vyre-conform 0.1.0

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

#[test]
fn conform_source_matches_build_time_integrity_hash() {
    let Some(expected) = option_env!("VYRE_CONFORM_SRC_INTEGRITY")
        .map(str::to_owned)
        .or_else(|| std::env::var("VYRE_CONFORM_SRC_INTEGRITY").ok())
    else {
        eprintln!(
            "skipping conform/src integrity check: VYRE_CONFORM_SRC_INTEGRITY is not configured"
        );
        return;
    };
    let actual = source_integrity_hash(Path::new(env!("CARGO_MANIFEST_DIR")).join("src"));
    assert_eq!(
        actual, expected,
        "conform/src integrity mismatch. Fix: rebuild tests from the reviewed source tree."
    );
}

fn source_integrity_hash(root: PathBuf) -> String {
    let mut files = Vec::new();
    collect_rs_files(&root, &mut files);
    files.sort();

    let mut hash = 0xcbf2_9ce4_8422_2325u64;
    for path in files {
        let rel = path.strip_prefix(&root).unwrap_or(&path).to_string_lossy();
        fnv1a_update(&mut hash, rel.as_bytes());
        fnv1a_update(&mut hash, &[0]);
        let bytes = std::fs::read(&path).unwrap_or_default();
        fnv1a_update(&mut hash, &bytes);
        fnv1a_update(&mut hash, &[0xff]);
    }
    format!("{hash:016x}")
}

fn collect_rs_files(dir: &Path, out: &mut Vec<PathBuf>) {
    for entry in std::fs::read_dir(dir).unwrap().flatten() {
        let path = entry.path();
        if path.is_dir() {
            collect_rs_files(&path, out);
        } else if path.extension().and_then(|s| s.to_str()) == Some("rs") {
            out.push(path);
        }
    }
}

fn fnv1a_update(hash: &mut u64, bytes: &[u8]) {
    for &byte in bytes {
        *hash ^= u64::from(byte);
        *hash = hash.wrapping_mul(0x0000_0100_0000_01b3);
    }
}