/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.adversaries;

import static java.util.stream.Collectors.toSet;

import java.lang.StackWalker.StackFrame;
import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Stream;

/**
 * An adversary that delegates failure injection only when invoked through certain call sites.
 * For every potential failure injection the current stack trace (the elements of it) are analyzed
 * and if there's a match with the specified victims then failure will be delegated to the actual
 * {@link Adversary} underneath.
 */
public class ClassGuardedAdversary extends StackTraceElementGuardedAdversary {

    public ClassGuardedAdversary(Adversary delegate, Class<?>... victimClassSet) {
        super(delegate, new ClassFramePredicate(victimClassSet));
    }

    /**
     * Specifies victims as arbitrary {@link StackTraceElement} {@link Predicate}.
     *
     * @param delegate {@link Adversary} to delegate calls to.
     * @param predicate arbitrary {@link Predicate} for {@link StackTraceElement} in the executing
     * thread and if any of the elements in the current stack trace matches then failure is injected.
     */
    public ClassGuardedAdversary(Adversary delegate, Predicate<StackFrame> predicate) {
        super(delegate, predicate);
    }

    private static class ClassFramePredicate implements Predicate<StackFrame> {
        private final Set<String> victimClasses;

        ClassFramePredicate(Class<?>... victimClassSet) {
            this.victimClasses = Stream.of(victimClassSet).map(Class::getName).collect(toSet());
        }

        @Override
        public boolean test(StackFrame stackFrame) {
            return victimClasses.contains(stackFrame.getClassName());
        }
    }
}
