#include <stdio.h> /* Standard input/output definitions */
#include <string.h> /* String function definitions */
#include <unistd.h> /* UNIX standard function definitions */
#include <fcntl.h> /* File control definitions */
#include <errno.h> /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */




//Initialize serial port
int initport(int fd)
{
    int portstatus = 0;

    struct termios options;
    // Get the current options for the port...
    tcgetattr(fd, &options);
    // Set the baud rates to 115200...
    cfsetispeed(&options, B115200);
    cfsetospeed(&options, B115200);
    // Enable the receiver and set local mode...
    options.c_cflag |= (CLOCAL | CREAD);

    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    //options.c_cflag |= SerialDataBitsInterp(8);           /* CS8 - Selects 8 data bits */
    options.c_cflag &= ~CRTSCTS;                            // disable hardware flow control
    //options.c_iflag &= ~(IXON | IXOFF | IXANY);           // disable XON XOFF (for transmit and
                                                               //receive)
    //options.c_cflag |= CRTSCTS;                     /* enable hardware flow control */


    options.c_cc[VMIN] = 0;     //min carachters to be read
    options.c_cc[VTIME] = 0;    //Time to wait for data (tenths of seconds)


    // Set the new options for the port...
    //tcsetattr(fd, TCSANOW, &options);


    //Set the new options for the port...
    tcflush(fd, TCIFLUSH);
    if (tcsetattr(fd, TCSANOW, &options)==-1)
    {
        perror("On tcsetattr:");
        portstatus = -1;
    }
    else
        portstatus = 1;


    return portstatus;
}


/*
* 'open_port()' - Open serial port 1.
*
* Returns the file descriptor on success or -1 on error.
*/
int open_port(void)
{
    int fd; /* File descriptor for the port */
    fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);

    if (fd == -1)
    {
        /*
        * Could not open the port.
        */
        perror("open_port: Unable to open /dev/ttyUSB0 --- \n");
    }
    else
        fcntl(fd, F_SETFL, 0);

    return (fd);
}

int main(void)
{

    int serial_fd = open_port();

    if(serial_fd == -1)
        printf("Error opening serial port /dev/ttyUSB0 \n");
    else
    {
        printf("Serial Port /dev/ttyUSB0 is now open \n");

        if(initport(serial_fd) == -1)
        {
            printf("Error Initializing port");
            close(serial_fd);
            return 0;
        }

        sleep(.5);
        //usleep(500000);
        //printf("size of data being sent = %ld", sizeof("~ver~\n\r"));

        int n = write(serial_fd, "~ver~\n\r", 8);

        if (n < 0)
            fputs("write() of 8 bytes failed!\n", stderr);
        else
        {
            printf("Successfully wrote 8 bytes\n");

            char buffer[32];
            int n = read(serial_fd, buffer, sizeof(buffer));
            if (n < 0)
                fputs("read failed!\n", stderr);
            else
                printf("Successfully read from serial port -- %s\n", buffer);

        }

        sleep(.5);
        //usleep(500000);

        printf("\n\nNow closing Serial Port /dev/ttyUSB0 \n\n");

        close(serial_fd);
    }


    return 0;
}