#![cfg_attr(feature = "ssr", allow(unused_variables, unused_imports))]

use crate::use_event_listener_with_options;
use cfg_if::cfg_if;
use leptos::ev::scroll;
use leptos::*;
use web_sys::AddEventListenerOptions;

/// Reactive window scroll.
///
/// ## Demo
///
/// [Link to Demo](https://github.com/Synphonyte/leptos-use/tree/main/examples/use_window_scroll)
///
/// ## Usage
///
/// ```
/// # use leptos::*;
/// # use leptos_use::use_window_scroll;
/// #
/// # #[component]
/// # fn Demo(cx: Scope) -> impl IntoView {
/// let (x, y) = use_window_scroll(cx);
/// #
/// # view! { cx, }
/// # }
/// ```
///
/// ## Server-Side Rendering
///
/// On the server this returns `Signal`s that are always `0.0`.
pub fn use_window_scroll(cx: Scope) -> (Signal<f64>, Signal<f64>) {
    cfg_if! { if #[cfg(feature = "ssr")] {
        let initial_x = 0.0;
        let initial_y = 0.0;
    } else {
        let initial_x = window().scroll_x().unwrap_or_default();
        let initial_y = window().scroll_y().unwrap_or_default();
    }}
    let (x, set_x) = create_signal(cx, initial_x);
    let (y, set_y) = create_signal(cx, initial_y);

    cfg_if! { if #[cfg(not(feature = "ssr"))] {
        let mut options = AddEventListenerOptions::new();
        options.capture(false);
        options.passive(true);

        let _ = use_event_listener_with_options(
            cx,
            window(),
            scroll,
            move |_| {
                set_x.set(window().scroll_x().unwrap_or_default());
                set_y.set(window().scroll_y().unwrap_or_default());
            },
            options,
        );
    }}

    (x.into(), y.into())
}