timvw-rust-runtime 0.2.0

use std::error::Error as StdError;
use std::fmt;

use crate::BoxError;

/// An error building a request, sending it, or reading the response body.
pub struct Error {
    kind: Kind,
    source: Option<BoxError>,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum Kind {
    Builder,
    Request,
    Body,
    Decode,
}

impl Error {
    pub(crate) fn builder(source: impl Into<BoxError>) -> Self {
        Self {
            kind: Kind::Builder,
            source: Some(source.into()),
        }
    }

    pub(crate) fn request(source: impl Into<BoxError>) -> Self {
        Self {
            kind: Kind::Request,
            source: Some(source.into()),
        }
    }

    pub(crate) fn body(source: impl Into<BoxError>) -> Self {
        Self {
            kind: Kind::Body,
            source: Some(source.into()),
        }
    }

    pub(crate) fn decode(source: impl Into<BoxError>) -> Self {
        Self {
            kind: Kind::Decode,
            source: Some(source.into()),
        }
    }

    /// The request could not be built: an invalid URL, header, or body.
    pub fn is_builder(&self) -> bool {
        self.kind == Kind::Builder
    }

    /// The service failed to send the request or to receive a response: connection refused, a timeout layer gave up,
    /// and so on. [`Error::source`](std::error::Error::source) is the service's error.
    pub fn is_request(&self) -> bool {
        self.kind == Kind::Request
    }

    /// Reading the response body failed.
    pub fn is_body(&self) -> bool {
        self.kind == Kind::Body
    }

    /// The response body could not be decoded.
    pub fn is_decode(&self) -> bool {
        self.kind == Kind::Decode
    }

    /// Whether the request timed out: a reqwest timeout or tower's `timeout` layer.
    pub fn is_timeout(&self) -> bool {
        let mut source: Option<&(dyn StdError + 'static)> = self.source.as_deref().map(|e| e as _);
        while let Some(error) = source {
            if error.to_string() == "request timed out" {
                return true;
            }
            #[cfg(feature = "reqwest")]
            if let Some(error) = error.downcast_ref::<reqwest::Error>() {
                if error.is_timeout() {
                    return true;
                }
            }
            source = error.source();
        }
        false
    }

    /// Whether connecting to the server failed (only known for reqwest).
    pub fn is_connect(&self) -> bool {
        #[cfg(feature = "reqwest")]
        {
            let mut source: Option<&(dyn StdError + 'static)> =
                self.source.as_deref().map(|e| e as _);
            while let Some(error) = source {
                if let Some(error) = error.downcast_ref::<reqwest::Error>() {
                    if error.is_connect() {
                        return true;
                    }
                }
                source = error.source();
            }
        }
        false
    }
}

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

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let what = match self.kind {
            Kind::Builder => "error building the request",
            Kind::Request => "error sending the request",
            Kind::Body => "error reading the response body",
            Kind::Decode => "error decoding the response body",
        };
        match &self.source {
            Some(source) => write!(f, "{what}: {source}"),
            None => f.write_str(what),
        }
    }
}

impl StdError for Error {
    fn source(&self) -> Option<&(dyn StdError + 'static)> {
        self.source.as_deref().map(|e| e as _)
    }
}