/*
 * AgentAttacher.java
 * Created on 2013/3/19
 *
 * Copyright (C) 2011-2013 Nippon Telegraph and Telephone Corporation
 *
 * This program 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

import java.lang.String;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.File;
import java.util.List;

import com.sun.tools.attach.AgentInitializationException;
import com.sun.tools.attach.AgentLoadException;
import com.sun.tools.attach.AttachNotSupportedException;
import com.sun.tools.attach.VirtualMachine;
import com.sun.tools.attach.VirtualMachineDescriptor;

class AgentAttacher
{
	
	static public void printAttachList(List<VirtualMachineDescriptor> vmlist)
	{
		/* Print vm list. */
		System.out.println("Num Process-Info");
		for(int i = 0, j = vmlist.size(); i < j; i++)
		{
			VirtualMachineDescriptor vmd = vmlist.get(i);
			System.out.printf("%3d %s%n", i, vmd.displayName());
		}
	}
	
	static public boolean attachProcess(VirtualMachineDescriptor vmd, String agentPath, String options)
	{
		try
		{
			/* attach to JVM. */
			VirtualMachine vm = VirtualMachine.attach(vmd);
			
			if (vm == null)
			{
				System.err.println("Not found virtual-machine...");
				return false;
			}
			
			/* load agent to JVM. */
			if (options.length() == 0)
			{
				vm.loadAgentPath(agentPath);
			}
			else
			{
				vm.loadAgentPath(agentPath, options);
			}
			
			/* detach JVM. */
			vm.detach();
		}
		catch (SecurityException e)
		{
			System.err.println("Attach is deny.");
			System.err.println("Please check security-manager in Java application.");
			
			return false;
		}
		catch (AttachNotSupportedException e)
		{
			System.err.println("Attach is not supported by JavaVM.");
			System.err.println("Or no respones attach-request by JavaVM.");
			
			return false;
		}
		catch (AgentLoadException e)
		{
			System.err.println("Failure agent-load.");
			System.err.println("Please confirm agent-load-method exists. e.g. Agent_OnAttach.");
			System.err.println("And confirm required shared-library exists.");
			
			return false;
		}
		catch (AgentInitializationException e)
		{
			System.err.println("Agent failure in initailization.");
			System.err.println("return code:" + Integer.toString(e.returnValue()));
			System.err.println("Please check agent library's log.");
			
			return false;
		}
		catch (IOException e)
		{
			/* Unknown exception. */
			e.printStackTrace();
			return false;
		}
		
		return true;
	}
	
	static public void main(String[] args)
	{
		/* Check arguments. */
		if (args.length == 1 && (args[0].equals("--help") || args[0].equals("-h")))
		{
			System.out.println("agentattacher agent-full-path [agent-options]");
			System.out.println("agentattacher --help|-h");
			
			return;
		}
		else if (args.length <= 0)
		{
			System.out.println("please set commandline argment...");
			
			return;
		}
		else if (args.length >= 3)
		{
			System.out.println("commandline argment is too large...");
			return;
		}
		
		/*
		 * args.length == 1
		 *  agentpath : args[0]
		 *  agent opt : ""
		 *  
		 *  like as below
		 *  # java -agentpath:args[0] ~java app~
		 * 
		 * args.length == 2
		 *  agentpath : args[0]
		 *  agent opt : args[1]
		 *  
		 *  like as below
		 *  # java -agentpath:args[0]=args[1] ~java app~
		 */
		
		/* Is exist agent file. */
		File agentFile = new File(args[0]);
		if (!agentFile.exists())
		{
			System.out.println("agent is no exist...");
			return;
		}
		
		/* Copy strings from arguments. */
		String agent_path = args[0];
		String options = "";
		if (args.length == 2)
		{
			options = args[1];
		}
		
		/* Get vm list. */
		List<VirtualMachineDescriptor> vmlist = VirtualMachine.list();
		if (vmlist == null)
		{
			System.out.println("Not found attachable process.");
			return;
		}
		
		/* Print attachable java application list. */
		printAttachList(vmlist);
		
		/* Get target process number. */
		System.out.print("Input attach target process-number:");
		BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));
		
		/* Parse Input integer. */
		int num;
		try
		{
			num = Integer.parseInt(bReader.readLine());
		}
		catch (NumberFormatException e)
		{
			num = -1;
		}
		catch (IOException e)
		{
			num = -1;
		}
		
		/* Check input number. */
		if (num < 0 || num >= vmlist.size())
		{
			System.out.println("Illegal Number");
			System.out.println("Attacher is terminating now...");
		}
		else
		{
			/* Attach process. */
			if (!attachProcess(vmlist.get(num), agent_path, options))
			{
				System.out.println("Attacher failed.");
			}
			else
			{
				System.out.println("Attacher is succeeded.");
			}
		}
	}
}