cloud-sdk-reqwest 0.24.0

use cloud_sdk::rate_limit::RateLimit;
use cloud_sdk::transport::ResponseHeaders;

use super::TransportError;

const LIMIT: &str = "ratelimit-limit";
const REMAINING: &str = "ratelimit-remaining";
const RESET: &str = "ratelimit-reset";

pub(crate) fn parse_rate_limit(
    headers: &ResponseHeaders,
) -> Result<Option<RateLimit>, TransportError> {
    let limit = headers.get(LIMIT);
    let remaining = headers.get(REMAINING);
    let reset = headers.get(RESET);
    if limit.is_none() && remaining.is_none() && reset.is_none() {
        return Ok(None);
    }
    let limit = parse_decimal(limit.ok_or(TransportError::InvalidRateLimitHeaders)?)?;
    let remaining = parse_decimal(remaining.ok_or(TransportError::InvalidRateLimitHeaders)?)?;
    let reset = parse_decimal(reset.ok_or(TransportError::InvalidRateLimitHeaders)?)?;
    RateLimit::new(limit, remaining, reset)
        .map(Some)
        .map_err(|_| TransportError::InvalidRateLimitHeaders)
}

fn parse_decimal(value: cloud_sdk::transport::ResponseHeader<'_>) -> Result<u64, TransportError> {
    let bytes = value.value();
    if bytes.is_empty() {
        return Err(TransportError::InvalidRateLimitHeaders);
    }
    let mut parsed = 0_u64;
    for byte in bytes {
        if !byte.is_ascii_digit() {
            return Err(TransportError::InvalidRateLimitHeaders);
        }
        parsed = parsed
            .checked_mul(10)
            .and_then(|value| value.checked_add(u64::from(*byte & 0x0f)))
            .ok_or(TransportError::InvalidRateLimitHeaders)?;
    }
    Ok(parsed)
}

#[cfg(test)]
mod tests {
    use super::{LIMIT, REMAINING, RESET, parse_rate_limit};
    use crate::shared::TransportError;
    use cloud_sdk::transport::{HeaderSensitivity, ResponseHeaders};

    #[test]
    fn accepts_absent_or_coherent_headers() {
        assert_eq!(parse_rate_limit(&ResponseHeaders::new()), Ok(None));
        let headers = headers("3600", "3599", "42");
        let parsed = parse_rate_limit(&headers);
        assert!(parsed.is_ok());
        let Some(rate_limit) = parsed.ok().flatten() else {
            return;
        };
        assert_eq!(rate_limit.limit(), 3600);
        assert_eq!(rate_limit.remaining(), 3599);
        assert_eq!(rate_limit.reset_epoch_seconds(), 42);
    }

    #[test]
    fn rejects_partial_nondecimal_overflow_and_incoherent_headers() {
        let mut partial = ResponseHeaders::new();
        assert_eq!(
            partial.try_push(LIMIT, b"3600", HeaderSensitivity::Public),
            Ok(())
        );
        assert_eq!(
            parse_rate_limit(&partial),
            Err(TransportError::InvalidRateLimitHeaders)
        );
        for values in [
            ("+3600", "1", "42"),
            ("3600", "3601", "42"),
            ("0", "0", "42"),
            ("18446744073709551616", "1", "42"),
        ] {
            assert_eq!(
                parse_rate_limit(&headers(values.0, values.1, values.2)),
                Err(TransportError::InvalidRateLimitHeaders)
            );
        }
    }

    fn headers(limit: &str, remaining: &str, reset: &str) -> ResponseHeaders {
        let mut headers = ResponseHeaders::new();
        for (name, value) in [(LIMIT, limit), (REMAINING, remaining), (RESET, reset)] {
            assert_eq!(
                headers.try_push(name, value.as_bytes(), HeaderSensitivity::Public),
                Ok(())
            );
        }
        headers
    }
}