#include <fstream>
#include <iostream>
using namespace std;

// parses a number with up to 3 digits
bool parseNumber(ifstream &input, int &x, char delim) {
  char c1;
  char c2;
  char c3;

  input >> c1;
  if (c1 < '0' || c1 > '9') return false;

  x = c1 - 48;
  if (input.peek() == delim) return true;

  input >> c2;
  if (c2 < '0' || c2 > '9') return false;
  x *= 10;
  x += c2 - 48;

  if (input.peek() == delim) return true;

  input >> c3;
  if (c3 < '0' || c3 > '9') return false;
  x *= 10;
  x += c3 - 48;

  return true; 
}

bool peekCheck (ifstream &input, char c) {
  char x;
  if (input.peek() == c) {
    input >> x;
    return true;
  }
  return false;
}

int day3(const char *path, bool extra = true) {
  ifstream input(path);
  int result = 0;
  char c;
  bool enable = true;

  while (input >> c) {
    if (extra) {
      if (c == 'd') {
        if (!peekCheck(input, 'o')) continue;

        if (peekCheck(input, '(') && peekCheck(input, ')')) {
          enable = true;
          continue;
        }

        if (!peekCheck(input, 'n')) continue;
        if (!peekCheck(input, '\'')) continue;
        if (!peekCheck(input, 't')) continue;
        if (!peekCheck(input, '(')) continue;
        if (!peekCheck(input, ')')) continue;

        enable = false;
      }
    }
    if (c == 'm') {
      if (!peekCheck(input, 'u')) continue;
      if (!peekCheck(input, 'l')) continue;
      if (!peekCheck(input, '(')) continue;

      int x;
      parseNumber(input, x, ',');

      if (!peekCheck(input, ',')) continue;

      int y;
      parseNumber(input, y, ')');

      if (!peekCheck(input, ')')) continue;

      if (enable) result += x * y;
    }
  }
  return result;
}

int main(int argc, char *argv[]) {
    int result = day3("example", false);
    cout << "example (without do)" << endl << result << endl;
    result = day3("example", true);
    cout << "example (with do)" << endl << result << endl;
    result = day3("input", false);
    cout << "input (without do)" << endl << result << endl;
    result = day3("input", true);
    cout << "input (without do)" << endl << result << endl;

    return 0;
}