Merge pull request #32 from braydonf/getchainwork

Added getChainWork method for determining the best chain.

integration/index.js

@@ -117,4 +117,23 @@ describe('Basic Functionality', function() {
     });
   });
 
+  describe('get chain work', function() {
+    it('will get the total work for the genesis block via hash', function() {
+      var hash = '000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f';
+      var work = bitcoind.getChainWork(hash);
+      work.should.equal('0000000000000000000000000000000000000000000000000000000100010001');
+    });
+    it('will get the total work for block #300000 via hash', function() {
+      var hash = '000000000000000082ccf8f1557c5d40b21edabb18d2d691cfbf87118bac7254';
+      var work = bitcoind.getChainWork(hash);
+      work.should.equal('000000000000000000000000000000000000000000005a7b3c42ea8b844374e9');
+    });
+    it('will return undefined for unknown block', function() {
+      var hash = 'ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff';
+      var work = bitcoind.getChainWork(hash);
+      should.equal(work, undefined);
+    });
+
+  });
+
 });

lib/bitcoind.js

@@ -327,6 +327,10 @@ Bitcoin.prototype.isSpent = function(txid, outputIndex) {
   return bitcoindjs.isSpent(txid, outputIndex);
 };
 
+Bitcoin.prototype.getChainWork = function(blockHash) {
+  return bitcoindjs.getChainWork(blockHash);
+};
+
 Bitcoin.prototype.getTransaction = function(txid, queryMempool, callback) {
   return bitcoindjs.getTransaction(txid, queryMempool, callback);
 };

src/bitcoindjs.cc

@@ -925,6 +925,32 @@ NAN_METHOD(IsSpent) {
   NanReturnValue(NanNew<Boolean>(true));
 };
 
+/**
+ * GetChainWork()
+ * bitcoindjs.getChainWork()
+ * Get the total amount of work (expected number of hashes) in the chain up to
+ * and including this block.
+ */
+NAN_METHOD(GetChainWork) {
+  Isolate* isolate = Isolate::GetCurrent();
+  HandleScope scope(isolate);
+
+  String::Utf8Value hash_(args[0]->ToString());
+  std::string hashStr = std::string(*hash_);
+  uint256 hash = uint256S(hashStr);
+
+  CBlockIndex* blockIndex;
+
+  if (mapBlockIndex.count(hash) == 0) {
+    NanReturnValue(Undefined(isolate));
+  } else {
+    blockIndex = mapBlockIndex[hash];
+    arith_uint256 cw = blockIndex->nChainWork;
+    NanReturnValue(Local<Value>::New(isolate, NanNew<String>(cw.GetHex())));
+  }
+
+};
+
 /**
  * GetInfo()
  * bitcoindjs.getInfo()
@@ -993,6 +1019,7 @@ init(Handle<Object> target) {
   NODE_SET_METHOD(target, "getTransaction", GetTransaction);
   NODE_SET_METHOD(target, "getInfo", GetInfo);
   NODE_SET_METHOD(target, "isSpent", IsSpent);
+  NODE_SET_METHOD(target, "getChainWork", GetChainWork);
 
 }
 

src/bitcoindjs.h

@@ -28,3 +28,4 @@ NAN_METHOD(GetBlock);
 NAN_METHOD(GetTransaction);
 NAN_METHOD(GetInfo);
 NAN_METHOD(IsSpent);
+NAN_METHOD(GetChainWork);