use std::io::Read;
use std::path::Path;

use nix_nar::Encoder;
use sha2::{Digest, Sha256};

use fix_error::{Error, Result};

pub fn compute_nar_hash(path: &Path) -> Result<[u8; 32]> {
    let mut hasher = Sha256::new();
    std::io::copy(
        &mut Encoder::new(path).map_err(|err| Error::internal(err.to_string()))?,
        &mut hasher,
    )
    .map_err(|err| Error::internal(err.to_string()))?;
    Ok(hasher.finalize().into())
}

pub fn pack_nar(path: &Path) -> Result<Vec<u8>> {
    let mut buffer = Vec::new();
    Encoder::new(path)
        .map_err(|err| Error::internal(err.to_string()))?
        .read_to_end(&mut buffer)
        .map_err(|err| Error::internal(err.to_string()))?;
    Ok(buffer)
}

#[cfg(test)]
#[allow(clippy::unwrap_used)]
mod tests {
    use std::fs;

    use tempfile::TempDir;

    use super::*;

    #[test_log::test]
    fn test_simple_file() {
        let temp = TempDir::new().unwrap();
        let file_path = temp.path().join("test.txt");
        fs::write(&file_path, "hello").unwrap();

        let hash = hex::encode(compute_nar_hash(&file_path).unwrap());
        assert_eq!(
            hash,
            "0a430879c266f8b57f4092a0f935cf3facd48bbccde5760d4748ca405171e969"
        );
        assert!(!hash.is_empty());
        assert_eq!(hash.len(), 64);
    }

    #[test_log::test]
    fn test_directory() {
        let temp = TempDir::new().unwrap();
        fs::write(temp.path().join("a.txt"), "aaa").unwrap();
        fs::write(temp.path().join("b.txt"), "bbb").unwrap();

        let hash = hex::encode(compute_nar_hash(temp.path()).unwrap());
        assert_eq!(
            hash,
            "0036c14209749bc9b9631e2077b108b701c322ab53853cd26f2746268a86fc0f"
        );
        assert!(!hash.is_empty());
        assert_eq!(hash.len(), 64);
    }
}