//! Horizontal alignment options
//!
//! Horizontal alignment types must implement [`HorizontalAlignment`].
use crate::align::{Alignment, HorizontalAlignment};
use embedded_graphics::{geometry::AnchorPoint, primitives::Rectangle};

/// Keep the objects' horizontal alignment unchanged
#[derive(Copy, Clone, Default)]
pub struct NoAlignment;
impl HorizontalAlignment for NoAlignment {}

impl Alignment for NoAlignment {
    #[inline]
    fn align_with_offset(&self, _object: Rectangle, _reference: Rectangle, _offset: i32) -> i32 {
        0
    }
}

/// Center the objects horizontally
///
/// *Note:* in certain cases it's not possible to center objects perfectly because of
///         the integer coordinates used.
#[derive(Copy, Clone, Default)]
pub struct Center;
impl HorizontalAlignment for Center {}

impl Alignment for Center {
    #[inline]
    fn align_with_offset(&self, object: Rectangle, reference: Rectangle, offset: i32) -> i32 {
        reference.anchor_point(AnchorPoint::Center).x - object.anchor_point(AnchorPoint::Center).x
            + offset
    }
}

/// Align the left edge of the object to the left edge of the reference
#[derive(Copy, Clone, Default)]
pub struct Left;
impl HorizontalAlignment for Left {}

impl Alignment for Left {
    #[inline]
    fn align_with_offset(&self, object: Rectangle, reference: Rectangle, offset: i32) -> i32 {
        reference.top_left.x - object.top_left.x + offset
    }
}

/// Align the right edge of the object to the right edge of the reference
#[derive(Copy, Clone, Default)]
pub struct Right;
impl HorizontalAlignment for Right {}

impl Alignment for Right {
    #[inline]
    fn align_with_offset(&self, object: Rectangle, reference: Rectangle, offset: i32) -> i32 {
        reference.anchor_point(AnchorPoint::BottomRight).x
            - object.anchor_point(AnchorPoint::BottomRight).x
            + offset
    }
}

/// Align the left edge of the object to the right edge of the reference, non-overlapping
#[derive(Copy, Clone, Default)]
pub struct LeftToRight;
impl HorizontalAlignment for LeftToRight {}

impl Alignment for LeftToRight {
    #[inline]
    fn align_with_offset(&self, object: Rectangle, reference: Rectangle, offset: i32) -> i32 {
        let offset = if object.size.width == 0 {
            offset
        } else {
            offset + 1
        };
        reference.anchor_point(AnchorPoint::BottomRight).x - object.top_left.x + offset
    }
}

/// Align the right edge of the object to the left edge of the reference, non-overlapping
#[derive(Copy, Clone, Default)]
pub struct RightToLeft;
impl HorizontalAlignment for RightToLeft {}

impl Alignment for RightToLeft {
    #[inline]
    fn align_with_offset(&self, object: Rectangle, reference: Rectangle, offset: i32) -> i32 {
        let offset = if object.size.width == 0 {
            offset
        } else {
            offset - 1
        };
        reference.top_left.x - object.anchor_point(AnchorPoint::BottomRight).x + offset
    }
}

#[cfg(test)]
mod test {
    use crate::prelude::*;
    use embedded_graphics::{
        geometry::{AnchorPoint, Point},
        prelude::Size,
        primitives::Rectangle,
    };

    #[test]
    fn test_center() {
        fn check_center_alignment(source: Rectangle, reference: Rectangle, result: Rectangle) {
            let center_of_reference = reference.top_left + reference.size() / 2;
            let center_of_result = result.top_left + result.size() / 2;

            // The size hasn't changed
            assert_eq!(result.size(), source.size());

            // Horizontal coordinate matches reference
            assert_eq!(center_of_result.x, center_of_reference.x);

            // Vertical coordinate is unchanged
            assert_eq!(result.top_left.y, source.top_left.y);
        }

        let rect1 = Rectangle::with_corners(Point::new(0, 0), Point::new(10, 10));
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::Center, vertical::NoAlignment);
        check_center_alignment(rect1, rect2, result);

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::Center, vertical::NoAlignment);
        check_center_alignment(rect2, rect1, result);
    }

    #[test]
    fn test_left() {
        fn check_left_alignment(source: Rectangle, reference: Rectangle, result: Rectangle) {
            // The size hasn't changed
            assert_eq!(result.size(), source.size());

            // Horizontal coordinate matches reference
            assert_eq!(result.top_left.x, reference.top_left.x);

            // Vertical coordinate is unchanged
            assert_eq!(result.top_left.y, source.top_left.y);
        }

        let rect1 = Rectangle::with_corners(Point::new(0, 0), Point::new(10, 10));
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::Left, vertical::NoAlignment);
        check_left_alignment(rect1, rect2, result);

