use bevy::{prelude::*, window::PrimaryWindow};

pub struct PointerPlugin;

impl Plugin for PointerPlugin {
    fn build(&self, app: &mut App) {
        app.init_resource::<PointerTarget>()
            .add_systems(Update, update_pointer_target);
    }
}

/// World position of the active touch or mouse cursor, if any.
#[derive(Resource, Default)]
pub struct PointerTarget(pub Option<Vec2>);

fn update_pointer_target(
    window: Single<&Window, With<PrimaryWindow>>,
    camera: Single<(&Camera, &GlobalTransform)>,
    touches: Res<Touches>,
    mut target: ResMut<PointerTarget>,
) {
    let (camera, camera_transform) = *camera;
    // Touch and cursor positions are both in logical window pixels
    target.0 = touches
        .first_pressed_position()
        .or_else(|| window.cursor_position())
        .and_then(|position| camera.viewport_to_world_2d(camera_transform, position).ok());
}