#include<stdio.h>
#include<stdlib.h>
#include<string.h>
FILE *fptr;
char line1[10000];
int floor_number;
int flag_a;
int char_zero_cross;
enum states{
  START,
  PROCESS,
} state;

enum events{
  START_LOOP,
  INCREMENT,
  DECREMENT,
  ERROR_EVENT
};

void step_state(enum events event){
  switch(state){
    case START:
      switch(event){
        case START_LOOP:
          state = PROCESS;
          break;
        default:
          exit(1);
          break;
      }
      break;
    case PROCESS:
      switch(event){
        case INCREMENT:
          floor_number++;
          break;
        case DECREMENT:
          floor_number--;    
          break; 
        case ERROR_EVENT:
          printf("ERROR!\n");
          exit(1);
          break;
        default:
          exit(1);
          break;
      }

  }
}

int main()
{
flag_a = 0;
floor_number = 0;
fptr = fopen("2015_day_1_input.txt", "r");  
if(fptr == NULL) {
  printf("Not able to open the file.");
}
fgets(line1, 10000, fptr);
fclose(fptr);
step_state(START_LOOP);
size_t i = 0;
while (line1[i] != '\0'){
  if (line1[i] == '('){
    step_state(INCREMENT);
  }
  else if (line1[i] == ')'){
    step_state(DECREMENT);
  }
  else{
    printf("\nCharacter not ( or ), ERROR!");
    exit(1);
  }
  i++;
  if (floor_number < 0 && flag_a == 0){
    printf("first zero-crossing is at position %lu\n", i);
    flag_a = 1;
  }
}

printf("\nThe Floor number is: %d\n\n", floor_number);
return 0;
}


//Sources:
//https://dev.to/zirkelc/how-to-iterate-over-c-string-lcj#:~:text=Pointer-,For%2DLoop,each%20iteration%20with%20*%2B%2Bp%20.
//https://yakking.branchable.com/posts/state-machines-in-c/