/*
 * JBoss, Home of Professional Open Source
 *
 * Copyright 2018 Red Hat, Inc. and/or its affiliates.
 *
 * 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 org.wildfly.security.manager;

import sun.reflect.Reflection;

/**
 * JDK-specific classes which are replaced for different JDK major versions. This class is for JDK 8.
 * @author <a href="mailto:jucook@redhat.com">Justin Cook</a>
 */
final class JDKSpecific {

    private static boolean active;
    private static int offset;

    static {

        boolean active = false;
        int offset = 0;
        try {
            // JDK-8014925 - An additional Reflection call may be on the call stack so check the offset needed.
            active = Reflection.getCallerClass(1) == WildFlySecurityManager.class || Reflection.getCallerClass(2) == WildFlySecurityManager.class;
            offset = Reflection.getCallerClass(1) == Reflection.class ? 2 : 1;
        } catch (Throwable ignored) {}

        JDKSpecific.active = active;
        // JDKSpecific.getCallerClass will also add 1 to the stack.
        JDKSpecific.offset = offset + 1;
    }

    public static Class<?> getCallerClass(int n) {
        if (active) {
            return Reflection.getCallerClass(n + offset);
        } else {
            throw new IllegalStateException("sun.reflect.Reflect.getCallerClass(int) not available.");
        }
    }

    public static boolean usingStackWalker() {
        return false;
    }

}
