use alpha_id::packed::{corpus_sha256, read_packed, write_packed, PackedHeader};
use std::io::Write;

fn header(n_rows: u32, dim: u32) -> PackedHeader {
    PackedHeader {
        n_rows,
        dim,
        embed_model: "test/model".to_string(),
        corpus_sha256: "deadbeef".to_string(),
        corpus_name: "corpus.txt".to_string(),
    }
}

#[test]
fn write_read_roundtrip_preserves_header_and_rows() {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("packed.bin");
    let rows = vec![vec![0.0f32, 1.5, -2.25], vec![3.0, 4.0, 5.0]];
    let h = header(2, 3);
    write_packed(&path, &h, &rows).unwrap();
    let (got_h, got_rows) = read_packed(&path).unwrap();
    assert_eq!(got_h, h);
    assert_eq!(got_rows, rows);
}

#[test]
fn corpus_sha256_stable_and_sensitive() {
    let dir = tempfile::tempdir().unwrap();
    let p = dir.path().join("c.txt");
    std::fs::write(&p, b"alpha|beta").unwrap();
    let a = corpus_sha256(p.to_str().unwrap()).unwrap();
    let b = corpus_sha256(p.to_str().unwrap()).unwrap();
    assert_eq!(a, b, "same bytes hash identically");
    std::fs::write(&p, b"alpha|betb").unwrap();
    let c = corpus_sha256(p.to_str().unwrap()).unwrap();
    assert_ne!(a, c, "one changed byte changes the hash");
}

#[test]
fn read_packed_rejects_bad_magic() {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("bad.bin");
    let mut f = std::fs::File::create(&path).unwrap();
    f.write_all(b"XXXX____________").unwrap();
    assert!(read_packed(&path).is_err());
}