1 files changed, 261 insertions, 0 deletions
diff --git a/pkg/blockchain/blockchain.go b/pkg/blockchain/blockchain.go
new file mode 100644
index 0000000..c456be1
--- /dev/null
+++ b/pkg/blockchain/blockchain.go
@@ -0,0 +1,261 @@
+package blockchain
+
+import (
+	"Chain/pkg/block"
+	"Chain/pkg/blockchain/blockinfodatabase"
+	"Chain/pkg/blockchain/chainwriter"
+	"Chain/pkg/blockchain/coindatabase"
+	"Chain/pkg/utils"
+)
+
+// BlockChain is the main type of this project.
+// Length is the length of the active chain.
+// LastBlock is the last block of the active chain.
+// LastHash is the hash of the last block of the active chain.
+// UnsafeHashes are the hashes of the "unsafe" blocks on the
+// active chain. These "unsafe" blocks may be reverted during a
+// fork.
+// maxHashes is the number of unsafe hashes that the chain keeps track of.
+// BlockInfoDB is a pointer to a block info database
+// ChainWriter is a pointer to a chain writer.
+// CoinDB is a pointer to a coin database.
+type BlockChain struct {
+	Length       uint32
+	LastBlock    *block.Block
+	LastHash     string
+	UnsafeHashes []string
+	maxHashes    int
+
+	BlockInfoDB *blockinfodatabase.BlockInfoDatabase
+	ChainWriter *chainwriter.ChainWriter
+	CoinDB      *coindatabase.CoinDatabase
+}
+
+// New returns a blockchain given a Config.
+func New(config *Config) *BlockChain {
+	genBlock := GenesisBlock(config)
+	hash := genBlock.Hash()
+	bc := &BlockChain{
+		Length:       1,
+		LastBlock:    genBlock,
+		LastHash:     hash,
+		UnsafeHashes: []string{},
+		maxHashes:    6,
+		BlockInfoDB:  blockinfodatabase.New(blockinfodatabase.DefaultConfig()),
+		ChainWriter:  chainwriter.New(chainwriter.DefaultConfig()),
+		CoinDB:       coindatabase.New(coindatabase.DefaultConfig()),
+	}
+	// have to store the genesis block
+	bc.CoinDB.StoreBlock(genBlock.Transactions, true)
+	ub := &chainwriter.UndoBlock{}
+	br := bc.ChainWriter.StoreBlock(genBlock, ub, 1)
+	bc.BlockInfoDB.StoreBlockRecord(hash, br)
+	return bc
+}
+
+// GenesisBlock creates the genesis Block, using the Config's
+// InitialSubsidy and GenesisPublicKey.
+func GenesisBlock(config *Config) *block.Block {
+	txo := &block.TransactionOutput{
+		Amount:        config.InitialSubsidy,
+		LockingScript: config.GenesisPublicKey,
+	}
+	genTx := &block.Transaction{
+		Version:  0,
+		Inputs:   nil,
+		Outputs:  []*block.TransactionOutput{txo},
+		LockTime: 0,
+	}
+	return &block.Block{
+		Header: &block.Header{
+			Version:          0,
+			PreviousHash:     "",
+			MerkleRoot:       "",
+			DifficultyTarget: "",
+			Nonce:            0,
+			Timestamp:        0,
+		},
+		Transactions: []*block.Transaction{genTx},
+	}
+}
+
+// HandleBlock handles a new Block. At a high level, it:
+// (1) Validates and stores the Block.
+// (2) Stores the Block and resulting Undoblock to Disk.
+// (3) Stores the BlockRecord in the BlockInfoDatabase.
+// (4) Handles a fork, if necessary.
+// (5) Updates the BlockChain's fields.
+func (bc *BlockChain) HandleBlock(b *block.Block) {
+	//TODO
+}
+
+// makeUndoBlock returns an UndoBlock given a slice of Transaction.
+func (bc *BlockChain) makeUndoBlock(txs []*block.Transaction) *chainwriter.UndoBlock {
+	var transactionHashes []string
+	var outputIndexes []uint32
+	var amounts []uint32
+	var lockingScripts []string
+	for _, tx := range txs {
+		for _, txi := range tx.Inputs {
+			cl := coindatabase.CoinLocator{
+				ReferenceTransactionHash: txi.ReferenceTransactionHash,
+				OutputIndex:              txi.OutputIndex,
+			}
+			coin := bc.CoinDB.GetCoin(cl)
+			// if the coin is nil it means this isn't even a possible fork
+			if coin == nil {
+				return &chainwriter.UndoBlock{
+					TransactionInputHashes: nil,
+					OutputIndexes:          nil,
+					Amounts:                nil,
+					LockingScripts:         nil,
+				}
+			}
+			transactionHashes = append(transactionHashes, txi.ReferenceTransactionHash)
+			outputIndexes = append(outputIndexes, txi.OutputIndex)
+			amounts = append(amounts, coin.TransactionOutput.Amount)
+			lockingScripts = append(lockingScripts, coin.TransactionOutput.LockingScript)
+		}
+	}
+	return &chainwriter.UndoBlock{
+		TransactionInputHashes: transactionHashes,
+		OutputIndexes:          outputIndexes,
+		Amounts:                amounts,
+		LockingScripts:         lockingScripts,
+	}
+}
+
+// getBlock uses the ChainWriter to retrieve a Block from Disk
+// given that Block's hash
+func (bc *BlockChain) getBlock(blockHash string) *block.Block {
+	br := bc.BlockInfoDB.GetBlockRecord(blockHash)
+	fi := &chainwriter.FileInfo{
+		FileName:    br.BlockFile,
+		StartOffset: br.BlockStartOffset,
+		EndOffset:   br.BlockEndOffset,
+	}
+	return bc.ChainWriter.ReadBlock(fi)
+}
+
+// getUndoBlock uses the ChainWriter to retrieve an UndoBlock
+// from Disk given the corresponding Block's hash
+func (bc *BlockChain) getUndoBlock(blockHash string) *chainwriter.UndoBlock {
+	br := bc.BlockInfoDB.GetBlockRecord(blockHash)
+	fi := &chainwriter.FileInfo{
+		FileName:    br.UndoFile,
+		StartOffset: br.UndoStartOffset,
+		EndOffset:   br.UndoEndOffset,
+	}
+	return bc.ChainWriter.ReadUndoBlock(fi)
+}
+
+// GetBlocks retrieves a slice of blocks from the main chain given a
+// starting and ending height, inclusive. Given a chain of length 50,
+// GetBlocks(10, 20) returns blocks 10 through 20.
