/// Remap a DB path (starting with `/libraries/`) to the local filesystem path
/// using the `LIBRARIES_ROOT_PATH` environment variable.
pub fn remap_libraries_path(path: &str) -> String {
    if let Ok(root) = std::env::var("LIBRARIES_ROOT_PATH") {
        if path.starts_with("/libraries/") {
            return path.replacen("/libraries", &root, 1);
        }
    }
    path.to_string()
}

/// Convert a local filesystem path back to a DB path (starting with `/libraries/`).
pub fn unmap_libraries_path(path: &str) -> String {
    if let Ok(root) = std::env::var("LIBRARIES_ROOT_PATH") {
        if path.starts_with(&root) {
            return path.replacen(&root, "/libraries", 1);
        }
    }
    path.to_string()
}

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

    // Serialize tests that modify env vars
    static ENV_LOCK: Mutex<()> = Mutex::new(());

    #[test]
    fn remap_with_env_set() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::set_var("LIBRARIES_ROOT_PATH", "/home/user/books");
        assert_eq!(
            remap_libraries_path("/libraries/BD/les geants/06. yatho.cbz"),
            "/home/user/books/BD/les geants/06. yatho.cbz"
        );
        std::env::remove_var("LIBRARIES_ROOT_PATH");
    }

    #[test]
    fn remap_without_env() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::remove_var("LIBRARIES_ROOT_PATH");
        assert_eq!(
            remap_libraries_path("/libraries/BD/test.cbz"),
            "/libraries/BD/test.cbz"
        );
    }

    #[test]
    fn remap_non_matching_prefix() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::set_var("LIBRARIES_ROOT_PATH", "/home/user/books");
        assert_eq!(
            remap_libraries_path("/other/path/file.cbz"),
            "/other/path/file.cbz"
        );
        std::env::remove_var("LIBRARIES_ROOT_PATH");
    }

    #[test]
    fn unmap_with_env_set() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::set_var("LIBRARIES_ROOT_PATH", "/home/user/books");
        assert_eq!(
            unmap_libraries_path("/home/user/books/BD/test.cbz"),
            "/libraries/BD/test.cbz"
        );
        std::env::remove_var("LIBRARIES_ROOT_PATH");
    }

    #[test]
    fn unmap_without_env() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::remove_var("LIBRARIES_ROOT_PATH");
        assert_eq!(
            unmap_libraries_path("/home/user/books/BD/test.cbz"),
            "/home/user/books/BD/test.cbz"
        );
    }

    #[test]
    fn roundtrip() {
        let _lock = ENV_LOCK.lock().unwrap();
        std::env::set_var("LIBRARIES_ROOT_PATH", "/mnt/data");
        let original = "/libraries/manga/naruto/vol01.cbz";
        let remapped = remap_libraries_path(original);
        assert_eq!(remapped, "/mnt/data/manga/naruto/vol01.cbz");
        assert_eq!(unmap_libraries_path(&remapped), original);
        std::env::remove_var("LIBRARIES_ROOT_PATH");
    }
}