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use crate::definitions::Image;
use crate::drawing::line::draw_line_segment_mut;
use crate::drawing::Canvas;
use crate::rect::Rect;
use image::{GenericImage, ImageBuffer};
use std::f32;

/// Draws the outline of a rectangle on a new copy of an image.
///
/// Draws as much of the boundary of the rectangle as lies inside the image bounds.
#[must_use = "the function does not modify the original image"]
pub fn draw_hollow_rect<I>(image: &I, rect: Rect, color: I::Pixel) -> Image<I::Pixel>
where
    I: GenericImage,
{
    let mut out = ImageBuffer::new(image.width(), image.height());
    out.copy_from(image, 0, 0).unwrap();
    draw_hollow_rect_mut(&mut out, rect, color);
    out
}

/// Draws the outline of a rectangle on an image in place.
///
/// Draws as much of the boundary of the rectangle as lies inside the image bounds.
pub fn draw_hollow_rect_mut<C>(canvas: &mut C, rect: Rect, color: C::Pixel)
where
    C: Canvas,
{
    let left = rect.left() as f32;
    let right = rect.right() as f32;
    let top = rect.top() as f32;
    let bottom = rect.bottom() as f32;

    draw_line_segment_mut(canvas, (left, top), (right, top), color);
    draw_line_segment_mut(canvas, (left, bottom), (right, bottom), color);
    draw_line_segment_mut(canvas, (left, top), (left, bottom), color);
    draw_line_segment_mut(canvas, (right, top), (right, bottom), color);
}

/// Draws a rectangle and its contents on a new copy of an image.
///
/// Draws as much of the rectangle and its contents as lies inside the image bounds.
#[must_use = "the function does not modify the original image"]
pub fn draw_filled_rect<I>(image: &I, rect: Rect, color: I::Pixel) -> Image<I::Pixel>
where
    I: GenericImage,
{
    let mut out = ImageBuffer::new(image.width(), image.height());
    out.copy_from(image, 0, 0).unwrap();
    draw_filled_rect_mut(&mut out, rect, color);
    out
}

/// Draws a rectangle and its contents on an image in place.
///
/// Draws as much of the rectangle and its contents as lies inside the image bounds.
pub fn draw_filled_rect_mut<C>(canvas: &mut C, rect: Rect, color: C::Pixel)
where
    C: Canvas,
{
    let canvas_bounds = Rect::at(0, 0).of_size(canvas.width(), canvas.height());
    if let Some(intersection) = canvas_bounds.intersect(rect) {
        for dy in 0..intersection.height() {
            for dx in 0..intersection.width() {
                let x = intersection.left() as u32 + dx;
                let y = intersection.top() as u32 + dy;
                canvas.draw_pixel(x, y, color);
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::drawing::Blend;
    use crate::rect::Rect;
    use image::{GrayImage, Luma, Pixel, Rgb, RgbImage, Rgba, RgbaImage};
    use test::{black_box, Bencher};

    #[bench]
    fn bench_draw_filled_rect_mut_rgb(b: &mut Bencher) {
        let mut image = RgbImage::new(200, 200);
        let color = Rgb([120u8, 60u8, 47u8]);
        let rect = Rect::at(50, 50).of_size(80, 90);
        b.iter(|| {
            draw_filled_rect_mut(&mut image, rect, color);
            black_box(&image);
        });
    }

    #[test]
    fn test_draw_hollow_rect() {
        let image = GrayImage::from_pixel(5, 5, Luma([1u8]));

        let expected = gray_image!(
            1, 1, 1, 1, 1;
            1, 1, 1, 1, 1;
            1, 1, 4, 4, 4;
            1, 1, 4, 1, 4;
            1, 1, 4, 4, 4);

        let actual = draw_hollow_rect(&image, Rect::at(2, 2).of_size(3, 3), Luma([4u8]));
        assert_pixels_eq!(actual, expected);
    }

    #[test]
    fn test_draw_filled_rect() {
        let image = GrayImage::from_pixel(5, 5, Luma([1u8]));

        let expected = gray_image!(
            1, 1, 1, 1, 1;
            1, 4, 4, 4, 1;
            1, 4, 4, 4, 1;
            1, 4, 4, 4, 1;
            1, 1, 1, 1, 1);

        let actual = draw_filled_rect(&image, Rect::at(1, 1).of_size(3, 3), Luma([4u8]));
        assert_pixels_eq!(actual, expected);
    }

    #[test]
    fn test_draw_blended_filled_rect() {
        // https://github.com/image-rs/imageproc/issues/261

        let white = Rgba([255u8, 255u8, 255u8, 255u8]);
        let blue = Rgba([0u8, 0u8, 255u8, 255u8]);
        let semi_transparent_red = Rgba([255u8, 0u8, 0u8, 127u8]);

        let mut image = Blend(RgbaImage::from_pixel(5, 5, white));

        draw_filled_rect_mut(&mut image, Rect::at(1, 1).of_size(3, 3), blue);
        draw_filled_rect_mut(
            &mut image,
            Rect::at(2, 2).of_size(1, 1),
            semi_transparent_red,
        );

        // The central pixel should be blended
        let mut blended = blue;
        blended.blend(&semi_transparent_red);

        #[rustfmt::skip]
        let expected = vec![
            white, white,   white, white, white,
            white,  blue,    blue,  blue, white,
            white,  blue, blended,  blue, white,
            white,  blue,    blue,  blue, white,
            white, white,   white, white, white
        ];
        let expected = RgbaImage::from_fn(5, 5, |x, y| expected[(y * 5 + x) as usize]);

        assert_pixels_eq!(image.0, expected);

        // Draw an opaque rectangle over the central pixel as a sanity check that
        // we're blending in the correct direction only.
        draw_filled_rect_mut(&mut image, Rect::at(2, 2).of_size(1, 1), blue);
        assert_eq!(*image.0.get_pixel(2, 2), blue);
    }
}