/******************************************************************************
 * Top contributors (to current version):
 *   Tim King, Gereon Kremer, Aina Niemetz
 *
 * This file is part of the cvc5 project.
 *
 * Copyright (c) 2009-2025 by the authors listed in the file AUTHORS
 * in the top-level source directory and their institutional affiliations.
 * All rights reserved.  See the file COPYING in the top-level source
 * directory for licensing information.
 * ****************************************************************************
 *
 * Multiprecision rational constants; wraps a CLN multiprecision rational.
 */

#include "cvc5_public.h"

#ifndef CVC5__RATIONAL_H
#define CVC5__RATIONAL_H

#include <cln/dfloat.h>
#include <cln/input.h>
#include <cln/io.h>
#include <cln/number_io.h>
#include <cln/output.h>
#include <cln/rational.h>
#include <cln/rational_io.h>
#include <cln/real.h>

#include <optional>
#include <sstream>
#include <string>

#include "base/exception.h"
#include "util/integer.h"

namespace cvc5::internal {

/**
 * A multi-precision rational constant.
 * This stores the rational as a pair of multi-precision integers,
 * one for the numerator and one for the denominator.
 * The number is always stored so that the gcd of the numerator and denominator
 * is 1.  (This is referred to as referred to as canonical form in GMP's
 * literature.) A consequence is that that the numerator and denominator may be
 * different than the values used to construct the Rational.
 *
 * NOTE: The correct way to create a Rational from an int is to use one of the
 * int numerator/int denominator constructors with the denominator 1.  Trying
 * to construct a Rational with a single int, e.g., Rational(0), will put you
 * in danger of invoking the char* constructor, from whence you will segfault.
 */

class Rational
{
 public:
  /**
   * Constructs a Rational from a cln::cl_RA object.
   * Does a deep copy.
   */
  Rational(const cln::cl_RA& val) : d_value(val) {}

  /**
   * Creates a rational from a decimal string (e.g., <code>"1.5"</code>).
   *
   * @param dec a string encoding a decimal number in the format
   * <code>[0-9]*\.[0-9]*</code>
   */
  static Rational fromDecimal(const std::string& dec);

  /** Constructs a rational with the value 0/1. */
  Rational() : d_value(0) {}
  /**
   * Constructs a Rational from a C string in a given base (defaults to 10).
   *
   * Throws std::invalid_argument if the string is not a valid rational, i.e.,
   * if it does not match sign{digit}+/sign{digit}+.
   */
  explicit Rational(const char* s, uint32_t base = 10);
  Rational(const std::string& s, uint32_t base = 10);

  /**
   * Creates a Rational from another Rational, q, by performing a deep copy.
   */
  Rational(const Rational& q) : d_value(q.d_value) {}

  /**
   * Constructs a canonical Rational from a numerator.
   */
  Rational(signed int n) : d_value((signed long int)n) {}
  Rational(unsigned int n) : d_value((unsigned long int)n) {}
  Rational(signed long int n) : d_value(n) {}
  Rational(unsigned long int n) : d_value(n) {}

#ifdef CVC5_NEED_INT64_T_OVERLOADS
  Rational(int64_t n) : d_value(n) {}
  Rational(uint64_t n) : d_value(n) {}
#endif /* CVC5_NEED_INT64_T_OVERLOADS */

  /**
   * Constructs a canonical Rational from a numerator and denominator.
   */
  Rational(signed int n, signed int d) : d_value((signed long int)n)
  {
    d_value /= cln::cl_I(d);
  }
  Rational(unsigned int n, unsigned int d) : d_value((unsigned long int)n)
  {
    d_value /= cln::cl_I(d);
  }
  Rational(signed long int n, signed long int d) : d_value(n)
  {
    d_value /= cln::cl_I(d);
  }
  Rational(unsigned long int n, unsigned long int d) : d_value(n)
  {
    d_value /= cln::cl_I(d);
  }

#ifdef CVC5_NEED_INT64_T_OVERLOADS
  Rational(int64_t n, int64_t d) : d_value(n) { d_value /= cln::cl_I(d); }
  Rational(uint64_t n, uint64_t d) : d_value(n) { d_value /= cln::cl_I(d); }
#endif /* CVC5_NEED_INT64_T_OVERLOADS */

  Rational(const Integer& n, const Integer& d) : d_value(n.get_cl_I())
  {
    d_value /= d.get_cl_I();
  }
  Rational(const Integer& n) : d_value(n.get_cl_I()) {}

