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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 crate::natural_polynomial::NaturalPolynomial;
use malachite_base::num::arithmetic::traits::{ModIsReduced, ModNeg, ModNegAssign};
fn assert_reduced(p: &NaturalPolynomial, m: &Natural) {
assert!(
p.mod_is_reduced(m),
"self must be reduced mod m, but {p} has a coefficient >= {m}"
);
}
// Negates every coefficient modulo m. The coefficients are reduced, so a nonzero one stays nonzero
// and nothing needs trimming.
fn negate(coefficients: &mut [Natural], m: &Natural) {
for c in coefficients {
c.mod_neg_assign(m);
}
}
fn mod_neg_ref(p: &NaturalPolynomial, m: &Natural) -> NaturalPolynomial {
assert_reduced(p, m);
let mut coefficients = p.coefficients.clone();
negate(&mut coefficients, m);
NaturalPolynomial { coefficients }
}
fn mod_neg_assign(p: &mut NaturalPolynomial, m: &Natural) {
assert_reduced(p, m);
negate(&mut p.coefficients, m);
}
impl ModNeg<Natural> for NaturalPolynomial {
type Output = Self;
/// Negates a [`NaturalPolynomial`] modulo `m`, taking the polynomial by value and the modulus
/// by value. The coefficients must already be reduced modulo `m`.
///
/// Each nonzero coefficient $c$ becomes $m - c$, which is also nonzero, so the degree is
/// unchanged. The zero polynomial is its own negation.
///
/// $$
/// f(p, m) = -p \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// assert_eq!(
/// p.clone().mod_neg(Natural::from(7u32)).to_string(),
/// "2*x^2+6*x+4"
/// );
/// assert_eq!(
/// NaturalPolynomial::ZERO.mod_neg(Natural::from(7u32)),
/// NaturalPolynomial::ZERO
/// );
/// ```
///
/// This is equivalent to `fmpz_mod_poly_neg` from `fmpz_mod_poly/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(mut self, m: Natural) -> Self {
mod_neg_assign(&mut self, &m);
self
}
}
impl ModNeg<&Natural> for NaturalPolynomial {
type Output = Self;
/// Negates a [`NaturalPolynomial`] modulo `m`, taking the polynomial by value and the modulus
/// by reference. The coefficients must already be reduced modulo `m`.
///
/// Each nonzero coefficient $c$ becomes $m - c$, which is also nonzero, so the degree is
/// unchanged. The zero polynomial is its own negation.
///
/// $$
/// f(p, m) = -p \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// assert_eq!(
/// p.clone().mod_neg(&Natural::from(7u32)).to_string(),
/// "2*x^2+6*x+4"
/// );
/// assert_eq!(
/// NaturalPolynomial::ZERO.mod_neg(&Natural::from(7u32)),
/// NaturalPolynomial::ZERO
/// );
/// ```
///
/// This is equivalent to `fmpz_mod_poly_neg` from `fmpz_mod_poly/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(mut self, m: &Natural) -> Self {
mod_neg_assign(&mut self, m);
self
}
}
impl ModNeg<Natural> for &NaturalPolynomial {
type Output = NaturalPolynomial;
/// Negates a [`NaturalPolynomial`] modulo `m`, taking the polynomial by reference and the
/// modulus by value. The coefficients must already be reduced modulo `m`.
///
/// Each nonzero coefficient $c$ becomes $m - c$, which is also nonzero, so the degree is
/// unchanged. The zero polynomial is its own negation.
///
/// $$
/// f(p, m) = -p \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// assert_eq!((&p).mod_neg(Natural::from(7u32)).to_string(), "2*x^2+6*x+4");
/// assert_eq!(
/// (&NaturalPolynomial::ZERO).mod_neg(Natural::from(7u32)),
/// NaturalPolynomial::ZERO
/// );
/// ```
///
/// This is equivalent to `fmpz_mod_poly_neg` from `fmpz_mod_poly/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(self, m: Natural) -> NaturalPolynomial {
mod_neg_ref(self, &m)
}
}
impl ModNeg<&Natural> for &NaturalPolynomial {
type Output = NaturalPolynomial;
/// Negates a [`NaturalPolynomial`] modulo `m`, taking the polynomial by reference and the
/// modulus by reference. The coefficients must already be reduced modulo `m`.
///
/// Each nonzero coefficient $c$ becomes $m - c$, which is also nonzero, so the degree is
/// unchanged. The zero polynomial is its own negation.
///
/// $$
/// f(p, m) = -p \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// assert_eq!(
/// (&p).mod_neg(&Natural::from(7u32)).to_string(),
/// "2*x^2+6*x+4"
/// );
/// assert_eq!(
/// (&NaturalPolynomial::ZERO).mod_neg(&Natural::from(7u32)),
/// NaturalPolynomial::ZERO
/// );
/// ```
///
/// This is equivalent to `fmpz_mod_poly_neg` from `fmpz_mod_poly/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(self, m: &Natural) -> NaturalPolynomial {
mod_neg_ref(self, m)
}
}
impl ModNegAssign<Natural> for NaturalPolynomial {
/// Negates a [`NaturalPolynomial`] modulo `m`, in place, taking the modulus by value. The
/// coefficients must already be reduced modulo `m`.
///
/// See [`mod_neg`](ModNeg::mod_neg).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNegAssign;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let mut p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// p.mod_neg_assign(Natural::from(7u32));
/// assert_eq!(p.to_string(), "2*x^2+6*x+4");
/// ```
#[inline]
fn mod_neg_assign(&mut self, m: Natural) {
mod_neg_assign(self, &m);
}
}
impl ModNegAssign<&Natural> for NaturalPolynomial {
/// Negates a [`NaturalPolynomial`] modulo `m`, in place, taking the modulus by reference. The
/// coefficients must already be reduced modulo `m`.
///
/// See [`mod_neg`](ModNeg::mod_neg).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients times
/// `m.significant_bits()`.
///
/// # Panics
/// Panics if `m` is 0, or if any coefficient of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNegAssign;
/// use malachite_nz::natural::Natural;
/// use malachite_nz::natural_polynomial::NaturalPolynomial;
///
/// let mut p = NaturalPolynomial::from_str("5*x^2+x+3").unwrap();
/// p.mod_neg_assign(&Natural::from(7u32));
/// assert_eq!(p.to_string(), "2*x^2+6*x+4");
/// ```
#[inline]
fn mod_neg_assign(&mut self, m: &Natural) {
mod_neg_assign(self, m);
}
}