From 1e3fd1ff806651aa3f55b691051367223961812e Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Mon, 3 Dec 2018 16:19:31 +1100
Subject: [PATCH] Add ssz encode/decode for AttestationData

---
 beacon_chain/types/src/attestation_data.rs | 65 ++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/beacon_chain/types/src/attestation_data.rs b/beacon_chain/types/src/attestation_data.rs
index 9088ce058..f0e7ea4c2 100644
--- a/beacon_chain/types/src/attestation_data.rs
+++ b/beacon_chain/types/src/attestation_data.rs
@@ -1,3 +1,4 @@
+use super::ssz::{Decodable, DecodeError, Encodable, SszStream};
 use super::Hash256;
 
 #[derive(Debug, Clone, PartialEq)]
@@ -11,3 +12,67 @@ pub struct AttestationData {
     pub justified_slot: u64,
     pub justified_block_hash: Hash256,
 }
+
+impl Encodable for AttestationData {
+    fn ssz_append(&self, s: &mut SszStream) {
+        s.append(&self.slot);
+        s.append(&self.shard);
+        s.append(&self.beacon_block_hash);
+        s.append(&self.epoch_boundary_hash);
+        s.append(&self.shard_block_hash);
+        s.append(&self.latest_crosslink_hash);
+        s.append(&self.justified_slot);
+        s.append(&self.justified_block_hash);
+    }
+}
+
+impl Decodable for AttestationData {
+    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
+        let (slot, i) = u64::ssz_decode(bytes, i)?;
+        let (shard, i) = u64::ssz_decode(bytes, i)?;
+        let (beacon_block_hash, i) = Hash256::ssz_decode(bytes, i)?;
+        let (epoch_boundary_hash, i) = Hash256::ssz_decode(bytes, i)?;
+        let (shard_block_hash, i) = Hash256::ssz_decode(bytes, i)?;
+        let (latest_crosslink_hash, i) = Hash256::ssz_decode(bytes, i)?;
+        let (justified_slot, i) = u64::ssz_decode(bytes, i)?;
+        let (justified_block_hash, i) = Hash256::ssz_decode(bytes, i)?;
+
+        let attestation_data = AttestationData {
+            slot,
+            shard,
+            beacon_block_hash,
+            epoch_boundary_hash,
+            shard_block_hash,
+            latest_crosslink_hash,
+            justified_slot,
+            justified_block_hash,
+        };
+        Ok((attestation_data, i))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::ssz::ssz_encode;
+    use super::*;
+
+    #[test]
+    pub fn test_attestation_record_ssz_round_trip() {
+        let original = AttestationData {
+            slot: 42,
+            shard: 16,
+            beacon_block_hash: Hash256::from("beacon".as_bytes()),
+            epoch_boundary_hash: Hash256::from("epoch".as_bytes()),
+            shard_block_hash: Hash256::from("shard".as_bytes()),
+            latest_crosslink_hash: Hash256::from("xlink".as_bytes()),
+            justified_slot: 8,
+            justified_block_hash: Hash256::from("justified".as_bytes()),
+        };
+
+        let ssz = ssz_encode(&original);
+
+        let (decoded, _) = AttestationData::ssz_decode(&ssz, 0).unwrap();
+
+        assert_eq!(original, decoded);
+    }
+}