ok-ready-go/receiver/src/comm.rs

use crypto_helper::crypto::Crypto;
use std::{time::Duration, cell::RefCell};
extern crate rumqttc as mqtt;

use serde::{Deserialize, Serialize};

pub type TimeCallback = fn(u32) -> ();

#[derive(Serialize, Deserialize, PartialEq)]
enum MqttMessageKind {
    Time,
    Confirm,
}

#[derive(Serialize, Deserialize)]
struct MqttMessage {
    id: uuid::Uuid,
    kind: MqttMessageKind,
    time: u32,
}

pub struct Comm {
    client: RefCell<mqtt::Client>,
    connection: RefCell<mqtt::Connection>,
    handler: TimeCallback,
    crypto: Crypto,
    topic: String,
}

impl Comm {
    pub fn new(
        broker_domain: &str,
        password: &str,
        handler: TimeCallback,
    ) -> Result<Self, mqtt::ClientError> {
        let mut create_opts =
            mqtt::MqttOptions::new(uuid::Uuid::new_v4().to_string(), broker_domain, 8883);
        create_opts.set_keep_alive(Duration::from_secs(5));
        let transport = mqtt::Transport::Tls(mqtt::TlsConfiguration::default());
        create_opts.set_transport(transport);
        let (mut cli, conn) = mqtt::Client::new(create_opts, 10);

        let crypto = Crypto::new(password, broker_domain);

        let topic = format!("org.speedclimbing.ok-ready-go.{password}");
        let topic = Crypto::sha256(&crypto.encrypt(&topic));

        cli.subscribe(&topic, mqtt::QoS::AtMostOnce)?;

        Ok(Comm {
            client: RefCell::new(cli),
            connection: RefCell::new(conn),
            handler,
            crypto,
            topic,
        })
    }

    pub fn listen(&self) {
        for (_, notification) in self.connection.borrow_mut().iter().enumerate() {
            if let Err(e) = notification {
                println!("Error: {:?}", e);
                continue;
            }

            let notification = notification.unwrap();
            if let mqtt::Event::Outgoing(_) = notification {
                continue;
            }

            if let mqtt::Event::Incoming(notification) = notification {
                self._handle_incoming_packet(notification);
            }
        }
    }

    fn _handle_incoming_packet(&self, packet: mqtt::Packet) {
        match packet {
            mqtt::Packet::Publish(publish) => self._handle_publish_packet(publish),
            _ => return,
        }
    }

    fn _handle_publish_packet(&self, packet: mqtt::Publish) {
        if packet.topic != self.topic {
            return;
        }

        let msg = String::from_utf8(packet.payload.to_vec()).unwrap();

        let msg = self.crypto.decrypt(&msg);
        println!("Got: {}", msg);
        let msg: MqttMessage = serde_json::from_str(&msg).unwrap();
        if msg.kind != MqttMessageKind::Time {
            return;
        }

        (self.handler)(msg.time);

        let reply = MqttMessage {
            id: msg.id,
            kind: MqttMessageKind::Confirm,
            time: 0,
        };

        let reply = serde_json::to_string(&reply).unwrap();
        let reply = self.crypto.encrypt(&reply);
        self.client.borrow_mut()
            .publish(&self.topic, mqtt::QoS::AtMostOnce, false, reply.as_bytes())
            .unwrap();
    }
}