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#![allow(dead_code)]

extern crate url;

use std::fmt;
use std::error::Error;
use std::io;
use std::str::Utf8Error;

#[derive(PartialEq, Eq, Copy, Clone, Debug)]
pub enum ErrorKind {
    ClientProtocolError,
    InvalidClientConfig,
    IoError,
    InvalidSchemeError,
    ServerProtocolError,
    TypeError,
}

#[derive(Debug)]
enum ErrorRepr {
    WithDescription(ErrorKind, &'static str),
    WithDescriptionAndDetail(ErrorKind, &'static str, String),
    IoError(io::Error),
    UrlParseError(url::ParseError),
}

#[derive(Debug)]
pub struct NatsError {
    repr: ErrorRepr,
}

impl Error for NatsError {
    fn description(&self) -> &str {
        match self.repr {
            ErrorRepr::WithDescription(_, description) |
            ErrorRepr::WithDescriptionAndDetail(_, description, _) => description,
            ErrorRepr::IoError(ref e) => e.description(),
            ErrorRepr::UrlParseError(ref e) => e.description(),
        }
    }

    fn cause(&self) -> Option<&Error> {
        match self.repr {
            ErrorRepr::IoError(ref e) => Some(e as &Error),
            _ => None,
        }
    }
}

impl fmt::Display for NatsError {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match self.repr {
            ErrorRepr::WithDescription(_, description) => description.fmt(f),
            ErrorRepr::WithDescriptionAndDetail(_, description, ref detail) => {
                try!(description.fmt(f));
                try!(f.write_str(": "));
                detail.fmt(f)
            }
            ErrorRepr::IoError(ref e) => e.fmt(f),
            ErrorRepr::UrlParseError(ref e) => e.fmt(f),
        }
    }
}

impl From<Utf8Error> for NatsError {
    fn from(_: Utf8Error) -> NatsError {
        NatsError { repr: ErrorRepr::WithDescription(ErrorKind::TypeError, "Invalid UTF-8") }
    }
}

impl From<(ErrorKind, &'static str)> for NatsError {
    fn from((kind, description): (ErrorKind, &'static str)) -> NatsError {
        NatsError { repr: ErrorRepr::WithDescription(kind, description) }
    }
}

impl From<(ErrorKind, &'static str, String)> for NatsError {
    fn from((kind, description, detail): (ErrorKind, &'static str, String)) -> NatsError {
        NatsError { repr: ErrorRepr::WithDescriptionAndDetail(kind, description, detail) }
    }
}

impl From<io::Error> for NatsError {
    fn from(e: io::Error) -> NatsError {
        NatsError { repr: ErrorRepr::IoError(e) }
    }
}

impl From<url::ParseError> for NatsError {
    fn from(e: url::ParseError) -> NatsError {
        NatsError { repr: ErrorRepr::UrlParseError(e) }
    }
}