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```
``````use std::ops::{Mul, Sub};

use glam::{IVec2, Vec2};

use crate::GridPoint;

/// A pivot point on a 2d rect.
#[derive(Eq, PartialEq, Clone, Copy, Debug)]
pub enum Pivot {
/// +X Right, +Y Down.
TopLeft,
/// +X Left, +Y Down.
TopRight,
/// +X Right, +Y Up.
Center,
/// +X Right, +Y Up.
BottomLeft,
/// +X Left, +Y Up
BottomRight,
}

impl Pivot {
/// Coordinate axis for each pivot, used when transforming a point into
/// the pivot's coordinate space
pub fn axis(&self) -> IVec2 {
match self {
Pivot::TopLeft => IVec2::new(1, -1),
Pivot::TopRight => IVec2::new(-1, -1),
Pivot::Center => IVec2::new(1, 1),
Pivot::BottomLeft => IVec2::new(1, 1),
Pivot::BottomRight => IVec2::new(-1, 1),
}
}

// #[inline]
// fn transform_point(&self, point: impl GridPoint) -> IVec2 {
//     point.as_ivec2() * self.axis()
// }

/// Transform a point to it's equivalent position from the perspective
/// of this pivot
#[inline]
pub fn transform_point(&self, point: impl GridPoint, size: impl GridPoint) -> IVec2 {
let origin = size.as_vec2().sub(1.0).mul(Vec2::from(*self));
let point = point.as_ivec2() * self.axis();
origin.round().as_ivec2() + point
}
}

impl From<Pivot> for Vec2 {
fn from(p: Pivot) -> Self {
match p {
Pivot::TopLeft => Vec2::new(0.0, 1.0),
Pivot::TopRight => Vec2::new(1.0, 1.0),
Pivot::Center => Vec2::new(0.5, 0.5),
Pivot::BottomLeft => Vec2::new(0.0, 0.0),
Pivot::BottomRight => Vec2::new(1.0, 0.0),
}
}
}

/// A 2d point on a rect aligned to a certain [Pivot].
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct PivotedPoint {
pub point: IVec2,
pub pivot: Pivot,
}

impl GridPoint for PivotedPoint {
#[inline]
fn x(&self) -> i32 {
self.point.x
}

#[inline]
fn y(&self) -> i32 {
self.point.y
}

// /// Retrieve the pivot aligned point.
// #[inline]
// fn get_aligned_point(&self, size: impl Size2d) -> IVec2 {
//     if let Some(pivot) = self.pivot {
//         todo!()
//     } else {
//         self.point
//     }
// }

fn get_pivot(self) -> Option<Pivot> {
Some(self.pivot)
}
}

#[cfg(test)]
mod tests {
use super::*;

// #[test]
// fn pivot_point() {
//     let p = [0, 0].pivot(Pivot::TopRight);
//     assert_eq!([9, 9], p.get_aligned_point([10, 10]).to_array());

//     let p = [3, 3].pivot(Pivot::TopLeft);
//     assert_eq!([3, 6], p.get_aligned_point([10, 10]).to_array());
// }

#[test]
fn transform_point() {
let pivot = Pivot::TopRight;
assert_eq!([8, 8], pivot.transform_point([1, 1], [10, 10]).to_array());
assert_eq!([9, 9], pivot.transform_point([0, 0], [10, 10]).to_array());
let pivot = Pivot::TopLeft;
assert_eq!([1, 8], pivot.transform_point([1, 1], [10, 10]).to_array());
let pivot = Pivot::BottomLeft;
assert_eq!([1, 1], pivot.transform_point([1, 1], [10, 10]).to_array());
let pivot = Pivot::BottomRight;
assert_eq!([8, 1], pivot.transform_point([1, 1], [10, 10]).to_array());
}
}
``````