file-attachments: Allow multiple downloads of same file name.

Previous flow used to overwrite the file if it has the same name.
Current flow is same as what Chrome uses (though we use timestamp
in the file name rather than increaments).

Fixes: #558.

app/main/index.js

@@ -1,5 +1,7 @@
 'use strict';
 const path = require('path');
+const fs = require('fs');
+
 const electron = require('electron');
 const windowStateKeeper = require('electron-window-state');
 const isDev = require('electron-is-dev');
@@ -272,7 +274,26 @@ app.on('ready', () => {
 		page.downloadURL(url);
 		page.session.once('will-download', (event, item) => {
 			const filePath = path.join(downloadPath, item.getFilename());
-			item.setSavePath(filePath);
+
+			const getTimeStamp = () => {
+				const date = new Date();
+				return date.getTime();
+			};
+
+			const formatFile = filePath => {
+				const fileExtension = path.extname(filePath);
+				const baseName = path.basename(filePath, fileExtension);
+				return `${baseName}-${getTimeStamp()}${fileExtension}`;
+			};
+
+			// Update the name and path of the file if it already exists
+
+			const updatedFilePath = path.join(downloadPath, formatFile(filePath));
+
+			const setFilePath = fs.existsSync(filePath) ? updatedFilePath : filePath;
+
+			item.setSavePath(setFilePath);
+
 			item.on('updated', (event, state) => {
 				switch (state) {
 					case 'interrupted': {
@@ -285,7 +306,7 @@ app.on('ready', () => {
 						if (item.isPaused()) {
 							item.cancel();
 						}
-						// This event can also be used to show progres in percentage in future.
+						// This event can also be used to show progress in percentage in future.
 						break;
 					}
 					default: {
@@ -294,8 +315,9 @@ app.on('ready', () => {
 				}
 			});
 			item.once('done', (event, state) => {
+				const getFileName = fs.existsSync(filePath) ? formatFile(filePath) : item.getFilename();
 				if (state === 'completed') {
-					page.send('downloadFileCompleted', item.getSavePath(), item.getFilename());
+					page.send('downloadFileCompleted', item.getSavePath(), getFileName);
 				} else {
 					console.log('Download failed state: ', state);
 					page.send('downloadFileFailed');