#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>




#define STRING1 "RX bytes:"
#define STRING2 "TX bytes:"
//#define DEVICE "eth0"
//#define DEVICE "ppp0"
//#define DEVICE "wlan0"
#define DEVICE "wlan5"

#define CAPTURE_PATH "bandwidth.cap"
#define MAX_CAPTURE 0x100000 * 2
#define USECOND_INTERVAL 1000000


char *device = DEVICE;
unsigned char *capture_buffer = 0;
int capture_allocated = 0;
int capture_size = 0;
struct timeval current_time;
struct timeval new_time;



void capture_text(char *text)
{
    if(capture_size > MAX_CAPTURE) return;
    int len = strlen(text);
    if(capture_size + len > capture_allocated)
    {
        capture_buffer = realloc(capture_buffer, capture_size + len);
        capture_allocated = capture_size + len;
    }
    memcpy(capture_buffer + capture_size, text, len);
    capture_size += len;
}

void signal_handler(int signum)
{
    FILE *out = fopen(CAPTURE_PATH, "w");
    fwrite(capture_buffer, capture_size, 1, out);
    fclose(out);
    abort();
}


int main(int argc, char *argv[])
{
	unsigned char *buffer = (unsigned char*)calloc(1, 0x1000);
	int64_t rx_bytes;
	int64_t tx_bytes;
	int64_t prev_rx_bytes = 0;
	int64_t prev_tx_bytes = 0;
	int use_bytes = 1;
    int use_table = 0;
	int i;

	if(argc > 1)
    {
		for(i = 1; i < argc; i++)
		{
        	if(!strcmp(argv[i], "-b"))
    			use_bytes = 0;
        	else
        	if(!strcmp(argv[i], "-t"))
            	use_table = 1;
			else
				device = argv[i];
		}
    }

    signal(SIGINT, signal_handler);

	while(1)
	{
		char string[1024];
		sprintf(string, "ifconfig %s", device);
		FILE *fd = popen(string, "r");
		if(!fd) 
		{
			perror("fopen");
			exit(1);
		}
		bzero(buffer, 0x1000);
		int bytes = fread(buffer, 1, 0x1000, fd);
		fclose(fd);

// Get RX bytes
		char *ptr = strstr((const char*)buffer, STRING1);
		if(ptr)
		{
			ptr += strlen(STRING1);
			sscanf(ptr, "%lld", &rx_bytes);
		}
		ptr = strstr((const char*)buffer, STRING2);
		if(ptr)
		{
			ptr += strlen(STRING2);
			sscanf(ptr, "%lld", &tx_bytes);
		}
		if(!prev_rx_bytes) prev_rx_bytes = rx_bytes;
		if(!prev_tx_bytes) prev_tx_bytes = tx_bytes;


//		if(rx_bytes != prev_rx_bytes || tx_bytes != prev_tx_bytes)
        gettimeofday(&new_time, 0);
        double seconds_elapsed = (double)(new_time.tv_usec - current_time.tv_usec) / 1000000 +
            (new_time.tv_sec - current_time.tv_sec);
        current_time = new_time;

        if(seconds_elapsed > 0.01)
		{
            char string[1024];
            if(use_table)
            {
                sprintf(string, 
                    "%.1f\t%.1f\n", 
                    (double)(rx_bytes - prev_rx_bytes) * 8 / seconds_elapsed,
                    (double)(tx_bytes - prev_tx_bytes) * 8 / seconds_elapsed);
            }
            else
			if(use_bytes)
			{
				sprintf(string, "Incoming: %.1f/%.1f  Outgoing: %.1f/%.1f\n",
					(double)(rx_bytes - prev_rx_bytes) * 8 / seconds_elapsed,
					(float)(rx_bytes - prev_rx_bytes) / seconds_elapsed / 1024,
					(double)(tx_bytes - prev_tx_bytes) * 8 / seconds_elapsed,
					(float)(tx_bytes - prev_tx_bytes) / seconds_elapsed / 1024);
			}
			else
			{
				sprintf(string, "Incoming: %lld (%.1f bits/sec) Outgoing: %lld (%.1f bits/sec)    \n",
					rx_bytes,
					(double)(rx_bytes - prev_rx_bytes) * 8 / seconds_elapsed,
					tx_bytes,
					(double)(tx_bytes - prev_tx_bytes) * 8 / seconds_elapsed);
			}

            printf("%s", string);
            capture_text(string);
			fflush(stdout);
			prev_rx_bytes = rx_bytes;
			prev_tx_bytes = tx_bytes;
			seconds_elapsed = 0;
		}

		usleep(USECOND_INTERVAL);
		seconds_elapsed += (double)USECOND_INTERVAL / 1000000;
	}
}