use bevy::prelude::*;

use crate::components::Star;
use crate::constants::{
    STAR_COUNT, STAR_MAX_SIZE, STAR_MAX_SPEED, STAR_MIN_SIZE, STAR_MIN_SPEED,
    STAR_Z_DEPTH, WINDOW_HEIGHT, WINDOW_WIDTH,
};

pub fn spawn_starfield(commands: &mut Commands) {
    for _ in 0..STAR_COUNT {
        let size = fastrand::f32() * (STAR_MAX_SIZE - STAR_MIN_SIZE) + STAR_MIN_SIZE;
        let speed = fastrand::f32() * (STAR_MAX_SPEED - STAR_MIN_SPEED) + STAR_MIN_SPEED;
        let brightness = fastrand::f32() * 0.5 + 0.5; // 0.5 to 1.0

        commands.spawn((
            SpriteBundle {
                sprite: Sprite {
                    color: Color::rgb(brightness, brightness, brightness),
                    custom_size: Some(Vec2::new(size, size)),
                    ..default()
                },
                transform: Transform::from_translation(Vec3::new(
                    fastrand::f32() * WINDOW_WIDTH - WINDOW_WIDTH / 2.0,
                    fastrand::f32() * WINDOW_HEIGHT - WINDOW_HEIGHT / 2.0,
                    STAR_Z_DEPTH,
                )),
                ..default()
            },
            Star { speed },
        ));
    }
}

pub fn scroll_starfield(mut star_query: Query<(&mut Transform, &Star)>, time: Res<Time>) {
    let dt = time.delta_seconds();
    let half_height = WINDOW_HEIGHT / 2.0;
    let half_width = WINDOW_WIDTH / 2.0;

    for (mut transform, star) in star_query.iter_mut() {
        let parallax = -transform.translation.y * 0.01;
        transform.translation.y -= (star.speed + parallax) * dt;

        if transform.translation.y < -half_height {
            transform.translation.y = half_height;
            transform.translation.x = fastrand::f32() * WINDOW_WIDTH - half_width;
        }
    }
}