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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::natural::Natural;
use malachite_base::num::arithmetic::traits::{ModNeg, ModNegAssign};
use malachite_base::num::basic::traits::Zero;
impl ModNeg<Self> for Natural {
type Output = Self;
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. Both [`Natural`]s are taken by value.
///
/// $f(x, m) = y$, where $x, y < m$ and $-x \equiv y \mod m$.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNeg, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::ZERO.mod_neg(Natural::from(5u32)), 0);
/// assert_eq!(Natural::from(7u32).mod_neg(Natural::from(10u32)), 3);
/// assert_eq!(
/// Natural::from(7u32).mod_neg(Natural::from(10u32).pow(12)),
/// 999999999993u64
/// );
/// ```
#[inline]
fn mod_neg(mut self, m: Self) -> Self {
self.mod_neg_assign(&m);
self
}
}
impl<'a> ModNeg<&'a Self> for Natural {
type Output = Self;
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. The first [`Natural`] is taken by value and the second by reference.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNeg, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::ZERO.mod_neg(&Natural::from(5u32)), 0);
/// assert_eq!(Natural::from(7u32).mod_neg(&Natural::from(10u32)), 3);
/// assert_eq!(
/// Natural::from(7u32).mod_neg(&Natural::from(10u32).pow(12)),
/// 999999999993u64
/// );
/// ```
#[inline]
fn mod_neg(mut self, m: &'a Self) -> Self {
self.mod_neg_assign(m);
self
}
}
impl ModNeg<Natural> for &Natural {
type Output = Natural;
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. The first [`Natural`] is taken by reference and the second by value.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNeg, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!((&Natural::ZERO).mod_neg(Natural::from(5u32)), 0);
/// assert_eq!((&Natural::from(7u32)).mod_neg(Natural::from(10u32)), 3);
/// assert_eq!(
/// (&Natural::from(7u32)).mod_neg(Natural::from(10u32).pow(12)),
/// 999999999993u64
/// );
/// ```
fn mod_neg(self, m: Natural) -> Natural {
assert!(*self < m, "self must be reduced mod m, but {self} >= {m}");
if *self == 0 { Natural::ZERO } else { m - self }
}
}
impl ModNeg<&Natural> for &Natural {
type Output = Natural;
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. Both [`Natural`]s are taken by reference.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNeg, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!((&Natural::ZERO).mod_neg(&Natural::from(5u32)), 0);
/// assert_eq!((&Natural::from(7u32)).mod_neg(&Natural::from(10u32)), 3);
/// assert_eq!(
/// (&Natural::from(7u32)).mod_neg(&Natural::from(10u32).pow(12)),
/// 999999999993u64
/// );
/// ```
fn mod_neg(self, m: &Natural) -> Natural {
assert!(self < m, "self must be reduced mod m, but {self} >= {m}");
if *self == 0 { Natural::ZERO } else { m - self }
}
}
impl ModNegAssign<Self> for Natural {
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. The [`Natural`] on the right-hand side is taken by value.
///
/// $x \gets y$, where $x, y < m$ and $-x \equiv y \mod m$.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNegAssign, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// let mut n = Natural::ZERO;
/// n.mod_neg_assign(Natural::from(5u32));
/// assert_eq!(n, 0);
///
/// let mut n = Natural::from(7u32);
/// n.mod_neg_assign(Natural::from(10u32));
/// assert_eq!(n, 3);
///
/// let mut n = Natural::from(7u32);
/// n.mod_neg_assign(Natural::from(10u32).pow(12));
/// assert_eq!(n, 999999999993u64);
/// ```
#[inline]
fn mod_neg_assign(&mut self, m: Self) {
self.mod_neg_assign(&m);
}
}
impl<'a> ModNegAssign<&'a Self> for Natural {
/// Negates a [`Natural`] modulo another [`Natural`] $m$. The input must be already reduced
/// modulo $m$. The [`Natural`] on the right-hand side is taken by reference.
///
/// $x \gets y$, where $x, y < m$ and $-x \equiv y \mod m$.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `m.significant_bits()`.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::{ModNegAssign, Pow};
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
///
/// let mut n = Natural::ZERO;
/// n.mod_neg_assign(&Natural::from(5u32));
/// assert_eq!(n, 0);
///
/// let mut n = Natural::from(7u32);
/// n.mod_neg_assign(&Natural::from(10u32));
/// assert_eq!(n, 3);
///
/// let mut n = Natural::from(7u32);
/// n.mod_neg_assign(&Natural::from(10u32).pow(12));
/// assert_eq!(n, 999999999993u64);
/// ```
fn mod_neg_assign(&mut self, m: &'a Self) {
assert!(&*self < m, "self must be reduced mod m, but {self} >= {m}");
if *self != 0 {
assert!(!self.sub_right_assign_no_panic(m));
}
}
}