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

static int fd;
#define MAX_STR_LEN 128
#define MODE_8E1 /**< enables the uart to be in 8E1 mode */
#define DDDEBUG

static void close_fd(void);
static int configure_uart(int rawbaud);
static int register_read_request(const uint16_t chip, const uint16_t address, const uint16_t naddr);

static void close_fd(void)
{
    int ret = close(fd);
    if (ret)
        printf("Could not close serial device... %s\n\r", strerror(errno));
}

int init_uart(char * port)
{
    /* open and configure serial port                    */
    /* O_RDWR   - Read/Write access to serial port       */
    /* O_NOCTTY - No terminal will control the process   */
    /* Open in blocking mode,read will wait              */
    fd = open(port, O_RDWR | O_NOCTTY);
    if (fd < 0){
        printf("Could not open port %s... %s\n\r", port, strerror(errno));
        return -1;
    }
    int ret = configure_uart(B230400);
    if (ret)
        return -1;

    printf("Connected to %s\n",port);
    return 0;
}

static int configure_uart(int rawbaud)
{
    int ret = 0;

    /* causes read to return 0 (non-blocking) */
#if 0
    fcntl(fd, F_SETFL, FNDELAY);
    /* causes read to block */
#endif
    fcntl(fd, F_SETFL, 0);

    struct termios attr;
    ret = tcgetattr(fd, &attr);
    if (ret < 0) {
        printf("from tcgetattr: %s\n", strerror(errno));
        return -1;
    }

    ret = cfsetispeed(&attr,rawbaud);
    if (ret){
        printf("from cfsetispeed: %s\n",strerror(errno));
        return -1;
    }

    ret = cfsetospeed(&attr,rawbaud);
    if (ret){
        printf("from cfsetospeed: %s\n",strerror(errno));
        return -1;
    }

    /* 8E1 mode */
#if defined(MODE_8E1)
#warning("MODE_8E1 ENABLED!");
    attr.c_cflag |= PARENB;  /* enable parity */
    attr.c_cflag &= ~PARODD; /* even parity */
    attr.c_cflag &= ~CSTOPB; /* only need 1 stop bit */
    attr.c_cflag &= ~CSIZE;  /* Clears the mask for setting the data size */
    attr.c_cflag |= CS8;     /* 8-bit characters */
#elif defined(MODE_8N1)
#warning("MODE_8N1 ENABLED!");
    attr.c_cflag &= ~PARENB; /* disable parity */
    attr.c_cflag &= ~CSTOPB; /* only need 1 stop bit */
    attr.c_cflag &= ~CSIZE;  /* Clears the mask for setting the data size */
    attr.c_cflag |= CS8;     /* 8-bit characters */
#else
    printf("Must define a mode\n");
    return -1;
#endif

    attr.c_cflag &= ~CRTSCTS;         /* no hardware flowcontrol */
    attr.c_cflag |= (CLOCAL | CREAD); /* ignore modem controls */

    ret = tcsetattr(fd,TCSANOW,&attr);
    if(ret){
        printf("from tcsetattr: %s\n", strerror(errno));
        return -1;
    }

    // tcflush(fd,TCIOFLUSH);

    return 0;
}

static int register_read_request(const uint16_t chip, const uint16_t address, const uint16_t naddr)
{
    uint16_t chipAddr = chip+address;
    char cmd[MAX_STR_LEN];
    memset(&cmd, MAX_STR_LEN, '\0');
    sprintf(cmd,"r %02x %02x%c",chipAddr,naddr,0xa);
    printf("strlen %d : %s\n",(int)strlen(cmd),cmd);
    #ifdef DDDEBUG
        int s = (int)strlen(cmd);
        int i;
        for(i = 0; i < s; i++){
            printf("tx cmd[%d] = %02x %c\n",i,cmd[i],cmd[i]);
            // ssize_t bytes_tx = write(fd, (char *)&cmd[i], 1);
            // printf("bytes : %d\n",(int)bytes_tx);
            // usleep(100);
            // tcflush(fd,TCIOFLUSH);
            // usleep(100);
        }
    #endif
    ssize_t bytes_tx = write(fd, (char *)cmd, strlen(cmd));
    printf("bytes_tx = %d\n",bytes_tx);
    printf("sizeof(\\n) : %d\n",sizeof('\n'));
    if (bytes_tx < 0){
        printf("%s\n",strerror(errno));
        return -1;
    }
    return 0;
}

int main()
{
    init_uart("/dev/ttyUSB0");
    register_read_request(0x40, 0x0, 0x0);
    close_fd();
    return 0;
}