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

#include "../../lib/aoc.h"

typedef struct Calibration {
  long test_value;
  int numbers[20];
  int number_count;
} Calibration;

void base_three(char *string, int number, int length) {
  int i = 0;
  for (; i < length; i++) {
    string[length - i - 1] = (number % 3) + '0';
    number /= 3;
  }
  string[length] = '\0';
}

bool true_permutation(Calibration *c, int permutation) {
  long value = c->numbers[0];
  for (int i = 1; i < c->number_count; i++) {
    int operator = permutation & 1;
    permutation >>= 1;
    if (operator == 0) {
      value += c->numbers[i];
    } else {
      value *= c->numbers[i];
    }
  }
  return value == c->test_value;
}

bool true_permutation_p2(Calibration *c, char *permutation) {
  long value = c->numbers[0];
  for (int i = 1; i < c->number_count; i++) {
    int operator = permutation[i - 1];
    if (operator == '0') {
      value += c->numbers[i];
    } else if (operator == '1') {
      value *= c->numbers[i];
    } else {
      char concat[100];
      sprintf(concat, "%ld%d", value, c->numbers[i]);
      value = atol(concat);
    }
  }
  return value == c->test_value;
}

bool true_calibration(Calibration *c) {
  int permutation_count = 2 << (c->number_count - 2);
  for (int i = 0; i < permutation_count; i++) {
    if (true_permutation(c, i)) return true;
  }
  return false;
}

bool true_calibration_p2(Calibration *c) {
  int permutation_count = 1;
  for (int i = 1; i < c->number_count; i++) {
    permutation_count *= 3;
  }
  char permutation_string[c->number_count];
  for (int i = 0; i < permutation_count; i++) {
    base_three(permutation_string, i, c->number_count - 1);
    if (true_permutation_p2(c, permutation_string)) return true;
  }
  return false;
}

void calibration_from_line(Calibration *c, char *line) {
  c->number_count = 0;
  char *token = strtok(line, ":");
  c->test_value = atol(token);
  while((token = strtok(NULL, " "))) {
    c->numbers[c->number_count++] = atoi(token);
  }
}

int main() {
  char *line;
  Calibration c;

  long long calibration_result = 0;
  long long calibration_result_p2 = 0;
  while((line = aoc_read_line()) != NULL) {
    calibration_from_line(&c, line);
    if (true_calibration(&c)) {
      calibration_result += c.test_value;
    }
    if (true_calibration_p2(&c)) {
      calibration_result_p2 += c.test_value;
    }
  }

  printf("Part 1: %lld\n", calibration_result);
  printf("Part 2: %lld\n", calibration_result_p2);

  aoc_free();
  return 0;
}