+func (bc *BlockChain) GetBlocks(start, end uint32) []*block.Block {
+	if start >= end || end <= 0 || start <= 0 || end > bc.Length {
+		utils.Debug.Printf("cannot get chain blocks with values start: %v end: %v", start, end)
+	}
+
+	var blocks []*block.Block
+	currentHeight := bc.Length
+	nextHash := bc.LastBlock.Hash()
+
+	for currentHeight >= start {
+		br := bc.BlockInfoDB.GetBlockRecord(nextHash)
+		fi := &chainwriter.FileInfo{
+			FileName:    br.BlockFile,
+			StartOffset: br.BlockStartOffset,
+			EndOffset:   br.BlockEndOffset,
+		}
+		if currentHeight <= end {
+			nextBlock := bc.ChainWriter.ReadBlock(fi)
+			blocks = append(blocks, nextBlock)
+		}
+		nextHash = br.Header.PreviousHash
+		currentHeight--
+	}
+	return reverseBlocks(blocks)
+}
+
+// GetHashes retrieves a slice of hashes from the main chain given a
+// starting and ending height, inclusive. Given a BlockChain of length
+// 50, GetHashes(10, 20) returns the hashes of Blocks 10 through 20.
+func (bc *BlockChain) GetHashes(start, end uint32) []string {
+	if start >= end || end <= 0 || start <= 0 || end > bc.Length {
+		utils.Debug.Printf("cannot get chain blocks with values start: %v end: %v", start, end)
+	}
+
+	var hashes []string
+	currentHeight := bc.Length
+	nextHash := bc.LastBlock.Hash()
+
+	for currentHeight >= start {
+		br := bc.BlockInfoDB.GetBlockRecord(nextHash)
+		if currentHeight <= end {
+			hashes = append(hashes, nextHash)
+		}
+		nextHash = br.Header.PreviousHash
+		currentHeight--
+	}
+	return reverseHashes(hashes)
+}
+
+// appendsToActiveChain returns whether a Block appends to the
+// BlockChain's active chain or not.
+func (bc *BlockChain) appendsToActiveChain(b *block.Block) bool {
+	return bc.LastBlock.Hash() == b.Header.PreviousHash
+}
+
+// getForkedBlocks returns a slice of Blocks given a starting hash.
+// It returns a maximum of maxHashes Blocks, where maxHashes is the
+// BlockChain's maximum number of unsafe hashes.
+func (bc *BlockChain) getForkedBlocks(startHash string) []*block.Block {
+	unsafeHashes := make(map[string]bool)
+	for _, h := range bc.UnsafeHashes {
+		unsafeHashes[h] = true
+	}
+	var forkedBlocks []*block.Block
+	nextHash := startHash
+	for i := 0; i < len(bc.UnsafeHashes); i++ {
+		forkedBlock := bc.getBlock(nextHash)
+		forkedBlocks = append(forkedBlocks, forkedBlock)
+		if _, ok := unsafeHashes[nextHash]; ok {
+			return forkedBlocks
+		}
+		nextHash = forkedBlock.Header.PreviousHash
+	}
+	return forkedBlocks
+}
+
+// getBlocksAndUndoBlocks returns a slice of n Blocks with a
+// corresponding slice of n UndoBlocks.
+func (bc *BlockChain) getBlocksAndUndoBlocks(n int) ([]*block.Block, []*chainwriter.UndoBlock) {
+	var blocks []*block.Block
+	var undoBlocks []*chainwriter.UndoBlock
+	nextHash := bc.LastHash
+	for i := 0; i < n; i++ {
+		b := bc.getBlock(nextHash)
+		ub := bc.getUndoBlock(nextHash)
+		blocks = append(blocks, b)
+		undoBlocks = append(undoBlocks, ub)
+		nextHash = b.Header.PreviousHash
+	}
+	return blocks, undoBlocks
+}
+
+// reverseBlocks returns a reversed slice of Blocks.
+func reverseBlocks(s []*block.Block) []*block.Block {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+	return s
+}
+
+// reverseHashes returns a reversed slice of hashes.
+func reverseHashes(s []string) []string {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+	return s
+}