use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .init_resource::<ResizeTimer>()
        .init_resource::<Resolution>()
        .init_resource::<Resolutions>()
        .add_startup_system(setup)
        .add_system(change_resolution)
        .run();
}

struct ResizeTimer(Timer);
impl Default for ResizeTimer {
    fn default() -> ResizeTimer {
        ResizeTimer(Timer::from_seconds(1.0, true))
    }
}

#[derive(Default)]
struct Resolution(usize);

struct Resolutions(Vec<Vec2>);
impl Default for Resolutions {
    fn default() -> Resolutions {
        Resolutions(vec![
            Vec2::new(256.0, 256.0),
            Vec2::new(128.0, 128.0),
            Vec2::new(64.0, 64.0),
            Vec2::new(32.0, 32.0),
            Vec2::new(8.0, 8.0),
            Vec2::new(1280.0, 1.0),
            Vec2::new(1.0, 720.0),
            Vec2::new(1280.0, 0.0),
            Vec2::new(0.0, 720.0),
            Vec2::new(0.0, 0.0),
            Vec2::new(720.0, 720.0),
            Vec2::new(1280.0, 720.0),
        ])
    }
}

fn setup(mut commands: Commands) {
    commands.spawn_bundle(OrthographicCameraBundle::new_3d());
}

/// This system will then change the resolution during execution
fn change_resolution(
    time: Res<Time>,
    mut resize_timer: ResMut<ResizeTimer>,
    mut index: ResMut<Resolution>,
    resolutions: Res<Resolutions>,
    mut windows: ResMut<Windows>,
) {
    resize_timer.0.tick(time.delta());
    if resize_timer.0.just_finished() {
        let window = windows.get_primary_mut().unwrap();

        info!("resizing to {:?}", resolutions.0[index.0]);

        window.set_resolution(resolutions.0[index.0].x, resolutions.0[index.0].y);

        index.0 += 1;
        if index.0 >= resolutions.0.len() {
            index.0 = 0;
        }
    }
}