Fetch cshtml from app to render correct app-frontend version in preview

backend/src/Designer/Controllers/PreviewController.cs

@@ -71,6 +71,24 @@ public IActionResult Index(string org, string app)
         {
             return View();
         }
+
+        /// <summary>
+        /// Endpoint to fetch the cshtml to render app-frontend specific to what is defined in the app-repo
+        /// </summary>
+        /// <param name="org">Unique identifier of the organisation responsible for the app.</param>
+        /// <param name="app">Application identifier which is unique within an organisation.</param>
+        /// <returns>The cshtml modified to ignore this route path added in the iframe.</returns>
+        [HttpGet]
+        [Route("/app-specific-preview/{org}/{app:regex(^(?!datamodels$)[[a-z]][[a-z0-9-]]{{1,28}}[[a-z0-9]]$)}")]
+        public async Task<IActionResult> AppFrontendSpecificPreview(string org, string app)
+        {
+            string developer = AuthenticationHelper.GetDeveloperUserName(_httpContextAccessor.HttpContext);
+            AltinnAppGitRepository altinnAppGitRepository = _altinnGitRepositoryFactory.GetAltinnAppGitRepository(org, app, developer);
+            var appFrontendCshtml = await altinnAppGitRepository.GetAppFrontendCshtml();
+            var modifiedContent = ReplaceIndexToFetchCorrectOrgAppInCshtml(appFrontendCshtml);
+
+            return Content(modifiedContent, "text/html");
+        }
 
         /// <summary>
         /// Action for getting local app-images
@@ -877,5 +895,15 @@ private string GetSelectedLayoutSetInEditorFromRefererHeader(string refererHeade
 
             return string.IsNullOrEmpty(layoutSetName) ? null : layoutSetName;
         }
+
+        private string ReplaceIndexToFetchCorrectOrgAppInCshtml(string originalContent)
+        {
+            // Replace the array indexes in the script in the cshtml that retrieves the org and app name since
+            // /app-specific-preview/ is added when fetching the cshtml file from endpoint instead of designer wwwroot
+            string modifiedContent = originalContent.Replace("window.org = appId[1];", "window.org = appId[2];");
+            modifiedContent = modifiedContent.Replace("window.app = appId[2];", "window.app = appId[3];");
+
+            return modifiedContent;
+        }
     }
 }

backend/src/Designer/Infrastructure/GitRepository/AltinnAppGitRepository.cs

@@ -38,6 +38,7 @@ public class AltinnAppGitRepository : AltinnGitRepository
         private const string LANGUAGE_RESOURCE_FOLDER_NAME = "texts/";
         private const string MARKDOWN_TEXTS_FOLDER_NAME = "md/";
         private const string PROCESS_DEFINITION_FOLDER_PATH = "App/config/process/";
+        private const string CSHTML_PATH = "App/views/Home/index.cshtml";
 
         private const string SERVICE_CONFIG_FILENAME = "config.json";
         private const string LAYOUT_SETTINGS_FILENAME = "Settings.json";
@@ -700,6 +701,23 @@ public async Task<LayoutSets> CreateLayoutSetFile(string layoutSetName)
             await WriteTextByRelativePathAsync(pathToLayOutSets, layoutSetsString);
             return layoutSets;
         }
+
+        /// <summary>
+        /// Gets the cshtml file for the app
+        /// </summary>
+        /// <param name="cancellationToken">A <see cref="CancellationToken"/> that observes if operation is cancelled.</param>
+        /// <returns>The content of Index.cshtml</returns>
+        public async Task<string> GetAppFrontendCshtml(CancellationToken cancellationToken = default)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            if (FileExistsByRelativePath(CSHTML_PATH))
+            {
+                string cshtml = await ReadTextByRelativePathAsync(CSHTML_PATH, cancellationToken);
+                return cshtml;
+            }
+
+            throw new FileNotFoundException("Index.cshtml was not found.");
+        }
 
         /// <summary>
         /// Gets the options list with the provided id.
@@ -854,8 +872,6 @@ private static string GetPathToRuleConfiguration(string layoutSetName)
                 Path.Combine(LAYOUTS_FOLDER_NAME, layoutSetName, RULE_CONFIGURATION_FILENAME);
         }
 
-
-
         /// <summary>
         /// String writer that ensures UTF8 is used.
         /// </summary>

frontend/packages/shared/src/api/paths.js

@@ -65,7 +65,7 @@ export const orgsListPath = () => `${basePath}/orgs`; // Get
 
 // Preview
 export const instanceIdForPreviewPath = (org, app) => `${basePath}/${org}/${app}/mock-instance-id`; // Get
-export const previewPage = (org, app, selectedLayoutSet) => `/designer/html/preview.html?${s({ org, app, selectedLayoutSet })}`;
+export const previewPage = (org, app, selectedLayoutSet) => `/app-specific-preview/${org}/${app}?${s({ selectedLayoutSet })}`;
 
 // Preview - SignalR Hub
 export const previewSignalRHubSubPath = () => `/previewHub`;