From dfcd22519be13d77407b588563a4da5e09958307 Mon Sep 17 00:00:00 2001
From: Zahary Karadjov <zahary@gmail.com>
Date: Thu, 7 Feb 2019 16:38:46 +0100
Subject: [PATCH] Fix for getting the current epoch number

---
 beacon_chain/beacon_node.nim | 4 ++--
 beacon_chain/time.nim        | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index 66ead101a..a3d01e9d3 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -93,7 +93,7 @@ proc sync*(node: BeaconNode): Future[bool] {.async.} =
     node.beaconState = await obtainTrustedStateSnapshot(node.db)
   else:
     node.beaconState = persistedState
-    var targetSlot = toSlot timeSinceGenesis(node.beaconState)
+    var targetSlot = node.beaconState.getSlotFromTime()
 
     let t = now()
     if t < node.beaconState.genesisTime * 1000:
@@ -388,7 +388,7 @@ proc processBlocks*(node: BeaconNode) =
 
     node.attestationPool.add(a, node.beaconState)
 
-  let epoch = node.beaconState.timeSinceGenesis().toSlot div EPOCH_LENGTH
+  let epoch = node.beaconState.getSlotFromTime div EPOCH_LENGTH
   node.scheduleEpochActions(epoch)
 
   runForever()
diff --git a/beacon_chain/time.nim b/beacon_chain/time.nim
index c062bef36..d2e3fd34a 100644
--- a/beacon_chain/time.nim
+++ b/beacon_chain/time.nim
@@ -16,8 +16,9 @@ proc timeSinceGenesis*(s: BeaconState): Timestamp =
   Timestamp(int64(fastEpochTime() - s.genesis_time * 1000) -
             detectedClockDrift)
 
-template toSlot*(t: Timestamp): uint64 =
-  t div (SLOT_DURATION * 1000)
+proc getSlotFromTime*(s: BeaconState, t = now()): SlotNumber =
+  GENESIS_SLOT + uint64((int64(t - s.genesis_time * 1000) - detectedClockDrift) div
+                         int64(SLOT_DURATION * 1000))
 
 template slotStart*(s: BeaconState, slot: uint64): Timestamp =
   (s.genesis_time + (slot * SLOT_DURATION)) * 1000