#define _POSIX_C_SOURCE 200809L

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

int is_integer(char * str);
int is_comma_list(char * str);
int * comma_list_stops(char * str);
int comma_list_num_stops(char * str);
int stoi_mini(char * str);

int main(int argc, char ** argv) {
  int *tab_stops;
  int col_pos, num_tab_stops = 0, cur_stop;
  FILE *current_file;
  int i = 1, j; char c;
  int all_good = 1;

  if(argv[1][0] == '-' && argv[1][1] == 't' && argv[1][2] == '\0') {
    i++;
    j = 2;
    if(is_comma_list(argv[j])) {
      num_tab_stops = comma_list_num_stops(argv[j]);
      tab_stops = comma_list_stops(argv[j]);
      i++;
    }
    else {
      while(is_integer(argv[j]) && j < (argc - 1)) {
        num_tab_stops++;
        i++;
        j++;
      }
    
      tab_stops = calloc(num_tab_stops, sizeof(*tab_stops));
    
      for(j = 2; j < num_tab_stops + 2; j++) {
        tab_stops[j-2] = stoi_mini(argv[j]);
      }
    }
  }
  else if(argv[1][0] == '-' && argv[1][1] == 't' &&
	        argv[1][2] <= '9' && argv[1][2] >= '0'){
    char * str = strtok(argv[1], "t");
    str = strtok(NULL, "\0");
    num_tab_stops = comma_list_num_stops(str);
    tab_stops = comma_list_stops(str);
    i++;
  }
  else {
    tab_stops = malloc(sizeof(*tab_stops));
    *tab_stops = 8;
    num_tab_stops = 1;
  }

  for(i = i; i < argc; i++) {
    current_file = fopen(argv[i], "r");
    if(current_file == NULL) {
      fprintf(stderr, "%s: %s: No such file or directory\n", argv[0], argv[i]);
      all_good = 0;
    }
    else {
      cur_stop = 0; col_pos = 0;
      for(c = fgetc(current_file); c != EOF; c = fgetc(current_file)) {
        if(c == '\t') {
          if(num_tab_stops == 1) {
            cur_stop++;
            printf(" "); col_pos++;
            while(col_pos % *tab_stops != 0) {
              printf(" "); col_pos++;
            }
          }
          else {
            if(cur_stop >= num_tab_stops) {
              printf(" ");
              col_pos++;
              cur_stop++;
            }
            else {
                printf(" "); col_pos++;
                while(col_pos % tab_stops[cur_stop] != 0) {
                  printf(" "); col_pos++;
                }
              cur_stop++;
            }
          }
        }
        else if(c == '\n') {
          printf("%c", c);
          col_pos = 0;
          cur_stop = 0;
        }
        else {
          printf("%c", c);
          col_pos++;
        }
      }
      fclose(current_file);
    }
  }
}

int is_integer(char * str) {
  int i = 0;
  
  while(str[i] != '\0' && str[i] != ',') {
    if(str[i] > 57 || str[i] < 48) {
      return 0;
    }
    i++;
  }

  return 1;
}

int is_comma_list(char * str) {
  int i = 0, has_comma = 0;
  
  while(str[i] != '\0') {
    if((str[i] > 57 || str[i] < 48) && str[i] != ',') {
      return 0;
    }
    if(str[i] == ',') {
      has_comma = 1;
    }
    i++;
  }

  return has_comma;
}

int stoi_mini(char * str) {
  int i, str_int = 0;

  for(i = 0; str[i] != '\0' && str[i] != ','; i++) {
    str_int *= 10;
    switch(str[i]) {
      case '0': str_int += 0; break;
      case '1': str_int += 1; break;
      case '2': str_int += 2; break;
      case '3': str_int += 3; break;
      case '4': str_int += 4; break;
      case '5': str_int += 5; break;
      case '6': str_int += 6; break;
      case '7': str_int += 7; break;
      case '8': str_int += 8; break;
      case '9': str_int += 9; break;
      default: return -1;
    }
  }

  return str_int;
}

int comma_list_num_stops(char * str) {
  int num_stops = 0;

  for(int i = 0; str[i] != '\0'; i++) {
    if(str[i] == ',') {
      num_stops++;
    }
  }

  return num_stops; 
}

int * comma_list_stops(char * str) {
  int * tab_stops;
  int num_stops = comma_list_num_stops(str), i;

  tab_stops = calloc(num_stops, sizeof(*tab_stops));

  char * stop = strtok(str, ",");
  i = 0;
  
  while(stop != NULL && i < num_stops) {
    tab_stops[i] = stoi_mini(stop);
    i++;
    stop = strtok(NULL, ",");
  }

  return tab_stops;
}