use std::sync::mpsc;
use std::sync::mpsc::{Receiver, Sender};
use std::thread;

fn main() {
    let outer_scope = 412;

    let join_handle = thread::spawn(move || {
        return outer_scope * 2;
    });

    let result = join_handle.join();
    match result {
        Ok(value) => {
            println!("{}", value);
        }
        Err(_) => {}
    }

    let (john_tx, john_rx) = mpsc::channel();
    let (sarah_tx, sarah_rx) = mpsc::channel();

    let john_handler = thread::spawn(move || {
        john_chat(sarah_tx, john_rx);
    });
    let sarah_handler = thread::spawn(move || {
        sarah_chat(john_tx, sarah_rx);
    });

    match john_handler.join() {
        Ok(_) => {}
        Err(_) => {}
    }
    match sarah_handler.join() {
        Ok(_) => {}
        Err(_) => {}
    };
}

fn sarah_chat(john_tx: Sender<&str>, sarah_rx: Receiver<&str>) {
    let result = sarah_rx.recv();
    // unwrap may panic if there is no message
    println!("{}", result.unwrap());

    let _send_result = john_tx.send("Hello John.");
}

fn john_chat(sarah_tx: Sender<&str>, john_rx: Receiver<&str>) {
    let _send_result = sarah_tx.send("Hello Sarah.");
    let result = john_rx.recv();

    println!("{}", result.unwrap());
}