use lazy_static::lazy_static;
use prometheus::{IntCounterVec, Opts, Registry};
use rocket::{
    fairing::{Fairing, Info, Kind},
    Data, Request, Response,
};

lazy_static! {
    pub static ref REGISTRY: Registry = Registry::new();
    static ref REQUEST_COUNTER: IntCounterVec =
        IntCounterVec::new(Opts::new("requests", "Requests"), &["method", "route"]).unwrap();
    static ref RESPONSE_COUNTER: IntCounterVec =
        IntCounterVec::new(Opts::new("responses", "Responses"), &["status", "route"]).unwrap();
}

pub fn init_metrics() {
    REGISTRY.register(Box::new(REQUEST_COUNTER.clone())).unwrap();
}

pub struct MetricProducer;

#[rocket::async_trait]
impl Fairing for MetricProducer {
    fn info(&self) -> Info {
        Info { name: "Metrics fairing", kind: Kind::Request }
    }

    async fn on_request(&self, req: &mut Request<'_>, _data: &mut Data<'_>) {
        if let Some(route) = req.route() {
            REQUEST_COUNTER
                .with_label_values(&[req.method().as_str(), &route.uri.to_string()])
                .inc();
        }
    }

    async fn on_response<'r>(&self, req: &'r Request<'_>, resp: &mut Response<'r>) {
        if let Some(route) = req.route() {
            RESPONSE_COUNTER
                .with_label_values(&[&resp.status().code.to_string(), &route.uri.to_string()])
                .inc();
        }
    }
}