use std::path::Path;
use piston_window::*;
use opengl_graphics::GlGraphics;
use opengl_graphics::Texture as GlTexture;

static DIGITS_WIDTH: f64 = 20.0;
static DIGITS_HEIGHT: f64 = 26.0;

pub struct NumberRenderer {
    image: GlTexture,
}

impl NumberRenderer {
    pub fn new() -> NumberRenderer {
        NumberRenderer {
            image: GlTexture::from_path(Path::new("bin/assets/digits.png")).unwrap(),
        }
    }

    pub fn render(&self, number: u32, center_x: f64, center_y: f64, max_width: f64,
                  color: [f32; 3], c: &Context, gl: &mut GlGraphics) {
        let digits = number_to_digits(number);
        let total_width = DIGITS_WIDTH * digits.len() as f64;
        let total_width = if total_width > max_width {
            max_width
        } else {
            total_width
        };
        let mut x = center_x - total_width / 2.0;
        let width = total_width / digits.len() as f64;
        let height = width / DIGITS_WIDTH * DIGITS_HEIGHT;
        let y = center_y - height / 2.0;

        for digit in digits.iter() {
            Image::new_color([color[0], color[1], color[2], 1.0])
                .src_rect([(*digit * DIGITS_WIDTH as u32) as f64, 0 as f64, DIGITS_WIDTH as f64, DIGITS_HEIGHT as f64])
                .rect([x, y, width, height])
                .draw(&self.image,
                      &DrawState::default(),
                      c.transform,
                      gl);

            x += width;
        }
    }
}

fn number_to_digits(number: u32) -> Vec<u32> {
    let mut digits = Vec::<u32>::new();

    if number == 0 {
        digits.push(0);
        return digits;
    }

    let mut n = number;

    while n != 0 {
        digits.insert(0, n % 10);
        n /= 10;
    }

    digits
}