//! Error and Result module
use std::cell::RefCell;
use std::io::Error as IoError;
use std::str::Utf8Error;
use std::string::FromUtf8Error;
use std::{fmt, io, result};

use actix::MailboxError;
use cookie;
use failure::{self, Backtrace, Fail};
use futures::Canceled;
use http::uri::InvalidUri;
use http::{header, Error as HttpError, StatusCode};
use http2::Error as Http2Error;
use http_range::HttpRangeParseError;
use httparse;
use serde::de::value::Error as DeError;
use serde_json::error::Error as JsonError;
pub use url::ParseError as UrlParseError;

// re-exports
pub use cookie::ParseError as CookieParseError;

use handler::Responder;
use httprequest::HttpRequest;
use httpresponse::HttpResponse;

/// A specialized [`Result`](https://doc.rust-lang.org/std/result/enum.Result.html)
/// for actix web operations
///
/// This typedef is generally used to avoid writing out
/// `actix_web::error::Error` directly and is otherwise a direct mapping to
/// `Result`.
pub type Result<T, E = Error> = result::Result<T, E>;

/// General purpose actix web error
pub struct Error {
    cause: Box<ResponseError>,
    backtrace: Option<Backtrace>,
}

impl Error {
    /// Returns a reference to the underlying cause of this Error.
    // this should return &Fail but needs this https://github.com/rust-lang/rust/issues/5665
    pub fn cause(&self) -> &ResponseError {
        self.cause.as_ref()
    }

    /// Returns a reference to the Backtrace carried by this error, if it
    /// carries one.
    pub fn backtrace(&self) -> Option<&Backtrace> {
        if let Some(bt) = self.cause.backtrace() {
            Some(bt)
        } else {
            self.backtrace.as_ref()
        }
    }
}

/// Error that can be converted to `HttpResponse`
pub trait ResponseError: Fail {
    /// Create response for error
    ///
    /// Internal server error is generated by default.
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::INTERNAL_SERVER_ERROR)
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.cause, f)
    }
}

impl fmt::Debug for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if let Some(bt) = self.cause.backtrace() {
            write!(f, "{:?}\n\n{:?}", &self.cause, bt)
        } else {
            write!(
                f,
                "{:?}\n\n{:?}",
                &self.cause,
                self.backtrace.as_ref().unwrap()
            )
        }
    }
}

/// `HttpResponse` for `Error`
impl From<Error> for HttpResponse {
    fn from(err: Error) -> Self {
        HttpResponse::from_error(err)
    }
}

/// `Error` for any error that implements `ResponseError`
impl<T: ResponseError> From<T> for Error {
    fn from(err: T) -> Error {
        let backtrace = if err.backtrace().is_none() {
            Some(Backtrace::new())
        } else {
            None
        };
        Error {
            cause: Box::new(err),
            backtrace,
        }
    }
}

/// Compatibility for `failure::Error`
impl<T> ResponseError for failure::Compat<T>
where
    T: fmt::Display + fmt::Debug + Sync + Send + 'static,
{
}

impl From<failure::Error> for Error {
    fn from(err: failure::Error) -> Error {
        err.compat().into()
    }
}

/// `InternalServerError` for `JsonError`
impl ResponseError for JsonError {}

/// `InternalServerError` for `UrlParseError`
impl ResponseError for UrlParseError {}

/// Return `BAD_REQUEST` for `de::value::Error`
impl ResponseError for DeError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// Return `BAD_REQUEST` for `Utf8Error`
impl ResponseError for Utf8Error {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// Return `InternalServerError` for `HttpError`,
/// Response generation can return `HttpError`, so it is internal error
impl ResponseError for HttpError {}

/// Return `InternalServerError` for `io::Error`
impl ResponseError for io::Error {
    fn error_response(&self) -> HttpResponse {
        match self.kind() {
            io::ErrorKind::NotFound => HttpResponse::new(StatusCode::NOT_FOUND),
            io::ErrorKind::PermissionDenied => HttpResponse::new(StatusCode::FORBIDDEN),
            _ => HttpResponse::new(StatusCode::INTERNAL_SERVER_ERROR),
        }
    }
}

