#include <stdio.h>
#include <stdlib.h>

/* Enums make words into numbers, ergo no magic numbers */
enum MODE {
  MODE_MAX,
  MODE_MIN,
  MODE_DIFF
};

void help(){
    printf("Usage: stats <numbers>\n");
    exit(1);
}

/* ADDING UP ALL THE VALUES */
long sigma(int argc, char * argv[]) {
  char *endptr;
  long sum = 0;

  for (int i = 1; i < argc; i++) {

  sum += strtol(argv[i], &endptr, 10); /* convert the value to an integer and add it on */
    if (endptr == argv[i] || *endptr != '\0') {
        help();
    } 

  }
  return sum;
}

/* FINDING MEAN */
float average(int n, int sum) {
  float mean = (float) sum / n;
  return mean;
}

/* FINDING THE MIN/MAX/DIFFERENCE */
long range(int argc, char * argv[], enum MODE mode) {
  long low  = strtol(argv[1], NULL, 10);
  long high = low; 

  for (int i = 1; i < argc; i++) {
    long val = strtol(argv[i], NULL, 10);
    if (val > high) high = val;
    if (low > val)  low  = val;
  }

  /* Check once and return what we need */
  switch (mode) {
    case MODE_MAX:
      return high;
    case MODE_MIN:
      return low;
    case MODE_DIFF:
      return high - low;
  }
  return 1;
}

int main(int argc, char * argv[]) {
  if (argc < 2) { /* Stop empty input */
    help();
  }

  long     n = argc - 1; /* this is how many numbers there are */
  long     sum = sigma(argc, argv); /* sigma means adding them all together */
  float    mean = average(n, sum); /* the sum divided by the however many numbers there are */
  long     min = range(argc, argv, MODE_MIN); /* Using enums here to use words instead of numbers */
  long     max = range(argc, argv, MODE_MAX);
  long     diff = range(argc, argv, MODE_DIFF);


  /* align text left for 6 and 12 right */
  printf("%-6s %12ld\n",   "num:", n);
  printf("%-6s %12ld\n",   "sum:", sum);
  printf("%-6s %12.3f\n",  "mean:", mean);
  printf("%-6s %12ld\n",   "min:", min);
  printf("%-6s %12ld\n",   "max:", max);
  printf("%-6s %12ld\n",   "range:", diff);
}