use std::io;

use nats::{Connection, Handler};

use crate::chat_message::ChatMessage;

const SERVER: &str = "127.0.0.1";
const SUBJECT_MESSAGES: &str = "here.happens.messaging";

pub fn connect_to_nats() -> io::Result<Connection> {
    nats::connect(SERVER)
}

pub fn subscribe_to_chat_messages(username: String, nc: &Connection) -> io::Result<Handler> {
    // This runs the closure in a separate Thread
    let subscription =
        nc.subscribe(SUBJECT_MESSAGES)?
            .with_handler(move |msg| -> Result<(), io::Error> {
                match ChatMessage::try_from(msg.data) {
                    Ok(message) => {
                        // Do not show messages from me
                        if message.author != username {
                            println!("Received {}", message);
                        }
                    }
                    Err(e) => eprintln!("{}", e),
                };
                Ok(())
            });
    Ok(subscription)
}

pub fn publish_message(message: &ChatMessage, nc: &Connection) -> io::Result<()> {
    let json_string_utf8 = serde_json::to_string(message).expect("Cannot serialize message");
    // TODO: there is no error if server is offline
    nc.publish(SUBJECT_MESSAGES, json_string_utf8)?;
    Ok(())
}