//! Cap'n Proto schemas, generated types, and serialisation helpers for quicnprotochat.
//!
//! # Design constraints
//!
//! This crate is intentionally restricted:
//! - **No crypto** — key material never enters this crate.
//! - **No I/O** — callers own transport; this crate only converts bytes ↔ types.
//! - **No async** — pure synchronous data-layer code.
//!
//! # Generated code
//!
//! `build.rs` invokes `capnpc` at compile time and writes generated Rust source
//! into `$OUT_DIR`. The `include!` macros below splice that code in as a module.

// ── Generated types ───────────────────────────────────────────────────────────

/// Cap'n Proto generated types for `schemas/auth.capnp`.
///
/// Do not edit this module by hand — it is entirely machine-generated.
pub mod auth_capnp {
    include!(concat!(env!("OUT_DIR"), "/auth_capnp.rs"));
}

/// Cap'n Proto generated types for `schemas/delivery.capnp`.
///
/// Do not edit this module by hand — it is entirely machine-generated.
pub mod delivery_capnp {
    include!(concat!(env!("OUT_DIR"), "/delivery_capnp.rs"));
}

/// Cap'n Proto generated types for `schemas/node.capnp`.
///
/// Do not edit this module by hand — it is entirely machine-generated.
pub mod node_capnp {
    include!(concat!(env!("OUT_DIR"), "/node_capnp.rs"));
}

// ── Low-level byte ↔ message conversions ──────────────────────────────────────

/// Serialise a Cap'n Proto message builder to unpacked wire bytes.
///
/// The output includes the segment table header. For transport, the
/// `quicnprotochat-core` frame codec prepends a 4-byte little-endian length field.
pub fn to_bytes<A: capnp::message::Allocator>(
    msg: &capnp::message::Builder<A>,
) -> Result<Vec<u8>, capnp::Error> {
    let mut buf = Vec::new();
    capnp::serialize::write_message(&mut buf, msg)?;
    Ok(buf)
}

/// Deserialise unpacked wire bytes into a message with owned segments.
///
/// Uses `ReaderOptions::new()` (default limits: 64 MiB, 512 nesting levels).
/// Callers that receive data from untrusted peers should consider tightening
/// the traversal limit via `ReaderOptions::traversal_limit_in_words`.
pub fn from_bytes(
    bytes: &[u8],
) -> Result<capnp::message::Reader<capnp::serialize::OwnedSegments>, capnp::Error> {
    let mut cursor = std::io::Cursor::new(bytes);
    capnp::serialize::read_message(&mut cursor, capnp::message::ReaderOptions::new())
}