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

enum Message {
    NewJob(Job),
    Terminate
}

pub struct ThreadPool{
    workers: Vec<Worker>,
    sender: mpsc::Sender<Message>,
}

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

impl ThreadPool {
    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(Worker::new(id, Arc::clone(&receiver)));
        }

        ThreadPool {
            workers,
            sender,
        }

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

        self.sender.send(Message::NewJob(job)).unwrap();
    }

    // pub fn spawn<F, T>(f: F) -> JoinHandle<T> 
    //     where 
    //         F: FnOnce() -> T + Send + 'static,
    //         T: Send + 'static
    // {

    // }

}

impl Drop for ThreadPool {
    fn drop(&mut self) {
        println!("Sending terminate message to all workers.");
        for _ in &mut self.workers {
            self.sender.send(Message::Terminate).unwrap();
        }
        println!("Shutting down all workers.");

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

            if let Some(thread) = worker.thread.take() {
                thread.join().unwrap();
            }
        }
    }
}

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

impl Worker {
    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Message>>>) ->
        Worker {

        let thread = thread::spawn(move ||{
            loop {
                let message = receiver.lock().unwrap().recv().unwrap();

                match message {
                    Message::NewJob(job) => {
                        println!("Worker {} got a job; executing.", id);

                        job();
                    },
                    Message::Terminate => {
                        println!("Worker {} was told to terminate.", id);

                        break;
                    },
                }
            }
        });

        Worker {
            id,
            thread: Some(thread),
        }
    }
}

pub struct Response {
    header: String,
    content: String,
}

impl Response {
    pub fn new(hdr: &str, cnt: &str) -> Response {
        Response {
            header: String::from(hdr),
            content: String::from(cnt),
        }
    }

    pub fn set_header(&mut self, hdr: &str) {
        self.header = String::from(hdr);
    }

    pub fn get_header(&self) {
        self.header
    }

    pub fn set_content(&mut self, cnt: &str) {
        self.content = String::from(cnt);
    }

    pub fn add_content(&mut self, cnt: &str) {
        self.content.push_str(cnt);
    }

    pub fn get_content(&self) {
        self.content
    }
}

pub struct Route {
    path: &'static str,
    action: fn(&&str, &mut Response),
}

impl Route {
    fn new(p: String, a: fn(&&str, &mut Response)) {
        Route {
            path: p,
            action: (a),
        }
    }
}