/*
	Daemon to monitor the CTS line of the selected serial device
	and send a predefined phrase to the currently focused window
	when the line goes high

	Build using:

	gcc -I/usr/X11R6/include -L/usr/X11R6/lib -lX11 -lXtst -o hotkey ./hotkey.c

	Currently port and phrase are hardcoded

*/

#include <X11/extensions/XTest.h>
#include <X11/keysym.h>
#include <X11/Xlib.h>
#include <stdio.h>
#include <string.h>
#include <termios.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/types.h>
#include <sys/stat.h>

#define DEVICE	"/dev/ttyUSB0"

#define PHRASE	"Longstaff-Tyrrell"
//#define PHRASE	"We apologise for any inconvenience caused to your journey."

#define SHIFTED_CHARS	"!\"£$%^&*()_+<>:@?"

void send_string(char *string, Display *pDisplay)
{
	while(*string!=0)
	{
		char symbol = *string;
		string++;

		// limit to range of chars
		if(symbol>'z'||symbol<' ')
			continue;

		KeyCode keycode;

		keycode = XKeysymToKeycode(pDisplay, symbol);

		//printf("sending %c:  keycode 0x%02X\n",symbol,keycode);

		// catch shift-modified characters
		if(strchr(SHIFTED_CHARS, symbol)!=NULL||isupper(symbol))
		{
			// press left shift
			XTestFakeKeyEvent( pDisplay, XKeysymToKeycode(pDisplay, XK_Shift_L),True, CurrentTime );
		}

		XTestFakeKeyEvent( pDisplay, keycode,True, CurrentTime );
		XTestFakeKeyEvent( pDisplay, keycode,False, CurrentTime );

		// release left shift
		XTestFakeKeyEvent( pDisplay, XKeysymToKeycode(pDisplay, XK_Shift_L),False, CurrentTime );

		XFlush(pDisplay);
	}
}

void send_phrase()
{
	// open display and send string
	Display* pDisplay = XOpenDisplay( NULL );

	if( pDisplay == NULL )
		return;

	send_string(PHRASE, pDisplay);
	XCloseDisplay(pDisplay);
}

void start_daemon()
{
	// start the daemon (from http://www.netzmafia.de/skripten/unix/linux-daemon-howto.html)
    // Our process ID and Session ID 
	pid_t pid, sid;

	// Fork off the parent process
	pid = fork();
	if(pid < 0)
		exit(EXIT_FAILURE);

	// If we got a good PID, then we can exit the parent process.
	if(pid > 0)
		exit(EXIT_SUCCESS);

	// Change the file mode mask
	umask(0);
		    
	// Open any logs here
		    
	// Create a new SID for the child process
	sid = setsid();
	if(sid < 0)
	{
		// Log the failure
		exit(EXIT_FAILURE);
	}

	// Change the current working directory
	if ((chdir("/")) < 0)
	{
		// Log the failure
		exit(EXIT_FAILURE);
	}

	// Close out the standard file descriptors
	close(STDIN_FILENO);
	close(STDOUT_FILENO);
	close(STDERR_FILENO);
}

int main(int argc, char **argv)
{
	char *device = DEVICE;

	start_daemon();

    int fd = open(device, O_RDWR | O_NDELAY);

    if(fd < 0)
    {
		perror(device);
        return -1;
    }

	struct termios newtio;

	newtio.c_cflag = B9600 | CS8 | CLOCAL | CREAD;
	newtio.c_iflag = IGNPAR;
	newtio.c_oflag = 0;
	newtio.c_lflag = 0;
	newtio.c_cc[VMIN]=1;
	newtio.c_cc[VTIME]=0;
	tcflush(fd, TCIFLUSH);
	tcsetattr(fd,TCSANOW,&newtio);

	int status;

	//
	ioctl(fd, TIOCMGET, &status);
	status &= ~TIOCM_DTR;
	status &= ~TIOCM_RTS;
	ioctl(fd, TIOCMSET, &status);


	// catch changes to CTS
	while(1)
	{	
        // block until line changes state
        if(ioctl(fd, TIOCMIWAIT, TIOCM_CTS) < 0)
        {
			perror(device);
            return -1;
        }

		usleep(75000); // debounce switch

		ioctl(fd, TIOCMGET, &status);
		if(status & TIOCM_CTS)
			send_phrase();
    }

	close(fd);
	exit(EXIT_SUCCESS);
}