/*!
`SipHash-2-4`

*/
use libc::{c_ulonglong, c_int};
use std::intrinsics::volatile_set_memory;
use randombytes::randombytes_into;

#[link(name = "sodium")]
extern {
    fn crypto_shorthash_siphash24(h: *mut u8,
                                  m: *const u8,
                                  mlen: c_ulonglong,
                                  k: *const u8) -> c_int;
}

pub const HASHBYTES: uint = 8;
pub const KEYBYTES: uint = 16;

/**
 * Digest-structure
 */
pub struct Digest(pub [u8, ..HASHBYTES]);

newtype_clone!(Digest)

/**
 * 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)

/**
 * `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(k): &Key) -> Digest {
    unsafe {
        let mut h = [0, ..HASHBYTES];
        crypto_shorthash_siphash24(h.as_mut_ptr(),
                                   m.as_ptr(), m.len() as c_ulonglong,
                                   k.as_ptr());
        Digest(h)
    }
}

#[test]
fn test_vectors() {
    let maxlen = 64;
    let mut m = Vec::with_capacity(64);
    for i in range(0u, 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 range(0u, maxlen) {
        let Digest(h) = shorthash(m.slice(0, i), &k);
        assert!(h == h_expecteds[i]);
    }
}

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

    const BENCH_SIZES: [uint, ..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.as_slice(), &k);
            }
        });
    }
}
