// written by Sunita Kanchinadam.
// This class is a test driver to create a pseudo file system and
// implement some of the  OS commands.
import EDU.neu.ccs.demeter.dj.*;

import DuVisitor;
import File;
import Directory;
import java.io.*;

public class OS {
 
// constructor
  OS()
  {
  }

/******************************************************************/
// method       : main
// parameters   : String array
// return value : void
// description  : creates filesystem, and lets the user run the 
//		  implemented commands on the file system.
/******************************************************************/


  public static void main(String argv[])
  {
    // creates a class graph object to define traversals
      cg = new ClassGraph();
      System.out.println("The class graph is");
      System.out.println(cg);                                           
      System.out.println("End class graph");

	// creates a pseudo file system.
      OS myos = new OS();
      Directory fs = myos.CreateFileSystem();

      System.out.println("The commands are - ");
      System.out.println("ls ");
      System.out.println("cp <file1> <file2> ");
      System.out.println("mv <file1> <file2> ");
      System.out.println("mkdir  <dirname> ");
      System.out.println("du [ -L ]");
      System.out.println("exit ");

	// lets the user login.
	// this does not perform any security checks, but has been 
	// implemented as a hook for any future implementation.
      try { 
         System.out.print("login : ");
     
         while ((numread = System.in.read(cmd)) >= 0)
         {
	  login =  new String(cmd, 0, numread);
	  break;
         }
      } catch (IOException ie) {
	System.out.println("OS crashed , Please reboot\n");
	System.exit(0);
      }
      System.out.print("\nprompt > ");

      String exit = new String("exit\n");

  	// waits in an infifite loop for the next command
	// and executes the command till the user
	// exits out of the system.

      while (true)
      {
	try {

	// read from the inputstream till end of line
	while ((numread = System.in.read(cmd)) >= 0)
	{
	   System.out.write(cmd, 0, numread);
	   break;
	}

	String command = new String(cmd, 0, numread);

	// if exit is typed , get out of OS
	if (command.equals(exit))
	   System.exit(0);

	// if ls is typed list all the files and subdirs 
	if (command.equals("ls\n"))
	   fs.List();
   
	// if cp is typed copy the file.
	if ( numread >= 2)
        {
            if (command.substring(0,2).equals("cp"))
   	    {
	   	String f1 = command.substring(3,command.indexOf(" ",4));
	   	String name = command.substring(f1.length()+3, command.indexOf("\n",f1.length()+3));
           	fs.CreateFile(name);
	    }

	    // if mv is typed replace the existing file 
	    // with the file with new name.
            else if (command.substring(0,2).equals("mv"))
   	    {
	   	String f1 = command.substring(3,command.indexOf(" ",4));
	   	String name = command.substring(f1.length()+3, command.indexOf("\n",f1.length()+3));
           	fs.moveFile(f1,name);
	    }
	    else if (command.substring(0,2).equals("du"))
	    {
		DuVisitor du;
	   	String name;
	        if ( numread >= 4 )
		{
		   name = command.substring(3, command.indexOf("\n",3));
		   System.out.println("option is " + name );
//	           du = new DuVisitor("-L");
		}
		else
		{
//		   System.out.println("option is ");
//	           du = new DuVisitor("-r");
		   name = "-r";
		}
		System.out.println("Total Size is " + fs.GetTotalSize(name));
	    }
	}

        // if mkdir is typed, create a new directory.
	if (numread >= 5)
	{
           if (command.substring(0,5).equals("mkdir"))
	   	fs.Mkdir(command.substring(5,command.indexOf("\n",5)));
        } 

	System.out.print("\nprompt > ");
	} catch (IOException ie) {
	   System.out.println("Exception raised");
	   System.out.println("Your OS crashed, Please reboot.");
	   System.exit(0);
	}

      }
 }

/******************************************************************/
// method       : CreateFileSystem
// parameters   : void
// return value : Directory
// description 	: Returns the directory that has been built with
//		  files and sub directories.
/******************************************************************/  

public Directory CreateFileSystem()
{
      Directory myFileSystem1 = new Directory("sunita1");
//      myFileSystem1.setOwner("root");

      Directory d1 = myFileSystem1.Mkdir("sk1");
      if ( d1 != null)
      {
          d1.CreateFile("sk11.java");
          Directory d11 = d1.Mkdir("sk11");
	  if (d11 != null)
	  {
             d11.CreateFile("sk111.java");
	  }
          d1.CreateFile("sk12.java");
      }

      Directory d2 = myFileSystem1.Mkdir("sk2");
      if ( d2 != null)
      {
         d2.CreateFile("sk21.java");
         d2.CreateFile("sk22.java");
         d2.CreateFile("sk23.java");
      }

      Directory d3 = myFileSystem1.Mkdir("sk3");
      if (d3 != null)
      {
         d3.CreateFile("sk31.java");
      }

    Directory myFileSystem2 = new Directory("sunita2");
    myFileSystem2.CreateFile("sk12link.java");
    Directory dlink1 = myFileSystem2.Mkdir("skl2");
    if (dlink1 != null)
    {
       dlink1.CreateFile("sklink1.java");
       dlink1.CreateFile("sklink2.java");
    }

//    myFileSystem1.CreateHardLink("sunitalink",myFileSystem2);
//    myFileSystem1.CreateSoftLink("sunitalink",myFileSystem2);

    return (myFileSystem1);

  }

private static byte cmd[] = new byte[1000];
private static int numread;
private static String login;

public static ClassGraph cg;
}