use std::fmt::Debug;

use async_trait::async_trait;
use http::Request;
use opentelemetry::propagation::{Extractor, Injector};
use opentelemetry::trace::TraceError;

pub struct HeaderInjector<'a>(pub &'a mut http::HeaderMap);

impl<'a> Injector for HeaderInjector<'a> {
    /// Set a key and value in the HeaderMap.  Does nothing if the key or value are not valid inputs.
    fn set(&mut self, key: &str, value: String) {
        if let Ok(name) = http::header::HeaderName::from_bytes(key.as_bytes()) {
            if let Ok(val) = http::header::HeaderValue::from_str(&value) {
                self.0.insert(name, val);
            }
        }
    }
}

pub struct HeaderExtractor<'a>(pub &'a http::HeaderMap);

impl<'a> Extractor for HeaderExtractor<'a> {
    /// Get a value for a key from the HeaderMap.  If the value is not valid ASCII, returns None.
    fn get(&self, key: &str) -> Option<&str> {
        self.0.get(key).and_then(|value| value.to_str().ok())
    }

    /// Collect all the keys from the HeaderMap.
    fn keys(&self) -> Vec<&str> {
        self.0
            .keys()
            .map(|value| value.as_str())
            .collect::<Vec<_>>()
    }
}

/// A minimal interface necessary for export spans over HTTP.
///
/// Users sometime choose http clients that relay on certain runtime. This trait
/// allows users to bring their choice of http clients.
#[async_trait]
pub trait HttpClient: Debug + Send + Sync {
    /// Send a batch of spans to collectors
    async fn send(&self, request: Request<Vec<u8>>) -> Result<(), TraceError>;
}

#[cfg(feature = "reqwest")]
mod reqwest {
    use super::{async_trait, HttpClient, Request, TraceError};
    use opentelemetry::sdk::export::ExportError;
    use std::convert::TryInto;
    use thiserror::Error;

    #[async_trait]
    impl HttpClient for reqwest::Client {
        async fn send(&self, request: Request<Vec<u8>>) -> Result<(), TraceError> {
            let request = request.try_into().map_err(ReqwestError::from)?;
            let _ = self
                .execute(request)
                .await
                .and_then(|rsp| rsp.error_for_status())
                .map_err(ReqwestError::from)?;
            Ok(())
        }
    }

    #[async_trait]
    impl HttpClient for reqwest::blocking::Client {
        async fn send(&self, request: Request<Vec<u8>>) -> Result<(), TraceError> {
            let _ = request
                .try_into()
                .and_then(|req| self.execute(req))
                .and_then(|rsp| rsp.error_for_status())
                .map_err(ReqwestError::from)?;
            Ok(())
        }
    }

    #[derive(Debug, Error)]
    #[error(transparent)]
    struct ReqwestError(#[from] reqwest::Error);

    impl ExportError for ReqwestError {
        fn exporter_name(&self) -> &'static str {
            "reqwest"
        }
    }
}

#[cfg(feature = "surf")]
mod surf {
    use super::{async_trait, HttpClient, Request, TraceError};
    use opentelemetry::sdk::export::ExportError;
    use std::fmt::{Display, Formatter};

    #[async_trait]
    impl HttpClient for surf::Client {
        async fn send(&self, request: Request<Vec<u8>>) -> Result<(), TraceError> {
            let (parts, body) = request.into_parts();
            let uri = parts
                .uri
                .to_string()
                .parse()
                .map_err(|_err: surf::http::url::ParseError| TraceError::from("error parse url"))?;

            let req = surf::Request::builder(surf::http::Method::Post, uri)
                .content_type("application/json")
                .body(body);
            let result = self.send(req).await.map_err::<SurfError, _>(Into::into)?;

            if result.status().is_success() {
                Ok(())
            } else {
                Err(SurfError(surf::Error::from_str(
                    result.status(),
                    result.status().canonical_reason(),
                ))
                .into())
            }
        }
    }

    #[derive(Debug)]
    struct SurfError(surf::Error);

    impl ExportError for SurfError {
        fn exporter_name(&self) -> &'static str {
            "surf"
        }
    }

    impl From<surf::Error> for SurfError {
        fn from(err: surf::Error) -> Self {
            SurfError(err)
        }
    }

    impl std::error::Error for SurfError {}

    impl Display for SurfError {
        fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
            write!(f, "{}", self.0.to_string())
        }
    }
}

#[cfg(feature = "isahc")]
mod isahc {
    use super::{async_trait, HttpClient, Request, TraceError};
    use opentelemetry::sdk::export::ExportError;
    use thiserror::Error;

    #[async_trait]
    impl HttpClient for isahc::HttpClient {
        async fn send(&self, request: Request<Vec<u8>>) -> Result<(), TraceError> {
            let res = self.send_async(request).await.map_err(IsahcError::from)?;

            if !res.status().is_success() {
                return Err(TraceError::from(format!(
                    "Expected success response, got {:?}",
                    res.status()
                )));
            }

            Ok(())
        }
    }

    #[derive(Debug, Error)]
    #[error(transparent)]
    struct IsahcError(#[from] isahc::Error);

    impl ExportError for IsahcError {
        fn exporter_name(&self) -> &'static str {
            "isahc"
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn http_headers_get() {
        let mut carrier = http::HeaderMap::new();
        HeaderInjector(&mut carrier).set("headerName", "value".to_string());

        assert_eq!(
            HeaderExtractor(&carrier).get("HEADERNAME"),
            Some("value"),
            "case insensitive extraction"
        )
    }

    #[test]
    fn http_headers_keys() {
        let mut carrier = http::HeaderMap::new();
        HeaderInjector(&mut carrier).set("headerName1", "value1".to_string());
        HeaderInjector(&mut carrier).set("headerName2", "value2".to_string());

        let extractor = HeaderExtractor(&carrier);
        let got = extractor.keys();
        assert_eq!(got.len(), 2);
        assert!(got.contains(&"headername1"));
        assert!(got.contains(&"headername2"));
    }
}