typesafe-sdk-rust 0.1.1

//! The names and defaults the SDK's behaviour is pinned to: the environment
//! variables, headers, API paths and defaults.

use std::{sync::LazyLock, time::Duration};

use http::{HeaderMap, HeaderName, HeaderValue, header};

/// The response header carrying the server's identifier for a request.
pub(crate) const REQUEST_ID_HEADER: &str = "x-typesafe-request-id";

/// The server's identifier for a request, when `headers` carry one as text.
pub(crate) fn request_id(headers: &HeaderMap) -> Option<&str> {
    headers.get(REQUEST_ID_HEADER).and_then(|value| value.to_str().ok())
}

/// The non-standard millisecond-precision companion to `Retry-After`.
pub(crate) const RETRY_AFTER_MS_HEADER: &str = "retry-after-ms";

// ------------------------------------------------- environment and defaults

/// The environment variable a client reads its API key from when none is
/// passed explicitly.
pub const API_KEY_ENV: &str = "TYPESAFE_API_KEY";

/// The environment variable a client reads its base URL from when none is
/// passed explicitly.
pub const BASE_URL_ENV: &str = "TYPESAFE_BASE_URL";

/// The environment variable a client reads its default model from when none
/// is passed explicitly.
pub const DEFAULT_MODEL_ENV: &str = "TYPESAFE_DEFAULT_MODEL";

/// The API root a client talks to when neither the caller nor
/// [`BASE_URL_ENV`] names one.
pub const DEFAULT_BASE_URL: &str = "https://api.typesafe.ai";

/// The model a request names when neither the call, the client nor
/// [`DEFAULT_MODEL_ENV`] names one.
pub const DEFAULT_MODEL: &str = "jev-latest";

/// The deadline each attempt of a request gets when the caller sets none.
///
/// It bounds one attempt from the first byte sent to the last byte received,
/// not the whole call: a retried call can take several of these.
pub const DEFAULT_TIMEOUT: Duration = Duration::from_secs(10);

/// The largest response body a client reads before giving up on it, in bytes.
///
/// A body is collected in memory before it is decoded, so without a cap a
/// broken or hostile endpoint could make one call hold as much memory as it
/// cared to send.
pub const DEFAULT_MAX_RESPONSE_BYTES: usize = 16 * 1024 * 1024;

// ------------------------------------------------------------ API paths

/// The path of the System One endpoint, appended to the base URL.
pub(crate) const SYSTEM_ONE_PATH: &str = "/v1/systemone";

/// The path of the model listing endpoint, appended to the base URL.
pub(crate) const MODELS_PATH: &str = "/v1/models";

// ------------------------------------------------------ request headers
//
// `http` keeps header names lower-cased, so these are spelled that way; on the
// wire HTTP/1.1 header names are case-insensitive and HTTP/2 requires lower
// case, so nothing is lost. The names `http` already defines (`authorization`,
// `accept`, `content-type`, `user-agent`) are used from `http::header` directly
// rather than restated here.

/// The header naming the SDK and its version on every request.
pub(crate) const SDK_HEADER: HeaderName = HeaderName::from_static("x-typesafe-sdk");

/// The header naming the language runtime, operating system and architecture
/// on every request.
pub(crate) const RUNTIME_HEADER: HeaderName = HeaderName::from_static("x-typesafe-runtime");

/// The header counting how many times a request has been retried, set by the
/// SDK on retries only. A caller-supplied one is dropped.
pub(crate) const RETRY_COUNT_HEADER: HeaderName = HeaderName::from_static("x-typesafe-retry-count");

/// The headers that frame a message or manage its connection, which belong
/// to the transport and are dropped from client defaults and per-call headers
/// on every protocol.
///
/// A caller's value for one of them disagrees with the body the SDK sends or
/// with how the transport runs the connection. HTTP/2 forbids the
/// connection-specific ones (RFC 9113, section 8.2.2), so hyper strips them
/// there; a `Content-Length` that disagrees with the body fails an HTTP/2
/// stream and leaves an HTTP/1.1 exchange waiting for bytes that never come,
/// on a connection other calls share. `Host` is not among them; see
/// [`ClientBuilder::default_header`](crate::ClientBuilder::default_header).
pub(crate) const TRANSPORT_HEADERS: [HeaderName; 8] = [
    header::CONTENT_LENGTH,
    header::TRANSFER_ENCODING,
    header::CONNECTION,
    HeaderName::from_static("keep-alive"),
    HeaderName::from_static("proxy-connection"),
    header::TE,
    header::TRAILER,
    header::UPGRADE,
];

/// The media type of every request body and of every response the SDK accepts.
pub(crate) const JSON_CONTENT_TYPE: HeaderValue = HeaderValue::from_static("application/json");

/// The headers the SDK sets on every request, which neither a client default
/// nor a per-call header can replace.
///
/// They say who is calling and with which credential; a caller who could
/// override them could send a request the SDK cannot vouch for. The Python
/// SDK protects the same five (`_core/transport.py`), and `Content-Type` is
/// forced on a request with a body on top of them.
pub(crate) const PROTECTED_HEADERS: [HeaderName; 5] =
    [header::AUTHORIZATION, header::ACCEPT, header::USER_AGENT, SDK_HEADER, RUNTIME_HEADER];

/// The header names whose values are credentials, and so are never logged.
///
/// Lower-cased, because that is how `http` stores every name. A name that
/// merely contains `token` or `secret` is treated the same way; that rule lives
/// in `redact::is_secret`, which both the log events and the connection
/// errors apply.
pub(crate) const SECRET_HEADERS: [&str; 6] =
    ["authorization", "proxy-authorization", "x-api-key", "api-key", "cookie", "set-cookie"];

// ------------------------------------------------------ SDK identification

/// What the SDK calls itself in `User-Agent` and [`SDK_HEADER`], as
/// `typesafe-sdk-rust/<version>`.
///
/// Deliberately not the official Python SDK's `typesafe-sdk/<version>`: the
/// server may count or treat SDKs by this value, and a port must not be
/// mistaken for the SDK it is a port of.
pub(crate) const SDK_IDENTIFIER: HeaderValue =
    HeaderValue::from_static(concat!("typesafe-sdk-rust/", env!("CARGO_PKG_VERSION")));

/// What the SDK sends in [`RUNTIME_HEADER`], as `rust (<os>; <arch>)`.
///
/// `std::env::consts` holds the target the crate was compiled for, such as
/// `macos` and `aarch64`. Those are constants but not literals, and `concat!`
/// takes only literals, so the value is built on first use and kept for the
/// life of the process.
pub(crate) static RUNTIME_IDENTIFIER: LazyLock<HeaderValue> = LazyLock::new(|| {
    let text = format!("rust ({}; {})", std::env::consts::OS, std::env::consts::ARCH);
    HeaderValue::from_str(&text)
        .expect("invariant: target OS and architecture names are printable ASCII")
});

#[cfg(test)]
#[path = "constants_tests.rs"]
mod tests;