use std::fmt;

/// A type map of protocol extensions.
///
/// `Extensions` can be used by [`Interceptor`] and [`Request`] to store extra data derived from
/// the underlying protocol.
///
/// [`Interceptor`]: crate::service::Interceptor
/// [`Request`]: crate::Request
#[derive(Default)]
pub struct Extensions {
    inner: http::Extensions,
}

impl Extensions {
    pub(crate) fn new() -> Self {
        Self {
            inner: http::Extensions::new(),
        }
    }

    /// Insert a type into this `Extensions`.
    ///
    /// If a extension of this type already existed, it will
    /// be returned.
    #[inline]
    pub fn insert<T: Send + Sync + 'static>(&mut self, val: T) -> Option<T> {
        self.inner.insert(val)
    }

    /// Get a reference to a type previously inserted on this `Extensions`.
    #[inline]
    pub fn get<T: Send + Sync + 'static>(&self) -> Option<&T> {
        self.inner.get()
    }

    /// Get a mutable reference to a type previously inserted on this `Extensions`.
    #[inline]
    pub fn get_mut<T: Send + Sync + 'static>(&mut self) -> Option<&mut T> {
        self.inner.get_mut()
    }

    /// Remove a type from this `Extensions`.
    ///
    /// If a extension of this type existed, it will be returned.
    #[inline]
    pub fn remove<T: Send + Sync + 'static>(&mut self) -> Option<T> {
        self.inner.remove()
    }

    /// Clear the `Extensions` of all inserted extensions.
    #[inline]
    pub fn clear(&mut self) {
        self.inner.clear()
    }

    #[inline]
    pub(crate) fn from_http(http: http::Extensions) -> Self {
        Self { inner: http }
    }

    /// Convert to `http::Extensions` and consume self.
    #[inline]
    pub fn into_http(self) -> http::Extensions {
        self.inner
    }
}

impl fmt::Debug for Extensions {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Extensions").finish()
    }
}

/// A gRPC Method info extension.
#[derive(Debug)]
pub struct GrpcMethod {
    service: &'static str,
    method: &'static str,
}

impl GrpcMethod {
    /// Create a new `GrpcMethod` extension.
    #[doc(hidden)]
    pub fn new(service: &'static str, method: &'static str) -> Self {
        Self { service, method }
    }

    /// gRPC service name
    pub fn service(&self) -> &str {
        self.service
    }
    /// gRPC method name
    pub fn method(&self) -> &str {
        self.method
    }
}