/// `BadRequest` for `InvalidHeaderValue`
impl ResponseError for header::InvalidHeaderValue {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// `BadRequest` for `InvalidHeaderValue`
impl ResponseError for header::InvalidHeaderValueBytes {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// `InternalServerError` for `futures::Canceled`
impl ResponseError for Canceled {}

/// `InternalServerError` for `actix::MailboxError`
impl ResponseError for MailboxError {}

/// A set of errors that can occur during parsing HTTP streams
#[derive(Fail, Debug)]
pub enum ParseError {
    /// An invalid `Method`, such as `GE.T`.
    #[fail(display = "Invalid Method specified")]
    Method,
    /// An invalid `Uri`, such as `exam ple.domain`.
    #[fail(display = "Uri error: {}", _0)]
    Uri(InvalidUri),
    /// An invalid `HttpVersion`, such as `HTP/1.1`
    #[fail(display = "Invalid HTTP version specified")]
    Version,
    /// An invalid `Header`.
    #[fail(display = "Invalid Header provided")]
    Header,
    /// A message head is too large to be reasonable.
    #[fail(display = "Message head is too large")]
    TooLarge,
    /// A message reached EOF, but is not complete.
    #[fail(display = "Message is incomplete")]
    Incomplete,
    /// An invalid `Status`, such as `1337 ELITE`.
    #[fail(display = "Invalid Status provided")]
    Status,
    /// A timeout occurred waiting for an IO event.
    #[allow(dead_code)]
    #[fail(display = "Timeout")]
    Timeout,
    /// An `io::Error` that occurred while trying to read or write to a network
    /// stream.
    #[fail(display = "IO error: {}", _0)]
    Io(#[cause] IoError),
    /// Parsing a field as string failed
    #[fail(display = "UTF8 error: {}", _0)]
    Utf8(#[cause] Utf8Error),
}

/// Return `BadRequest` for `ParseError`
impl ResponseError for ParseError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

impl From<IoError> for ParseError {
    fn from(err: IoError) -> ParseError {
        ParseError::Io(err)
    }
}

impl From<InvalidUri> for ParseError {
    fn from(err: InvalidUri) -> ParseError {
        ParseError::Uri(err)
    }
}

impl From<Utf8Error> for ParseError {
    fn from(err: Utf8Error) -> ParseError {
        ParseError::Utf8(err)
    }
}

impl From<FromUtf8Error> for ParseError {
    fn from(err: FromUtf8Error) -> ParseError {
        ParseError::Utf8(err.utf8_error())
    }
}

impl From<httparse::Error> for ParseError {
    fn from(err: httparse::Error) -> ParseError {
        match err {
            httparse::Error::HeaderName
            | httparse::Error::HeaderValue
            | httparse::Error::NewLine
            | httparse::Error::Token => ParseError::Header,
            httparse::Error::Status => ParseError::Status,
            httparse::Error::TooManyHeaders => ParseError::TooLarge,
            httparse::Error::Version => ParseError::Version,
        }
    }
}

#[derive(Fail, Debug)]
/// A set of errors that can occur during payload parsing
pub enum PayloadError {
    /// A payload reached EOF, but is not complete.
    #[fail(display = "A payload reached EOF, but is not complete.")]
    Incomplete,
    /// Content encoding stream corruption
    #[fail(display = "Can not decode content-encoding.")]
    EncodingCorrupted,
    /// A payload reached size limit.
    #[fail(display = "A payload reached size limit.")]
    Overflow,
    /// A payload length is unknown.
    #[fail(display = "A payload length is unknown.")]
    UnknownLength,
    /// Io error
    #[fail(display = "{}", _0)]
    Io(#[cause] IoError),
    /// Http2 error
    #[fail(display = "{}", _0)]
    Http2(#[cause] Http2Error),
}

impl From<IoError> for PayloadError {
    fn from(err: IoError) -> PayloadError {
        PayloadError::Io(err)
    }
}

/// `InternalServerError` for `PayloadError`
impl ResponseError for PayloadError {}

/// Return `BadRequest` for `cookie::ParseError`
impl ResponseError for cookie::ParseError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// Http range header parsing error
#[derive(Fail, PartialEq, Debug)]
pub enum HttpRangeError {
    /// Returned if range is invalid.
    #[fail(display = "Range header is invalid")]
    InvalidRange,
    /// Returned if first-byte-pos of all of the byte-range-spec
    /// values is greater than the content size.
    /// See `https://github.com/golang/go/commit/aa9b3d7`
    #[fail(
        display = "First-byte-pos of all of the byte-range-spec values is greater than the content size"
    )]
    NoOverlap,
}

