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/*
 * Copyright 2012-2016 the original author or 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 io.joshworks.snappy.loader;

import java.lang.Thread.UncaughtExceptionHandler;
import java.lang.reflect.Method;

/**
 * Utility class that used by {@link Launcher}s to call a main method. This class allows
 * methods to be executed within a thread configured with a specific context class loader.
 *
 * @author Phillip Webb
 */
public class MainMethodRunner implements Runnable {

    private final String mainClassName;

    private final String[] args;

    /**
     * Create a new {@link MainMethodRunner} instance.
     *
     * @param mainClass the main class
     * @param args      incoming arguments
     */
    public MainMethodRunner(String mainClass, String[] args) {
        this.mainClassName = mainClass;
        this.args = (args == null ? null : args.clone());
    }

    @Override
    public void run() {
        try {
            Class mainClass = Thread.currentThread().getContextClassLoader()
                    .loadClass(this.mainClassName);
            Method mainMethod = mainClass.getDeclaredMethod("main", String[].class);
            if (mainMethod == null) {
                throw new IllegalStateException(
                        this.mainClassName + " does not have a main method");
            }
            mainMethod.invoke(null, new Object[]{this.args});
        } catch (Exception ex) {
            UncaughtExceptionHandler handler = Thread.currentThread()
                    .getUncaughtExceptionHandler();
            if (handler != null) {
                handler.uncaughtException(Thread.currentThread(), ex);
            }
            throw new RuntimeException(ex);
        }
    }

}