Surgically insert new versions

Closes #9

package.json

@@ -3,6 +3,7 @@
   "dependencies": {
     "gh-got": "5.0.0",
     "got": "6.6.3",
+    "lodash": "4.17.4",
     "mkdirp": "0.5.1",
     "nodegit": "0.16.0",
     "rimraf": "2.5.4",

src/helpers/packageJson.js

+const _ = require('lodash');
+
+module.exports = {
+  setNewValue: function(currentFileContent, depType, depName, newVersion) {
+    const parsedContents = JSON.parse(currentFileContent);
+    // Save the old version
+    const oldVersion = parsedContents[depType][depName];
+    // Update the file = this is what we want
+    parsedContents[depType][depName] = newVersion;
+    // Look for the old version number
+    const versionHits = indexes(currentFileContent, `"${oldVersion}"`);
+    let newSource = null;
+    // Loop through all instances of string until one matches
+    versionHits.some(function(index) {
+      // Replace the string and parse the result
+      const testSource = replaceStringAtIndex(currentFileContent, oldVersion, newVersion, index+1);
+      if (_.isEqual(parsedContents, JSON.parse(testSource))) {
+        newSource = testSource;
+        return true;
+      }
+    });
+    return newSource;
+  }
+};
+
+function indexes(currentFileContent, find) {
+  var result = [];
+  for (i = 0; i < currentFileContent.length; ++i) {
+    if (currentFileContent.substring(i, i + find.length) == find) {
+      result.push(i);
+    }
+  }
+  return result;
+}
+
+function replaceStringAtIndex(currentFileContent, oldStr, newStr, index) {
+  return currentFileContent.substr(0, index) + newStr + currentFileContent.substr(index + oldStr.length);
+}

src/index.js

@@ -4,6 +4,7 @@ const stable = require('semver-stable');
 const config = require('./config');
 const github = require('./github');
 const npm = require('./npm');
+const packageJson = require('./helpers/packageJson');
 
 npm.init(config.verbose);
 
@@ -115,14 +116,14 @@ function updateDependency(depType, depName, currentVersion, nextVersion) {
     // Retrieve the package.json from this renovate branch
     return github.getFile(packageFile, branchName).then(res => {
       const currentSHA = res.body.sha;
-      let currentFileContent = JSON.parse(new Buffer(res.body.content, 'base64').toString());
-      if (currentFileContent[depType][depName] !== nextVersion) {
+      const currentFileContent = new Buffer(res.body.content, 'base64').toString();
+      const currentFileContentJson = JSON.parse(currentFileContent);
+      if (currentFileContentJson[depType][depName] !== nextVersion) {
         // Branch is new, or needs version updated
         if (config.verbose) {
           console.log(`${depName}: Updating to ${nextVersion} in branch ${branchName}`);
         }
-        currentFileContent[depType][depName] = nextVersion;
-        const newPackageContents = JSON.stringify(currentFileContent, null, 2) + '\n';
+        const newPackageContents = packageJson.setNewValue(currentFileContent, depType, depName, nextVersion);
         return github.writeFile(branchName, currentSHA, packageFile, newPackageContents, commitMessage);
       } else {
         if (config.verbose) {