// Copyright (C) 2025 Emilis Bliūdžius
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
use core::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;

use tokio::sync::Mutex;
use werewolves_proto::player::PlayerId;

#[derive(Debug, Clone)]
pub struct ConnectUpdate {
    updated: Arc<AtomicBool>,
    connected: Arc<Mutex<Vec<PlayerId>>>,
}

impl ConnectUpdate {
    pub fn new() -> Self {
        Self {
            updated: Arc::new(AtomicBool::new(false)),
            connected: Arc::new(Mutex::new(Vec::new())),
        }
    }

    pub async fn connect(&self, pid: PlayerId) {
        let mut connected = self.connected.lock().await;
        if connected.iter().any(|c| c == &pid) {
            return;
        }
        connected.push(pid);
        self.updated.store(true, Ordering::SeqCst);
    }

    pub async fn disconnect(&self, pid: PlayerId) {
        let mut connected = self.connected.lock().await;
        if let Some(idx) = connected
            .iter()
            .enumerate()
            .find_map(|(idx, c)| (c == &pid).then_some(idx))
        {
            connected.swap_remove(idx);
            self.updated.store(true, Ordering::SeqCst);
        }
    }
}

impl Future for ConnectUpdate {
    type Output = Arc<[PlayerId]>;

    fn poll(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Self::Output> {
        if self.updated.load(Ordering::SeqCst)
            && let Ok(connected) = self.connected.try_lock()
        {
            self.updated.store(false, Ordering::SeqCst);
            std::task::Poll::Ready(connected.clone().into())
        } else {
            cx.waker().wake_by_ref();
            std::task::Poll::Pending
        }
    }
}