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

//The transmit command is an enhanced feature of our OS simulator
//this command enables inter-process communication
//transmit's functionality is similar to 'send' however, the messaging
//is between processes rather than users

public class transmit extends VMachine {
    
    public transmit() {
    }
    
    public void run() {
        
        try
        {
		//if there are two arguments
		//then try to 'transmit' the message
            if(args.length == 2)
            {
			//show error if not possible to 'transmit'
                if(!sysapi.writeProcessMsg(args[0],args[1]))
                { sysapi.Write(OUT,"Thread Not Found.\n"); }
            }
		//if there is only one arg, prompt the user for more input
            else if(args.length == 1)
            {
                String buffer = "";
                String str = "";
                
                str = sysapi.Read(IN);
			//while there is still input
                while(str.compareTo("") != 0)
                {
			//if a blank line, then finish
                    if(buffer.compareTo("") == 0)
                    { buffer = str; }
			//if more input, add to buffer
                    else
                    { buffer = buffer + "\n" + str; }
			//ask for more input
                    str = sysapi.Read(IN);
                }
                //try to 'transmit'
                if(!sysapi.writeProcessMsg(args[0],buffer))
                { sysapi.Write(OUT,"Thread Not Found.\n"); }
            }
		//if there is more than 2 args then loop through all of them passing from one to the other
            else if(args.length > 2)
            {
                String buffer = "";
			//for each process; add message to buffer
                for(int i = 1; i < args.length; i++)
                { buffer = buffer + " " + args[i]; }
                buffer = buffer + "\n";
                //try to 'transmit'
                if(!sysapi.writeProcessMsg(args[0],buffer))
                { sysapi.Write(OUT,"Thread Not Found.\n"); }
            }
		//if no arguments are given then prompt the user for the parameters
            else if(args.length == 0)
            {
                String buffer = "";
                String str = "";

		//prompt user for input                
                sysapi.Write(OUT,"Enter Process ID: ");
                String ThreadID = sysapi.Read(IN);
                
                str = sysapi.Read(IN);
		//loop until there is no more user input
                while(str.compareTo("") != 0)
                {
                    if(buffer.compareTo("") == 0)
			//if blank line, then finish
                    { buffer = str; }
                    else
			//add message to buffer
                    { buffer = buffer + "\n" + str; }
			//prompt for more input
                    str = sysapi.Read(IN);
                }
			//try to 'transmit'                
                if(!sysapi.writeProcessMsg(ThreadID,buffer))
                { sysapi.Write(OUT,"Thread Not Found.\n"); }
            }
        }
        catch(Exception ex)
        { System.out.println(ex); }
        sysapi.Exit(vmh,owner);
    }
}