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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::InnerFloat::{Finite, Infinity, NaN, Zero};
use crate::{Float, significand_bits};
use core::cmp::Ordering::{self, *};
use malachite_base::num::arithmetic::traits::Sign;
use malachite_base::num::conversion::traits::ExactFrom;
use malachite_q::Rational;
impl PartialOrd<Rational> for Float {
/// Compares a [`Float`] to a [`Rational`].
///
/// NaN is not comparable to any [`Rational`]. $\infty$ is greater than any [`Rational`], and
/// $-\infty$ is less. Both the [`Float`] zero and the [`Float`] negative zero are equal to the
/// [`Rational`] zero.
///
/// # 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::basic::traits::{Infinity, NegativeInfinity};
/// use malachite_float::Float;
/// use malachite_q::Rational;
///
/// assert!(Float::from(80) < Rational::from(100));
/// assert!(Float::from(-80) > Rational::from(-100));
/// assert!(Float::INFINITY > Rational::from(100));
/// assert!(Float::NEGATIVE_INFINITY < Rational::from(-100));
/// assert!(Float::from(1.0f64 / 3.0) < Rational::from_unsigneds(1u8, 3));
/// ```
fn partial_cmp(&self, other: &Rational) -> Option<Ordering> {
match (self, other) {
(float_nan!(), _) => None,
(float_infinity!(), _) => Some(Greater),
(float_negative_infinity!(), _) => Some(Less),
(float_either_zero!(), y) => 0u32.partial_cmp(y),
(
Self(Finite {
sign: s_x,
exponent: e_x,
significand: significand_x,
..
}),
y,
) => Some(if *y == 0u32 {
if *s_x { Greater } else { Less }
} else {
let s_cmp = s_x.cmp(&(*y > 0));
if s_cmp != Equal {
return Some(s_cmp);
}
let e_x = i64::from(*e_x);
let exp_cmp = (e_x - 1).cmp(&other.floor_log_base_2_abs());
if exp_cmp != Equal {
return Some(if *s_x { exp_cmp } else { exp_cmp.reverse() });
}
let shift = e_x - i64::exact_from(significand_bits(significand_x));
let abs_shift = shift.unsigned_abs();
let prod_cmp = match shift.sign() {
Equal => (significand_x * other.denominator_ref()).cmp(other.numerator_ref()),
Greater => ((significand_x * other.denominator_ref()) << abs_shift)
.cmp(other.numerator_ref()),
Less => {
let n_trailing_zeros = significand_x.trailing_zeros().unwrap();
if abs_shift <= n_trailing_zeros {
((significand_x >> abs_shift) * other.denominator_ref())
.cmp(other.numerator_ref())
} else {
((significand_x >> n_trailing_zeros) * other.denominator_ref())
.cmp(&(other.numerator_ref() << (abs_shift - n_trailing_zeros)))
}
}
};
if *s_x { prod_cmp } else { prod_cmp.reverse() }
}),
}
}
}
impl PartialOrd<Float> for Rational {
/// Compares an [`Rational`] to a [`Float`].
///
/// No [`Rational`] is comparable to NaN. Every [`Rational`] is smaller than $\infty$ and
/// greater than $-\infty$. The [`Rational`] zero is equal to both the [`Float`] zero and the
/// [`Float`] negative zero.
///
/// # 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::basic::traits::{Infinity, NegativeInfinity};
/// use malachite_float::Float;
/// use malachite_q::Rational;
///
/// assert!(Rational::from(100) > Float::from(80));
/// assert!(Rational::from(-100) < Float::from(-80));
/// assert!(Rational::from(100) < Float::INFINITY);
/// assert!(Rational::from(-100) > Float::NEGATIVE_INFINITY);
/// assert!(Rational::from_unsigneds(1u8, 3) > Float::from(1.0f64 / 3.0));
/// ```
#[inline]
fn partial_cmp(&self, other: &Float) -> Option<Ordering> {
other.partial_cmp(self).map(Ordering::reverse)
}
}