//! `SipHash-2-4`
use ffi;
use libc::c_ulonglong;
use randombytes::randombytes_into;

pub const HASHBYTES: usize = ffi::crypto_shorthash_siphash24_BYTES;
pub const KEYBYTES: usize = ffi::crypto_shorthash_siphash24_KEYBYTES;

/// Digest-structure
#[derive(Copy)]
pub struct Digest(pub [u8; HASHBYTES]);

newtype_clone!(Digest);
newtype_impl!(Digest, HASHBYTES);

/// Key
///
/// When a `Key` goes out of scope its contents
/// will be zeroed out
pub struct Key(pub [u8; KEYBYTES]);

newtype_drop!(Key);
newtype_clone!(Key);
newtype_impl!(Key, KEYBYTES);

/// `gen_key()` randomly generates a key for shorthash
///
/// THREAD SAFETY: `gen_key()` is thread-safe provided that you have
/// called `sodiumoxide::init()` once before using any other function
/// from sodiumoxide.
pub fn gen_key() -> Key {
    let mut k = [0; KEYBYTES];
    randombytes_into(&mut k);
    Key(k)
}

/// `shorthash` hashes a message `m` under a key `k`. It
/// returns a hash `h`.
pub fn shorthash(m: &[u8],
                 &Key(ref k): &Key) -> Digest {
    unsafe {
        let mut h = [0; HASHBYTES];
        ffi::crypto_shorthash_siphash24(&mut h, m.as_ptr(),
                                        m.len() as c_ulonglong,
                                        k);
        Digest(h)
    }
}

