import java.util.*;
import java.io.*;
import java.net.*;

class VirtualMachineManager
{
	Map allVMs = null;
	Map pipes = null;
	static LoadClass loader;
	public VirtualMachineManager()
	{
		allVMs = Collections.synchronizedMap(new HashMap());
		pipes = Collections.synchronizedMap(new HashMap());
		try {
			loader = new LoadClass();
		}
		catch (Exception e) {
			System.out.println("Error creating kernel!");
			System.exit(1);
		}
	}
	
	public boolean createVM(String id, String filename, String par, String child, String sib, String i, String o, String args)
	{
		VirtualMachine returned = null;
		VirtualMachine finder = null;
		if (args == null) args = new String();
		try {
			returned = (VirtualMachine)loader.classLoader(filename, args);
		}
		catch (Exception e) {
			System.out.println(e.toString());return false;}
		String inputSrcID = null;
		String outputSrcID = null;
		int keyStart = 0;
		int keyEnd = 0;
		String ioID = null;
		if (returned == null)//if class failed to load
		{
			return false;
		}
		else
		{
			//set input of new virtual machine
			if (i.equals("System.in"))
			{
				returned.in = new BufferedReader(new InputStreamReader(System.in));
			}
			else
			{
				keyEnd = i.indexOf(".");
				if (keyEnd != -1)
				{
					ioID = i.substring(keyStart,keyEnd);
					if (allVMs.containsKey(ioID))
					{
						finder = (VirtualMachine)allVMs.get(ioID);
						returned.in = finder.in;
					}
					else return false;
				}
			}
			//set output of new virtual machne
			if (o.equals("System.out"))
			{
				returned.out = new BufferedWriter(new PrintWriter(System.out));
			}
			else
			{
				keyEnd = o.indexOf(".");
				ioID = o.substring(keyStart,keyEnd);
				if (allVMs.containsKey(ioID))
				{
					finder = (VirtualMachine)allVMs.get(ioID);
					returned.out = finder.out;
				}
				else return false;
			}
			//if new shell being created, ensure kernel being passed
			if (filename.equals("Shell"))
			{
				((Shell)returned).setKernel(this);
			}
			//set child
			if (child.equals("NULL"))
			{
				returned.setChild(null);
			}
			else
			{
				if (allVMs.containsKey(child))
				{
					finder = (VirtualMachine)allVMs.get(child);
					returned.setChild(finder);
				}
				else return false;
			}
			//set sib
			if (sib.equals("NULL"))
			{
				returned.setSibling(null);
			}
			else
			{
				if (allVMs.containsKey(sib))
				{
					finder = (VirtualMachine)allVMs.get(sib);
					returned.setSibling(finder);
				}
				else return false;
			}
			//set par
			if (par.equals("NULL"))
			{
				returned.setParent(null);
			}
			else
			{
				if (allVMs.containsKey(par))
				{
					finder = (VirtualMachine)allVMs.get(par);
					returned.setParent(finder);
				}
				else return false;
			}
			//add to structure
			allVMs.put(id,returned);
			return true;
		}
	}
	
	public void createPipe(String id)
	{
		Pipe pipe = new Pipe();
		pipes.put(id, pipe);
	}
	
	
	public void setPipeInput(String vmID, String pID)
	{
		VirtualMachine finder = null;
		Pipe pipe = null;
		if (pipes.containsKey(pID))
		{
			pipe = (Pipe)pipes.get(pID);
			if (allVMs.containsKey(vmID))
			{
				finder = (VirtualMachine)allVMs.get(vmID);
				pipe.pIn = new PipedReader();
				pipe.inID = vmID;
				finder.in = new BufferedReader(pipe.pIn);
				try {
					pipe.pIn.connect(pipe.pOut);
				}
				catch (IOException e) {System.out.println(e.toString());}
			}
		}
	}
	
	public void setPipeOutput(String vmID, String pID)
	{
		VirtualMachine finder = null;
		Pipe pipe = null;
		if (allVMs.containsKey(vmID))
		{
			finder = (VirtualMachine)allVMs.get(vmID);
			if (pipes.containsKey(pID))
			{
				pipe = (Pipe)pipes.get(pID);
				pipe.pOut = new PipedWriter();
				pipe.outID = vmID;
			}
			finder.out = new BufferedWriter(pipe.pOut);
		}
	}
	
	public void setInput(String srcVMID, String filename)
	{
		VirtualMachine finder = null;
		if (allVMs.containsKey(srcVMID))
		{
			finder = (VirtualMachine)allVMs.get(srcVMID);
			try {
				finder.in = new BufferedReader (new FileReader (filename));
			}
			catch (FileNotFoundException e) {System.out.println(filename + "was not found");}
		}
	}
	
	public void setOutput(String srcVMID, String filename)
	{
		VirtualMachine finder = null;
		if (allVMs.containsKey(srcVMID))
		{
			finder = (VirtualMachine)allVMs.get(srcVMID);	
			try {
				finder.out = new BufferedWriter (new FileWriter (filename));
			}
			catch (IOException e) {System.out.println(e.toString());}
		}
	}

	public void executeShell()
	{
		VirtualMachine runner = null;
		String x = "VM1000";
		runner = (VirtualMachine)allVMs.get(x);
		runner.start();
	}

	public void executeScript()
	{
		VirtualMachine runner = null;
		String curntID;
		HashSet allIDs = null;
		allIDs = (new HashSet(allVMs.keySet()));
		for (Iterator i = allIDs.iterator(); i.hasNext();)
		{
			curntID = (String)i.next();
			if (!(curntID.equals("VM1000")))
			{
				runner = (VirtualMachine)allVMs.get(curntID);
				runner.start();
			}
		}
		for (Iterator i = allIDs.iterator(); i.hasNext();)
		{
			curntID = (String)i.next();
			if (!(curntID.equals("VM1000")))
			{
			runner = (VirtualMachine)allVMs.get(curntID);
			while (runner.isAlive())
			{
				Thread.currentThread().yield();
			}
			}
		}
	}
}