//! Axum HTTP/WS server — admin UI is built-in, modules are Lua-side.

use axum::{
    body::Body,
    extract::{Path, ws::{Message, WebSocket, WebSocketUpgrade}},
    http::{header, StatusCode},
    response::{Html, IntoResponse, Response},
    routing::{get, post},
    Router,
};
use std::sync::atomic::{AtomicBool, Ordering as AtomicOrdering};
use std::sync::{Mutex, OnceLock};
use std::collections::HashMap;

use crate::{bridge, logging};

const BUILD_TS: &str = match option_env!("ARZ_BUILD_TS") {
    Some(v) => v,
    None => "dev",
};

static SHUTDOWN: AtomicBool = AtomicBool::new(false);
static MODULE_DIRS: OnceLock<Mutex<HashMap<String, String>>> = OnceLock::new();
static RT_HANDLE: OnceLock<tokio::runtime::Handle> = OnceLock::new();

pub fn runtime_handle() -> Option<&'static tokio::runtime::Handle> {
    RT_HANDLE.get()
}

/// Registered commands: name → owner module
static COMMANDS: OnceLock<Mutex<Vec<(String, String)>>> = OnceLock::new();

fn commands() -> &'static Mutex<Vec<(String, String)>> {
    COMMANDS.get_or_init(|| Mutex::new(Vec::new()))
}

fn module_dirs() -> &'static Mutex<HashMap<String, String>> {
    MODULE_DIRS.get_or_init(|| Mutex::new(HashMap::new()))
}

pub fn register_module(name: &str, static_dir: &str) {
    if static_dir.is_empty() {
        module_dirs().lock().unwrap().remove(name);
    } else {
        module_dirs().lock().unwrap().insert(name.to_string(), static_dir.to_string());
    }
}

pub fn unregister_module(name: &str) {
    module_dirs().lock().unwrap().remove(name);
}

pub fn list_modules() -> Vec<String> {
    module_dirs().lock().unwrap().keys().cloned().collect()
}

/// Check if a module has a static/index.html registered
pub fn module_has_static(name: &str) -> bool {
    let dirs = module_dirs().lock().unwrap();
    dirs.get(name).map(|d| !d.is_empty()).unwrap_or(false)
}

pub fn register_command(name: &str, owner: &str) {
    let mut cmds = commands().lock().unwrap();
    // Avoid duplicates
    if !cmds.iter().any(|(n, _)| n == name) {
        cmds.push((name.to_string(), owner.to_string()));
    }
}

pub fn get_commands_json() -> String {
    let cmds = commands().lock().unwrap();
    let items: Vec<String> = cmds.iter()
        .map(|(n, o)| format!(r#"{{"name":"{}","owner":"{}"}}"#, n, o))
        .collect();
    format!("[{}]", items.join(","))
}

pub fn start(port: u16) -> Result<(), String> {
    let _initial_rx = bridge::init_event_channel();

    let (rt_tx, rt_rx) = std::sync::mpsc::sync_channel(1);

    std::thread::Builder::new()
        .name("rgl-server".into())
        .spawn(move || {
            let rt = match tokio::runtime::Builder::new_multi_thread()
                .worker_threads(2)
                .enable_all()
                .build()
            {
                Ok(rt) => rt,
                Err(_) => { rt_tx.send(false).ok(); return; },
            };

            RT_HANDLE.set(rt.handle().clone()).ok();
            rt_tx.send(true).ok();  // Signal that runtime is ready

            rt.block_on(async move {
                let app = Router::new()
                    .route("/", get(index_handler))
                    .route("/admin", get(admin_handler))
                    .route("/ws", get(ws_handler))
                    .route("/api/modules", get(modules_list_handler))
                    .route("/api/commands", get(commands_list_handler))
                    .route("/api/{module}/{action}", post(api_handler))
                    .fallback(static_file_handler);

                let addr = format!("0.0.0.0:{port}");
                let socket = match tokio::net::TcpSocket::new_v4() {
                    Ok(s) => s,
                    Err(_) => return,
                };
                socket.set_reuseaddr(true).ok();
                let bind_addr: std::net::SocketAddr = addr.parse().unwrap();
                if socket.bind(bind_addr).is_err() { return; }
                if let Ok(listener) = socket.listen(128) {
                    SHUTDOWN.store(false, AtomicOrdering::Relaxed);
                    let graceful = axum::serve(listener, app)
                        .with_graceful_shutdown(async {
                            while !SHUTDOWN.load(AtomicOrdering::Relaxed) {
                                tokio::time::sleep(std::time::Duration::from_millis(100)).await;
                            }
                        });
                    graceful.await.ok();
                }
            });
        })
        .map_err(|e| format!("thread spawn error: {e}"))?;

