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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::integer::Integer;
use crate::integer::conversion::to_twos_complement_limbs::{
limbs_twos_complement, limbs_twos_complement_in_place,
};
use crate::natural::Natural;
use crate::platform::Limb;
use alloc::vec::Vec;
use malachite_base::num::basic::integers::PrimitiveInt;
use malachite_base::num::basic::traits::Zero;
impl Integer {
/// Converts a slice of [limbs](crate#limbs) to an [`Integer`], in ascending order, so that less
/// significant limbs have lower indices in the input slice.
///
/// The limbs are in two's complement, and the most significant bit of the limbs indicates the
/// sign; if the bit is zero, the [`Integer`] is non-negative, and if the bit is one it is
/// negative. If the slice is empty, zero is returned.
///
/// This function borrows a slice. If taking ownership of a [`Vec`] is possible instead,
/// [`from_owned_twos_complement_limbs_asc`](`Self::from_owned_twos_complement_limbs_asc`) is
/// more efficient.
///
/// This function is more efficient than
/// [`from_twos_complement_limbs_desc`](`Self::from_twos_complement_limbs_desc`).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `xs.len()`.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::integers::PrimitiveInt;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::platform::Limb;
///
/// if Limb::WIDTH == u32::WIDTH {
/// assert_eq!(Integer::from_twos_complement_limbs_asc(&[]), 0);
/// assert_eq!(Integer::from_twos_complement_limbs_asc(&[123]), 123);
/// assert_eq!(Integer::from_twos_complement_limbs_asc(&[4294967173]), -123);
/// // 10^12 = 232 * 2^32 + 3567587328
/// assert_eq!(
/// Integer::from_twos_complement_limbs_asc(&[3567587328, 232]),
/// 1000000000000u64
/// );
/// assert_eq!(
/// Integer::from_twos_complement_limbs_asc(&[727379968, 4294967063]),
/// -1000000000000i64
/// );
/// }
/// ```
pub fn from_twos_complement_limbs_asc(xs: &[Limb]) -> Self {
match xs {
&[] => Self::ZERO,
&[.., last] if !last.get_highest_bit() => Self::from(Natural::from_limbs_asc(xs)),
xs => -Natural::from_owned_limbs_asc(limbs_twos_complement(xs)),
}
}
/// Converts a slice of [limbs](crate#limbs) to an [`Integer`], in descending order, so that
/// less significant limbs have higher indices in the input slice.
///
/// The limbs are in two's complement, and the most significant bit of the limbs indicates the
/// sign; if the bit is zero, the [`Integer`] is non-negative, and if the bit is one it is
/// negative. If the slice is empty, zero is returned.
///
/// This function borrows a slice. If taking ownership of a [`Vec`] is possible instead,
/// [`from_owned_twos_complement_limbs_desc`](`Self::from_owned_twos_complement_limbs_desc`) is
/// more efficient.
///
/// This function is less efficient than
/// [`from_twos_complement_limbs_asc`](`Self::from_twos_complement_limbs_asc`).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `xs.len()`.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::integers::PrimitiveInt;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::platform::Limb;
///
/// if Limb::WIDTH == u32::WIDTH {
/// assert_eq!(Integer::from_twos_complement_limbs_desc(&[]), 0);
/// assert_eq!(Integer::from_twos_complement_limbs_desc(&[123]), 123);
/// assert_eq!(
/// Integer::from_twos_complement_limbs_desc(&[4294967173]),
/// -123
/// );
/// // 10^12 = 232 * 2^32 + 3567587328
/// assert_eq!(
/// Integer::from_twos_complement_limbs_desc(&[232, 3567587328]),
/// 1000000000000u64
/// );
/// assert_eq!(
/// Integer::from_twos_complement_limbs_desc(&[4294967063, 727379968]),
/// -1000000000000i64
/// );
/// }
/// ```
pub fn from_twos_complement_limbs_desc(xs: &[Limb]) -> Self {
Self::from_owned_twos_complement_limbs_asc(xs.iter().copied().rev().collect())
}
/// Converts a slice of [limbs](crate#limbs) to an [`Integer`], in ascending order, so that less
/// significant limbs have lower indices in the input slice.
///
/// The limbs are in two's complement, and the most significant bit of the limbs indicates the
/// sign; if the bit is zero, the [`Integer`] is non-negative, and if the bit is one it is
/// negative. If the slice is empty, zero is returned.
///
/// This function takes ownership of a [`Vec`]. If it's necessary to borrow a slice instead, use
/// [`from_twos_complement_limbs_asc`](`Self::from_twos_complement_limbs_asc`)
///
/// This function is more efficient than
/// [`from_owned_twos_complement_limbs_desc`](`Self::from_owned_twos_complement_limbs_desc`).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `xs.len()`.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::integers::PrimitiveInt;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::platform::Limb;
///
/// if Limb::WIDTH == u32::WIDTH {
/// assert_eq!(Integer::from_owned_twos_complement_limbs_asc(vec![]), 0);
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_asc(vec![123]),
/// 123
/// );
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_asc(vec![4294967173]),
/// -123
/// );
/// // 10^12 = 232 * 2^32 + 3567587328
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_asc(vec![3567587328, 232]),
/// 1000000000000i64
/// );
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_asc(vec![727379968, 4294967063]),
/// -1000000000000i64
/// );
/// }
/// ```
pub fn from_owned_twos_complement_limbs_asc(mut xs: Vec<Limb>) -> Self {
match *xs.as_slice() {
[] => Self::ZERO,
[.., last] if !last.get_highest_bit() => Self::from(Natural::from_owned_limbs_asc(xs)),
_ => {
assert!(!limbs_twos_complement_in_place(&mut xs));
-Natural::from_owned_limbs_asc(xs)
}
}
}
/// Converts a slice of [limbs](crate#limbs) to an [`Integer`], in descending order, so that
/// less significant limbs have higher indices in the input slice.
///
/// The limbs are in two's complement, and the most significant bit of the limbs indicates the
/// sign; if the bit is zero, the [`Integer`] is non-negative, and if the bit is one it is
/// negative. If the slice is empty, zero is returned.
///
/// This function takes ownership of a [`Vec`]. If it's necessary to borrow a slice instead, use
/// [`from_twos_complement_limbs_desc`](`Self::from_twos_complement_limbs_desc`).
///
/// This function is less efficient than
/// [`from_owned_twos_complement_limbs_asc`](`Self::from_owned_twos_complement_limbs_asc`).
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `xs.len()`.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::integers::PrimitiveInt;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::platform::Limb;
///
/// if Limb::WIDTH == u32::WIDTH {
/// assert_eq!(Integer::from_owned_twos_complement_limbs_desc(vec![]), 0);
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_desc(vec![123]),
/// 123
/// );
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_desc(vec![4294967173]),
/// -123
/// );
/// // 10^12 = 232 * 2^32 + 3567587328
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_desc(vec![232, 3567587328]),
/// 1000000000000i64
/// );
/// assert_eq!(
/// Integer::from_owned_twos_complement_limbs_desc(vec![4294967063, 727379968]),
/// -1000000000000i64
/// );
/// }
/// ```
pub fn from_owned_twos_complement_limbs_desc(mut xs: Vec<Limb>) -> Self {
xs.reverse();
Self::from_owned_twos_complement_limbs_asc(xs)
}
}