use std::time::Duration;

use circulate::Relay;
use tokio::time::sleep;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let relay = Relay::default();

    let subscriber = relay.create_subscriber();
    // Subscribe for messages sent to the topic "pong"
    subscriber.subscribe_to(&"pong")?;

    // Launch a task that sends out "ping" messages.
    tokio::spawn(pinger(relay.clone()));
    // Launch a task that receives "ping" messages and sends "pong" responses.
    tokio::spawn(ponger(relay.clone()));

    // Loop until a we receive a message letting us know when the ponger() has
    // no pings remaining.
    loop {
        let message = subscriber.receiver().recv_async().await?;
        let pings_remaining = message.payload::<usize>()?;
        println!(
            "<-- Received {}, pings remaining: {}",
            message.topic::<String>()?,
            pings_remaining
        );
        if pings_remaining == 0 {
            break;
        }
    }

    println!("Received all pongs.");

    Ok(())
}

async fn pinger(pubsub: Relay) -> anyhow::Result<()> {
    let mut ping_count = 0u32;
    loop {
        ping_count += 1;
        println!("-> Sending ping {}", ping_count);
        pubsub.publish(&"ping", &ping_count)?;
        sleep(Duration::from_millis(250)).await;
    }
}

async fn ponger(pubsub: Relay) -> anyhow::Result<()> {
    const NUMBER_OF_PONGS: usize = 5;
    let subscriber = pubsub.create_subscriber();
    subscriber.subscribe_to(&"ping")?;
    let mut pings_remaining = NUMBER_OF_PONGS;

    println!(
        "Ponger started, waiting to respond to {} pings",
        pings_remaining
    );

    while pings_remaining > 0 {
        let message = subscriber.receiver().recv_async().await?;
        println!(
            "<- Received {}, id {}",
            message.topic::<String>()?,
            message.payload::<u32>()?
        );
        pings_remaining -= 1;
        pubsub.publish(&"pong", &pings_remaining)?;
    }

    println!("Ponger finished.");

    Ok(())
}