1 files changed, 127 insertions, 0 deletions
diff --git a/pkg/blockchain/chainwriter/chainwriter.go b/pkg/blockchain/chainwriter/chainwriter.go
new file mode 100644
index 0000000..67a7d49
--- /dev/null
+++ b/pkg/blockchain/chainwriter/chainwriter.go
@@ -0,0 +1,127 @@
+package chainwriter
+
+import (
+	"Chain/pkg/block"
+	"Chain/pkg/blockchain/blockinfodatabase"
+	"Chain/pkg/pro"
+	"Chain/pkg/utils"
+	"google.golang.org/protobuf/proto"
+	"log"
+	"os"
+)
+
+// ChainWriter handles all I/O for the BlockChain. It stores and retrieves
+// Blocks and UndoBlocks.
+// See config.go for more information on its fields.
+// Block files are of the format:
+// "DataDirectory/BlockFileName_CurrentBlockFileNumber.FileExtension"
+// Ex: "data/block_0.txt"
+// UndoBlock files are of the format:
+// "DataDirectory/UndoFileName_CurrentUndoFileNumber.FileExtension"
+// Ex: "data/undo_0.txt"
+type ChainWriter struct {
+	// data storage information
+	FileExtension string
+	DataDirectory string
+
+	// block information
+	BlockFileName          string
+	CurrentBlockFileNumber uint32
+	CurrentBlockOffset     uint32
+	MaxBlockFileSize       uint32
+
+	// undo block information
+	UndoFileName          string
+	CurrentUndoFileNumber uint32
+	CurrentUndoOffset     uint32
+	MaxUndoFileSize       uint32
+}
+
+// New returns a ChainWriter given a Config.
+func New(config *Config) *ChainWriter {
+	if err := os.MkdirAll(config.DataDirectory, 0700); err != nil {
+		log.Fatalf("Could not create ChainWriter's data directory")
+	}
+	return &ChainWriter{
+		FileExtension:          config.FileExtension,
+		DataDirectory:          config.DataDirectory,
+		BlockFileName:          config.BlockFileName,
+		CurrentBlockFileNumber: 0,
+		CurrentBlockOffset:     0,
+		MaxBlockFileSize:       config.MaxBlockFileSize,
+		UndoFileName:           config.UndoFileName,
+		CurrentUndoFileNumber:  0,
+		CurrentUndoOffset:      0,
+		MaxUndoFileSize:        config.MaxUndoFileSize,
+	}
+}
+
+// StoreBlock stores a Block and its corresponding UndoBlock to Disk,
+// returning a BlockRecord that contains information for later retrieval.
+func (cw *ChainWriter) StoreBlock(bl *block.Block, undoBlock *UndoBlock, height uint32) *blockinfodatabase.BlockRecord {
+	// serialize block
+	b := block.EncodeBlock(bl)
+	serializedBlock, err := proto.Marshal(b)
+	if err != nil {
+		utils.Debug.Printf("Failed to marshal block")
+	}
+	// serialize undo block
+	ub := EncodeUndoBlock(undoBlock)
+	serializedUndoBlock, err := proto.Marshal(ub)
+	if err != nil {
+		utils.Debug.Printf("Failed to marshal undo block")
+	}
+	// write block to disk
+	bfi := cw.WriteBlock(serializedBlock)
+	// create an empty file info, which we will update if the function is passed an undo block.
+	ufi := &FileInfo{}
+	if undoBlock.Amounts != nil {
+		ufi = cw.WriteUndoBlock(serializedUndoBlock)
+	}
+
+	return &blockinfodatabase.BlockRecord{
+		Header:               bl.Header,
+		Height:               height,
+		NumberOfTransactions: uint32(len(bl.Transactions)),
+		BlockFile:            bfi.FileName,
+		BlockStartOffset:     bfi.StartOffset,
+		BlockEndOffset:       bfi.EndOffset,
+		UndoFile:             ufi.FileName,
+		UndoStartOffset:      ufi.StartOffset,
+		UndoEndOffset:        ufi.EndOffset,
+	}
+}
+
+// WriteBlock writes a serialized Block to Disk and returns
+// a FileInfo for storage information.
+func (cw *ChainWriter) WriteBlock(serializedBlock []byte) *FileInfo {
+	//TODO
+	return nil
+}
+
+// WriteUndoBlock writes a serialized UndoBlock to Disk and returns
+// a FileInfo for storage information.
+func (cw *ChainWriter) WriteUndoBlock(serializedUndoBlock []byte) *FileInfo {
+	//TODO
+	return nil
+}
+
+// ReadBlock returns a Block given a FileInfo.
+func (cw *ChainWriter) ReadBlock(fi *FileInfo) *block.Block {
+	bytes := readFromDisk(fi)
+	pb := &pro.Block{}
+	if err := proto.Unmarshal(bytes, pb); err != nil {
+		utils.Debug.Printf("failed to unmarshal block from file info {%v}", fi)
+	}
+	return block.DecodeBlock(pb)
+}
+
+// ReadUndoBlock returns an UndoBlock given a FileInfo.
+func (cw *ChainWriter) ReadUndoBlock(fi *FileInfo) *UndoBlock {
+	bytes := readFromDisk(fi)
+	pub := &pro.UndoBlock{}
+	if err := proto.Unmarshal(bytes, pub); err != nil {
+		utils.Debug.Printf("failed to unmarshal undo block from file info {%v}", fi)
+	}
+	return DecodeUndoBlock(pub)
+}