Add model logic & api endpoint for reverting page versions

app/controllers/api/v1/Page.controller.js

@@ -12,6 +12,38 @@ class Page extends Controller {
         return [...super.services, 'models']
     }
 
+    async revert_version(req, res, next) {
+        const PageId = req.params.PageId
+        const user = req.user
+
+        let page = await PageModel.findOne({UUID: PageId})
+        if ( !page ) return res.status(404).message('Page not found with that ID.').api({})
+
+        if ( !(await page.is_accessible_by(user)) ) return req.security.deny()
+        const level = await page.access_level_for(req.user)
+
+        if ( !req.body.version_num ) {
+            return res.status(400)
+                .message('Missing required field: version_num')
+                .api()
+        }
+
+        if ( !page.has_version(req.body.version_num) ) {
+            return res.status(400)
+                .message('Invalid version_num')
+                .api()
+        }
+
+        const reverted_page = await page.revert_to_version(req.body.version_num, req.user.id)
+        await reverted_page.save()
+
+        const data = reverted_page.toJSON()
+        delete data.version_archive
+        data.level = level
+        data._id = reverted_page.id
+        return res.api(data)
+    }
+
     async get_page_versions(req, res, next) {
         const User = this.models.get('auth:User')
         const PageId = req.params.PageId