//! Wrapper around tiny-keccak crate.

use std::mem::uninitialized;
use tiny_keccak::Keccak;
use bytes::{BytesConvertable,Populatable};
use hash::H256;

/// Types implementing this trait are sha3able.
///
/// ```
/// extern crate ethcore_util as util;
/// use std::str::FromStr;
/// use util::sha3::*;
/// use util::hash::*;
///
/// fn main() {
/// 	assert_eq!([0u8; 0].sha3(), H256::from_str("c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470").unwrap());
/// }
/// ```
pub trait Hashable {
	fn sha3(&self) -> H256;
	fn sha3_into(&self, dest: &mut [u8]) {
		self.sha3().copy_to(dest);
	}
}

impl<T> Hashable for T where T: BytesConvertable {
	fn sha3(&self) -> H256 {
		unsafe {
			let mut keccak = Keccak::new_keccak256();
			keccak.update(self.bytes());
			let mut ret: H256 = uninitialized();
			keccak.finalize(ret.as_slice_mut());
			ret
		}
	}
	fn sha3_into(&self, dest: &mut [u8]) {
		let mut keccak = Keccak::new_keccak256();
		keccak.update(self.bytes());
		keccak.finalize(dest);
	}
}

#[test]
fn sha3_empty() {
	use std::str::FromStr;
	assert_eq!([0u8; 0].sha3(), H256::from_str("c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470").unwrap());
}
#[test]
fn sha3_as() {
	use std::str::FromStr;
	assert_eq!([0x41u8; 32].sha3(), H256::from_str("59cad5948673622c1d64e2322488bf01619f7ff45789741b15a9f782ce9290a8").unwrap());
}