  ~Rational() {}

  /**
   * Returns a copy of d_value to enable public access of CLN data.
   */
  const cln::cl_RA& getValue() const { return d_value; }

  /**
   * Returns the value of numerator of the Rational.
   * Note that this makes a deep copy of the numerator.
   */
  Integer getNumerator() const { return Integer(cln::numerator(d_value)); }

  /**
   * Returns the value of denominator of the Rational.
   * Note that this makes a deep copy of the denominator.
   */
  Integer getDenominator() const { return Integer(cln::denominator(d_value)); }

  /** Return an exact rational for a double d. */
  static std::optional<Rational> fromDouble(double d);

  /**
   * Get a double representation of this Rational, which is
   * approximate: truncation may occur, overflow may result in
   * infinity, and underflow may result in zero.
   */
  double getDouble() const { return cln::double_approx(d_value); }

  Rational inverse() const { return Rational(cln::recip(d_value)); }

  int cmp(const Rational& x) const
  {
    // Don't use mpq_class's cmp() function.
    // The name ends up conflicting with this function.
    return cln::compare(d_value, x.d_value);
  }

  int sgn() const;

  bool isZero() const { return cln::zerop(d_value); }

  bool isOne() const { return d_value == 1; }

  bool isNegativeOne() const { return d_value == -1; }

  Rational abs() const
  {
    if (sgn() < 0)
    {
      return -(*this);
    }
    else
    {
      return *this;
    }
  }

  bool isIntegral() const { return cln::denominator(d_value) == 1; }

  Integer floor() const { return Integer(cln::floor1(d_value)); }

  Integer ceiling() const { return Integer(cln::ceiling1(d_value)); }

  Rational floor_frac() const { return (*this) - Rational(floor()); }

  Rational& operator=(const Rational& x)
  {
    if (this == &x) return *this;
    d_value = x.d_value;
    return *this;
  }

  Rational operator-() const { return Rational(-(d_value)); }

  bool operator==(const Rational& y) const { return d_value == y.d_value; }

  bool operator!=(const Rational& y) const { return d_value != y.d_value; }

  bool operator<(const Rational& y) const { return d_value < y.d_value; }

  bool operator<=(const Rational& y) const { return d_value <= y.d_value; }

  bool operator>(const Rational& y) const { return d_value > y.d_value; }

  bool operator>=(const Rational& y) const { return d_value >= y.d_value; }

  Rational operator+(const Rational& y) const
  {
    return Rational(d_value + y.d_value);
  }
  Rational operator-(const Rational& y) const
  {
    return Rational(d_value - y.d_value);
  }

  Rational operator*(const Rational& y) const
  {
    return Rational(d_value * y.d_value);
  }
  Rational operator/(const Rational& y) const
  {
    return Rational(d_value / y.d_value);
  }

  Rational& operator+=(const Rational& y)
  {
    d_value += y.d_value;
    return (*this);
  }

  Rational& operator-=(const Rational& y)
  {
    d_value -= y.d_value;
    return (*this);
  }

  Rational& operator*=(const Rational& y)
  {
    d_value *= y.d_value;
    return (*this);
  }

  Rational& operator/=(const Rational& y)
  {
    d_value /= y.d_value;
    return (*this);
  }

  /** Returns a string representing the rational in the given base. */
  std::string toString(int base = 10) const
  {
    cln::cl_print_flags flags;
    flags.rational_base = base;
    flags.rational_readably = false;
    std::stringstream ss;
    print_rational(ss, flags, d_value);
    return ss.str();
  }

  /**
   * Computes the hash of the rational from hashes of the numerator and the
   * denominator.
   */
  size_t hash() const { return equal_hashcode(d_value); }

  uint32_t complexity() const
  {
    return getNumerator().length() + getDenominator().length();
  }

  /** Equivalent to calling (this->abs()).cmp(b.abs()) */
  int absCmp(const Rational& q) const;

 private:
  /**
   * Stores the value of the rational in a C++ CLN rational class.
   */
  cln::cl_RA d_value;

}; /* class Rational */

struct RationalHashFunction
{
  inline size_t operator()(const cvc5::internal::Rational& r) const { return r.hash(); }
}; /* struct RationalHashFunction */

std::ostream& operator<<(std::ostream& os, const Rational& n);

}  // namespace cvc5::internal

#endif /* CVC5__RATIONAL_H */
