1 files changed, 65 insertions, 1 deletions
diff --git a/pkg/blockchain/blockchain.go b/pkg/blockchain/blockchain.go
index c456be1..7b92b1a 100644
--- a/pkg/blockchain/blockchain.go
+++ b/pkg/blockchain/blockchain.go
@@ -6,6 +6,7 @@ import (
 	"Chain/pkg/blockchain/chainwriter"
 	"Chain/pkg/blockchain/coindatabase"
 	"Chain/pkg/utils"
+	"math"
 )
 
 // BlockChain is the main type of this project.
@@ -86,7 +87,70 @@ func GenesisBlock(config *Config) *block.Block {
 // (4) Handles a fork, if necessary.
 // (5) Updates the BlockChain's fields.
 func (bc *BlockChain) HandleBlock(b *block.Block) {
-	//TODO
+	appends := bc.appendsToActiveChain(b)
+	blockHash := b.Hash()
+
+	// 1. Validate Block
+	if appends && !bc.CoinDB.ValidateBlock(b.Transactions) {
+		return
+	}
+
+	// 2. Make Undo Block
+	ub := bc.makeUndoBlock(b.Transactions)
+
+	// 3. Store Block in CoinDatabase
+	bc.CoinDB.StoreBlock(b.Transactions, appends)
+
+	// 4. Get BlockRecord for previous Block
+	previousBr := bc.BlockInfoDB.GetBlockRecord(b.Header.PreviousHash)
+
+	// 5. Store UndoBlock and Block to Disk
+	height := previousBr.Height + 1
+	br := bc.ChainWriter.StoreBlock(b, ub, height)
+
+	// 6. Store BlockRecord to BlockInfoDatabase
+	bc.BlockInfoDB.StoreBlockRecord(blockHash, br)
+
+	if appends {
+		// 7. Handle appending Block
+		bc.Length++
+		bc.LastBlock = b
+		bc.LastHash = blockHash
+		if len(bc.UnsafeHashes) >= 6 {
+			bc.UnsafeHashes = bc.UnsafeHashes[1:]
+		}
+		bc.UnsafeHashes = append(bc.UnsafeHashes, blockHash)
+	} else if height > bc.Length {
+		// 8. Handle fork
+		bc.handleFork(b, blockHash, height)
+	}
+}
+
+// handleFork updates the BlockChain when a fork occurs. First, it
+// finds the Blocks the BlockChain must revert. Once found, it uses
+// those Blocks to update the CoinDatabase. Lastly, it updates the
+// BlockChain's fields to reflect the fork.
+func (bc *BlockChain) handleFork(b *block.Block, blockHash string, height uint32) {
+	bc.Length = height
+	forkedBlocks := bc.getForkedBlocks(blockHash)
+	var forkedUnsafeHashes []string
+	min := int(math.Min(float64(6), float64(len(forkedBlocks))))
+	for i := 0; i < min; i++ {
+		forkedHash := forkedBlocks[i].Hash()
+		forkedUnsafeHashes = append(forkedUnsafeHashes, forkedHash)
+	}
+	// likely have to add unsafe hashes
+	bc.UnsafeHashes = forkedUnsafeHashes
+	blocks, undoBlocks := bc.getBlocksAndUndoBlocks(len(forkedBlocks) - 1)
+	bc.CoinDB.UndoCoins(blocks, undoBlocks)
+	for _, bl := range forkedBlocks {
+		if !bc.CoinDB.ValidateBlock(bl.Transactions) {
+			utils.Debug.Printf("Validation failed for forked block {%v}", b.Hash())
+		}
+		bc.CoinDB.StoreBlock(bl.Transactions, true)
+	}
+	bc.LastBlock = b
+	bc.LastHash = b.Hash()
 }
 
 // makeUndoBlock returns an UndoBlock given a slice of Transaction.