#include "fraction.hpp"

namespace FractionNS {

  int gcd(int p, int q) {
    if(p < 0) p = -p;
    if(q < 0) q = -q;
    while(true) {
      if(p == 0) return q;
      q %= p;
      if(q == 0) return p;
      p %= q;
    }
  }

  int lcm(int p, int q) {
    int gcd = FractionNS::gcd(p, q);

    return gcd != 0 ? (p / gcd * q) : 0;
  }

  void Fraction::reduce()
  {
    auto gcd = FractionNS::gcd(m_numerator, m_denominator);
    if((gcd == 1 && m_denominator >= 0) || gcd == 0) return;

    if(gcd == 1 && m_denominator < 0) {
      m_numerator = -m_numerator;
      m_denominator = -m_denominator;
    }
    else if(m_denominator < 0)
    {
      m_numerator = -m_numerator / gcd;
      m_denominator = -m_denominator / gcd;
    } else {
      m_numerator /= gcd;
      m_denominator /= gcd;
    }
  }

  Fraction::Fraction(int numerator, int denominator)
  {
    if(denominator == 0) throw std::range_error("Tried to divide by 0.");
    this->m_numerator = numerator;
    this->m_denominator = denominator;
    reduce();
  }
  Fraction::Fraction(const int n) {
    this->m_numerator = n;
    this->m_denominator = 1;
  }
  Fraction::Fraction(const Fraction& n) {
    this->m_numerator = n.getNumerator();
    this->m_denominator = n.getDenominator();
  }

  int Fraction::getNumerator() const { return m_numerator; }
  int Fraction::getDenominator() const { return m_denominator; }

  void Fraction::setNumerator(int numerator) {
    auto gcd = FractionNS::gcd(numerator, this->m_denominator);
    this->m_numerator = numerator / gcd;
  }
  void Fraction::setDenominator(int denominator) {
    if(denominator == 0) throw std::range_error("Tried to divide by 0.");
    auto gcd = FractionNS::gcd(this->m_numerator, denominator);
    this->m_denominator = denominator / gcd;
  }

  QString Fraction::display() const {
    return QString::number(m_numerator) + '/' + QString::number(m_denominator);
  }

  bool Fraction::operator==(const int n) const {
    return (double(m_numerator) / double(m_denominator)) == n;
  }
  bool Fraction::operator==(const float n) const {
    return (float(m_numerator) / float(m_denominator)) == n;
  }
  bool Fraction::operator==(const double n) const {
    return (double(m_numerator) / double(m_denominator)) == n;
  }
  bool Fraction::operator==(const Fraction& n) const {
    return (this->m_numerator == n.getNumerator())
        && (this->m_denominator == n.getDenominator());
  }

  bool Fraction::operator!=(const int n) const {
    return (double(m_numerator) / double(m_denominator)) != n;
  }
  bool Fraction::operator!=(const float n) const {
    return (double(m_numerator) / double(m_denominator)) != n;
  }
  bool Fraction::operator!=(const double n) const {
    return (double(m_numerator) / double(m_denominator)) != n;
  }
  bool Fraction::operator!=(const Fraction& n) const {
    return (this->m_numerator != n.getNumerator())
        || (this->m_denominator != n.getDenominator());
  }

  Fraction& Fraction::operator+(const int n) const {
    auto newNumerator = m_numerator + (n * m_denominator);
    return *new Fraction(newNumerator, m_denominator);
  }
  Fraction& Fraction::operator+(const Fraction& other) const {
    auto lcm = FractionNS::lcm(m_denominator, other.getDenominator());

    auto ownNumeratorPart = m_numerator * (lcm / m_denominator);
    auto otherNumeratorPart = other.getNumerator() * (lcm / other.getDenominator());

    return *new Fraction(ownNumeratorPart + otherNumeratorPart, lcm);
  }

  Fraction& Fraction::operator+=(const int other) {
    this->m_numerator = m_numerator + (other * m_denominator);
    reduce();
    return *this;
  }
  Fraction& Fraction::operator+=(const Fraction& other) {
    // Sanity check for Clang
    // Not strictly necessary since setting to 0 is checked against in setDenominator and constructor(s).
    if(other.getDenominator() == 0) return *this;

    auto lcm = FractionNS::lcm(m_denominator, other.getDenominator());

    auto ownNumeratorPart = m_numerator * (lcm / m_denominator);
    auto otherNumeratorPart = other.getNumerator() * (lcm / other.getDenominator());

    this->m_numerator = ownNumeratorPart + otherNumeratorPart;
    this->m_denominator = lcm;

    reduce();
    return *this;
  }

  Fraction& Fraction::operator-(const int n) const {
    auto newNumerator = m_numerator - (n * m_denominator);
    return *new Fraction(newNumerator, m_denominator);
  };
  Fraction& Fraction::operator-(const Fraction& other) const {
    auto lcm = FractionNS::lcm(m_denominator, other.getDenominator());

    auto ownNumeratorPart = m_numerator * (lcm / m_denominator);
    auto otherNumeratorPart = other.getNumerator() * (lcm / other.getDenominator());

    return *new Fraction(ownNumeratorPart - otherNumeratorPart, lcm);
  }

  Fraction& Fraction::operator-=(const int n) {
    auto newNumerator = m_numerator - (n * m_denominator);
    return *new Fraction(newNumerator, m_denominator);
  };
  Fraction& Fraction::operator-=(const Fraction& other) {
    // Sanity check for Clang
    // Not strictly necessary since setting to 0 is checked against in setDenominator and constructor(s).
    if(other.getDenominator() == 0) return *this;
    auto lcm = FractionNS::lcm(m_denominator, other.getDenominator());

    auto ownNumeratorPart = m_numerator * (lcm / m_denominator);
    auto otherNumeratorPart = other.getNumerator() * (lcm / other.getDenominator());

    return *new Fraction(ownNumeratorPart - otherNumeratorPart, lcm);
  }
}