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pub use blake2b_rs::{Blake2b, Blake2bBuilder};

pub const BLAKE2B_KEY: &[u8] = &[];
pub const BLAKE2B_LEN: usize = 32;
pub const CKB_HASH_PERSONALIZATION: &[u8] = b"ckb-default-hash";
pub const BLANK_HASH: [u8; 32] = [
    68, 244, 198, 151, 68, 213, 248, 197, 93, 100, 32, 98, 148, 157, 202, 228, 155, 196, 231, 239,
    67, 211, 136, 197, 161, 47, 66, 181, 99, 61, 22, 62,
];

pub fn new_blake2b() -> Blake2b {
    Blake2bBuilder::new(32)
        .personal(CKB_HASH_PERSONALIZATION)
        .build()
}

pub fn blake2b_256<T: AsRef<[u8]>>(s: T) -> [u8; 32] {
    if s.as_ref().is_empty() {
        return BLANK_HASH;
    }
    inner_blake2b_256(s)
}

fn inner_blake2b_256<T: AsRef<[u8]>>(s: T) -> [u8; 32] {
    let mut result = [0u8; 32];
    let mut blake2b = new_blake2b();
    blake2b.update(s.as_ref());
    blake2b.finalize(&mut result);
    result
}

#[test]
fn empty_blake2b() {
    let actual = inner_blake2b_256([]);
    assert_eq!(actual, BLANK_HASH);
}