/// Return `BadRequest` for `HttpRangeError`
impl ResponseError for HttpRangeError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::with_body(
            StatusCode::BAD_REQUEST,
            "Invalid Range header provided",
        )
    }
}

impl From<HttpRangeParseError> for HttpRangeError {
    fn from(err: HttpRangeParseError) -> HttpRangeError {
        match err {
            HttpRangeParseError::InvalidRange => HttpRangeError::InvalidRange,
            HttpRangeParseError::NoOverlap => HttpRangeError::NoOverlap,
        }
    }
}

/// A set of errors that can occur during parsing multipart streams
#[derive(Fail, Debug)]
pub enum MultipartError {
    /// Content-Type header is not found
    #[fail(display = "No Content-type header found")]
    NoContentType,
    /// Can not parse Content-Type header
    #[fail(display = "Can not parse Content-Type header")]
    ParseContentType,
    /// Multipart boundary is not found
    #[fail(display = "Multipart boundary is not found")]
    Boundary,
    /// Multipart stream is incomplete
    #[fail(display = "Multipart stream is incomplete")]
    Incomplete,
    /// Error during field parsing
    #[fail(display = "{}", _0)]
    Parse(#[cause] ParseError),
    /// Payload error
    #[fail(display = "{}", _0)]
    Payload(#[cause] PayloadError),
}

impl From<ParseError> for MultipartError {
    fn from(err: ParseError) -> MultipartError {
        MultipartError::Parse(err)
    }
}

impl From<PayloadError> for MultipartError {
    fn from(err: PayloadError) -> MultipartError {
        MultipartError::Payload(err)
    }
}

/// Return `BadRequest` for `MultipartError`
impl ResponseError for MultipartError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// Error during handling `Expect` header
#[derive(Fail, PartialEq, Debug)]
pub enum ExpectError {
    /// Expect header value can not be converted to utf8
    #[fail(display = "Expect header value can not be converted to utf8")]
    Encoding,
    /// Unknown expect value
    #[fail(display = "Unknown expect value")]
    UnknownExpect,
}

impl ResponseError for ExpectError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::with_body(StatusCode::EXPECTATION_FAILED, "Unknown Expect")
    }
}

/// A set of error that can occure during parsing content type
#[derive(Fail, PartialEq, Debug)]
pub enum ContentTypeError {
    /// Can not parse content type
    #[fail(display = "Can not parse content type")]
    ParseError,
    /// Unknown content encoding
    #[fail(display = "Unknown content encoding")]
    UnknownEncoding,
}

/// Return `BadRequest` for `ContentTypeError`
impl ResponseError for ContentTypeError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// A set of errors that can occur during parsing urlencoded payloads
#[derive(Fail, Debug)]
pub enum UrlencodedError {
    /// Can not decode chunked transfer encoding
    #[fail(display = "Can not decode chunked transfer encoding")]
    Chunked,
    /// Payload size is bigger than 256k
    #[fail(display = "Payload size is bigger than 256k")]
    Overflow,
    /// Payload size is now known
    #[fail(display = "Payload size is now known")]
    UnknownLength,
    /// Content type error
    #[fail(display = "Content type error")]
    ContentType,
    /// Parse error
    #[fail(display = "Parse error")]
    Parse,
    /// Payload error
    #[fail(display = "Error that occur during reading payload: {}", _0)]
    Payload(#[cause] PayloadError),
}

/// Return `BadRequest` for `UrlencodedError`
impl ResponseError for UrlencodedError {
    fn error_response(&self) -> HttpResponse {
        match *self {
            UrlencodedError::Overflow => {
                HttpResponse::new(StatusCode::PAYLOAD_TOO_LARGE)
            }
            UrlencodedError::UnknownLength => {
                HttpResponse::new(StatusCode::LENGTH_REQUIRED)
            }
            _ => HttpResponse::new(StatusCode::BAD_REQUEST),
        }
    }
}

impl From<PayloadError> for UrlencodedError {
    fn from(err: PayloadError) -> UrlencodedError {
        UrlencodedError::Payload(err)
    }
}

