use poly::Poly;
use poly::Number;
use poly::Lerp;

use sdl2::pixels::Color;
use sdl2::event::Event;
use sdl2::keyboard::Keycode;
use sdl2::rect::Rect;

use std::thread;
use std::time::Duration;

fn eval_poly(p: &Poly, t: Number) -> Number {
    let mut r = 0.0;
    for i in 0..p.len() {
        r += p[i] * t.powi(i as i32);
    }
    r
}

fn main() {
    let a = Lerp::new(vec![100.0, 200.0, 300.0, 500.0]);
    let b = Lerp::new(vec![400.0, 140.0, 500.0, 300.0]);
    let pa = poly::lp(a);
    let pb = poly::lp(b);

    let sdl_context = sdl2::init().unwrap();
    let video_subsystem = sdl_context.video().unwrap();

    let window = video_subsystem.window("rust-sdl2 demo", 800, 600)
        .position_centered()
        .build()
        .unwrap();

    let mut canvas = window.into_canvas().build().unwrap();

    let mut event_pump = sdl_context.event_pump().unwrap();
    'running: loop {
        canvas.set_draw_color(Color::RGB(20, 20, 20));
        canvas.clear();
        for event in event_pump.poll_iter() {
            match event {
                Event::Quit {..} |
                    Event::KeyDown { keycode: Some(Keycode::Escape), .. } => {
                        break 'running
                    },
                _ => {}
            }
        }

        for t in 0..800 {
            let x = eval_poly(&pa, t as Number / 800.0);
            let y = eval_poly(&pb, t as Number / 800.0);
            canvas.set_draw_color(Color::RGB(180, 20, 20));
            canvas.fill_rect(Rect::new(t, x as i32, 5, 5)).unwrap();
            canvas.set_draw_color(Color::RGB(20, 180, 20));
            canvas.fill_rect(Rect::new(t, y as i32, 5, 5)).unwrap();
        }

        canvas.present();
        thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
    }
}