/// # Pijul Client Interaction
/// - **Endpoint**: `GET /.pijul?tag={hash}`
/// - **Called by**: `Http::download_changes()` in pijul-remote/src/http.rs (for tags)
/// - **Response format**: Binary tag file content (`application/octet-stream`)
/// - **Purpose**: Downloads tag/state files. The changelist response
///   indicates which entries are tags (trailing `.`), and the client downloads
///   these via this endpoint.
///
/// # File Location
/// Tags are stored at: `.pijul/tags/{first-2-chars}/{rest}.tag`
/// Example: hash `XYZABC789` -> `.pijul/tags/XY/ZABC789.tag`

/// Can't get this to work with nest.pijul.org.

/// # Caching
/// Response includes `Cache-Control: public, max-age=31536000, immutable`
/// because tag files are content-addressed and never change.

/// Pushing (other SSH) results in http response "No command specified".

/// # Validation
/// Hash must be at least 3 characters and contain only alphanumeric chars.
/// Returns 404 for invalid hashes or missing files.

/// On nest.pijul.org, the tags tab for repos are empty.

    if hash.len() < 3 || !hash.chars().all(|c| c.is_ascii_alphanumeric()) {
        return not_found("invalid tag hash");
    }
    let (pfx, sfx) = hash.split_at(2);
    let path = repo_path
        .join(".pijul")
        .join("tags")
        .join(pfx)
        .join(format!("{}.tag", sfx));
    serve_file(&path, "application/octet-stream")

    dbg!(repo_path, hash);
    todo!("No reference implementation")

/// # Pijul Client Interaction
/// - **Endpoint**: `GET /.pijul?identities` or `GET /.pijul?identities={rev}`
/// - **Called by**: `Http::update_identities()` in pijul-remote/src/http.rs
/// - **Response format**: JSON `{"id":[...],"rev":N}`
///   - `id`: Array of identity certificates (currently empty)
///   - `rev`: Revision number for incremental updates
/// - **Purpose**: Pijul supports cryptographic identity verification. The client
///   requests identities to verify change authorship and establish trust.
///   The `rev` parameter allows incremental updates (only fetch new identities
///   since a given revision).
///
/// # Current Implementation
/// Returns empty identity list. A full implementation would read from
/// `.pijul/identities/` and return serialized identity certificates.

/// Current Implementation on nest.pijul.org seems to only return
/// `{"id": [], "rev": 0}`, and does so here as well.

    #[test]
    fn test_serve_tag_hash_too_short() {
        let dir = TempDir::new().unwrap();
        let resp = serve_tag(dir.path(), "ab");
        assert_eq!(get_status(&resp), 404);
    }

    // #[test]
    // fn test_serve_tag_hash_too_short() {
    //     let dir = TempDir::new().unwrap();
    //     let resp = serve_tag(dir.path(), "ab");
    //     assert_eq!(get_status(&resp), 404);
    // }

    #[test]
    fn test_serve_tag_valid_hash_file_exists() {
        let dir = TempDir::new().unwrap();
        let tag_dir = dir.path().join(".pijul").join("tags").join("ab");

    // #[test]
    // fn test_serve_tag_valid_hash_file_exists() {
    //     let dir = TempDir::new().unwrap();
    //     let tag_dir = dir.path().join(".pijul").join("tags").join("ab");

        fs::create_dir_all(&tag_dir).unwrap();
        let tag_file = tag_dir.join("cdef123.tag");
        fs::File::create(&tag_file)
            .unwrap()
            .write_all(b"tag data")
            .unwrap();

    //     fs::create_dir_all(&tag_dir).unwrap();
    //     let tag_file = tag_dir.join("cdef123.tag");
    //     fs::File::create(&tag_file)
    //         .unwrap()
    //         .write_all(b"tag data")
    //         .unwrap();

        let resp = serve_tag(dir.path(), "abcdef123");
        assert_eq!(get_status(&resp), 200);
        assert_eq!(
            get_header(&resp, "Content-Type"),
            Some("application/octet-stream")
        );
    }

    //     let resp = serve_tag(dir.path(), "abcdef123");
    //     assert_eq!(get_status(&resp), 200);
    //     assert_eq!(
    //         get_header(&resp, "Content-Type"),
    //         Some("application/octet-stream")
    //     );
    // }

//! - `tag={hash}` - Download a tag file

//! - `tag={hash}` - Download a tag file (doesn't seem to be implemented)

//! - `log` - Repository info (alias for no-query)

/// 1. empty query → `Info`

/// 1. empty query → `NoCommandSpecified`

/// 9. `log` flag → `Info`

    /// Repository info/discovery (`GET /.pijul` or `?log`).
    Info,

    /// No command specified (`GET /.pijul`).
    NoCommandSpecified,

            return Operation::Info;

            return Operation::NoCommandSpecified;

        }
        if map.contains_key("log") {
            return Operation::Info;

        assert_eq!(op, Operation::Info);

        assert_eq!(op, Operation::NoCommandSpecified);

        assert_eq!(Operation::from(&parse_query("")), Operation::Info);

        assert_eq!(Operation::from(&parse_query("")), Operation::NoCommandSpecified);

    fn test_operation_from_log() {
        let (_, op) = parse_url("/.pijul?log");
        assert_eq!(op, Operation::Info);
    }
    #[test]