1 files changed, 30 insertions, 0 deletions
diff --git a/app/assets/javascripts/ide/lib/diff/diff.js b/app/assets/javascripts/ide/lib/diff/diff.js
new file mode 100644
index 00000000000..0e37f5c4704
--- /dev/null
+++ b/app/assets/javascripts/ide/lib/diff/diff.js
@@ -0,0 +1,30 @@
+import { diffLines } from 'diff';
+
+// eslint-disable-next-line import/prefer-default-export
+export const computeDiff = (originalContent, newContent) => {
+  const changes = diffLines(originalContent, newContent);
+
+  let lineNumber = 1;
+  return changes.reduce((acc, change) => {
+    const findOnLine = acc.find(c => c.lineNumber === lineNumber);
+
+    if (findOnLine) {
+      Object.assign(findOnLine, change, {
+        modified: true,
+        endLineNumber: (lineNumber + change.count) - 1,
+      });
+    } else if ('added' in change || 'removed' in change) {
+      acc.push(Object.assign({}, change, {
+        lineNumber,
+        modified: undefined,
+        endLineNumber: (lineNumber + change.count) - 1,
+      }));
+    }
+
+    if (!change.removed) {
+      lineNumber += change.count;
+    }
+
+    return acc;
+  }, []);
+};