/// A set of errors that can occur during parsing json payloads
#[derive(Fail, Debug)]
pub enum JsonPayloadError {
    /// Payload size is bigger than 256k
    #[fail(display = "Payload size is bigger than 256k")]
    Overflow,
    /// Content type error
    #[fail(display = "Content type error")]
    ContentType,
    /// Deserialize error
    #[fail(display = "Json deserialize error: {}", _0)]
    Deserialize(#[cause] JsonError),
    /// Payload error
    #[fail(display = "Error that occur during reading payload: {}", _0)]
    Payload(#[cause] PayloadError),
}

/// Return `BadRequest` for `UrlencodedError`
impl ResponseError for JsonPayloadError {
    fn error_response(&self) -> HttpResponse {
        match *self {
            JsonPayloadError::Overflow => {
                HttpResponse::new(StatusCode::PAYLOAD_TOO_LARGE)
            }
            _ => HttpResponse::new(StatusCode::BAD_REQUEST),
        }
    }
}

impl From<PayloadError> for JsonPayloadError {
    fn from(err: PayloadError) -> JsonPayloadError {
        JsonPayloadError::Payload(err)
    }
}

impl From<JsonError> for JsonPayloadError {
    fn from(err: JsonError) -> JsonPayloadError {
        JsonPayloadError::Deserialize(err)
    }
}

/// Errors which can occur when attempting to interpret a segment string as a
/// valid path segment.
#[derive(Fail, Debug, PartialEq)]
pub enum UriSegmentError {
    /// The segment started with the wrapped invalid character.
    #[fail(display = "The segment started with the wrapped invalid character")]
    BadStart(char),
    /// The segment contained the wrapped invalid character.
    #[fail(display = "The segment contained the wrapped invalid character")]
    BadChar(char),
    /// The segment ended with the wrapped invalid character.
    #[fail(display = "The segment ended with the wrapped invalid character")]
    BadEnd(char),
}

/// Return `BadRequest` for `UriSegmentError`
impl ResponseError for UriSegmentError {
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST)
    }
}

/// Errors which can occur when attempting to generate resource uri.
#[derive(Fail, Debug, PartialEq)]
pub enum UrlGenerationError {
    #[fail(display = "Resource not found")]
    ResourceNotFound,
    #[fail(display = "Not all path pattern covered")]
    NotEnoughElements,
    #[fail(display = "Router is not available")]
    RouterNotAvailable,
    #[fail(display = "{}", _0)]
    ParseError(#[cause] UrlParseError),
}

/// `InternalServerError` for `UrlGeneratorError`
impl ResponseError for UrlGenerationError {}

impl From<UrlParseError> for UrlGenerationError {
    fn from(err: UrlParseError) -> Self {
        UrlGenerationError::ParseError(err)
    }
}

/// Helper type that can wrap any error and generate custom response.
///
/// In following example any `io::Error` will be converted into "BAD REQUEST"
/// response as opposite to *INNTERNAL SERVER ERROR* which is defined by
/// default.
///
/// ```rust
/// # extern crate actix_web;
/// # use actix_web::*;
/// use actix_web::fs::NamedFile;
///
/// fn index(req: HttpRequest) -> Result<fs::NamedFile> {
///    let f = NamedFile::open("test.txt").map_err(error::ErrorBadRequest)?;
///    Ok(f)
/// }
/// # fn main() {}
/// ```
pub struct InternalError<T> {
    cause: T,
    status: InternalErrorType,
    backtrace: Backtrace,
}

unsafe impl<T> Sync for InternalError<T> {}
unsafe impl<T> Send for InternalError<T> {}

enum InternalErrorType {
    Status(StatusCode),
    Response(RefCell<Option<HttpResponse>>),
}

impl<T> InternalError<T> {
    /// Create `InternalError` instance
    pub fn new(cause: T, status: StatusCode) -> Self {
        InternalError {
            cause,
            status: InternalErrorType::Status(status),
            backtrace: Backtrace::new(),
        }
    }

