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use pavex::{middleware::Next, response::Response};
use std::future::IntoFuture;
use tokio::time::{timeout, error::Elapsed};

pub async fn timeout_middleware<C>(
    // A handle on the rest of the processing pipeline for the incoming
    // request. 
    //
    // Middlewares can choose to short-circuit the execution (i.e. 
    // return an error and abort the processing) or perform some 
    // computation and then delegate to `next` by awaiting it.
    //
    // All middlewares in Pavex *must* take `Next<_>` as an input.
    next: Next<C>,
    // Middlewares can take advantage of dependency injection! 
    // You just list what inputs you need and the framework will provide them
    // (if possible, or return a nice error at *compile-time* if not).
    //
    // `TimeoutConfig` could be defined at start-up time, sharing the same 
    // value for all routes, or it could be customised at runtime on a 
    // per-request basis (e.g. to provide a configurable quality of service
    // depending on the pricing plan of the client issueing the request).
    // `timeout_middleware` doesn't care how or when `TimeoutConfig`
    // gets computed. 
    // Happy decoupling!
    config: TimeoutConfig
) -> Result<Response, Elapsed>
where
    C: IntoFuture<Output = Response>
{
    timeout(config.request_timeout, next.into_future()).await
}