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extern crate unicode_normalization;

#[cfg(test)]
extern crate rustc_serialize;

#[macro_use]
pub mod macros;

pub mod hasher;
pub mod types;

const MAX_OUTPUT_LEN: usize = 32;

pub struct Digest {
    output_len: usize,
    value: [u8; MAX_OUTPUT_LEN],
}

impl Digest {
    pub fn new(bytes: &[u8]) -> Result<Digest, ()> {
        if bytes.len() > MAX_OUTPUT_LEN {
            return Err(());
        }

        let mut digest_bytes = [0u8; MAX_OUTPUT_LEN];
        digest_bytes.copy_from_slice(bytes);

        Ok(Digest {
            output_len: bytes.len(),
            value: digest_bytes,
        })
    }
}

impl AsRef<[u8]> for Digest {
    #[inline]
    fn as_ref(&self) -> &[u8] {
        &self.value[..self.output_len]
    }
}

#[cfg(feature = "objecthash-ring")]
pub fn digest<T: ObjectHash + ?Sized>(msg: &T) -> Digest {
    let mut hasher = hasher::default();
    msg.objecthash(&mut hasher);
    hasher.finish()
}

pub trait ObjectHasher {
    fn output_len(&self) -> usize;
    fn update(&mut self, bytes: &[u8]);
    fn update_nested<F>(&mut self, nested: F) where F: Fn(&mut Self);
    fn finish(self) -> Digest;
}

pub trait ObjectHash {
    fn objecthash<H: ObjectHasher>(&self, hasher: &mut H);
}

#[cfg(test)]
#[cfg(feature = "objecthash-ring")]
mod tests {
    use digest;
    use rustc_serialize::hex::ToHex;

    #[test]
    fn digest_test() {
        let result = digest(&1000);
        assert_eq!(result.as_ref().to_hex(),
                   "a3346d18105ef801c3598fec426dcc5d4be9d0374da5343f6c8dcbdf24cb8e0b");
    }
}