    /// Create `InternalError` with predefined `HttpResponse`.
    pub fn from_response(cause: T, response: HttpResponse) -> Self {
        InternalError {
            cause,
            status: InternalErrorType::Response(RefCell::new(Some(response))),
            backtrace: Backtrace::new(),
        }
    }
}

impl<T> Fail for InternalError<T>
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    fn backtrace(&self) -> Option<&Backtrace> {
        Some(&self.backtrace)
    }
}

impl<T> fmt::Debug for InternalError<T>
where
    T: Send + Sync + fmt::Debug + 'static,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(&self.cause, f)
    }
}

impl<T> fmt::Display for InternalError<T>
where
    T: Send + Sync + fmt::Display + 'static,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.cause, f)
    }
}

impl<T> ResponseError for InternalError<T>
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    fn error_response(&self) -> HttpResponse {
        match self.status {
            InternalErrorType::Status(st) => HttpResponse::new(st),
            InternalErrorType::Response(ref resp) => {
                if let Some(resp) = resp.borrow_mut().take() {
                    resp
                } else {
                    HttpResponse::new(StatusCode::INTERNAL_SERVER_ERROR)
                }
            }
        }
    }
}

impl<T> Responder for InternalError<T>
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    type Item = HttpResponse;
    type Error = Error;

    fn respond_to(self, _: HttpRequest) -> Result<HttpResponse, Error> {
        Err(self.into())
    }
}

/// Helper function that creates wrapper of any error and generate *BAD
/// REQUEST* response.
#[allow(non_snake_case)]
pub fn ErrorBadRequest<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::BAD_REQUEST).into()
}

/// Helper function that creates wrapper of any error and generate
/// *UNAUTHORIZED* response.
#[allow(non_snake_case)]
pub fn ErrorUnauthorized<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::UNAUTHORIZED).into()
}

/// Helper function that creates wrapper of any error and generate *FORBIDDEN*
/// response.
#[allow(non_snake_case)]
pub fn ErrorForbidden<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::FORBIDDEN).into()
}

/// Helper function that creates wrapper of any error and generate *NOT FOUND*
/// response.
#[allow(non_snake_case)]
pub fn ErrorNotFound<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::NOT_FOUND).into()
}

/// Helper function that creates wrapper of any error and generate *METHOD NOT
/// ALLOWED* response.
#[allow(non_snake_case)]
pub fn ErrorMethodNotAllowed<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::METHOD_NOT_ALLOWED).into()
}

/// Helper function that creates wrapper of any error and generate *REQUEST
/// TIMEOUT* response.
#[allow(non_snake_case)]
pub fn ErrorRequestTimeout<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::REQUEST_TIMEOUT).into()
}

/// Helper function that creates wrapper of any error and generate *CONFLICT*
/// response.
#[allow(non_snake_case)]
pub fn ErrorConflict<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::CONFLICT).into()
}

/// Helper function that creates wrapper of any error and generate *GONE*
/// response.
#[allow(non_snake_case)]
pub fn ErrorGone<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::GONE).into()
}

/// Helper function that creates wrapper of any error and generate
/// *PRECONDITION FAILED* response.
#[allow(non_snake_case)]
pub fn ErrorPreconditionFailed<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::PRECONDITION_FAILED).into()
}

/// Helper function that creates wrapper of any error and generate
/// *EXPECTATION FAILED* response.
#[allow(non_snake_case)]
pub fn ErrorExpectationFailed<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::EXPECTATION_FAILED).into()
}

/// Helper function that creates wrapper of any error and
/// generate *INTERNAL SERVER ERROR* response.
#[allow(non_snake_case)]
pub fn ErrorInternalServerError<T>(err: T) -> Error
where
    T: Send + Sync + fmt::Debug + fmt::Display + 'static,
{
    InternalError::new(err, StatusCode::INTERNAL_SERVER_ERROR).into()
}

#[cfg(test)]
mod tests {
    use super::*;
    use cookie::ParseError as CookieParseError;
    use failure;
    use http::{Error as HttpError, StatusCode};
    use httparse;
    use std::env;
    use std::error::Error as StdError;
    use std::io;

    #[test]
    #[cfg(actix_nightly)]
    fn test_nightly() {
        let resp: HttpResponse =
            IoError::new(io::ErrorKind::Other, "test").error_response();
        assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
    }

