Added getBackupFilePath to settings-path-manager module

refs https://linear.app/tryghost/issue/CORE-35/refactor-route-and-redirect-settings

- getBackupFilePath is yet another utility function tha's used often with Ghost config files like so:
- ca149f2c0e/core/server/services/redirects/settings.js (L147-L151)
- ca149f2c0e/core/server/services/route-settings/route-settings.js (L42-L45)

ghost/settings-path-manager/lib/settings-path-manager.js

@@ -1,5 +1,6 @@
 const path = require('path');
 const tpl = require('@tryghost/tpl');
+const format = require('date-fns/format');
 const {IncorrectUsageError} = require('@tryghost/errors');
 
 const messages = {
@@ -35,6 +36,12 @@ class SettingsPathManager {
         const settingsFolder = this.defaultPath;
         return path.join(settingsFolder, `${this.filename}.${this.defaultExtension}`);
     }
+
+    getBackupFilePath() {
+        const settingsFolder = this.defaultPath;
+        const dateStamp = format(new Date(), 'yyyy-MM-dd-HH-mm-ss');
+        return path.join(settingsFolder, `${this.filename}-${dateStamp}.${this.defaultExtension}`);
+    }
 }
 
 module.exports = SettingsPathManager;

ghost/settings-path-manager/package.json

@@ -25,6 +25,7 @@
     "sinon": "11.1.2"
   },
   "dependencies": {
+    "date-fns": "^2.24.0",
     "tpl": "^0.3.0"
   }
 }

ghost/settings-path-manager/test/settings-path-manager.test.js

@@ -54,4 +54,18 @@ describe('Settings Path Manager', function () {
             path.should.equal('/content/data/redirects.json');
         });
     });
+
+    describe('getBackupFilePath', function () {
+        it('returns a path to store a backup', function (){
+            const settingsPathManager = new SettingsPathManager({
+                paths: ['/content/data', '/content/settings'],
+                type: 'routes',
+                extensions: ['yaml']
+            });
+
+            const path = settingsPathManager.getBackupFilePath();
+
+            path.should.match(/\/content\/data\/routes-\d{4}-\d{2}-\d{2}-\d{2}-\d{2}-\d{2}.yaml/);
+        });
+    });
 });