//! The browser shell: web `Services` and the eframe web runner.

use figcraft_engine::Session;
use figcraft_ui_egui::{FigApp, Services};
use wasm_bindgen::JsCast as _;

const CANVAS_ID: &str = "figcraft_canvas";
const LOADING_ID: &str = "figcraft_loading";

pub fn start() {
    eframe::WebLogger::init(log::LevelFilter::Info).ok();
    wasm_bindgen_futures::spawn_local(async {
        let Some(document) = web_sys::window().and_then(|w| w.document()) else {
            log::error!("no document");
            return;
        };
        let Some(canvas) = document.get_element_by_id(CANVAS_ID).and_then(|e| e.dyn_into::<web_sys::HtmlCanvasElement>().ok()) else {
            log::error!("missing <canvas id=\"{CANVAS_ID}\">");
            return;
        };
        let mut options = eframe::WebOptions::default();
        // `?webgl`: force the WebGL2 backend (troubleshooting, and headless browsers whose WebGPU
        // adapter request returns nothing).
        if query().contains("webgl")
            && let eframe::egui_wgpu::WgpuSetup::CreateNew(create) = &mut options.wgpu_options.wgpu_setup
        {
            create.instance_descriptor.backends = eframe::wgpu::Backends::GL;
        }
        let result = eframe::WebRunner::new()
            .start(
                canvas,
                options,
                Box::new(|cc| {
                    if let Some(rs) = &cc.wgpu_render_state {
                        log::info!("figcraft-web: wgpu backend {:?}", rs.adapter.get_info().backend);
                    }
                    let reduce_motion = web_sys::window().and_then(|w| w.match_media("(prefers-reduced-motion: reduce)").ok().flatten());
                    let mut session = Session::new();
                    // Live sessions: the browser joins sessions a desktop app hosts; whatever arrives
                    // on the socket wakes the page for a frame.
                    let ctx = cc.egui_ctx.clone();
                    session.live.install(Box::new(figcraft_collab_net::NetLink::new(std::sync::Arc::new(move || ctx.request_repaint()))));
                    let fig = FigApp::new(session, Box::new(WebServices { reduce_motion }));
                    Ok(Box::new(WebShell { fig }))
                }),
            )
            .await;
        if let Some(el) = document.get_element_by_id(LOADING_ID) {
            match result {
                Ok(()) => el.remove(),
                Err(e) => el.set_inner_html(&format!("<p>FigCraft failed to start: {e:?}</p><p>A browser with WebGPU or WebGL2 is required.</p>")),
            }
        }
    });
}

fn query() -> String {
    web_sys::window().and_then(|w| w.location().search().ok()).unwrap_or_default()
}

struct WebShell {
    fig: FigApp,
}

impl eframe::App for WebShell {
    // `FigApp::ui` runs its own per-frame logic first (fonts, theme), like the desktop app.
    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
        self.fig.ui(ui);
    }
}

/// Browser services. File dialogs return nothing for now (the trait's defaults); the clipboard
/// goes through egui's own web clipboard handling.
struct WebServices {
    /// `prefers-reduced-motion: reduce` (it follows the setting while the page is open).
    reduce_motion: Option<web_sys::MediaQueryList>,
}

impl Services for WebServices {
    fn open_url(&mut self, url: &str) {
        let Some(window) = web_sys::window() else { return };
        if let Err(e) = window.open_with_url_and_target(url, "_blank") {
            log::error!("couldn't open {url}: {e:?}");
        }
    }
    fn reduce_motion(&self) -> bool {
        self.reduce_motion.as_ref().is_some_and(web_sys::MediaQueryList::matches)
    }
}