From 68f4bcde5dcbf50242abc89371958173117b2951 Mon Sep 17 00:00:00 2001
From: Vincent Batts <vbatts@hashbangbash.com>
Date: Thu, 26 Mar 2015 16:46:02 -0400
Subject: [PATCH] stream: first chunk made into a node

---
 node.go        |  8 +++++---
 stream.go      | 39 +++++++++++++++++++++++----------------
 stream_test.go |  6 ++++++
 3 files changed, 34 insertions(+), 19 deletions(-)
 create mode 100644 stream_test.go

diff --git a/node.go b/node.go
index 678774c..88888d9 100644
--- a/node.go
+++ b/node.go
@@ -25,12 +25,14 @@ func NewNodeHash(h HashMaker) *Node {
 }
 
 // NewNodeHashBlock returns a new Node using the provided crypto.Hash, and calculates the block's checksum
-func NewNodeHashBlock(h HashMaker, b []byte) *Node {
+func NewNodeHashBlock(h HashMaker, b []byte) (*Node, error) {
 	n := &Node{hash: h}
 	h1 := n.hash()
-	h1.Write(b)
+	if _, err := h1.Write(b); err != nil {
+		return nil, err
+	}
 	n.checksum = h1.Sum(nil)
-	return n
+	return n, nil
 }
 
 // Node is a fundamental part of the tree.
diff --git a/stream.go b/stream.go
index ed9b708..d23c2e0 100644
--- a/stream.go
+++ b/stream.go
@@ -13,6 +13,7 @@ func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
 	mh.blockSize = merkleBlockLength
 	mh.hm = hm
 	mh.tree = &Tree{Nodes: []*Node{}, BlockLength: merkleBlockLength}
+	mh.lastBlock = make([]byte, merkleBlockLength)
 	return mh
 }
 
@@ -22,11 +23,12 @@ func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
 
 // TODO satisfy the hash.Hash interface
 type merkleHash struct {
-	blockSize        int
-	tree             *Tree
-	hm               HashMaker
-	lastBlock        []byte // as needed, for Sum()
-	partialLastBlock bool
+	blockSize    int
+	tree         *Tree
+	hm           HashMaker
+	lastBlock    []byte // as needed, for Sum()
+	lastBlockLen int
+	//partialLastBlock bool
 }
 
 // XXX this will be tricky, as the last block can be less than the BlockSize.
@@ -48,6 +50,7 @@ func (mh *merkleHash) Sum(b []byte) []byte {
 
 func (mh *merkleHash) Write(b []byte) (int, error) {
 	// basically we need to:
+	// * include prior partial lastBlock, if any
 	// * chunk these writes into blockSize
 	// * create Node of the sum
 	// * add the Node to the tree
@@ -57,22 +60,26 @@ func (mh *merkleHash) Write(b []byte) (int, error) {
 		curBlock       = make([]byte, mh.blockSize)
 		numBytes   int = 0
 		numWritten int
+		offset     int = 0
 	)
-	if mh.lastBlock != nil && len(mh.lastBlock) > 0 {
-		numBytes = copy(curBlock, mh.lastBlock)
+	if mh.lastBlock != nil && mh.lastBlockLen > 0 {
+		numBytes = copy(curBlock[:], mh.lastBlock[:])
 		// not adding to numWritten, since these blocks were accounted for in a
 		// prior Write()
+
+		// then we'll chunk the front of the incoming bytes
+		offset = copy(curBlock[numBytes:], b[:(mh.blockSize-numBytes)])
+		n, err := NewNodeHashBlock(mh.hm, curBlock)
+		if err != nil {
+			// XXX might need to stash again the prior lastBlock and first little
+			// chunk
+			return numWritten, err
+		}
+		mh.tree.Nodes = append(mh.tree.Nodes, n)
+		numWritten += offset
 	}
 
-	if numBytes > 0 {
-		copy(curBlock, b[:(mh.blockSize-numBytes)])
-		numWritten += (mh.blockSize - numBytes)
-		// TODO Node for curBlock
-		n := NewNodeHashBlock(mh.hm, curBlock)
-		_ = n
-	}
-
-	numBytes = len(b) - numBytes
+	numBytes = (len(b) - offset)
 	for i := 0; i < numBytes/mh.blockSize; i++ {
 		// TODO Node for curBlock
 	}
diff --git a/stream_test.go b/stream_test.go
new file mode 100644
index 0000000..283becc
--- /dev/null
+++ b/stream_test.go
@@ -0,0 +1,6 @@
+package merkle
+
+import "testing"
+
+func TestMerkleHashWriter(t *testing.T) {
+}