use std::{sync::{mpsc, Arc, Mutex}, thread};

pub mod leb128;
pub mod status;
pub mod http;
pub mod dns;
pub use status::MinecraftStatus;

pub struct ThreadPool {
    workers: Vec<ThreadWorker>,
    sender: Option<mpsc::Sender<Job>>,
}

type Job = Box<dyn FnOnce() + Send + 'static>;

impl ThreadPool {
    // Create a new ThreadPool with `size` available threads.
    //
    // # Panics
    //
    // `new` will panic if `size` is zero.
    pub fn new(size: usize) -> ThreadPool {
        assert!(size > 0);

        let (sender, receiver) = mpsc::channel();

        let receiver = Arc::new(Mutex::new(receiver));

        let mut workers = Vec::with_capacity(size);

        for id in 0..size {
            workers.push(ThreadWorker::new(id, Arc::clone(&receiver)));
        }

        ThreadPool {
            workers,
            sender: Some(sender)
        }
    }

    pub fn execute<F>(&self, f: F)
    where
        F: FnOnce() + Send + 'static
    {
        let job = Box::new(f);

        self.sender.as_ref().unwrap().send(job).unwrap();
    }
}

impl Drop for ThreadPool {
    fn drop(&mut self) {
        drop(self.sender.take());

        for worker in &mut self.workers.drain(..) {
            println!("Shutting down worker {}", worker.id);

            worker.thread.join().unwrap();
        }
    }
}

struct ThreadWorker {
    id: usize,
    thread: thread::JoinHandle<()>,
}

impl ThreadWorker {
    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Job>>>) -> ThreadWorker {
        let thread = thread::spawn(move || loop {
            let msg = receiver.lock().unwrap().recv();

            match msg {
                Ok(job) => {
                    // println!("Job received by worker {id}");
                    job();
                }
                Err(_) => {
                    // println!("Worker {id} disconnected. Shutting down...");
                    break;
                }
            }
        });

        ThreadWorker { id, thread }
    }    
}