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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::Rational;
use core::mem::swap;
use malachite_base::num::arithmetic::traits::{DivRound, DivRoundAssign, Floor, FloorAssign};
use malachite_base::num::basic::traits::One;
use malachite_base::rounding_modes::RoundingMode::*;
use malachite_nz::integer::Integer;
use malachite_nz::natural::Natural;
impl Floor for Rational {
type Output = Integer;
/// Finds the floor of a [`Rational`], taking the [`Rational`] by value.
///
/// $$
/// f(x) = \lfloor x \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n \log n \log\log n)$
///
/// $M(n) = O(n \log n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `max(self.significant_bits(),
/// other.significant_bits())`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Floor;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_q::Rational;
///
/// assert_eq!(Rational::ZERO.floor(), 0);
/// assert_eq!(Rational::from_signeds(22, 7).floor(), 3);
/// assert_eq!(Rational::from_signeds(-22, 7).floor(), -4);
/// ```
fn floor(self) -> Integer {
if self.sign {
Integer::from(self.numerator / self.denominator)
} else {
Integer::from_sign_and_abs(false, self.numerator.div_round(self.denominator, Ceiling).0)
}
}
}
impl Floor for &Rational {
type Output = Integer;
/// Finds the floor of a [`Rational`], taking the [`Rational`] by reference.
///
/// $$
/// f(x) = \lfloor x \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n \log n \log\log n)$
///
/// $M(n) = O(n \log n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `max(self.significant_bits(),
/// other.significant_bits())`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Floor;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_q::Rational;
///
/// assert_eq!((&Rational::ZERO).floor(), 0);
/// assert_eq!((&Rational::from_signeds(22, 7)).floor(), 3);
/// assert_eq!((&Rational::from_signeds(-22, 7)).floor(), -4);
/// ```
fn floor(self) -> Integer {
if self.sign {
Integer::from(&self.numerator / &self.denominator)
} else {
Integer::from_sign_and_abs(
false,
(&self.numerator).div_round(&self.denominator, Ceiling).0,
)
}
}
}
impl FloorAssign for Rational {
/// Replaces a [`Rational`] with its floor.
///
/// $$
/// x \gets \lfloor x \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n \log n \log\log n)$
///
/// $M(n) = O(n \log n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `max(self.significant_bits(),
/// other.significant_bits())`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::FloorAssign;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_q::Rational;
///
/// let mut x = Rational::ZERO;
/// x.floor_assign();
/// assert_eq!(x, 0);
///
/// let mut x = Rational::from_signeds(22, 7);
/// x.floor_assign();
/// assert_eq!(x, 3);
///
/// let mut x = Rational::from_signeds(-22, 7);
/// x.floor_assign();
/// assert_eq!(x, -4);
/// ```
fn floor_assign(&mut self) {
let mut d = Natural::ONE;
swap(&mut self.denominator, &mut d);
if self.sign {
self.numerator /= d;
} else {
self.numerator.div_round_assign(d, Ceiling);
if !self.sign && self.numerator == 0 {
self.sign = true;
}
}
}
}