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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, ModSub, ModSubAssign};
use crate::num::basic::unsigneds::PrimitiveUnsigned;
use crate::unsigned_vector::UnsignedVector;
// Subtracts each element of `ys` from the element of `xs` at the same index, modulo `m`.
pub(crate) fn mod_sub_assign_slice<T: PrimitiveUnsigned>(xs: &mut [T], ys: &[T], m: T) {
for (x, &y) in xs.iter_mut().zip(ys) {
*x = x.mod_sub(y, m);
}
}
fn assert_reduced<T: PrimitiveUnsigned>(v: &UnsignedVector<T>, w: &UnsignedVector<T>, m: T) {
assert_eq!(
v.elements.len(),
w.elements.len(),
"cannot subtract vectors of different dimensions"
);
assert!(
v.mod_is_reduced(&m),
"self must be reduced mod m, but {v} has an element >= {m}"
);
assert!(
w.mod_is_reduced(&m),
"other must be reduced mod m, but {w} has an element >= {m}"
);
}
fn mod_sub_assign<T: PrimitiveUnsigned>(v: &mut UnsignedVector<T>, w: &UnsignedVector<T>, m: T) {
assert_reduced(v, w, m);
mod_sub_assign_slice(&mut v.elements, &w.elements, m);
}
fn mod_sub_ref_val<T: PrimitiveUnsigned>(v: &UnsignedVector<T>, w: &mut UnsignedVector<T>, m: T) {
assert_reduced(v, w, m);
for (x, &y) in w.elements.iter_mut().zip(&v.elements) {
*x = y.mod_sub(*x, m);
}
}
impl<T: PrimitiveUnsigned> ModSub<Self, T> for UnsignedVector<T> {
type Output = Self;
/// Subtracts two [`UnsignedVector`]s modulo $m$, taking the first by value and the second by
/// value. The elements of both must already be reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSub;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// assert_eq!(v.mod_sub(w, 8).to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub(mut self, other: Self, m: T) -> Self {
mod_sub_assign(&mut self, &other, m);
self
}
}
impl<T: PrimitiveUnsigned> ModSub<&Self, T> for UnsignedVector<T> {
type Output = Self;
/// Subtracts two [`UnsignedVector`]s modulo $m$, taking the first by value and the second by
/// reference. The elements of both must already be reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSub;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// assert_eq!(v.mod_sub(&w, 8).to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub(mut self, other: &Self, m: T) -> Self {
mod_sub_assign(&mut self, other, m);
self
}
}
impl<T: PrimitiveUnsigned> ModSub<UnsignedVector<T>, T> for &UnsignedVector<T> {
type Output = UnsignedVector<T>;
/// Subtracts two [`UnsignedVector`]s modulo $m$, taking the first by reference and the second
/// by value. The elements of both must already be reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSub;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// assert_eq!((&v).mod_sub(w, 8).to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub(self, mut other: UnsignedVector<T>, m: T) -> UnsignedVector<T> {
mod_sub_ref_val(self, &mut other, m);
other
}
}
impl<T: PrimitiveUnsigned> ModSub<&UnsignedVector<T>, T> for &UnsignedVector<T> {
type Output = UnsignedVector<T>;
/// Subtracts two [`UnsignedVector`]s modulo $m$, taking the first by reference and the second
/// by reference. The elements of both must already be reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSub;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// assert_eq!((&v).mod_sub(&w, 8).to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub(self, other: &UnsignedVector<T>, m: T) -> UnsignedVector<T> {
let mut v = self.clone();
mod_sub_assign(&mut v, other, m);
v
}
}
impl<T: PrimitiveUnsigned> ModSubAssign<Self, T> for UnsignedVector<T> {
/// Subtracts an [`UnsignedVector`] from an [`UnsignedVector`] modulo $m$, in place, taking the
/// [`UnsignedVector`] on the right-hand side by value. The elements of both must already be
/// reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSubAssign;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let mut v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// v.mod_sub_assign(w, 8);
/// assert_eq!(v.to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub_assign(&mut self, other: Self, m: T) {
mod_sub_assign(self, &other, m);
}
}
impl<T: PrimitiveUnsigned> ModSubAssign<&Self, T> for UnsignedVector<T> {
/// Subtracts an [`UnsignedVector`] from an [`UnsignedVector`] modulo $m$, in place, taking the
/// [`UnsignedVector`] on the right-hand side by reference. The elements of both must already be
/// reduced modulo $m$.
///
/// The difference is taken element by element, each reduced modulo $m$, so the result has the
/// same dimension as the operands.
///
/// $$
/// f(v, w, m) = v - w \bmod m.
/// $$
///
/// # 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, if `self` and `other` have different dimensions, or if any element of
/// either is greater than or equal to `m`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModSubAssign;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let mut v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// let w = UnsignedVector::<u8>::from_str("(4, 7, 0)").unwrap();
/// v.mod_sub_assign(&w, 8);
/// assert_eq!(v.to_string(), "(1, 2, 3)");
/// ```
///
/// This is equivalent to `_nmod_vec_sub` from `nmod_vec/sub.c`, FLINT 3.6.0.
#[inline]
fn mod_sub_assign(&mut self, other: &Self, m: T) {
mod_sub_assign(self, other, m);
}
}