use crate::entities::motion::Velocity;
use crate::entities::{BoxSize, CollisionGroup, Player};
use crate::system::{Background, BACKGROUND_HEIGHT, BACKGROUND_WIDTH};
use bevy::ecs::system::SystemParam;
use bevy::prelude::{AssetServer, Commands, Entity, Res, Sprite, SpriteBundle, Transform, Vec2};

static Z_PLAYER: f32 = 300.0;
static Z_ITEMS: f32 = 200.0;
static Z_ENEMY: f32 = 250.0;
static Z_BACKGROUND: f32 = 50.0;

#[derive(SystemParam)]
pub struct EntitySpawner<'w, 's> {
	commands: Commands<'w, 's>,
	assets: Res<'w, AssetServer>,
}

impl<'w, 's> EntitySpawner<'w, 's> {
	pub fn spawn_player_at(&mut self, position: Vec2) -> Entity {
		self.commands
			.spawn((
				SpriteBundle {
					texture: self.assets.load("sprites/ship.png"),
					transform: Transform::from_translation(position.extend(Z_PLAYER)),
					..Default::default()
				},
				Velocity::ZERO,
				Player,
			))
			.id()
	}

	pub fn spawn_background_at(&mut self, position: Vec2) -> Entity {
		self.commands
			.spawn((
				SpriteBundle {
					texture: self.assets.load("sprites/background.png"),
					transform: Transform::from_translation(position.extend(Z_BACKGROUND)),
					..Default::default()
				},
				Velocity::from(Vec2::new(-75.0, 0.0)),
				Background,
				BoxSize::from(Vec2::new(BACKGROUND_WIDTH, BACKGROUND_HEIGHT)),
			))
			.id()
	}

	pub fn spawn_alien_at(&mut self, position: Vec2) -> Entity {
		self.commands
			.spawn((
				SpriteBundle {
					texture: self.assets.load("sprites/alien_ship.png"),
					transform: Transform::from_translation(position.extend(Z_ENEMY)),
					sprite: Sprite {
						flip_x: true,
						..Default::default()
					},
					..Default::default()
				},
				BoxSize::from(Vec2::new(50.0, 25.0)),
				CollisionGroup::Enemy,
			))
			.id()
	}
}