Solution

src/app.js

@@ -1 +1,57 @@
-// write code here
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+function writeError(message) {
+  process.stderr.write(`${message}\n`);
+}
+
+function main() {
+  const [source, destination] = process.argv.slice(2);
+
+  if (!source || !destination) {
+    writeError('Source and destination are required');
+
+    return;
+  }
+
+  if (!fs.existsSync(source)) {
+    writeError('Source file does not exist');
+
+    return;
+  }
+
+  if (source === destination) {
+    return;
+  }
+
+  let finalDestination = destination;
+
+  if (destination.endsWith('/') || destination.endsWith('\\')) {
+    if (!fs.existsSync(destination)) {
+      writeError('Destination directory does not exist');
+
+      return;
+    }
+
+    finalDestination = path.join(destination, path.basename(source));
+  } else if (
+    fs.existsSync(destination) &&
+    fs.statSync(destination).isDirectory()
+  ) {
+    finalDestination = path.join(destination, path.basename(source));
+  } else {
+    const destinationDir = path.dirname(destination);
+
+    if (destinationDir !== '.' && !fs.existsSync(destinationDir)) {
+      writeError('Destination directory does not exist');
+
+      return;
+    }
+  }
+
+  fs.renameSync(source, finalDestination);
+}
+
+main();