extern crate piston_window;

use piston_window::*;

enum Tile {
    Empty,
    Wall,
}

struct Position {
    x: f64,
    y: f64,
}

struct Player {
   pos: Position,
   angle: f64, // radian or degree
}


fn main() {
    let mut window: PistonWindow =
        WindowSettings::new("Rustenstein", [640, 480])
        .exit_on_esc(true)
        .resizable(false)
        .build().unwrap();

    let level: [Tile; 5 * 5] = [
        Tile::Wall, Tile::Wall, Tile::Wall, Tile::Wall, Tile::Wall,
        Tile::Wall, Tile::Empty, Tile::Empty, Tile::Empty, Tile::Wall,
        Tile::Wall, Tile::Empty, Tile::Empty, Tile::Empty, Tile::Wall,
        Tile::Wall, Tile::Empty, Tile::Empty, Tile::Empty, Tile::Wall,
        Tile::Wall, Tile::Wall, Tile::Wall, Tile::Wall, Tile::Wall,
    ];

    let mut player = Player { pos: Position { x: 2.0, y: 2.0}, angle: 0.0};

    let horiz_fov = 90 as f64;
    //let height_unit = 64;

    while let Some(event) = window.next() {
        let window_size = window.size();
        let w = window_size.width as f64;
        let h = window_size.height as f64;

        window.draw_2d(&event, |context, graphics| {
            clear([1.0; 4], graphics);

            rectangle([1.0, 0.0, 0.0, 1.0], // red
                      [0.0, 0.0, 100.0, 100.0],
                      context.transform,
                      graphics);

            // Ceiling
            let ceiling_color = [0.3, 0.3, 0.3, 1.0];
            rectangle(ceiling_color,
                      [0.0, 0.0, w, h / 2.0],
                      context.transform,
                      graphics);

            // Floor
            let floor_color = [0.5, 0.5, 0.5, 1.0];
            rectangle(floor_color,
                      [0.0, h / 2.0, w, h / 2.0],
                      context.transform,
                      graphics);

            // Walls
            let left = player.angle + (horiz_fov / 2.0);
            let right = player.angle - (horiz_fov / 2.0);
            // for every angle (range / w)
            let step = (left - right) / w;
            let mut ray_angle = left;
            for n in 0..(window_size.width - 1) {
                //   cast a ray
                //   see what wall it hits
                //   compute wall height
                //   draw wall portion
                ray_angle += step;
            }
        });
    }
}