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::Left, vertical::NoAlignment);
        check_left_alignment(rect2, rect1, result);
    }

    #[test]
    fn test_right() {
        fn check_right_alignment(source: Rectangle, reference: Rectangle, result: Rectangle) {
            // The size hasn't changed
            assert_eq!(result.size(), source.size());

            // Horizontal coordinate matches reference
            assert_eq!(
                result.anchor_point(AnchorPoint::BottomRight).x,
                reference.anchor_point(AnchorPoint::BottomRight).x
            );

            // Vertical coordinate is unchanged
            assert_eq!(
                result.anchor_point(AnchorPoint::BottomRight).y,
                source.anchor_point(AnchorPoint::BottomRight).y
            );
        }

        let rect1 = Rectangle::with_corners(Point::new(0, 0), Point::new(10, 10));
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::Right, vertical::NoAlignment);
        check_right_alignment(rect1, rect2, result);

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::Right, vertical::NoAlignment);
        check_right_alignment(rect2, rect1, result);
    }

    #[test]
    fn test_left_to_right() {
        fn check_left_to_right_alignment(
            source: Rectangle,
            reference: Rectangle,
            result: Rectangle,
        ) {
            // The size hasn't changed
            assert_eq!(result.size(), source.size());

            // Left is at right + 1
            assert_eq!(
                result.top_left.x,
                reference.anchor_point(AnchorPoint::BottomRight).x + 1
            );

            // Vertical coordinate is unchanged
            assert_eq!(
                result.anchor_point(AnchorPoint::BottomRight).y,
                source.anchor_point(AnchorPoint::BottomRight).y
            );
        }

        let rect1 = Rectangle::with_corners(Point::new(0, 0), Point::new(10, 10));
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::LeftToRight, vertical::NoAlignment);
        check_left_to_right_alignment(rect1, rect2, result);

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::LeftToRight, vertical::NoAlignment);
        check_left_to_right_alignment(rect2, rect1, result);
    }

    #[test]
    fn test_left_to_right_empty() {
        let rect1 = Rectangle::new(Point::new(0, 0), Size::zero());
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::LeftToRight, vertical::NoAlignment);
        // The size hasn't changed
        assert_eq!(result.size(), rect1.size());

        // Left is at right
        assert_eq!(
            result.top_left.x,
            rect2.anchor_point(AnchorPoint::BottomRight).x
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect1.anchor_point(AnchorPoint::BottomRight).y
        );

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::LeftToRight, vertical::NoAlignment);

        // The size hasn't changed
        assert_eq!(result.size(), rect2.size());

        // Left is at right
        assert_eq!(
            result.top_left.x,
            rect1.anchor_point(AnchorPoint::BottomRight).x + 1
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect2.anchor_point(AnchorPoint::BottomRight).y
        );
    }

    #[test]
    fn test_right_to_left() {
        let rect1 = Rectangle::with_corners(Point::new(0, 0), Point::new(10, 10));
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::RightToLeft, vertical::NoAlignment);
        // The size hasn't changed
        assert_eq!(result.size(), rect1.size());

        // Left is at right - 1
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).x,
            rect2.top_left.x - 1
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect1.anchor_point(AnchorPoint::BottomRight).y
        );

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::RightToLeft, vertical::NoAlignment);
        // The size hasn't changed
        assert_eq!(result.size(), rect2.size());

        // Left is at right + 1
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).x,
            rect1.top_left.x - 1
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect2.anchor_point(AnchorPoint::BottomRight).y
        );
    }

    #[test]
    fn test_right_to_left_empty() {
        let rect1 = Rectangle::new(Point::new(0, 0), Size::zero());
        let rect2 = Rectangle::with_corners(Point::new(30, 20), Point::new(40, 50));

        let result = rect1.align_to(&rect2, horizontal::RightToLeft, vertical::NoAlignment);
        // The size hasn't changed
        assert_eq!(result.size(), rect1.size());

        // Left is at right
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).x,
            rect2.top_left.x
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect1.anchor_point(AnchorPoint::BottomRight).y
        );

        // Test the other direction
        let result = rect2.align_to(&rect1, horizontal::RightToLeft, vertical::NoAlignment);
        // The size hasn't changed
        assert_eq!(result.size(), rect2.size());

        // Left is at right + 1
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).x,
            rect1.top_left.x - 1
        );

        // Vertical coordinate is unchanged
        assert_eq!(
            result.anchor_point(AnchorPoint::BottomRight).y,
            rect2.anchor_point(AnchorPoint::BottomRight).y
        );
    }
}