#include <linux/input.h>
#include <sys/ioctl.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <malloc.h>

int list_input_devices();
int* read_numbers(FILE* fd, int num);

int main()
{
	int numdev, i;
	int* numbers;
	const int numbers_to_read = 10;
	char temp[100];
	char output1[100], output2[100];
	int max, min;
	FILE* fd;

	numdev = list_input_devices();
	if(numdev == 0)
	{
		printf("Error. Couldn't find any usable input devices.\n");
		return -1;
	}
	do
	{
		printf("Enter the number of your keyboard device: ");
		fgets(temp, sizeof(temp), stdin);
	} while(sscanf(temp, "%d", &numdev) != 1);

	snprintf(temp, sizeof(temp), "/dev/input/event%d", numdev);
	fd = fopen(temp, "rb");
	if(fd == 0)
	{
		printf("Error. Couldn't open input device.\n");
		return -2;
	}
	numbers = read_numbers(fd, 10);
	fclose(fd);
	if(numbers == NULL)
	{
		printf("Error. Couldn't read from input device.\n");
		return -3;
	}
	min = max = sizeof(numbers[0]);
	printf("\nNumbers:\n");
	for(i=0; i<numbers_to_read; i++)
	{
		if(min > sizeof(numbers[i]))
			min = sizeof(numbers[i]);
		if(max < sizeof(numbers[i]))
			max = sizeof(numbers[i]);
		printf(" %d\n", numbers[i]);
	}
	sprintf(output1, "Index(es) of smallest element(s): ");
	sprintf(output2, "Index(es) of largest element(s):  ");
	for(i=0; i<numbers_to_read; i++)
	{
		sprintf(temp, "%d ", i);
		if(sizeof(numbers[i] == min))
			strcat(output1, temp);
		if(sizeof(numbers[i] == max))
			strcat(output2, temp);
	}
	free(numbers);

	strcat(output1, "\n");
	strcat(output2, "\n");

	printf("Smallest element is %d bytes\n", min);
	printf("Largest element is  %d bytes\n", max);
	printf(output1);
	printf(output2);

	return 0;
}

int list_input_devices()
{
	int fd, count = 0;
	struct dirent* dp;
	char name[100];
	char dev[100];
	char devnum[10];
	DIR* dir;

	dir = opendir("/dev/input");
	if(!dir)
		return 0;

	while((dp = readdir(dir)) != NULL)
	{
		if(dp->d_name && !strncmp(dp->d_name, "event", 5))
		{
			snprintf(dev, sizeof(dev), "/dev/input/%s", dp->d_name);
			fd = open(dev, O_RDONLY);
			if(fd == -1)
			{
				continue;
			}
			if(ioctl(fd, EVIOCGNAME(sizeof(name)), name) < 0)
			{
				close(fd);
				continue;
			}
			else
			{
				snprintf(devnum, sizeof(devnum), "%s", dp->d_name+5);
				printf("%s : %s\n", devnum, name);
				close(fd);
				count++;
			}
		}
	}
	closedir(dir);
	return count;
}

int* read_numbers(FILE* fd, int num)
{
	int* ret;
	if(num < 1)
		return NULL;
	ret = malloc(sizeof(int) * num);
	if(fread(ret, sizeof(int), num, fd) != num)
	{
		free(ret);
		return NULL;
	}
	return ret;
}