    #[test]
    fn test_into_response() {
        let resp: HttpResponse = ParseError::Incomplete.error_response();
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);

        let resp: HttpResponse = HttpRangeError::InvalidRange.error_response();
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);

        let resp: HttpResponse = CookieParseError::EmptyName.error_response();
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);

        let resp: HttpResponse = MultipartError::Boundary.error_response();
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);

        let err: HttpError = StatusCode::from_u16(10000).err().unwrap().into();
        let resp: HttpResponse = err.error_response();
        assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
    }

    #[test]
    fn test_cause() {
        let orig = io::Error::new(io::ErrorKind::Other, "other");
        let desc = orig.description().to_owned();
        let e = ParseError::Io(orig);
        assert_eq!(format!("{}", e.cause().unwrap()), desc);
    }

    #[test]
    fn test_backtrace() {
        let e = ErrorBadRequest("err");
        assert!(e.backtrace().is_some());
    }

    #[test]
    fn test_error_cause() {
        let orig = io::Error::new(io::ErrorKind::Other, "other");
        let desc = orig.description().to_owned();
        let e = Error::from(orig);
        assert_eq!(format!("{}", e.cause()), desc);
    }

    #[test]
    fn test_error_display() {
        let orig = io::Error::new(io::ErrorKind::Other, "other");
        let desc = orig.description().to_owned();
        let e = Error::from(orig);
        assert_eq!(format!("{}", e), desc);
    }

    #[test]
    fn test_error_http_response() {
        let orig = io::Error::new(io::ErrorKind::Other, "other");
        let e = Error::from(orig);
        let resp: HttpResponse = e.into();
        assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
    }

    #[test]
    fn test_range_error() {
        let e: HttpRangeError = HttpRangeParseError::InvalidRange.into();
        assert_eq!(e, HttpRangeError::InvalidRange);
        let e: HttpRangeError = HttpRangeParseError::NoOverlap.into();
        assert_eq!(e, HttpRangeError::NoOverlap);
    }

    #[test]
    fn test_expect_error() {
        let resp: HttpResponse = ExpectError::Encoding.error_response();
        assert_eq!(resp.status(), StatusCode::EXPECTATION_FAILED);
        let resp: HttpResponse = ExpectError::UnknownExpect.error_response();
        assert_eq!(resp.status(), StatusCode::EXPECTATION_FAILED);
    }

    macro_rules! from {
        ($from:expr => $error:pat) => {
            match ParseError::from($from) {
                e @ $error => {
                    assert!(format!("{}", e).len() >= 5);
                }
                e => unreachable!("{:?}", e),
            }
        };
    }

    macro_rules! from_and_cause {
        ($from:expr => $error:pat) => {
            match ParseError::from($from) {
                e @ $error => {
                    let desc = format!("{}", e.cause().unwrap());
                    assert_eq!(desc, $from.description().to_owned());
                }
                _ => unreachable!("{:?}", $from),
            }
        };
    }

    #[test]
    fn test_from() {
        from_and_cause!(io::Error::new(io::ErrorKind::Other, "other") => ParseError::Io(..));

        from!(httparse::Error::HeaderName => ParseError::Header);
        from!(httparse::Error::HeaderName => ParseError::Header);
        from!(httparse::Error::HeaderValue => ParseError::Header);
        from!(httparse::Error::NewLine => ParseError::Header);
        from!(httparse::Error::Status => ParseError::Status);
        from!(httparse::Error::Token => ParseError::Header);
        from!(httparse::Error::TooManyHeaders => ParseError::TooLarge);
        from!(httparse::Error::Version => ParseError::Version);
    }

    #[test]
    fn failure_error() {
        const NAME: &str = "RUST_BACKTRACE";
        let old_tb = env::var(NAME);
        env::set_var(NAME, "0");
        let error = failure::err_msg("Hello!");
        let resp: Error = error.into();
        assert_eq!(
            format!("{:?}", resp),
            "Compat { error: ErrorMessage { msg: \"Hello!\" } }\n\n"
        );
        match old_tb {
            Ok(x) => env::set_var(NAME, x),
            _ => env::remove_var(NAME),
        }
    }

    #[test]
    fn test_internal_error() {
        let err = InternalError::from_response(
            ExpectError::Encoding,
            HttpResponse::Ok().into(),
        );
        let resp: HttpResponse = err.error_response();
        assert_eq!(resp.status(), StatusCode::OK);
    }
}