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``````// SPDX-FileCopyrightText: 2022 Thomas Kramer
//

//! Describe alignment and orientation along coordinate axes.

use num_traits::Signed;

/// Direction in one dimension.
#[derive(Copy, Clone, Debug, Hash, Ord, PartialOrd, Eq, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum Direction1D {
/// Towards negative coordinates.
Low,
/// Towards positive coordinates.
High,
}

impl Direction1D {
/// Return the opposite direction.
pub fn reversed(self) -> Self {
match self {
Direction1D::Low => Direction1D::High,
Direction1D::High => Direction1D::Low,
}
}

/// Map `Low` to `-1` and `High` to `+1`.
pub fn sign<N>(&self) -> N
where
N: Signed,
{
match self {
Direction1D::Low => N::one().neg(),
Direction1D::High => N::one(),
}
}
}

impl From<Direction2D> for Direction1D {
/// Downcast 2D direction to 1D direction by preserving the sign.
fn from(d2: Direction2D) -> Self {
match d2 {
Direction2D::Right | Direction2D::Up => Direction1D::High,
Direction2D::Left | Direction2D::Down => Direction1D::Low,
}
}
}

/// Orientation in two dimensions along one of the axes.
#[derive(Copy, Clone, Debug, Hash, Ord, PartialOrd, Eq, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum Orientation2D {
/// Oriented parallel to the x axis.
Horizontal,
/// Oriented parallel to the y axis.
Vertical,
}

impl Orientation2D {
/// Get the orthogonal orientation.
pub fn other(self) -> Self {
match self {
Orientation2D::Horizontal => Self::Vertical,
Orientation2D::Vertical => Self::Horizontal,
}
}

/// Get the positive or negative direction aligned with this orientation.
pub fn direction(self, d1: Direction1D) -> Direction2D {
use Direction1D::*;
use Direction2D::*;
use Orientation2D::*;
match (self, d1) {
(Horizontal, Low) => Right,
(Horizontal, High) => Left,
(Vertical, Low) => Down,
(Vertical, High) => Up,
}
}

/// Check if orientation is vertical.
pub fn is_vertical(&self) -> bool {
self == &Self::Vertical
}

/// Check if orientation is horizontal.
pub fn is_horizontal(&self) -> bool {
self == &Self::Horizontal
}
}

/// Directions along the coordinate axes in two dimensions.
#[derive(Copy, Clone, Debug, Hash, Ord, PartialOrd, Eq, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum Direction2D {
/// Positive x direction.
Left,
/// Positive y direction.
Up,
/// Negative x direction.
Right,
/// Negative y direction.
Down,
}

impl Direction2D {
/// Get the opposite direction.
pub fn reversed(self) -> Self {
match self {
Direction2D::Left => Self::Right,
Direction2D::Up => Self::Down,
Direction2D::Right => Self::Left,
Direction2D::Down => Self::Up,
}
}

/// Get the orientation of this direction.
pub fn orientation(&self) -> Orientation2D {
match self {
Direction2D::Left | Direction2D::Right => Orientation2D::Horizontal,
Direction2D::Up | Direction2D::Down => Orientation2D::Vertical,
}
}

/// Get the sign of the direction.
pub fn sign<N>(self) -> N
where
N: Signed,
{
let d1: Direction1D = self.into();
d1.sign()
}
}
``````