mikronova/modgunn

crates/modgunn-build-thing/src/emit.rs

//! **modgunn's half of the emitter** — `code → toml`, one-directional.
//!
//! The WRITER is `nornir_build_thing::emit` (one writer for every repo's recipe
//! crate, lane AG 2026-08-30); what lives here is this repo's own
//! [`EMITTED_HEADER`] and the three calls. The committed
//! `.nornir/build-variants.toml` is [`emitted_toml`]'s output and nothing else:
//! an edit to it has ZERO effect on what the recipe declares
//! (`tests/toml_parity.rs` measures that), and the only way to change the
//! description is to change the code and re-emit.

use std::path::{Path, PathBuf};

use anyhow::Result;
use nornir_build_thing::emit;
use nornir_build_thing::plugin::BuildThing;

use crate::recipe::ModgunnBuildThing;

/// The header every emission starts with — says what the file is, and what it
/// is not.
pub const EMITTED_HEADER: &str = "\
# modgunn — .nornir/build-variants.toml — EMITTED, NOT SOURCE.
#
# Generated by `cargo run -p modgunn-build-thing -- emit` from
# crates/modgunn-build-thing (the Rust `impl BuildThing`). The code is the one
# source; this file DESCRIBES the build. Editing it changes NOTHING: re-emit
# after changing the code. Do not edit by hand.
#
# Model: variant → features → settings/sub-settings → typ. modgunn declares ONE
# atom — the fat client — because it genuinely has one and only one. The four
# the five-shape matrix would have it claim (server · cli · ui · solo) are named
# FICTIONS, each measured on this checkout; four fictions named beats four stubs
# that build and do nothing, and `tests/build_variants.rs` asserts every gap as a
# POSITIVE claim so it cannot quietly turn back into a phantom. The measurements
# and the six declared-but-never-built features are in
# .nornir/build-thing-design.md, which is where the prose that used to sit
# between these rows now lives.";

/// The emission — what `.nornir/build-variants.toml` must contain.
pub fn emitted_toml() -> Result<String> {
    emit::emitted_toml(EMITTED_HEADER, &ModgunnBuildThing)
}

/// Regenerate `<repo_root>/.nornir/build-variants.toml` from the code.
pub fn write_emitted(repo_root: &Path) -> Result<PathBuf> {
    emit::write_emitted(EMITTED_HEADER, &ModgunnBuildThing, repo_root)
}

/// The repo root, from this crate's manifest directory.
#[must_use]
pub fn repo_root() -> PathBuf {
    Path::new(env!("CARGO_MANIFEST_DIR"))
        .parent()
        .and_then(Path::parent)
        .expect("crates/modgunn-build-thing has 2 ancestor(s)")
        .to_path_buf()
}

/// The set this recipe declares.
#[must_use]
pub fn declared() -> nornir_build_thing::variant::BuildVariantSet {
    ModgunnBuildThing.variants()
}