systemprompt-models 0.55.1

//! Server-Sent Events framing shared by every provider SSE codec.
//!
//! Copyright (c) systemprompt.io — Business Source License 1.1.
//! See <https://systemprompt.io> for licensing details.

pub fn frame_end(buf: &[u8]) -> Option<usize> {
    let mut i = 0;
    while i < buf.len() {
        let Some(first) = newline_len(buf, i) else {
            i += 1;
            continue;
        };
        let after_first = i + first;
        if let Some(second) = newline_len(buf, after_first) {
            return Some(after_first + second);
        }
        i = after_first;
    }
    None
}

fn newline_len(buf: &[u8], idx: usize) -> Option<usize> {
    match buf.get(idx) {
        Some(b'\r') if buf.get(idx + 1) == Some(&b'\n') => Some(2),
        Some(b'\n' | b'\r') => Some(1),
        _ => None,
    }
}

// Why: Providers can signal mid-stream failure with an `{"error": {...}}` chunk
// after the HTTP response has already returned 200.
// JSON: Upstream provider error body; every vendor uses a different shape.
pub fn upstream_error_message(value: &serde_json::Value) -> Option<String> {
    let error = value.get("error")?;
    if error.is_null() {
        return None;
    }
    if let Some(message) = error.as_str() {
        return Some(message.to_owned());
    }
    let message = error
        .get("message")
        .and_then(serde_json::Value::as_str)
        .unwrap_or("upstream error");
    // Why: Google's `{code, status, message}` shape names the failure class in
    // `status`; without it "Invalid value at contents[1]…" reads as ours.
    let code = error.get("code").and_then(serde_json::Value::as_u64);
    let status = error
        .get("status")
        .and_then(serde_json::Value::as_str)
        .filter(|s| !s.is_empty());
    Some(match (code, status) {
        (Some(code), Some(status)) => format!("upstream {code} {status}: {message}"),
        (Some(code), None) => format!("upstream {code}: {message}"),
        (None, Some(status)) => format!("upstream {status}: {message}"),
        (None, None) => message.to_owned(),
    })
}