#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <errno.h>
#include <stdexcept>
#include <string>

using namespace std;

struct termios oldterm, newterm;
int fd = 0;
string strRecvBuf;

bool serial_init(int port, int baudrate)
{
	bool result = false;
	char portname[81] = { 0 };
	unsigned int baud_symbol = 0;
	sprintf(portname, "/dev/ttyAMA%d", port);

	baud_symbol = B115200;	// HARD-CODED FOR THIS TEST

	fd = open(portname, O_RDWR | O_NOCTTY );

	// if we were able to open the serial port
	if (fd)
	{
		// preserve current settings
		if (tcgetattr(fd, &oldterm) != -1)
		{
			bzero(&newterm, sizeof(newterm)); // clear structure
			newterm.c_cflag = baud_symbol | CS8 | CLOCAL | CREAD;
			newterm.c_iflag = IGNPAR;	// do not want to translate CR to newline
			newterm.c_oflag = 0;
			newterm.c_lflag &= ~ICANON;
			newterm.c_cc[VTIME] = 0;	// block for 1 sec for emergencies
			newterm.c_cc[VMIN] = 1;	// no character

			// flush something <grin> and check for error
			if (tcflush(fd, TCIFLUSH) != -1)
			{
				// setup the port for our new settings and check for any errors
				if (tcsetattr(fd, TCSANOW, &newterm) != -1)
				{
					result = true;
				}
			}
		}
	}

	return(result);
}

int serial_tx(unsigned char ch)
{
	return (write(fd, &ch, 1));
}

string serial_rx_buf()
{
	string strRes;

	unsigned char buf[4096];	// size is somewhat arbitrary

	ssize_t sstBytesRead = read(fd, buf, sizeof(buf));
	if (sstBytesRead < 0)
	{
		char buf[80];
		strerror_r(errno, buf, sizeof(buf));
		string strMsg = "serial_rx_buf read got error: ";
		strMsg += buf;
		throw runtime_error(strMsg.c_str());
	}
	else if (sstBytesRead > 0)
	{
		strRes = string((char *) buf, sstBytesRead);
	}
	else
	{
		throw runtime_error("Got unexpected EOF!");
	}

	return strRes;
}

void serial_close()
{
	tcsetattr(fd, TCSANOW, &oldterm) ;
	close(fd);
}

/////////////////////////////

int main()
{
	const size_t BOUNDARIES = 1000;
	size_t stNextBoundary = BOUNDARIES;
	size_t stBytesRcvd = 0;
	serial_init(0, 115200);

	for (;;)
	{
		string s = serial_rx_buf();
		stBytesRcvd += s.size();
		if (stBytesRcvd > stNextBoundary)
		{
			printf("%u\n", stBytesRcvd);
			stNextBoundary += BOUNDARIES;
		}
	}

	serial_close();

	return 0;
}