#include "TtyProcess.h"

//Standard C library functions for PTY access/setup
#include <stdlib.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <signal.h>

TTYProcess::TTYProcess(QObject *parent) : QSerialPort(parent){
  childProc = 0;	
}

TTYProcess::~TTYProcess(){
  kill(childProc, SIGKILL);
}
		
// === PUBLIC ===
bool TTYProcess::start(QString prog, QStringList args){
  //Turn the program/arguments into C-compatible arrays
  char cprog[prog.length()]; strcpy(cprog, prog.toLocal8Bit().data());
  char *cargs[args.length()+1];
  for(int i=0; i<args.length()+1; i++){
    if(i<args.length()){
      cargs[i] = new char[ args[i].toLocal8Bit().size()+1];
      strcpy( cargs[i], args[i].toLocal8Bit().data() );
    }else{
      cargs[i] = new char[1];
      strcpy(cargs[i],"\0");
    }
  }
  qDebug() << "PTY Start:" << prog;
  //Launch the process attached to a new PTY
  int FD = 0;
  pid_t tmp = LaunchProcess(FD, cprog, cargs);
  qDebug() << " - PID:" << tmp;
  qDebug() << " - FD:" << FD;
  if(tmp<0){ return false; } //error
  else{
    childProc = tmp;
    this->setPortName( ptsname(FD) );
    qDebug() << " - PTY:" << this->portName();
    return this->open(QIODevice::ReadWrite);
  }
}

// === PRIVATE ===
pid_t TTYProcess::LaunchProcess(int& fd, char *prog, char **child_args){
  //Returns: -1 for errors, positive value (file descriptor) for the master side of the TTY to watch	

  //First open/setup a new pseudo-terminal file/device on the system (master side)
  fd = posix_openpt(O_RDWR); //open read/write
  if(fd<0){ return -1; } //could not create pseudo-terminal
  int rc = grantpt(fd); //set permissions
  if(rc!=0){ return -1; }
  rc = unlockpt(fd); //unlock file (ready for use)
  if(rc!=0){ return -1; }	
  //Now fork, return the Master device and setup the child
  pid_t PID = fork();
  if(PID==0){
    //SLAVE/child
    int fds = ::open(ptsname(fd), O_RDWR); //open slave side read/write
    ::close(fd); //close the master side from the slave thread
	  
    //Adjust the slave side mode to RAW
    struct termios TSET;
    rc = tcgetattr(fds, &TSET); //read the current settings
    cfmakeraw(&TSET); //set the RAW mode on the settings
    tcsetattr(fds, TCSANOW, &TSET); //apply the changed settings

    //Change the controlling terminal in child thread to the slave PTY
    ::close(0); //close current terminal standard input
    ::close(1); //close current terminal standard output
    ::close(2); //close current terminal standard error
    dup(fds); // Set slave PTY as standard input (0);
    dup(fds); // Set slave PTY as standard output (1);
    dup(fds); // Set slave PTY as standard error (2);
	  
    setsid();  //Make current process new session leader (so we can set controlling terminal)
    ioctl(0,TIOCSCTTY, 1); //Set the controlling terminal to the slave PTY
	  
    //Execute the designated program
    rc = execvp(prog, child_args);
    ::close(fds); //no need to keep original file descriptor open any more
    exit(rc);
  }
  //MASTER thread (or error)
  return PID;
}