

}