use std::time::Duration;
use tokio::time::timeout;
use cave::config::LoadConfig;

mod config;
mod scheduler;
mod worker;
mod trend_setter;

use worker::Message;

#[tokio::main]
async fn main() {
    cave::init::exit_on_panic();
    cave::init::init_logger();

    let config = config::Config::load();

    let mut store = cave::store::Store::new(config.redis).await;

    cave::systemd::status("Starting trend_setter");
    let trend_setter_tx = trend_setter::start(store.clone());

    cave::systemd::status("Starting scheduler");
    let mut scheduler = scheduler::Scheduler::new();
    cave::systemd::status("Loading known hosts from config");
    for host in config.hosts.into_iter() {
        scheduler.introduce(host).await;
    }
    cave::systemd::status("Loading known hosts from redis");
    for host in store.get_hosts().await.unwrap().into_iter() {
        scheduler.introduce(host).await;
    }

    cave::systemd::status("Starting HTTP client");
    let client = reqwest::Client::builder()
        .timeout(Duration::from_secs(30))
        .pool_max_idle_per_host(0)
        .user_agent(concat!(
            env!("CARGO_PKG_NAME"),
            "/",
            env!("CARGO_PKG_VERSION"),
        ))
        .deflate(true)
        .gzip(true)
        .build()
        .expect("reqwest::Client");

    cave::systemd::ready();

    let mut workers_active = 0usize;
    let (message_tx, mut message_rx) = tokio::sync::mpsc::unbounded_channel();
    loop {
        log::trace!("{} workers active, queued {} of {}", workers_active, scheduler.queue_len(), scheduler.size());
        cave::systemd::status(&format!("{} workers active, queued {} of {}", workers_active, scheduler.queue_len(), scheduler.size()));
        let next_task = if workers_active < config.max_workers {
            scheduler.dequeue()
        } else {
            Err(Duration::from_secs(5))
        };
        match next_task {
            Err(duration) => {
                let _ = timeout(duration, async {
                    let message = message_rx.recv().await.unwrap();
                    match message {
                        Message::Fetched { host, mean_interval, new_post_ratio } => {
                            workers_active -= 1;
                            scheduler.reenqueue(host, new_post_ratio, mean_interval);
                        }
                        Message::IntroduceHosts { hosts } => {
                            for host in hosts.into_iter() {
                                scheduler.introduce(host).await;
                            }
                        }
                    }
                }).await;
            }
            Ok(host) => {
                workers_active += 1;
                tokio::spawn(worker::run(
                    message_tx.clone(),
                    store.clone(),
                    trend_setter_tx.clone(),
                    client.clone(),
                    host
                ));
                cave::systemd::watchdog();
            }
        }
    }
}