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

//The retrieve command is an added feature to our OS simulator, which is complimentary to transmit
//retrieve is similar to 'receive' however, it is applied to inter-process communication rather than
//user-to-user communication
//the retrieve command displays all of the messages that have been transmitted to a process

public class retrieve extends VMachine {
    
    public retrieve() {
    }
    
    public void run() {
        
        try
        {
		//if there are no arguments, prompt the user for them
            if(args.length == 0)
            {
			//prompt user
                sysapi.Write(OUT,"Enter Process ID: ");
                String ThreadID = sysapi.Read(IN);
			//display the messages
                sysapi.Write(OUT,sysapi.getProcessMsg(ThreadID) + "\n");
            }
		//if there is one argument, display the messages for the process
		//that is passed in as an arg
            else if(args.length == 1)
            { sysapi.Write(OUT,sysapi.getProcessMsg(args[0])+ "\n"); }
		//if there is more than one argument, then display an error
            else if(args.length > 1)
            { sysapi.Write(OUT,"Too many arguments.\n"); }
        }
        catch(Exception ex)
        { System.out.println(ex); }
        sysapi.Exit(vmh,owner);
    }
}