extern crate integral_geometry;

extern crate vec2d;

use std::cmp;

use std::ops;

use integral_geometry::{ArcPoints, EquidistantPoints, LinePoints, Point};

pub struct Land2D<T> {

    pixels: vec2d::Vec2D<T>,

    width_mask: usize,

    height_mask: usize,

}

impl<T: Copy + PartialEq> Land2D<T> {

    pub fn new(width: usize, height: usize, fill_value: T) -> Self {

        assert!(width.is_power_of_two());

        assert!(height.is_power_of_two());

        Self {

            pixels: vec2d::Vec2D::new(width, height, fill_value),

            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_x(&self, x: i32) -> bool {

        (x as usize & self.width_mask) == 0

    }

    #[inline]

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

        (y as usize & self.height_mask) == 0

    }

    #[inline]

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

        self.is_valid_x(x) && self.is_valid_y(y)

    }

    #[inline]

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

        if self.is_valid_coordinate(x, y) {

            unsafe {

                // hey, I just checked that coordinates are valid!

                f(self.pixels.get_unchecked_mut(y as usize, x as usize))

            }

        } else {

            U::default()

        }

    }

    #[inline]

    pub fn map_point<U: Default, F: FnOnce(&mut T) -> U>(&mut self, point: Point, f: F) -> U {

        self.map(point.y, point.x, f)

    }

    pub fn fill_from_iter<I>(&mut self, i: I, value: T) -> usize

    where

        I: std::iter::Iterator<Item = Point>,

    {

        i.map(|p| {

            self.map(p.y, p.x, |v| {

                *v = value;

                1

            })

        }).count()

    }

    pub fn draw_line(&mut self, from: Point, to: Point, value: T) -> usize {

        self.fill_from_iter(LinePoints::new(from, to), value)

    }

    pub fn fill(&mut self, start_point: Point, border_value: T, fill_value: T) {

        debug_assert!(self.is_valid_coordinate(start_point.x - 1, start_point.y));

        debug_assert!(self.is_valid_coordinate(start_point.x, start_point.y));

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

        fn push<T: Copy + PartialEq>(

            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_point.x - 1) as usize;

        let start_x_r = start_point.x as usize;

        push(

            self,

            &mut stack,

            start_x_l,

            start_x_r,

            start_point.y as usize,

            -1,

        );

        push(

            self,

            &mut stack,

            start_x_l,

            start_x_r,

            start_point.y as usize,

            1,

        );

                }

            }

        }

    }

    #[inline]

    fn fill_circle_line<F: Fn(&mut T) -> usize>(

        &mut self,

        y: i32,

        x_from: i32,

        x_to: i32,

        f: &F,

    ) -> usize {

        let mut result = 0;

        if self.is_valid_y(y) {

            for i in cmp::min(x_from, 0) as usize..cmp::max(x_to as usize, self.width() - 1) {

                unsafe {

                    // coordinates are valid at this point

                    result += f(self.pixels.get_unchecked_mut(y as usize, i));

                }

            }

        }

        result

    }

    #[inline]

    fn fill_circle_lines<F: Fn(&mut T) -> usize>(

        &mut self,

        x: i32,

        y: i32,

        dx: i32,

        dy: i32,

        f: &F,

    ) -> usize {

        self.fill_circle_line(y + dy, x - dx, x + dx, f)

            + self.fill_circle_line(y - dy, x - dx, x + dx, f)

            + self.fill_circle_line(y + dx, x - dy, x + dy, f)

            + self.fill_circle_line(y - dx, x - dy, x + dy, f)

    }

    pub fn change_round<F: Fn(&mut T) -> usize>(

        &mut self,

        x: i32,

        y: i32,

        radius: i32,

        f: F,

    ) -> usize {

        ArcPoints::new(radius)

            .map(&mut |p: Point| self.fill_circle_lines(x, y, p.x, p.y, &f))

            .sum()

    }

    pub fn draw_thick_line(&mut self, from: Point, to: Point, radius: i32, value: T) -> usize {

        let mut result = 0;

        for vector in ArcPoints::new(radius) {

            for delta in EquidistantPoints::new(vector) {

                for point in LinePoints::new(from, to) {

                    self.map_point(point + delta, |p| {

                        if *p != value {

                            *p = value;

                            result += 1;

                        }

                    })

                }

            }

        }

        result

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn basics() {

        let l: Land2D<u8> = Land2D::new(32, 64, 0);

        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() {

        let mut l: Land2D<u8> = Land2D::new(128, 128, 0);

        l.draw_line(Point::new(0, 0), Point::new(32, 96), 1);

        l.draw_line(Point::new(32, 96), Point::new(64, 32), 1);

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

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

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

        l.draw_line(Point::new(128, 128), Point::new(64, 96), 1);

        l.fill(Point::new(32, 32), 1, 2);

        l.fill(Point::new(16, 96), 1, 3);

        l.fill(Point::new(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);

    }

}