use crate::prelude::*;
use crate::client::input::CursorWorldCoordinates;
use crate::ecs::StarguideCamera;

pub fn starguide_input_plugin(app: &mut App) {
    app
       .add_systems(Update, (on_click, starguide_drag))
       .insert_resource(StarguideDrag::default());
}

#[derive(Resource, Default)]
struct StarguideDrag {
    is_dragging: bool,
    init_cursor_pos: Vec2,
    init_camera_pos: Vec2,
}

fn on_click(
    ev: Res<ButtonInput<MouseButton>>,
    mut drag: ResMut<StarguideDrag>,
    camera: Single<&Transform, With<StarguideCamera>>,
    cursor: Res<CursorWorldCoordinates>
) {
    let Some(cursor) = cursor.0 else { return };
    if ev.just_pressed(MouseButton::Left) {
        drag.is_dragging = true;
        drag.init_cursor_pos = cursor;
        drag.init_camera_pos = camera.translation.truncate();
    }
    if ev.just_released(MouseButton::Left) {
        drag.is_dragging = false;
    }
}

fn starguide_drag(
    drag: ResMut<StarguideDrag>,
    mut camera: Single<&mut Transform, (With<StarguideCamera>)>,
    cursor: Res<CursorWorldCoordinates>,
) {
    if !drag.is_dragging { return }
    let Some(cursor) = cursor.0 else { return };

    camera.translation = drag.init_camera_pos.extend(0.0) - (cursor - drag.init_cursor_pos).extend(0.0);
}