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

    #[test]
    fn test_vectors() {
        let maxlen = 64;
        let mut m = Vec::with_capacity(64);
        for i in (0usize..64) {
            m.push(i as u8);
        }
        let h_expecteds = [[0x31, 0x0e, 0x0e, 0xdd, 0x47, 0xdb, 0x6f, 0x72]
                          ,[0xfd, 0x67, 0xdc, 0x93, 0xc5, 0x39, 0xf8, 0x74]
                          ,[0x5a, 0x4f, 0xa9, 0xd9, 0x09, 0x80, 0x6c, 0x0d]
                          ,[0x2d, 0x7e, 0xfb, 0xd7, 0x96, 0x66, 0x67, 0x85]
                          ,[0xb7, 0x87, 0x71, 0x27, 0xe0, 0x94, 0x27, 0xcf]
                          ,[0x8d, 0xa6, 0x99, 0xcd, 0x64, 0x55, 0x76, 0x18]
                          ,[0xce, 0xe3, 0xfe, 0x58, 0x6e, 0x46, 0xc9, 0xcb]
                          ,[0x37, 0xd1, 0x01, 0x8b, 0xf5, 0x00, 0x02, 0xab]
                          ,[0x62, 0x24, 0x93, 0x9a, 0x79, 0xf5, 0xf5, 0x93]
                          ,[0xb0, 0xe4, 0xa9, 0x0b, 0xdf, 0x82, 0x00, 0x9e]
                          ,[0xf3, 0xb9, 0xdd, 0x94, 0xc5, 0xbb, 0x5d, 0x7a]
                          ,[0xa7, 0xad, 0x6b, 0x22, 0x46, 0x2f, 0xb3, 0xf4]
                          ,[0xfb, 0xe5, 0x0e, 0x86, 0xbc, 0x8f, 0x1e, 0x75]
                          ,[0x90, 0x3d, 0x84, 0xc0, 0x27, 0x56, 0xea, 0x14]
                          ,[0xee, 0xf2, 0x7a, 0x8e, 0x90, 0xca, 0x23, 0xf7]
                          ,[0xe5, 0x45, 0xbe, 0x49, 0x61, 0xca, 0x29, 0xa1]
                          ,[0xdb, 0x9b, 0xc2, 0x57, 0x7f, 0xcc, 0x2a, 0x3f]
                          ,[0x94, 0x47, 0xbe, 0x2c, 0xf5, 0xe9, 0x9a, 0x69]
                          ,[0x9c, 0xd3, 0x8d, 0x96, 0xf0, 0xb3, 0xc1, 0x4b]
                          ,[0xbd, 0x61, 0x79, 0xa7, 0x1d, 0xc9, 0x6d, 0xbb]
                          ,[0x98, 0xee, 0xa2, 0x1a, 0xf2, 0x5c, 0xd6, 0xbe]
                          ,[0xc7, 0x67, 0x3b, 0x2e, 0xb0, 0xcb, 0xf2, 0xd0]
                          ,[0x88, 0x3e, 0xa3, 0xe3, 0x95, 0x67, 0x53, 0x93]
                          ,[0xc8, 0xce, 0x5c, 0xcd, 0x8c, 0x03, 0x0c, 0xa8]
                          ,[0x94, 0xaf, 0x49, 0xf6, 0xc6, 0x50, 0xad, 0xb8]
                          ,[0xea, 0xb8, 0x85, 0x8a, 0xde, 0x92, 0xe1, 0xbc]
                          ,[0xf3, 0x15, 0xbb, 0x5b, 0xb8, 0x35, 0xd8, 0x17]
                          ,[0xad, 0xcf, 0x6b, 0x07, 0x63, 0x61, 0x2e, 0x2f]
                          ,[0xa5, 0xc9, 0x1d, 0xa7, 0xac, 0xaa, 0x4d, 0xde]
                          ,[0x71, 0x65, 0x95, 0x87, 0x66, 0x50, 0xa2, 0xa6]
                          ,[0x28, 0xef, 0x49, 0x5c, 0x53, 0xa3, 0x87, 0xad]
                          ,[0x42, 0xc3, 0x41, 0xd8, 0xfa, 0x92, 0xd8, 0x32]
                          ,[0xce, 0x7c, 0xf2, 0x72, 0x2f, 0x51, 0x27, 0x71]
                          ,[0xe3, 0x78, 0x59, 0xf9, 0x46, 0x23, 0xf3, 0xa7]
                          ,[0x38, 0x12, 0x05, 0xbb, 0x1a, 0xb0, 0xe0, 0x12]
                          ,[0xae, 0x97, 0xa1, 0x0f, 0xd4, 0x34, 0xe0, 0x15]
                          ,[0xb4, 0xa3, 0x15, 0x08, 0xbe, 0xff, 0x4d, 0x31]
                          ,[0x81, 0x39, 0x62, 0x29, 0xf0, 0x90, 0x79, 0x02]
                          ,[0x4d, 0x0c, 0xf4, 0x9e, 0xe5, 0xd4, 0xdc, 0xca]
                          ,[0x5c, 0x73, 0x33, 0x6a, 0x76, 0xd8, 0xbf, 0x9a]
                          ,[0xd0, 0xa7, 0x04, 0x53, 0x6b, 0xa9, 0x3e, 0x0e]
                          ,[0x92, 0x59, 0x58, 0xfc, 0xd6, 0x42, 0x0c, 0xad]
                          ,[0xa9, 0x15, 0xc2, 0x9b, 0xc8, 0x06, 0x73, 0x18]
                          ,[0x95, 0x2b, 0x79, 0xf3, 0xbc, 0x0a, 0xa6, 0xd4]
                          ,[0xf2, 0x1d, 0xf2, 0xe4, 0x1d, 0x45, 0x35, 0xf9]
                          ,[0x87, 0x57, 0x75, 0x19, 0x04, 0x8f, 0x53, 0xa9]
                          ,[0x10, 0xa5, 0x6c, 0xf5, 0xdf, 0xcd, 0x9a, 0xdb]
                          ,[0xeb, 0x75, 0x09, 0x5c, 0xcd, 0x98, 0x6c, 0xd0]
                          ,[0x51, 0xa9, 0xcb, 0x9e, 0xcb, 0xa3, 0x12, 0xe6]
                          ,[0x96, 0xaf, 0xad, 0xfc, 0x2c, 0xe6, 0x66, 0xc7]
                          ,[0x72, 0xfe, 0x52, 0x97, 0x5a, 0x43, 0x64, 0xee]
                          ,[0x5a, 0x16, 0x45, 0xb2, 0x76, 0xd5, 0x92, 0xa1]
                          ,[0xb2, 0x74, 0xcb, 0x8e, 0xbf, 0x87, 0x87, 0x0a]
                          ,[0x6f, 0x9b, 0xb4, 0x20, 0x3d, 0xe7, 0xb3, 0x81]
                          ,[0xea, 0xec, 0xb2, 0xa3, 0x0b, 0x22, 0xa8, 0x7f]
                          ,[0x99, 0x24, 0xa4, 0x3c, 0xc1, 0x31, 0x57, 0x24]
                          ,[0xbd, 0x83, 0x8d, 0x3a, 0xaf, 0xbf, 0x8d, 0xb7]
                          ,[0x0b, 0x1a, 0x2a, 0x32, 0x65, 0xd5, 0x1a, 0xea]
                          ,[0x13, 0x50, 0x79, 0xa3, 0x23, 0x1c, 0xe6, 0x60]
                          ,[0x93, 0x2b, 0x28, 0x46, 0xe4, 0xd7, 0x06, 0x66]
                          ,[0xe1, 0x91, 0x5f, 0x5c, 0xb1, 0xec, 0xa4, 0x6c]
                          ,[0xf3, 0x25, 0x96, 0x5c, 0xa1, 0x6d, 0x62, 0x9f]
                          ,[0x57, 0x5f, 0xf2, 0x8e, 0x60, 0x38, 0x1b, 0xe5]
                          ,[0x72, 0x45, 0x06, 0xeb, 0x4c, 0x32, 0x8a, 0x95]];
        let k = Key([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
        for i in (0usize..maxlen) {
            let Digest(h) = shorthash(&m[..i], &k);
            assert!(h == h_expecteds[i]);
        }
    }
}

#[cfg(feature = "benchmarks")]
#[cfg(test)]
mod bench {
    extern crate test;
    use randombytes::randombytes;
    use super::*;

    const BENCH_SIZES: [usize; 14] = [0, 1, 2, 4, 8, 16, 32, 64,
                                      128, 256, 512, 1024, 2048, 4096];

    #[bench]
    fn bench_shorthash(b: &mut test::Bencher) 

}

{
        let k = gen_key();
        let ms: Vec<Vec<u8>> = BENCH_SIZES.iter().map(|s| {
            randombytes(*s)
        }).collect();
        b.iter(|| {
            for m in ms.iter() {
                shorthash(m, &k);
            }
        });
    }