//! Service that applies a timeout to requests.
//!
//! If the response does not complete within the specified timeout, the response
//! will be aborted.
use std::{fmt, marker};

use ntex_service::{Middleware, Service, ServiceCtx};

use crate::future::{select, Either};
use crate::time::{sleep, Millis};

/// Applies a timeout to requests.
///
/// Timeout transform is disabled if timeout is set to 0
#[derive(Debug)]
pub struct Timeout<E = ()> {
    timeout: Millis,
    _t: marker::PhantomData<E>,
}

/// Timeout error
pub enum TimeoutError<E> {
    /// Service error
    Service(E),
    /// Service call timeout
    Timeout,
}

impl<E> From<E> for TimeoutError<E> {
    fn from(err: E) -> Self {
        TimeoutError::Service(err)
    }
}

impl<E: fmt::Debug> fmt::Debug for TimeoutError<E> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            TimeoutError::Service(e) => write!(f, "TimeoutError::Service({:?})", e),
            TimeoutError::Timeout => write!(f, "TimeoutError::Timeout"),
        }
    }
}

impl<E: fmt::Display> fmt::Display for TimeoutError<E> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            TimeoutError::Service(e) => e.fmt(f),
            TimeoutError::Timeout => write!(f, "Service call timeout"),
        }
    }
}

impl<E: fmt::Display + fmt::Debug> std::error::Error for TimeoutError<E> {}

impl<E: PartialEq> PartialEq for TimeoutError<E> {
    fn eq(&self, other: &TimeoutError<E>) -> bool {
        match self {
            TimeoutError::Service(e1) => match other {
                TimeoutError::Service(e2) => e1 == e2,
                TimeoutError::Timeout => false,
            },
            TimeoutError::Timeout => match other {
                TimeoutError::Service(_) => false,
                TimeoutError::Timeout => true,
            },
        }
    }
}

impl Timeout {
    pub fn new<T: Into<Millis>>(timeout: T) -> Self {
        Timeout {
            timeout: timeout.into(),
            _t: marker::PhantomData,
        }
    }
}

impl Clone for Timeout {
    fn clone(&self) -> Self {
        Timeout {
            timeout: self.timeout,
            _t: marker::PhantomData,
        }
    }
}

impl<S> Middleware<S> for Timeout {
    type Service = TimeoutService<S>;

    fn create(&self, service: S) -> Self::Service {
        TimeoutService {
            service,
            timeout: self.timeout,
        }
    }
}

/// Applies a timeout to requests.
#[derive(Debug, Clone)]
pub struct TimeoutService<S> {
    service: S,
    timeout: Millis,
}

impl<S> TimeoutService<S> {
    pub fn new<T, R>(timeout: T, service: S) -> Self
    where
        T: Into<Millis>,
        S: Service<R>,
    {
        TimeoutService {
            service,
            timeout: timeout.into(),
        }
    }
}

impl<S, R> Service<R> for TimeoutService<S>
where
    S: Service<R>,
{
    type Response = S::Response;
    type Error = TimeoutError<S::Error>;

    async fn call(
        &self,
        request: R,
        ctx: ServiceCtx<'_, Self>,
    ) -> Result<Self::Response, Self::Error> {
        if self.timeout.is_zero() {
            ctx.call(&self.service, request)
                .await
                .map_err(TimeoutError::Service)
        } else {
            match select(sleep(self.timeout), ctx.call(&self.service, request)).await {
                Either::Left(_) => Err(TimeoutError::Timeout),
                Either::Right(res) => res.map_err(TimeoutError::Service),
            }
        }
    }

    ntex_service::forward_poll!(service, TimeoutError::Service);
    ntex_service::forward_ready!(service, TimeoutError::Service);
    ntex_service::forward_shutdown!(service);
}

#[cfg(test)]
mod tests {
    use std::time::Duration;

    use ntex_service::{apply, fn_factory, Pipeline, ServiceFactory};

    use super::*;

    #[derive(Clone, Debug, PartialEq)]
    struct SleepService(Duration);

    #[derive(Clone, Debug, PartialEq)]
    struct SrvError;

    impl fmt::Display for SrvError {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            write!(f, "SrvError")
        }
    }

    impl Service<()> for SleepService {
        type Response = ();
        type Error = SrvError;

        async fn call(&self, _: (), _: ServiceCtx<'_, Self>) -> Result<(), SrvError> {
            crate::time::sleep(self.0).await;
            Ok::<_, SrvError>(())
        }
    }

    #[ntex_macros::rt_test2]
    async fn test_success() {
        let resolution = Duration::from_millis(100);
        let wait_time = Duration::from_millis(50);

        let timeout =
            Pipeline::new(TimeoutService::new(resolution, SleepService(wait_time)).clone());
        assert_eq!(timeout.call(()).await, Ok(()));
        assert_eq!(timeout.ready().await, Ok(()));
        timeout.shutdown().await;
    }

    #[ntex_macros::rt_test2]
    async fn test_zero() {
        let wait_time = Duration::from_millis(50);
        let resolution = Duration::from_millis(0);

        let timeout =
            Pipeline::new(TimeoutService::new(resolution, SleepService(wait_time)));
        assert_eq!(timeout.call(()).await, Ok(()));
        assert_eq!(timeout.ready().await, Ok(()));
    }

    #[ntex_macros::rt_test2]
    async fn test_timeout() {
        let resolution = Duration::from_millis(100);
        let wait_time = Duration::from_millis(500);

        let timeout =
            Pipeline::new(TimeoutService::new(resolution, SleepService(wait_time)));
        assert_eq!(timeout.call(()).await, Err(TimeoutError::Timeout));
    }

    #[ntex_macros::rt_test2]
    #[allow(clippy::redundant_clone)]
    async fn test_timeout_middleware() {
        let resolution = Duration::from_millis(100);
        let wait_time = Duration::from_millis(500);

        let timeout = apply(
            Timeout::new(resolution).clone(),
            fn_factory(|| async { Ok::<_, ()>(SleepService(wait_time)) }),
        );
        let srv = timeout.pipeline(&()).await.unwrap();

        let res = srv.call(()).await.unwrap_err();
        assert_eq!(res, TimeoutError::Timeout);
    }

    #[test]
    fn test_error() {
        let err1 = TimeoutError::<SrvError>::Timeout;
        assert!(format!("{:?}", err1).contains("TimeoutError::Timeout"));
        assert!(format!("{}", err1).contains("Service call timeout"));

        let err2: TimeoutError<_> = SrvError.into();
        assert!(format!("{:?}", err2).contains("TimeoutError::Service"));
        assert!(format!("{}", err2).contains("SrvError"));
    }
}