struct Ant {
    x: usize,
    y: usize,
    dir: Direction
}

#[derive(Clone,Copy)]
enum Direction {
    North,
    East,
    South,
    West
}

use Direction::*;

impl Ant {
    fn mv(&mut self, vec: &mut Vec<Vec<u8>>) {
        let pointer = &mut vec[self.y][self.x];
        //change direction
        match *pointer {
            0 => self.dir = self.dir.right(),
            1 => self.dir = self.dir.left(),
            _ => panic!("Unexpected colour in grid")
        }
        //flip colour
        //if it's 1 it's black
        //if it's 0 it's white
        *pointer ^= 1;

        //move direction
        match self.dir {
            North => self.y -= 1,
            South => self.y += 1,
            East => self.x += 1,
            West => self.x -= 1,
        }

    }
}

impl Direction {
    fn right(self) -> Direction {
        match self {
            North => East,
            East => South,
            South => West,
            West => North,
        }
    }

    fn left(self) -> Direction {
        //3 rights equal a left
        self.right().right().right()
    }
}

fn main(){
    //create a 100x100 grid using vectors
    let mut grid: Vec<Vec<u8>> = vec![vec![0; 100]; 100];
    let mut ant = Ant {
        x: 50, y: 50, dir: Direction::North
    };

    while ant.x < 100 && ant.y < 100 {
        ant.mv(&mut grid);
    }
    for each in grid.iter() {
        //construct string
        //using iterator methods to quickly convert the vector
        //to a string
        let string = each.iter()
                         .map(|&x| if x == 0 { " " } else { "#" })
                         .fold(String::new(), |x, y| x+y);
        println!("{}", string);
    }
}