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pub use bit_vec::BitVec;

use crate::{BinaryImage, Shape};

impl BinaryImage {
    pub fn operation(
        &self,
        other: &BinaryImage,
        operator: impl FnMut((&mut u8, &u8)),
    ) -> BinaryImage {
        assert_eq!(self.width, other.width);
        assert_eq!(self.height, other.height);
        let mut i = self.pixels.to_bytes();
        let u = other.pixels.to_bytes();
        i.iter_mut().zip(u.iter()).for_each(operator);
        BinaryImage {
            pixels: BitVec::from_bytes(&i),
            width: self.width,
            height: self.height,
        }
    }

    pub fn negative(&self) -> BinaryImage {
        let i = self.pixels.to_bytes();
        use std::ops::Not;
        let ii = i.iter().map(|x| x.not()).collect::<Vec<u8>>();
        BinaryImage {
            pixels: BitVec::from_bytes(&ii.as_slice()),
            width: self.width,
            height: self.height,
        }
    }

    pub fn diff(&self, other: &BinaryImage) -> BinaryImage {
        self.operation(other, |(x1, x2)| *x1 ^= *x2)
    }

    pub fn union(&self, other: &BinaryImage) -> BinaryImage {
        self.operation(other, |(x1, x2)| *x1 |= *x2)
    }

    pub fn intersect(&self, other: &BinaryImage) -> BinaryImage {
        self.operation(other, |(x1, x2)| *x1 &= *x2)
    }

    pub fn clustered_diff(&self, other: &BinaryImage) -> u32 {
        self.diff(other).significance(self.area(), std::u32::MAX)
    }

    /// early return if diff >= threshold, so maximum return value is equal to threshold
    pub fn significance(&self, area: u64, threshold: u32) -> u32 {
        let clusters = self.to_clusters(false);
        let mut diff: u64 = 0;
        let scale = 4 * 128 * 128;
        let divisor = area * self.width as u64;
        let threshold_u64 = threshold as u64 * divisor;
        for cluster in clusters.iter() {
            let size = cluster.size() as u64;
            let cluster_image = cluster.to_binary_image();
            let boundary = Shape::image_boundary_list(&cluster_image);
            let skeleton = cluster_image.to_skeleton();
            diff += scale * size *
                skeleton.stat.mean as u64 *
                skeleton.stat.count as u64 /
                boundary.len() as u64;
            if diff >= threshold_u64 {
                break;
            }
        }
        (diff / divisor) as u32
    }

    pub fn diff_and_count(&self, other: &BinaryImage) -> usize {
        assert_eq!(self.width, other.width);
        assert_eq!(self.height, other.height);
        let mut i = self.pixels.to_bytes();
        let u = other.pixels.to_bytes();
        i.iter_mut().zip(u.iter()).for_each(|(x1, x2)| *x1 ^= *x2);
        while i.len() % 4 != 0 {
            i.push(0);
        }
        let mut count = 0;
        for ii in (0..i.len()).step_by(4) {
            count += Self::popcount(u32::from_be_bytes([i[ii], i[ii + 1], i[ii + 2], i[ii + 3]]))
                as usize;
        }
        count
    }

    #[inline(always)]
    pub fn popcount(i: u32) -> u32 {
        i.count_ones()
    }

    /// expand a binary image using a circular brush
    pub fn stroke(&self, s: u32) -> BinaryImage {
        let mut new_image = BinaryImage::new_w_h(self.width + s as usize, self.height + s as usize);
        let ox = (s as usize) >> 1;
        let oy = (s as usize) >> 1;
        let ss = (s >> 1) as i32;
        for y in 0..self.height {
            for x in 0..self.width {
                let v = self.get_pixel(x, y);
                if v {
                    for yy in -ss..ss {
                        for xx in -ss..ss {
                            if (((xx * xx + yy * yy) as f64).sqrt() as i32) < ss {
                                new_image.set_pixel(
                                    (x as i32 + xx + ox as i32) as usize,
                                    (y as i32 + yy + oy as i32) as usize,
                                    true,
                                );
                            }
                        }
                    }
                }
            }
        }
        new_image
    }
}

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

    #[test]
    fn image_diff() {
        let mut a = BinaryImage::new_w_h(2, 2);
        a.set_pixel(0, 0, true);
        let mut b = BinaryImage::new_w_h(2, 2);
        b.set_pixel(1, 1, true);
        assert_eq!(a.diff_and_count(&b), 2);

        let mut a = BinaryImage::new_w_h(3, 3);
        a.set_pixel(1, 1, true);
        let mut b = BinaryImage::new_w_h(3, 3);
        b.set_pixel(1, 1, true);
        assert_eq!(a.diff_and_count(&b), 0);

        let mut a = BinaryImage::new_w_h(3, 3);
        a.set_pixel(0, 0, true);
        a.set_pixel(1, 1, true);
        let mut b = BinaryImage::new_w_h(3, 3);
        b.set_pixel(1, 1, true);
        b.set_pixel(2, 2, true);
        assert_eq!(a.diff_and_count(&b), 2);
    }

    #[test]
    fn negative_image() {
        assert_eq!(
            BinaryImage::from_string(&(
                "*-*\n".to_owned() +
                "-*-\n" +
                "*-*\n"
            ))
            .negative()
            .to_string(),
            BinaryImage::from_string(&(
                "-*-\n".to_owned() +
                "*-*\n" +
                "-*-\n"
            )).to_string()
        );
    }
}