extern crate vec2d;

use std::cmp;

pub struct Land2D<T> {

    pixels: vec2d::Vec2D<T>,

    width_mask: usize,

    height_mask: usize,

}

        assert!(width.is_power_of_two());

        assert!(height.is_power_of_two());

        Self {

            width_mask: !(width - 1),

            height_mask: !(height - 1),

        }

    }

    #[inline]

    pub fn width(&self) -> usize {

        self.pixels.width()

    }

    #[inline]

    pub fn height(&self) -> usize {

        self.pixels.height()

    }

    #[inline]

    pub fn is_valid_coordinate(&self, x: i32, y: i32) -> bool {

    }

    #[inline]

    pub fn map<U, F: FnOnce(&mut T) -> U>(&mut self, y: i32, x: i32, f: F) {

        if self.is_valid_coordinate(x, y) {

        }

    }

    pub fn draw_line(&mut self, x1: i32, y1: i32, x2: i32, y2: i32, value: T) {

        let mut e_x: i32 = 0;

        let mut e_y: i32 = 0;

        let mut d_x: i32 = x2 - x1;

        let mut d_y: i32 = y2 - y1;

        let s_x: i32;

        let s_y: i32;

        if d_x > 0 {

            s_x = 1;

        } else if d_x < 0 {

            s_x = -1;

            d_x = -d_x;

        } else {

            s_x = d_x;

        }

        if d_y > 0 {

            s_y = 1;

        } else if d_y < 0 {

            s_y = -1;

            d_y = -d_y;

        } else {

            s_y = d_y;

        }

        let d = cmp::max(d_x, d_y);

        let mut x = x1;

        let mut y = y1;

        for _i in 0..=d {

            e_x += d_x;

            e_y += d_y;

            if e_x > d {

                e_x -= d;

                x += s_x;

            }

            if e_y > d {

                e_y -= d;

                y += s_y;

            }

            self.map(y, x, |p| *p = value);

        }

    }

    pub fn fill(&mut self, start_x: i32, start_y: i32, border_value: T, fill_value: T) {

        debug_assert!(self.is_valid_coordinate(start_x - 1, start_y));

        debug_assert!(self.is_valid_coordinate(start_x, start_y));

        let mut stack: Vec<(usize, usize, usize, isize)> = Vec::new();

            land: &Land2D<T>,

            stack: &mut Vec<(usize, usize, usize, isize)>,

            xl: usize,

            xr: usize,

            y: usize,

            dir: isize,

        ) {

            let yd = y as isize + dir;

            if land.is_valid_coordinate(0, yd as i32) {

                stack.push((xl, xr, yd as usize, dir));

            }

        };

        let start_x_l = (start_x - 1) as usize;

        let start_x_r = start_x as usize;

        push(self, &mut stack, start_x_l, start_x_r, start_y as usize, -1);

        push(self, &mut stack, start_x_l, start_x_r, start_y as usize, 1);

        loop {

            let a = stack.pop();

            match a {

                None => return,

                Some(a) => {

                    let (mut xl, mut xr, y, mut dir) = a;

                    while xl > 0 && self

                        .pixels

                        .get(y, xl)

                        .map_or(false, |v| *v != border_value && *v != fill_value)

                    {

                        xl -= 1;

                    }

                    while xr < self.width() - 1 && self

                        .pixels

                        .get(y, xr)

                        .map_or(false, |v| *v != border_value && *v != fill_value)

                    {

                        xr += 1;

                    }

                    while xl < xr {

                        while xl <= xr

                            && (self.pixels[y][xl] == border_value

                                || self.pixels[y][xl] == fill_value)

                        {

                            xl += 1;

                        }

                        let mut x = xl;

                        while xl <= xr

                            && (self.pixels[y][xl] != border_value

                                && self.pixels[y][xl] != fill_value)

                        {

                            self.pixels[y][xl] = fill_value;

                            xl += 1;

                        }

                        if x < xl {

                            push(self, &mut stack, x, xl - 1, y, dir);

                            push(self, &mut stack, x, xl - 1, y, -dir);

                        }

                    }

                }

            }

        }

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn basics() {

        assert!(l.is_valid_coordinate(0, 0));

        assert!(!l.is_valid_coordinate(-1, -1));

        assert!(l.is_valid_coordinate(31, 63));

        assert!(!l.is_valid_coordinate(32, 63));

        assert!(!l.is_valid_coordinate(31, 64));

    }

    #[test]

    fn fill() {

        l.draw_line(0, 0, 32, 96, 1);

        l.draw_line(32, 96, 64, 32, 1);

        l.draw_line(64, 32, 96, 80, 1);

        l.draw_line(96, 80, 128, 0, 1);

        l.draw_line(0, 128, 64, 96, 1);

        l.draw_line(128, 128, 64, 96, 1);

        l.fill(32, 32, 1, 2);

        l.fill(16, 96, 1, 3);

        l.fill(60, 100, 1, 4);

        assert_eq!(l.pixels[0][0], 1);

        assert_eq!(l.pixels[96][64], 1);

        assert_eq!(l.pixels[40][32], 2);

        assert_eq!(l.pixels[40][96], 2);

        assert_eq!(l.pixels[5][0], 3);

        assert_eq!(l.pixels[120][0], 3);

        assert_eq!(l.pixels[5][127], 3);

        assert_eq!(l.pixels[120][127], 3);

        assert_eq!(l.pixels[35][64], 3);

        assert_eq!(l.pixels[120][20], 4);

        assert_eq!(l.pixels[120][100], 4);

        assert_eq!(l.pixels[100][64], 4);

    }

}