use rand::Rng;
use sdl2::event::Event;
use sdl2::EventPump;
use sdl2::keyboard::Keycode;
use sdl2::pixels::Color;
use sdl2::render::BlendMode;
use sdl2::render::Canvas;
use sdl2::video::Window;

use {SCREEN_HEIGHT, SCREEN_WIDTH};
use boll::*;
use common::Point2D;
use sprites::SpriteManager;
use NS_PER_FRAME;
use point; // defined in common, but loaded from main...

pub type Nanoseconds = u64;

pub struct App {
    pub canvas: Canvas<Window>,
    pub event_pump: EventPump,
    pub sprites: SpriteManager,
    pub state: Box<AppState>,
}

impl App {
    pub fn new() -> App {
        let context = sdl2::init().unwrap();
        sdl2::image::init(sdl2::image::InitFlag::PNG).unwrap();
        let window = context.video().unwrap().window("SDL test", SCREEN_WIDTH, SCREEN_HEIGHT)
            .position_centered()
            .opengl()
            .build()
            .unwrap();
        context.mouse().show_cursor(false);
        let mut canvas = window.into_canvas().build().unwrap();
        canvas.set_blend_mode(BlendMode::Add);
        canvas.set_draw_color(Color::RGB(0, 0, 0));
        canvas.clear();
        canvas.present();
        let event_pump = context.event_pump().unwrap();
        let sprites = SpriteManager::new(canvas.texture_creator());
        App {
            canvas,
            event_pump,
            sprites,
            state: Box::new(ActiveState::new()),
        }
    }

    pub fn load_sprites(&mut self, sprites: &[(&'static str, &str)]) {
        for (name, file) in sprites {
            self.sprites.load(name, file);
        }
    }
}

pub trait AppState {
    fn update(&mut self, dt: Nanoseconds);
    fn render(&self, canvas: &mut Canvas<Window>);
    fn leave(&self);
    fn on_event(&mut self, event: Event);
}

type Bollar = Vec<Box<dyn Boll>>;

pub struct ActiveState {
    bolls: Bollar,
    boll_size: u32,
}

impl ActiveState {
    fn new() -> ActiveState {
        ActiveState {
            bolls: Bollar::new(),
            boll_size: 1,
        }
    }

    fn change_boll_count(&mut self, delta: i32) {
        if delta > 0 {
            for _i in 0..delta {
                self.add_boll();
            }
        } else if delta < 0 {
            for _i in 0..delta {
                self.bolls.pop();
            }
        }
    }

    fn add_boll(&mut self) {
        let mut rng = rand::thread_rng();
        self.bolls.push(Box::new(SquareBoll {
            pos: point!(rng.gen_range(0, SCREEN_WIDTH) as f64, rng.gen_range(0, SCREEN_HEIGHT) as f64),
            vel: point!(rng.gen_range(-2.0, 2.0), rng.gen_range(-2.0, 2.0)),
        }));
    }
}

impl AppState for ActiveState {
    fn update(&mut self, dt: Nanoseconds) {
        for b in &mut self.bolls {
            b.update();
        }

        match dt {
            ns if ns < (NS_PER_FRAME - 90_0000) as u64 => { self.change_boll_count(100) }
            ns if ns > (NS_PER_FRAME + 90_0000) as u64 => { self.change_boll_count(-100) }
            _ => {}
        }
    }

    fn render(&self, canvas: &mut Canvas<Window>) {
        for b in &self.bolls {
            b.draw(canvas, self.boll_size);
        }
    }

    fn leave(&self) {
        println!("number of bolls: {}", self.bolls.len());
    }

    fn on_event(&mut self, event: Event) {
        match event {
            Event::KeyDown { keycode: Some(Keycode::KpPlus), .. } => { self.boll_size = std::cmp::min(self.boll_size + 1, 32) }
            Event::KeyDown { keycode: Some(Keycode::KpMinus), .. } => { self.boll_size = std::cmp::max(self.boll_size - 1, 1) }
            Event::MouseMotion { x, y, .. } => {
                self.bolls.push(Box::new(CircleBoll::new(
                    point!(x as f64, y as f64),
                    point!(0.0, 0.0),
                )))
            }
            _ => {}
        }
    }
}