From 1996ee1f262ce2eed7c69e3979c8a3a2fe563f00 Mon Sep 17 00:00:00 2001
From: presstab <presstab1337@gmail.com>
Date: Thu, 3 Jan 2019 23:55:19 -0700
Subject: [PATCH] Chainwork ultimately decided by PoS. Add max past time drift.

---
 src/chain.cpp      | 16 ++++++++++++++++
 src/chain.h        |  5 ++++-
 src/validation.cpp | 25 +++++--------------------
 3 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/src/chain.cpp b/src/chain.cpp
index 0f62889c9e..d504c6c66e 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -121,6 +121,22 @@ void CBlockIndex::BuildSkip()
         pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
 }
 
+int64_t CBlockIndex::GetBlockWork() const
+{
+    int64_t nTimeSpan = 0;
+    if (pprev && pprev->pprev)
+        nTimeSpan = pprev->GetBlockTime() - pprev->pprev->GetBlockTime();
+    int64_t nBlockWork = 1000 - nTimeSpan;
+    if (nBlockWork <= 0)
+        nBlockWork = 1;
+
+    //PoS blocks have the final decision on consensus, if it is between a PoW block and PoS block
+    if (IsProofOfStake())
+        nBlockWork += 1001;
+
+    return nBlockWork;
+}
+
 arith_uint256 GetBlockProof(const CBlockIndex& block)
 {
     arith_uint256 bnTarget;
diff --git a/src/chain.h b/src/chain.h
index 711fd653e6..2a78f13815 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -21,7 +21,8 @@
  * Maximum amount of time that a block timestamp is allowed to exceed the
  * current network-adjusted time before the block will be accepted.
  */
-static const int64_t MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60;
+static const int64_t MAX_FUTURE_BLOCK_TIME = 75;
+static const int64_t MAX_PAST_BLOCK_TIME = 15;
 
 /**
  * Timestamp window used as a grace period by code that compares external
@@ -369,6 +370,8 @@ class CBlockIndex
         return (int64_t)nTimeMax;
     }
 
+    int64_t GetBlockWork() const;
+
     /** Returns the hash of the accumulator for the specified denomination. If it doesn't exist then a new uint256 is returned*/
     uint256 GetAccumulatorHash(libzerocoin::CoinDenomination denom) const
     {
diff --git a/src/validation.cpp b/src/validation.cpp
index 6da0a51103..3703f48e0a 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3565,15 +3565,7 @@ CBlockIndex* CChainState::AddToBlockIndex(const CBlockHeader& block, bool fProof
     }
     pindexNew->nTimeMax = (pindexNew->pprev ? std::max(pindexNew->pprev->nTimeMax, pindexNew->nTime) : pindexNew->nTime);
 
-    int nTimeElapsed = 60;
-    if (pindexNew->pprev)
-        nTimeElapsed = pindexNew->GetBlockTime() - pindexNew->pprev->GetBlockTime();
-
-    nTimeElapsed = 1000 - nTimeElapsed;
-    if (nTimeElapsed <= 0)
-        nTimeElapsed = 1;
-
-    pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + nTimeElapsed;
+    pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + pindexNew->GetBlockWork();
     //pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + GetBlockProof(*pindexNew);
     pindexNew->RaiseValidity(BLOCK_VALID_TREE);
 
@@ -3998,7 +3990,7 @@ static bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationSta
         return state.DoS(1, error("%s: forked chain older than max reorganization depth (height %d)", __func__, nHeight), REJECT_DEPTH, "bad-fork-prior-to-max-reorg-depth");
 
     // Check timestamp against prev
-    if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
+    if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast() || (pindexPrev->nHeight > 5000 && block.GetBlockTime() < pindexPrev->GetBlockTime() - MAX_PAST_BLOCK_TIME))
         return state.Invalid(false, REJECT_INVALID, "time-too-old", "block's timestamp is too early");
 
     // Check timestamp
@@ -4662,16 +4654,9 @@ bool CChainState::LoadBlockIndex(const Consensus::Params& consensus_params, CBlo
     for (const std::pair<int, CBlockIndex*>& item : vSortedByHeight)
     {
         CBlockIndex* pindex = item.second;
-        int64_t nTimeElapsed = 60;
-        if (pindex->pprev)
-            nTimeElapsed = pindex->GetBlockTime() - pindex->pprev->GetBlockTime();
-        nTimeElapsed = 1000 - nTimeElapsed;
-        if (nTimeElapsed <= 0)
-            nTimeElapsed = 1;
-
-        pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + nTimeElapsed;
-        //pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + 10000 - nTimeElapsed;
-        //pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + GetBlockProof(*pindex);
+        int64_t nTimeSpan = 0;
+
+        pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + pindex->GetBlockWork();
         pindex->nTimeMax = (pindex->pprev ? std::max(pindex->pprev->nTimeMax, pindex->nTime) : pindex->nTime);
         // We can link the chain of blocks for which we've received transactions at some point.
         // Pruned nodes may have deleted the block.