//File:  edit.java
//CS 471 - Operating Systems Project
//Dennis Pereira, Ely Soto, John Cavalieri

//Edit is a command that is part of the baseline simulator
//it is a simple program the takes a filename as an argument
//or if no file name is given, then the user is prompted for one
//The file is created and all text typed from that point forward
//is saved in the file
//the user can stop the edit command by typing a blank line
//this will end the edit command, and close the file for editing


import java.io.*;

public class edit extends VMachine {
    
    /** Creates new edit */
    public edit() {
    }
    
    public void run() {
        
        RandomAccessFile editstream = null;
        
        try
        {
		//string variable for the filename
            String input;
		if there is a file, then read it into the args array
            if(args.length > 0)
            {
                input = args[0];
            }
            else
            {
			//no file was given in the command, so prompt the user for one
                sysapi.Write(OUT,"Please enter the file to edit: ");
                input = sysapi.Read(IN);
            }
            
		//see if the user has typed a blank line
            if(input.compareTo("")!=0)
            {
			//create the file in the users path
                File editFile = new File(sysapi.findUser(owner).getcurrentPath() + input);
                editFile.createNewFile();
                editstream = new RandomAccessFile(editFile,"rw");
                
                sysapi.Write(OUT,"Editing file: " + input + "\n");
			//while the user hasn't typed a blank line, continue to read
			//the user input
                while(input.compareTo("")!=0)
                {
                    input = sysapi.Read(IN);
                    if(input.compareTo("")!=0)
                    {
                        editstream.writeBytes(input + "\n");
                    }
                }
                sysapi.Write(OUT,editFile.getName() + " saved.\n");
                
                editstream.close();
            }
            else
            {
			//the user did not type a name when prompted
                sysapi.Write(OUT,"No file edited.\n");
            }
        }
        catch(Exception ex)
        {
		//something out of the ordinary happened
            System.out.println("edit threw Exception: " + ex);
        }
        
        sysapi.Exit(vmh,owner);
    }
    
}