From 4358ad5c2c989424ae5df154733bc3d941cf9e8b Mon Sep 17 00:00:00 2001
From: Andrea Maria Piana <andrea.maria.piana@gmail.com>
Date: Wed, 20 Mar 2019 10:16:40 +0100
Subject: [PATCH] Allow owner to remove nodes

---
 contracts/Nodes.sol | 29 ++++++++++++++++++++++++++---
 package.json        |  4 +++-
 test/TestNodes.js   | 30 ++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/contracts/Nodes.sol b/contracts/Nodes.sol
index 8c2cd48..f10e62f 100644
--- a/contracts/Nodes.sol
+++ b/contracts/Nodes.sol
@@ -4,7 +4,7 @@ contract Nodes
 {
   address owner;
   string[] public nodes;
-  uint public nodeCount;
+  mapping(string => uint) nodeIndex;
 
   modifier onlyOwner() {
     require(msg.sender == owner);
@@ -17,12 +17,29 @@ contract Nodes
     owner = msg.sender;
   }
 
+  function nodeCount()
+  view
+  public
+  returns
+  (uint)
+  {
+    return nodes.length;
+  }
+
   function addNode(string memory _node)
   public
   onlyOwner
   {
+    nodeIndex[_node] = nodes.length;
     nodes.push(_node);
-    nodeCount++;
+  }
+
+  function deleteNode(string memory _node)
+  public
+  onlyOwner
+  {
+    uint index = nodeIndex[_node];
+    _deleteNode(index);
   }
 
   function deleteAll()
@@ -30,7 +47,13 @@ contract Nodes
   onlyOwner
   {
     delete nodes;
-    nodeCount = 0;
+  }
+
+  function _deleteNode(uint index) internal {
+    require(index < nodes.length);
+    nodes[index] = nodes[nodes.length-1];
+    delete nodes[nodes.length-1];
+    nodes.length--;
   }
 
   function () external payable {
diff --git a/package.json b/package.json
index 29d559b..88bc6c6 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,9 @@
   "scripts": {
     "test": "truffle test",
     "lint": "eslint . --ext .js",
-    "lint-watch": "nodemon --exec 'npm run lint'",
+    "lint-watch": "nodemon --exec 'npm run lint' -e js,sol",
+    "test-watch": "nodemon --exec 'npm test' -e js,sol",
+    "watch": "nodemon --exec 'npm test && npm run lint' -e js,sol",
     "validate": "npm test && npm run lint"
   },
   "author": "",
diff --git a/test/TestNodes.js b/test/TestNodes.js
index 934d570..45cf129 100644
--- a/test/TestNodes.js
+++ b/test/TestNodes.js
@@ -45,6 +45,36 @@ contract('Nodes', async (accounts) => {
     });
   });
 
+  describe('deleteNode', async () => {
+    describe('called by the owner', async () => {
+      beforeEach(async () => {
+        await instance.addNode(node1);
+        await instance.addNode(node2);
+        await instance.deleteNode(node1);
+      });
+
+      it('removes the first node', async () => {
+        const actualNode2 = await instance.nodes(0);
+        assert.equal(actualNode2, node2);
+      });
+
+      it('sets the count', async () => {
+        const actualNodeCount = await instance.nodeCount();
+        assert.equal(1, actualNodeCount);
+      });
+    });
+    describe('called by someone else', async () => {
+      it('throws an exception', async () => {
+        try {
+          await instance.deleteNode(node1, { from: accounts[1] });
+        } catch (error) {
+          return;
+        }
+        assert.fail('it should throw an exception');
+      });
+    });
+  });
+
   describe('deleteAll', async () => {
     beforeEach(async () => {
       await instance.addNode(node1);