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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::num::arithmetic::traits::{ModIsReduced, ModNeg, ModNegAssign};
use crate::num::basic::unsigneds::PrimitiveUnsigned;
use crate::unsigned_vector::UnsignedVector;
fn assert_reduced<T: PrimitiveUnsigned>(v: &UnsignedVector<T>, m: T) {
assert!(
v.mod_is_reduced(&m),
"self must be reduced mod m, but {v} has an element >= {m}"
);
}
// Negates every element modulo m.
fn negate<T: PrimitiveUnsigned>(elements: &mut [T], m: T) {
for x in elements {
if *x != T::ZERO {
*x = m - *x;
}
}
}
impl<T: PrimitiveUnsigned> ModNeg<T> for UnsignedVector<T> {
type Output = Self;
/// Negates an [`UnsignedVector`] modulo $m$, taking the vector by value. The elements must
/// already be reduced modulo $m$.
///
/// Each element $x$ becomes $-x \bmod m$: $m - x$ if $x$ is nonzero, and 0 if it is zero. The
/// dimension is unchanged.
///
/// $$
/// f(v, m) = -v \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Panics
/// Panics if `m` is zero, or if any element of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 0)").unwrap();
/// assert_eq!(v.mod_neg(7).to_string(), "(2, 6, 0)");
/// ```
///
/// This is equivalent to `_nmod_vec_neg` from `nmod_vec/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(mut self, m: T) -> Self {
self.mod_neg_assign(m);
self
}
}
impl<T: PrimitiveUnsigned> ModNeg<T> for &UnsignedVector<T> {
type Output = UnsignedVector<T>;
/// Negates an [`UnsignedVector`] modulo $m$, taking the vector by reference. The elements must
/// already be reduced modulo $m$.
///
/// Each element $x$ becomes $-x \bmod m$: $m - x$ if $x$ is nonzero, and 0 if it is zero. The
/// dimension is unchanged.
///
/// $$
/// f(v, m) = -v \bmod m.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Panics
/// Panics if `m` is zero, or if any element of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNeg;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 0)").unwrap();
/// assert_eq!((&v).mod_neg(7).to_string(), "(2, 6, 0)");
/// ```
///
/// This is equivalent to `_nmod_vec_neg` from `nmod_vec/neg.c`, FLINT 3.6.0.
#[inline]
fn mod_neg(self, m: T) -> UnsignedVector<T> {
assert_reduced(self, m);
let mut elements = self.elements.clone();
negate(&mut elements, m);
UnsignedVector { elements }
}
}
impl<T: PrimitiveUnsigned> ModNegAssign<T> for UnsignedVector<T> {
/// Negates an [`UnsignedVector`] modulo $m$, in place. The elements 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 `self.dimension()`.
///
/// # Panics
/// Panics if `m` is zero, or if any element of `self` is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModNegAssign;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let mut v = UnsignedVector::<u8>::from_str("(5, 1, 0)").unwrap();
/// v.mod_neg_assign(7);
/// assert_eq!(v.to_string(), "(2, 6, 0)");
/// ```
#[inline]
fn mod_neg_assign(&mut self, m: T) {
assert_reduced(self, m);
negate(&mut self.elements, m);
}
}