use std::fmt::{Display, Formatter};
use std::convert::From;
use std::str::Utf8Error;


// error when attempting to tell a request handler whether to release or deny crednetials
pub enum SendResponseError {
    NotFound, // no request with the given id
    Abandoned, // request has already been closed by client
}

impl Display for SendResponseError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        use SendResponseError::*;
        match self {
            NotFound => write!(f, "The specified command was not found."),
            Abandoned => write!(f, "The specified request was closed by the client."),
        }
    }
}


// errors encountered while handling an HTTP request
pub enum RequestError {
    StreamIOError(std::io::Error),
    InvalidUtf8,
    MalformedHttpRequest,
    RequestTooLarge,
}

impl From<tokio::io::Error> for RequestError {
    fn from(e: std::io::Error) -> RequestError {
        RequestError::StreamIOError(e)
    }
}
impl From<Utf8Error> for RequestError {
    fn from(_e: Utf8Error) -> RequestError {
        RequestError::InvalidUtf8
    }
}

impl Display for RequestError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        use RequestError::*;
        match self {
            StreamIOError(e) => write!(f, "Stream IO error: {e}"),
            InvalidUtf8 => write!(f, "Could not decode UTF-8 from bytestream"),
            MalformedHttpRequest => write!(f, "Maformed HTTP request"),
            RequestTooLarge => write!(f, "HTTP request too large"),
        }
    }
}