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//! Hashing made *really* easy.
//!
//! ```rust
//! use easy_hash::{Sha256, Hasher, HashResult};
//! assert_eq!(Sha256::hash("test".as_bytes()).hex(),
//!     "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08");
//! ```

pub trait Hasher {
    type Output: HashResult;
    fn hash(input: &[u8]) -> Self::Output;
}

pub trait HashResult {
    /// Get the output in hex notation.
    fn hex(&self) -> String;
    /// Size of the output in bytes.
    fn size() -> usize;
}

#[cfg(feature = "SHA2")]
extern crate sha2;
#[cfg(feature = "SHA2")]
pub struct Sha256;

#[cfg(feature = "SHA2")]
impl Hasher for Sha256 {
    type Output = [u8; 32];

    fn hash(input: &[u8]) -> Self::Output {
        use sha2::*;
        let mut tmp = Sha256::new();
        tmp.input(input);
        let r = tmp.result().as_slice().to_vec();
        [r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7],
        r[8], r[9], r[10], r[11], r[12], r[13], r[14], r[15],
        r[16], r[17], r[18], r[19], r[20], r[21], r[22], r[23],
        r[24], r[25], r[26], r[27], r[28], r[29], r[30], r[31]]
    }
}

impl HashResult for [u8; 32] {
    fn hex(&self) -> String {
        const HEX: [char; 16] = ['0', '1', '2', '3', '4', '5', '6', '7',
            '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];
        let mut tmp = String::with_capacity(32*2);
        for byte in self {
            tmp.push(HEX[*byte as usize/16]);
            tmp.push(HEX[*byte as usize%16]);
        }
        tmp
    }

    fn size() -> usize { 32 }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[cfg(feature = "SHA2")]
    fn it_works() {
        assert_eq!(Sha256::hash("test".as_bytes()).hex(),
            "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08");
    }
}