From 1b77fdf5e4a1deab4e547341e39069871b1eef00 Mon Sep 17 00:00:00 2001
From: Chris Kleeschulte <chrisk@bitpay.com>
Date: Mon, 26 Jun 2017 15:28:22 -0400
Subject: [PATCH] wip

---
 lib/services/block/index.js       | 56 +++++++++++++------------------
 test/services/block/index.unit.js | 35 ++++++++++++++++++-
 2 files changed, 58 insertions(+), 33 deletions(-)

diff --git a/lib/services/block/index.js b/lib/services/block/index.js
index 2a90600a..0c5ab433 100644
--- a/lib/services/block/index.js
+++ b/lib/services/block/index.js
@@ -265,67 +265,59 @@ BlockService.prototype._blockAlreadyProcessed = function(block) {
 
 BlockService.prototype._mergeBlockIntoChainTips = function(block) {
 
-  function getPrevHashChain(keys, hash) {
-
-    for(var i = 0; i <  keys.length; i++) {
-console.log('here');
-
-      var key = keys[i];
-
-      var searchChain = this._chainTips.get(key);
-      console.log(searchChain);
-
-      var chainIndex = searchChain.indexOf(hash);
-
-      if (chainIndex > -1) {
-        return searchChain.slice(chainIndex);
-      }
-    }
-
-  }
-
-
   var prevHash = utils.reverseBufferToString(block.header.prevHash);
   var hasChildren = false;
 
   var chain = this._chainTips.get(prevHash);
+
+  this._chainTips.del(prevHash);
+
   if (chain) {
     chain.unshift(prevHash);
   }
 
   var keys = this._chainTips.keys();
-
-  // looking for chains where this block is an ancestor of the tip of the chain
   for(var i = 0; i < keys.length; i++) {
-
     var key = keys[i];
     var searchChain = this._chainTips.get(key);
 
+    assert(searchChain.length > 0, 'chain tips collection appears to be invalid');
+
     var chainIndex = searchChain.indexOf(block.hash);
 
     if (chainIndex > -1) {
       hasChildren = true;
-      var newChain = searchChain.concat(chain || getPrevHashChain(keys, prevHash));
-      this._chainTips.set(key, newChain);
+      this._chainTips.set(key, searchChain.concat(chain || [prevHash]));
     }
-
   }
 
   if (chain && !hasChildren) {
-
     this._chainTips.set(block.hash, chain);
-
   }
 
-  this._chainTips.del(prevHash);
+  if (!chain && !hasChildren) {
 
-  // if we have don't have any parents or children in chainTips, then create a new chain with this block
-  if (!hasChildren && !chain) {
-    this._chainTips.set(block.hash, getPrevHashChain(keys, prevHash));
+    var longestChain = [];
+    for(var j = 0; j < keys.length; j++) {
+      var key = keys[j];
+      var searchChain = this._chainTips.get(key);
+      var chainIndex = searchChain.indexOf(prevHash);
+      if (chainIndex > -1) {
+        var chain = searchChain.slice(chainIndex);
+        if (chain.length > longestChain.length) {
+          longestChain = chain;
+        }
+      }
+    }
+    longestChain = longestChain.length <= 1 ? [prevHash] : longestChain;
+    this._chainTips.set(block.hash, longestChain);
   }
+console.log(block.hash);
+console.log(this._chainTips);
 
 };
 
+BlockService.prototype._onBlock = function(block) {
 BlockService.prototype._onBlock = function(block) {
 
   // 1. have we already seen this block?
diff --git a/test/services/block/index.unit.js b/test/services/block/index.unit.js
index 5b140f4a..7651a8d6 100644
--- a/test/services/block/index.unit.js
+++ b/test/services/block/index.unit.js
@@ -49,7 +49,7 @@ describe('Block Service', function() {
       expect(blockService._chainTips.get('ee')).to.deep.equal(['dd', 'cc', 'bb', 'aa', '00']);
     });
 
-    it('should merge chain tips where there is a fork (a parent block has more than one child)' , function() {
+    it('should merge blocks where there is a fork (a parent block has more than one child)' , function() {
 
       var blocks = ['aa','bb','cc','dd','ee'];
       var prevBlocks = ['00','aa','aa','cc','dd'];
@@ -62,8 +62,41 @@ describe('Block Service', function() {
 
       expect(blockService._chainTips.length).to.equal(2);
       expect(blockService._chainTips.get('ee')).to.deep.equal(['dd', 'cc', 'aa', '00']);
+      expect(blockService._chainTips.get('bb')).to.deep.equal(['aa', '00']);
     });
 
+    it('should merge blocks where there is a fork (a parent block has more than one child) and blocks are received out of order' , function() {
+
+      var blocks = ['cc','aa','bb','ee','dd'];
+      var prevBlocks = ['aa','00','aa','dd','cc'];
+
+      blocks.forEach(function(n, index) {
+        var block = { header: { prevHash: new Buffer(prevBlocks[index], 'hex') }, hash: n };
+        blockService._mergeBlockIntoChainTips(block);
+      });
+
+
+      expect(blockService._chainTips.length).to.equal(2);
+      expect(blockService._chainTips.get('ee')).to.deep.equal(['dd', 'cc', 'aa', '00']);
+      expect(blockService._chainTips.get('bb')).to.deep.equal(['aa', '00']);
+    });
+
+    it('should merge blocks where there is a three-way fork (a parent block has more than one child) and blocks are received out of order' , function() {
+
+      var blocks = ['cc','aa','bb','ee','dd'];
+      var prevBlocks = ['aa','00','aa','dd','aa'];
+
+      blocks.forEach(function(n, index) {
+        var block = { header: { prevHash: new Buffer(prevBlocks[index], 'hex') }, hash: n };
+        blockService._mergeBlockIntoChainTips(block);
+      });
+
+
+      expect(blockService._chainTips.length).to.equal(3);
+      expect(blockService._chainTips.get('ee')).to.deep.equal(['dd', 'aa', '00']);
+      expect(blockService._chainTips.get('bb')).to.deep.equal(['aa', '00']);
+      expect(blockService._chainTips.get('cc')).to.deep.equal(['aa', '00']);
+    });
 
   });