    // Wait for tokio runtime to be ready before returning
    match rt_rx.recv() {
        Ok(true) => Ok(()),
        _ => Err("runtime init failed".to_string()),
    }
}

pub fn stop() {
    SHUTDOWN.store(true, AtomicOrdering::Relaxed);
}

// --- Built-in pages ---

async fn index_handler() -> Html<String> {
    let html = include_str!("../static/index.html")
        .replace("{{BUILD_TS}}", BUILD_TS);
    Html(html)
}

async fn admin_handler() -> Html<String> {
    let html = include_str!("../static/ui_page.html")
        .replace("{{MODULE}}", "admin")
        .replace("{{TITLE}}", "Admin");
    Html(html)
}

async fn commands_list_handler() -> impl IntoResponse {
    let json = get_commands_json();
    Response::builder()
        .header(header::CONTENT_TYPE, "application/json")
        .body(Body::from(json))
        .unwrap()
}

// --- API ---

async fn modules_list_handler() -> impl IntoResponse {
    axum::Json(serde_json::json!({
        "modules": list_modules(),
        "build": BUILD_TS,
    }))
}

async fn api_handler(
    Path((module, action)): Path<(String, String)>,
    body: String,
) -> impl IntoResponse {
    let code = format!(
        "return __arz_handle_api([=[{module}]=], [=[{action}]=], [=[{body}]=])"
    );
    let id = bridge::request_lua_exec(code);

    // Poll for result with async timeout — never blocks tokio workers
    let result = tokio::time::timeout(
        std::time::Duration::from_secs(2),
        async {
            loop {
                if let Some(r) = bridge::try_get_result(id) {
                    return r;
                }
                tokio::time::sleep(std::time::Duration::from_millis(5)).await;
            }
        }
    ).await;

    match result {
        Ok(r) => Response::builder()
            .header(header::CONTENT_TYPE, "application/json")
            .body(Body::from(r))
            .unwrap(),
        Err(_) => Response::builder()
            .status(StatusCode::GATEWAY_TIMEOUT)
            .body(Body::from(r#"{"error":"lua timeout"}"#))
            .unwrap(),
    }
}

// --- Static files ---

async fn static_file_handler(uri: axum::http::Uri) -> Response {
    let path = uri.path();
    let Some(rest) = path.strip_prefix("/m/") else {
        return (StatusCode::NOT_FOUND, "not found").into_response();
    };

    let (module, file_path) = match rest.find('/') {
        Some(i) => (&rest[..i], &rest[i+1..]),
        None => (rest, ""),
    };

    let base_dir = {
        let dirs = module_dirs().lock().unwrap();
        match dirs.get(module) {
            Some(d) if d == "__render__" => {
                // Module uses render() API — serve auto-UI page
                let html = include_str!("../static/ui_page.html")
                    .replace("{{MODULE}}", module)
                    .replace("{{TITLE}}", module);
                return ([(header::CONTENT_TYPE, "text/html; charset=utf-8")], html).into_response();
            }
            Some(d) if !d.is_empty() => d.clone(),
            _ => {
                return (StatusCode::NOT_FOUND, "module not found").into_response();
            }
        }
    };

    let full_path = if file_path.is_empty() || file_path == "/" {
        format!("{}/index.html", base_dir)
    } else {
        let clean = file_path.trim_start_matches('/');
        if clean.contains("..") {
            return (StatusCode::FORBIDDEN, "forbidden").into_response();
        }
        format!("{}/{}", base_dir, clean)
    };

    match tokio::fs::read(&full_path).await {
        Ok(contents) => {
            let ct = match full_path.rsplit('.').next() {
                Some("html") => "text/html; charset=utf-8",
                Some("css") => "text/css",
                Some("js") => "application/javascript",
                Some("json") => "application/json",
                Some("png") => "image/png",
                Some("svg") => "image/svg+xml",
                _ => "application/octet-stream",
            };
            ([(header::CONTENT_TYPE, ct)], contents).into_response()
        }
        Err(_) => (StatusCode::NOT_FOUND, "not found").into_response(),
    }
}

// --- WebSocket ---

async fn ws_handler(ws: WebSocketUpgrade) -> impl IntoResponse {
    ws.on_upgrade(handle_ws)
}

async fn handle_ws(mut socket: WebSocket) {
    let mut event_rx = match bridge::subscribe_events() {
        Some(rx) => rx,
        None => return,
    };

    loop {
        tokio::select! {
            Ok(event) = event_rx.recv() => {
                let json = serde_json::json!({
                    "type": "event",
                    "event": event.event,
                    "args": serde_json::from_str::<serde_json::Value>(&event.args)
                        .unwrap_or(serde_json::Value::Null),
                });
                if socket.send(Message::Text(json.to_string().into())).await.is_err() {
                    break;
                }
            }
            msg = socket.recv() => {
                match msg {
                    Some(Ok(Message::Text(text))) => {
                        if text.as_str() == "ping" {
                            if socket.send(Message::Text("pong".into())).await.is_err() {
                                break;
                            }
                        }
                    }
                    Some(Ok(Message::Close(_))) | None => break,
                    _ => {}
                }
            }
        }
    }
}