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use core::{
fmt::{self, Display, Formatter},
num::NonZero,
str::FromStr,
};
use serde::{Deserialize, Deserializer, Serialize, Serializer, de};
use crate::util;
/// A NATS status code
///
/// Constants are provided for known and accurately status codes
/// within the NATS Server.
///
/// Values are guaranteed to be in range `100..1000`.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub struct StatusCode(NonZero<u16>);
impl StatusCode {
/// The Jetstream consumer hearthbeat timeout has been reached with no new messages to deliver
///
/// See [ADR-9].
///
/// [ADR-9]: https://github.com/nats-io/nats-architecture-and-design/blob/main/adr/ADR-9.md
pub const IDLE_HEARTBEAT: StatusCode = Self::new_internal(100);
/// The request has successfully been sent
pub const OK: StatusCode = Self::new_internal(200);
/// The requested Jetstream resource doesn't exist
pub const NOT_FOUND: StatusCode = Self::new_internal(404);
/// The pull consumer batch reached the timeout
pub const TIMEOUT: StatusCode = Self::new_internal(408);
/// The pull consumer batch has been terminated by the server
///
/// This status code is used by the NATS Server for multiple unrelated
/// conditions, which can only be told apart via
/// [`ServerMessage::status_description`]. Known descriptions include
/// `Batch Completed`, `Server Shutdown`, `Leadership Change`,
/// `Consumer Deleted`, `Consumer is push based`,
/// `Exceeded MaxRequestBatch of %d`, `Exceeded MaxRequestExpires of %v`,
/// `Exceeded MaxRequestMaxBytes of %v`, `Exceeded MaxWaiting` and
/// `Message Size Exceeds MaxBytes`.
///
/// [`ServerMessage::status_description`]: crate::ServerMessage::status_description
pub const CONFLICT: StatusCode = Self::new_internal(409);
/// The request was sent to a subject that does not appear to have any subscribers listening
pub const NO_RESPONDERS: StatusCode = Self::new_internal(503);
/// Decodes a status code from a slice of ASCII characters.
///
/// The ASCII representation is expected to be in the form of `"NNN"`, where `N` is a numeric
/// digit.
///
/// # Errors
///
/// It returns an error if the slice of bytes does not contain a valid status code.
pub fn from_ascii_bytes(buf: &[u8]) -> Result<Self, StatusCodeError> {
if buf.len() != 3 {
return Err(StatusCodeError);
}
util::parse_u16(buf)
.map_err(|_| StatusCodeError)?
.try_into()
.map(Self)
.map_err(|_| StatusCodeError)
}
const fn new_internal(val: u16) -> Self {
Self(NonZero::new(val).unwrap())
}
}
impl FromStr for StatusCode {
type Err = StatusCodeError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
Self::from_ascii_bytes(s.as_bytes())
}
}
impl Display for StatusCode {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Display::fmt(&self.0, f)
}
}
impl TryFrom<u16> for StatusCode {
type Error = StatusCodeError;
fn try_from(value: u16) -> Result<Self, Self::Error> {
if (100..1000).contains(&value) {
Ok(Self(NonZero::new(value).unwrap()))
} else {
Err(StatusCodeError)
}
}
}
impl From<StatusCode> for u16 {
fn from(value: StatusCode) -> Self {
value.0.get()
}
}
impl Serialize for StatusCode {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
u16::from(*self).serialize(serializer)
}
}
impl<'de> Deserialize<'de> for StatusCode {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
let n = u16::deserialize(deserializer)?;
n.try_into().map_err(de::Error::custom)
}
}
/// An error encountered while parsing [`StatusCode`]
#[derive(Debug, thiserror::Error)]
#[non_exhaustive]
#[error("invalid status code")]
pub struct StatusCodeError;
#[cfg(test)]
mod tests {
use alloc::string::ToString;
use claims::assert_err;
use super::StatusCode;
#[test]
fn valid_status_codes() {
let status_codes = [100, 200, 404, 408, 409, 503];
for status_code in status_codes {
assert_eq!(
status_code,
u16::from(StatusCode::try_from(status_code).unwrap())
);
let s = status_code.to_string();
assert_eq!(
status_code,
u16::from(StatusCode::from_ascii_bytes(s.as_bytes()).unwrap())
);
}
}
#[test]
fn invalid_status_codes() {
let status_codes = [0, 5, 55, 9999];
for status_code in status_codes {
assert_err!(StatusCode::try_from(status_code));
let s = status_code.to_string();
assert_err!(StatusCode::from_ascii_bytes(s.as_bytes()));
}
}
}