//! Git LFS over HTTP: the batch API, object GET and PUT, and verify. See
//! `docs/wave-b-interfaces.md`, section 2.
//!
//! Objects are content-addressed under `<data_dir>/lfs/<oid[0..2]>/<oid[2..4]>/<oid>` and shared by
//! every repo. The `lfs_objects` table says which repo may use which object. Uploads stream into
//! `<data_dir>/lfs/tmp` first and are renamed into place once their SHA-256 matches. Locks are not
//! implemented, so the lock paths answer 404. `admin lfs-gc` lives in [`gc`].

pub mod gc;
#[cfg(test)]
mod route_tests;
mod routes;

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

use forge_core::Result;

use crate::state::AppState;

/// True for a 64-character lowercase hex SHA-256.
pub fn is_valid_oid(oid: &str) -> bool {
    oid.len() == 64
        && oid
            .bytes()
            .all(|b| b.is_ascii_digit() || (b'a'..=b'f').contains(&b))
}

/// Root of the object store: `<data_dir>/lfs`.
pub fn lfs_root(data_dir: &Path) -> PathBuf {
    data_dir.join("lfs")
}

/// Where in-flight uploads are written before they are renamed into place.
pub fn tmp_dir(data_dir: &Path) -> PathBuf {
    lfs_root(data_dir).join("tmp")
}

/// The on-disk path of object `oid`. Callers pass a validated oid (see [`is_valid_oid`]); for any
/// other input the path is still inside the store, just not in a fan-out directory.
pub fn object_path(data_dir: &Path, oid: &str) -> PathBuf {
    match (oid.get(0..2), oid.get(2..4)) {
        (Some(first), Some(second)) => lfs_root(data_dir).join(first).join(second).join(oid),
        _ => lfs_root(data_dir).join(oid),
    }
}

/// The size of object `oid` as linked to `repo_id`, or `None` when that repo does not link it.
/// The UI uses this for pointer display. It reads the link only, not the file.
pub async fn has_object(state: &AppState, repo_id: &str, oid: &str) -> Result<Option<u64>> {
    state.store.lfs_object_size(repo_id, oid).await
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn oid_must_be_64_lowercase_hex() {
        let good = "4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393";
        assert!(is_valid_oid(good));
        assert!(!is_valid_oid(&good[..63]));
        assert!(!is_valid_oid(&format!("{good}0")));
        assert!(!is_valid_oid(&good.to_uppercase()));
        assert!(!is_valid_oid(&format!("{}g", &good[..63])));
        assert!(!is_valid_oid(""));
    }

    #[test]
    fn object_path_fans_out_by_prefix() {
        let oid = "4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393";
        let path = object_path(Path::new("/data"), oid);
        assert_eq!(
            path,
            Path::new("/data/lfs/4d/7a").join(oid),
            "two-level fan-out under lfs/"
        );
        assert_eq!(
            object_path(Path::new("/data"), "x"),
            Path::new("/data/lfs/x")
        );
    }
}