From ec62ffa064238d2820a667620994d725af6ae52e Mon Sep 17 00:00:00 2001
From: Stefan Bratanov <stefan.bratanov93@gmail.com>
Date: Thu, 29 Jun 2023 10:26:17 +0100
Subject: [PATCH] better calculation

---
 .../logic/common/helpers/MiscHelpers.java     | 10 +++----
 .../deneb/util/AttestationUtilDeneb.java      | 28 ++++++++++---------
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/common/helpers/MiscHelpers.java b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/common/helpers/MiscHelpers.java
index 82d23743406..f279cbf2a66 100644
--- a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/common/helpers/MiscHelpers.java
+++ b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/common/helpers/MiscHelpers.java
@@ -122,13 +122,13 @@ public UInt64 computeStartSlotAtEpoch(final UInt64 epoch) {
     return epoch.times(specConfig.getSlotsPerEpoch());
   }
 
-  public UInt64 computeSlotAtTime(final UInt64 genesisTime, final UInt64 time) {
-    return time.minusMinZero(genesisTime).dividedBy(specConfig.getSecondsPerSlot());
+  public UInt64 computeTimeAtSlot(final UInt64 genesisTime, final UInt64 slot) {
+    return genesisTime.plus(slot.times(specConfig.getSecondsPerSlot()));
   }
 
-  public UInt64 computeEpochAtTime(final UInt64 genesisTime, final UInt64 time) {
-    final UInt64 slot = computeSlotAtTime(genesisTime, time);
-    return computeEpochAtSlot(slot);
+  public UInt64 computeStartTimeAtEpoch(final UInt64 genesisTime, final UInt64 epoch) {
+    final UInt64 epochStartSlot = computeStartSlotAtEpoch(epoch);
+    return computeTimeAtSlot(genesisTime, epochStartSlot);
   }
 
   public UInt64 computeTimeAtSlot(final BeaconState state, final UInt64 slot) {
diff --git a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/deneb/util/AttestationUtilDeneb.java b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/deneb/util/AttestationUtilDeneb.java
index 65265ccae26..b478e8b9977 100644
--- a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/deneb/util/AttestationUtilDeneb.java
+++ b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/deneb/util/AttestationUtilDeneb.java
@@ -13,7 +13,7 @@
 
 package tech.pegasys.teku.spec.logic.versions.deneb.util;
 
-import static tech.pegasys.teku.infrastructure.time.TimeUtilities.millisToSeconds;
+import static tech.pegasys.teku.infrastructure.time.TimeUtilities.secondsToMillis;
 
 import java.util.Optional;
 import tech.pegasys.teku.infrastructure.unsigned.UInt64;
@@ -67,22 +67,24 @@ && isFromFarFuture(attestation, genesisTime, currentTimeMillis)) {
 
   private boolean isAttestationSlotAfterCurrentTime(
       final UInt64 attestationSlot, final UInt64 genesisTime, final UInt64 currentTimeMillis) {
-    final UInt64 currentTimeWithDisparity = calculateCurrentTimeWithDisparity(currentTimeMillis);
-    final UInt64 currentSlot = miscHelpers.computeSlotAtTime(genesisTime, currentTimeWithDisparity);
-    return attestationSlot.isGreaterThan(currentSlot);
+    final UInt64 attestationSlotTimeMillis =
+        secondsToMillis(miscHelpers.computeTimeAtSlot(genesisTime, attestationSlot));
+    return attestationSlotTimeMillis.isGreaterThan(
+        currentTimeMillis.plus(specConfig.getMaximumGossipClockDisparity()));
   }
 
   private boolean isAttestationSlotCurrentOrPreviousEpoch(
       final UInt64 attestationSlot, final UInt64 genesisTime, final UInt64 currentTimeMillis) {
-    final UInt64 currentTimeWithDisparity = calculateCurrentTimeWithDisparity(currentTimeMillis);
-    final UInt64 currentEpoch =
-        miscHelpers.computeEpochAtTime(genesisTime, currentTimeWithDisparity);
     final UInt64 attestationEpoch = miscHelpers.computeEpochAtSlot(attestationSlot);
-    return attestationEpoch.equals(currentEpoch)
-        || attestationEpoch.equals(currentEpoch.minusMinZero(1));
-  }
-
-  private UInt64 calculateCurrentTimeWithDisparity(final UInt64 currentTimeMillis) {
-    return millisToSeconds(currentTimeMillis.plus(specConfig.getMaximumGossipClockDisparity()));
+    final UInt64 nextEpochStartTimeMillis =
+        secondsToMillis(miscHelpers.computeStartTimeAtEpoch(genesisTime, attestationEpoch.plus(1)));
+    final UInt64 previousEpochStartTimeMillis =
+        secondsToMillis(
+            miscHelpers.computeStartTimeAtEpoch(genesisTime, attestationEpoch.minusMinZero(1)));
+    return currentTimeMillis
+            .minusMinZero(specConfig.getMaximumGossipClockDisparity())
+            .isGreaterThanOrEqualTo(previousEpochStartTimeMillis)
+        && currentTimeMillis.isLessThan(
+            nextEpochStartTimeMillis.plus(specConfig.getMaximumGossipClockDisparity()));
   }
 }