//! Builds a document in Rust and writes a v1 update to stdout, so the JS
//! side can verify it reads what Rust writes. This is the direction Task 3
//! cannot test: a Rust implementation that reads JS updates but writes
//! something JS cannot read would have passed Task 3 completely.
use std::io::Write;
use yrs::types::Attrs;
use yrs::{Doc, Options, ReadTxn, Text, Transact};

fn main() {
    // Both values fixed: never drawn from yrs (Global Constraints -- see
    // core/src/lib.rs and clippy.toml, which bans the alternatives that draw
    // entropy).
    let guid: yrs::Uuid = "emit-update-guid".into();
    let doc = Doc::with_options(Options::with_guid_and_client_id(guid, 7001));
    {
        let text = doc.get_or_insert_text("content");
        let mut txn = doc.transact_mut();
        text.insert(&mut txn, 0, "from rust 🦀 café");
        // Format part of the inserted text so the emitted update carries
        // real formatting bytes, not just plain-text inserts. A plain-text
        // check alone cannot distinguish a correct implementation from one
        // that dropped formatting (see fixtures/verify-rust.mjs).
        let attrs: Attrs = Attrs::from([("bold".into(), true.into())]);
        text.format(&mut txn, 5, 4, attrs);
    }
    let txn = doc.transact();
    let update = txn.encode_state_as_update_v1(&yrs::StateVector::default());
    std::io::stdout().write_all(&update).unwrap();
}