use dioxus::dioxus_core::{Runtime, ScopeId, queue_effect};
use dioxus::html::geometry::ClientPoint;
use dioxus::prelude::*;

#[derive(Debug)]
pub struct Pointer {
    pub id: i32,
    pub position: ClientPoint,
}

pub static POINTERS: GlobalSignal<Vec<Pointer>> = Global::new(|| {
    let runtime = Runtime::current();
    queue_effect(move || {
        runtime.spawn(ScopeId::ROOT, async move {
            let mut pointer_updates = dioxus::document::eval(
                "window.addEventListener('pointerdown', (e) => {
                    dioxus.send(['down', [e.pointerId, e.clientX, e.clientY]]);
                });
                window.addEventListener('pointermove', (e) => {
                    dioxus.send(['move', [e.pointerId, e.clientX, e.clientY]]);
                });
                window.addEventListener('pointerup', (e) => {
                    dioxus.send(['up', [e.pointerId, e.clientX, e.clientY]]);
                });",
            );

            while let Ok((event_type, (pointer_id, x, y))) =
                pointer_updates.recv::<(String, (i32, f64, f64))>().await
            {
                let position = ClientPoint::new(x, y);

                match event_type.as_str() {
                    "down" => {
                        let mut ptrs = POINTERS.write();
                        if !ptrs.iter().any(|p| p.id == pointer_id) {
                            ptrs.push(Pointer {
                                id: pointer_id,
                                position,
                            });
                        }
                    }
                    "move" => {
                        if let Some(pointer) =
                            POINTERS.write().iter_mut().find(|p| p.id == pointer_id)
                        {
                            pointer.position = position;
                        }
                    }
                    "up" => {
                        POINTERS.write().retain(|p| p.id != pointer_id);
                    }
                    _ => {}
                }
            }
        });
    });

    Vec::new()
});

/// Get the current position of a tracked pointer, or `None` if it's not active.
pub fn pointer_position(id: i32) -> Option<ClientPoint> {
    POINTERS
        .read()
        .iter()
        .find(|p| p.id == id)
        .map(|p| p.position)
}