use std::{
    convert::{From, Into, TryFrom},
    ops::Sub,
};

#[derive(Debug)]
pub struct Pixmap<T> {
    pub width: u32,
    pub height: u32,
    pub data: Vec<T>,
}

#[derive(Copy, Clone, Debug)]
pub struct MapPoint {
    pub x: u32,
    pub y: u32,
}

impl From<(u32, u32)> for MapPoint {
    fn from((x, y): (u32, u32)) -> MapPoint {
        MapPoint { x, y }
    }
}

impl TryFrom<(i32, i32)> for MapPoint {
    type Error = ();
    fn try_from((x, y): (i32, i32)) -> Result<Self, Self::Error> {
        if x < 0 || y < 0 {
            return Err(());
        } else {
            Ok(MapPoint {
                x: x as u32,
                y: y as u32,
            })
        }
    }
}

impl TryFrom<(i64, i64)> for MapPoint {
    type Error = ();
    fn try_from((x, y): (i64, i64)) -> Result<Self, Self::Error> {
        if x < 0 || y < 0 {
            return Err(());
        } else {
            Ok(MapPoint {
                x: x as u32,
                y: y as u32,
            })
        }
    }
}

impl<T> Pixmap<T>
where
    T: Copy + Clone + Default,
{
    pub fn new(width: u32, height: u32) -> Self {
        let data = vec![Default::default(); (width * height) as usize];
        Pixmap {
            width,
            height,
            data,
        }
    }

    pub fn new_with(width: u32, height: u32, start: T) -> Self {
        let data = vec![start; (width * height) as usize];
        Pixmap {
            width,
            height,
            data,
        }
    }

    pub fn is_inside<P: Into<MapPoint>>(&self, pt: P) -> bool {
        let MapPoint { x, y } = pt.into();
        x < self.width && y < self.height
    }

    pub fn idx<P: Into<MapPoint>>(&self, pt: P) -> usize {
        let MapPoint { x, y } = pt.into();
        (y * self.width + x) as usize
    }

    pub fn get<P: Into<MapPoint>>(&self, pt: P) -> T {
        let idx = self.idx(pt);
        self.data[idx]
    }

    pub fn set<P: Into<MapPoint>>(&mut self, pt: P, new_val: T) -> T {
        let pt = pt.into();
        let old_val = self.get(pt);
        let idx = self.idx(pt);
        self.data[idx] = new_val;
        old_val
    }

    pub fn get_circle<P: Into<MapPoint>>(&self, center: P, radius: u32) -> Vec<MapPoint> {
        let mut circle: Vec<(i64, i64)> = vec![];
        let MapPoint { x, y } = center.into();
        let x = x as i64;
        let y = y as i64;
        let (mut dx, mut dy, mut err) = (radius as i64, 0i64, 1 - radius as i64);
        while dx >= dy {
            circle.push((x + dx, y + dy));
            circle.push((x - dx, y + dy));
            circle.push((x + dx, y - dy));
            circle.push((x - dx, y - dy));
            circle.push((x + dy, y + dx));
            circle.push((x - dy, y + dx));
            circle.push((x + dy, y - dx));
            circle.push((x - dy, y - dx));
            dy = dy + 1;
            if err < 0 {
                err = err + 2 * dy + 1;
            } else {
                dx -= 1;
                err += 2 * (dy - dx) + 1;
            }
        }
        for xi in 0..radius as i64 {
            for yi in 0..radius as i64 {
                if xi.pow(2) + yi.pow(2) < (radius as i64).pow(2) {
                    circle.push((x + xi, y + yi));
                    circle.push((x - xi, y + yi));
                    circle.push((x + xi, y - yi));
                    circle.push((x - xi, y - yi));
                }
            }
        }
        circle
            .into_iter()
            .flat_map(|pt| MapPoint::try_from(pt))
            .filter(|&pt| self.is_inside(pt))
            .collect()
    }

    pub fn get_line<P: Into<MapPoint>>(&self, start: P, end: P) -> Vec<MapPoint> {
        let MapPoint { x: x1, y: y1 } = start.into();
        let MapPoint { x: x2, y: y2 } = end.into();
        let mut coordinates = vec![];
        let dx = abs_difference(x1, x2) as i64;
        let dy = abs_difference(y1, y2) as i64;
        let sx = {
            if x1 < x2 {
                1
            } else {
                -1
            }
        };
        let sy = {
            if y1 < y2 {
                1
            } else {
                -1
            }
        };
        let mut err: i64 = dx - dy;
        let mut current_x = x1 as i64;
        let mut current_y = y1 as i64;
        loop {
            coordinates.push((current_x, current_y));
            if current_x == x2 as i64 && current_y == y2 as i64 {
                break;
            }
            let e2 = 2 * err;
            if e2 > -dy {
                err -= dy;
                current_x += sx;
            }
            if e2 < dx {
                err += dx;
                current_y += sy;
            }
        }
        coordinates
            .into_iter()
            .flat_map(|pt| MapPoint::try_from(pt))
            .filter(|&pt| self.is_inside(pt))
            .collect()
    }
}

fn abs_difference<T: Sub<Output = T> + Ord>(x: T, y: T) -> T {
    if x < y {
        y - x
    } else {
        x - y
    }
}