use std::ptr::NonNull;

use anyhow::Result;
use nix_c_raw as raw;
use nix_util::{
    result_string_init,
    string_return::{callback_get_result_string, callback_get_result_string_data},
};

pub struct StorePath {
    raw: NonNull<raw::StorePath>,
}
impl StorePath {
    /// Get the name of the store path.
    ///
    /// For a store path like `/nix/store/abc1234...-foo-1.2`, this function will return `foo-1.2`.
    pub fn name(&self) -> Result<String> {
        unsafe {
            let mut r = result_string_init!();
            raw::store_path_name(
                self.as_ptr(),
                Some(callback_get_result_string),
                callback_get_result_string_data(&mut r),
            );
            r
        }
    }

    /// This is a low level function that you shouldn't have to call unless you are developing the Nix bindings.
    ///
    /// Construct a new `StorePath` by first cloning the C store path.
    ///
    /// # Safety
    ///
    /// This does not take ownership of the C store path, so it should be a borrowed pointer, or you should free it.
    pub unsafe fn new_raw_clone(raw: NonNull<raw::StorePath>) -> Self {
        Self::new_raw(
            NonNull::new(raw::store_path_clone(raw.as_ptr()))
                .or_else(|| panic!("nix_store_path_clone returned a null pointer"))
                .unwrap(),
        )
    }

    /// This is a low level function that you shouldn't have to call unless you are developing the Nix bindings.
    ///
    /// Takes ownership of a C `nix_store_path`. It will be freed when the `StorePath` is dropped.
    ///
    /// # Safety
    ///
    /// The caller must ensure that the provided `NonNull<raw::StorePath>` is valid and that the ownership
    /// semantics are correctly followed. The `raw` pointer must not be used after being passed to this function.
    pub unsafe fn new_raw(raw: NonNull<raw::StorePath>) -> Self {
        StorePath { raw }
    }

    /// This is a low level function that you shouldn't have to call unless you are developing the Nix bindings.
    ///
    /// Get a pointer to the underlying Nix C API store path.
    ///
    /// # Safety
    ///
    /// This function is unsafe because it returns a raw pointer. The caller must ensure that the pointer is not used beyond the lifetime of this `StorePath`.
    pub unsafe fn as_ptr(&self) -> *mut nix_c_raw::StorePath {
        self.raw.as_ptr()
    }
}
impl Drop for StorePath {
    fn drop(&mut self) {
        unsafe {
            raw::store_path_free(self.as_ptr());
        }
    }
}

#[cfg(test)]
mod tests {
    #[test]
    #[cfg(nix_at_least = "2.26" /* get_storedir */)]
    fn store_path_name() {
        let mut store = crate::store::Store::open(Some("dummy://"), []).unwrap();
        let store_dir = store.get_storedir().unwrap();
        let store_path_string =
            format!("{store_dir}/rdd4pnr4x9rqc9wgbibhngv217w2xvxl-bash-interactive-5.2p26");
        let store_path = store.parse_store_path(store_path_string.as_str()).unwrap();
        assert_eq!(store_path.name().unwrap(), "bash-interactive-5.2p26");
    }
}