use std::fs;
use sha2::{  Digest, Sha256 };

quick_error! {
    #[derive(Debug)]
    pub enum DigestError {
        FileOpenError(f: String, m: String) {
            display("Read file: {}, failed: {}", f, m)
        }
    }
}

// pub type XResult<T> = Result<T, Box<dyn std::error::Error>>;

pub fn digest_file_sha256(file: &str) -> Result<Vec<u8>, DigestError> {
    let bs = match fs::read(file) {
        Ok(bs) => bs, Err(e) => return Err(DigestError::FileOpenError(file.into(), e.to_string())),
    };
    Ok(digest_sha256(&bs))
}

pub fn digest_sha256(bs: &[u8]) -> Vec<u8> {
    let mut sha256 = Sha256::new();
    sha256.update(bs);
    sha256.finalize().to_vec()
}

#[test]
fn test_digest_sha256() {
    assert_eq!(hex::decode("b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9").unwrap(), digest_sha256(b"hello world"));
}