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

typedef struct {
  char name;
  bool completed;
  char requirements[50];
  char requirements_count;
} Step;

typedef struct {
  Step steps[50];
  int size;
} StepList;

Step *step_list_find_step(StepList *list, char key) {
  for (int i = 0; i < list->size; i++) {
    if (list->steps[i].name == key) {
      return &(list->steps[i]);
    }
  }
  return NULL;
}

void step_list_add_step(StepList *list, char name) {
  list->steps[list->size++].name = name;
}

void step_add_requirement(Step *step, char requirement) {
  step->requirements[step->requirements_count++] = requirement;
}

bool read_line(FILE *input, StepList *list) {
  char name;
  char requirement;
  bool success = fscanf(input, "Step %c must be finished before step %c can begin.\n", &name, &requirement) == 2;
  if (!success) return false;

  Step *step = step_list_find_step(list, name);
  if (step == NULL) {
    step_list_add_step(list, name);
    step = step_list_find_step(list, name);
  }
  step_add_requirement(step, requirement);
  return true;
}

int part_1(FILE *input) {
  rewind(input);
  StepList step_list = {0};
  while (read_line(input, &step_list)) {}
  for (int i = 0; i < step_list.size; i++) {
    Step step = step_list.steps[i];
    for (int j = 0; j < step.requirements_count; j++) {
      printf("Step %c must be finished before step %c can begin.\n", step.name, step.requirements[j]);
    }
  }
  return -1;
}

int part_2(FILE *input) {
  rewind(input);
  return -1;
}

int main() {
  char *input_file_path = "../data/2018/7/input.txt";
  FILE *input = fopen(input_file_path, "r");
  if (input == NULL) {
    printf("Can't open file %s\n", input_file_path);
    return 1;
  }

  printf("Part 1: %d\n", part_1(input));
  printf("Part 2: %d\n", part_2(input));
  fclose(input);
}