From 22e2484878d7b3faba0b66641e39ffa05b8d9c7f Mon Sep 17 00:00:00 2001
From: Aditya Sripal <adityasripal@gmail.com>
Date: Tue, 13 Aug 2019 16:58:06 -0700
Subject: [PATCH] start revert logic

---
 state/execution.go | 20 ++++++++++++++++++++
 store/store.go     | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/state/execution.go b/state/execution.go
index 2ac2e968..9268fc28 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -442,6 +442,26 @@ func updateState(
 	}, nil
 }
 
+func revertState(
+	state State,
+	reverted *types.Block,
+	newHead *types.Block,
+) State {
+	var lastValidators *types.ValidatorSet
+	lastValidators, _ := LoadValidators(blockExec.db, lastValidatorsInfo.LastHeightChanged)
+	return State{
+		Version:          state.Version,
+		ChainID:          state.ChainID,
+		LastBlockHeight:  state.LastBlockHeight - 1,
+		LastBlockTotalTx: state.LastBlockTotalTx - len(reverted.Data.Txs),
+		LastBlockID:      reverted.Header.LastBlockID,
+		LastBlockTime:    newHead.Header.LastBlockTime,
+		NextValidators:   state.Validators.Copy(),
+		Validators:       state.LastValidators.Copy(),
+		LastValidators:   lastValidators.Copy(),
+	}
+}
+
 // Fire NewBlock, NewBlockHeader.
 // Fire TxEvent for every tx.
 // NOTE: if Tendermint crashes before commit, some or all of these events may be published again.
diff --git a/store/store.go b/store/store.go
index c16d5efe..d51a407e 100644
--- a/store/store.go
+++ b/store/store.go
@@ -195,6 +195,45 @@ func (bs *BlockStore) saveBlockPart(height int64, index int, part *types.Part) {
 	bs.db.Set(calcBlockPartKey(height, index), partBytes)
 }
 
+// RevertBlock reverts the store changes from the latest SaveBlock.
+// Only modifies blockstore, does not change TM state
+// For now, seenCommit for reverted block remains in db
+// Returns the block that got reverted and the newest lastBlock
+func (bs *BlockStore) RevertBlock() (reverted *types.Block, newHead *types.Block) {
+	bs.mtx.RLock()
+	latest := bs.height
+	bs.mtx.RUnlock()
+
+	// Load block to return later
+	reverted = bs.LoadBlock(latest)
+	newHead = bs.LoadBlock(latest - 1)
+
+	// Delete block meta
+	blockMeta := bs.LoadBlockMeta(latest)
+	blockID = blockMeta.BlockID
+	bs.db.Delete(calcBlockMetaKey(latest))
+
+	// Delete block parts
+	for i := 0; i < blockID.PartsHeader.Total; i++ {
+		bs.db.Delete(calcBlockPartKey(latest, i))
+	}
+
+	// Delete block commit
+	bs.db.Delete(calcBlockCommitKey(latest - 1))
+
+	// Update BlockStateStateJSON descriptor
+	BlockStateStateJSON{Height: latest - 1}.Save(bs.db)
+
+	// Update height
+	bs.mtx.Lock()
+	bs.height = latest - 1
+	bs.mtx.Unlock()
+
+	// Flush
+	bs.db.SetSync(nil, nil)
+
+}
+
 //-----------------------------------------------------------------------------
 
 func calcBlockMetaKey(height int64) []byte {