(core) allow a doc owner to test access as a different user

Summary:
This adds back-end support for query parameters `aclAsUser_` and
`aclAsUserId_` which, when either is present, direct Grist to
process granular access control rules from the point of view
of that user (specified by email or id respectively).

Some front end support is added, in the form of a tag that
shows up when in this mode, and a way to cancel the mode.
No friendly way to initiate the mode is offered yet.

Test Plan: added test

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2704

app/client/models/DocPageModel.ts

@@ -16,7 +16,7 @@ import {menu, menuDivider, menuIcon, menuItem, menuText} from 'app/client/ui2018
 import {confirmModal} from 'app/client/ui2018/modals';
 import {AsyncFlow, CancelledError, FlowRunner} from 'app/common/AsyncFlow';
 import {delay} from 'app/common/delay';
-import {OpenDocMode} from 'app/common/DocListAPI';
+import {OpenDocMode, UserOverride} from 'app/common/DocListAPI';
 import {IGristUrlState, parseUrlId, UrlIdParts} from 'app/common/gristUrls';
 import {getReconnectTimeout} from 'app/common/gutil';
 import {canEdit} from 'app/common/roles';
@@ -32,6 +32,7 @@ export interface DocInfo extends Document {
   isPreFork: boolean;
   isFork: boolean;
   isRecoveryMode: boolean;
+  userOverride: UserOverride|null;
   isBareFork: boolean;  // a document created without logging in, which is treated as a
                         // fork without an original.
   idParts: UrlIdParts;
@@ -56,6 +57,7 @@ export interface DocPageModel {
   isPrefork: Observable<boolean>;
   isFork: Observable<boolean>;
   isRecoveryMode: Observable<boolean>;
+  userOverride: Observable<UserOverride|null>;
   isBareFork: Observable<boolean>;
   isSample: Observable<boolean>;
 
@@ -93,6 +95,7 @@ export class DocPageModelImpl extends Disposable implements DocPageModel {
   public readonly isPrefork = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.isPreFork : false);
   public readonly isFork = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.isFork : false);
   public readonly isRecoveryMode = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.isRecoveryMode : false);
+  public readonly userOverride = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.userOverride : null);
   public readonly isBareFork = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.isBareFork : false);
   public readonly isSample = Computed.create(this, this.currentDoc, (use, doc) => doc ? doc.isSample : false);
 
@@ -245,8 +248,9 @@ export class DocPageModelImpl extends Disposable implements DocPageModel {
     flow.onDispose(() => comm.releaseDocConnection(doc.id));
 
     const openDocResponse = await comm.openDoc(doc.id, doc.openMode, linkParameters);
-    if (openDocResponse.recoveryMode) {
-      doc.isRecoveryMode = true;
+    if (openDocResponse.recoveryMode || openDocResponse.userOverride) {
+      doc.isRecoveryMode = Boolean(openDocResponse.recoveryMode);
+      doc.userOverride = openDocResponse.userOverride || null;
       this.currentDoc.set({...doc});
     }
     const gdModule = await gristDocModulePromise;
@@ -329,6 +333,7 @@ function buildDocInfo(doc: Document, mode: OpenDocMode): DocInfo {
     ...doc,
     isFork,
     isRecoveryMode: false,  // we don't know yet, will learn when doc is opened.
+    userOverride: null,     // ditto.
     isSample,
     isPreFork,
     isBareFork,

app/client/ui/TopBar.ts

@@ -44,10 +44,12 @@ export function createTopBarDoc(owner: MultiHolder, appModel: AppModel, pageMode
           docNameSave: renameDoc,
           pageNameSave: getRenamePageFn(gristDoc),
           cancelRecoveryMode: getCancelRecoveryModeFn(gristDoc),
+          cancelUserOverride: getCancelUserOverrideFn(gristDoc),
           isPageNameReadOnly: (use) => use(gristDoc.isReadonly) || typeof use(gristDoc.activeViewId) !== 'number',
           isDocNameReadOnly: (use) => use(gristDoc.isReadonly) || use(pageModel.isFork),
           isFork: pageModel.isFork,
           isRecoveryMode: pageModel.isRecoveryMode,
+          userOverride: pageModel.userOverride,
           isFiddle: Computed.create(owner, (use) => use(pageModel.isPrefork) && !use(pageModel.isSample)),
           isSnapshot: Computed.create(owner, doc, (use, _doc) => Boolean(_doc && _doc.idParts.snapshotId)),
           isPublic: Computed.create(owner, doc, (use, _doc) => Boolean(_doc && _doc.public)),
@@ -100,6 +102,15 @@ function getCancelRecoveryModeFn(gristDoc: GristDoc): () => Promise<void> {
   };
 }
 
+function getCancelUserOverrideFn(gristDoc: GristDoc): () => Promise<void> {
+  return async () => {
+    const url = new URL(window.location.href);
+    url.searchParams.delete('aclAsUser_');
+    url.searchParams.delete('aclAsUserId_');
+    window.location.assign(url.href);
+  };
+}
+
 function topBarUndoBtn(iconName: IconName, ...domArgs: DomElementArg[]): Element {
   return cssHoverCircle(
     cssTopBarUndoBtn(iconName),

app/client/ui2018/breadcrumbs.ts

@@ -9,6 +9,7 @@ import { urlState } from 'app/client/models/gristUrlState';
 import { colors, testId } from 'app/client/ui2018/cssVars';
 import { editableLabel } from 'app/client/ui2018/editableLabel';
 import { icon } from 'app/client/ui2018/icons';
+import { UserOverride } from 'app/common/DocListAPI';
 import { BindableValue, dom, Observable, styled } from 'grainjs';
 import { tooltip } from 'popweasel';
 
@@ -85,11 +86,13 @@ export function docBreadcrumbs(
     docNameSave: (val: string) => Promise<void>,
     pageNameSave: (val: string) => Promise<void>,
     cancelRecoveryMode: () => Promise<void>,
+    cancelUserOverride: () => Promise<void>,
     isDocNameReadOnly?: BindableValue<boolean>,
     isPageNameReadOnly?: BindableValue<boolean>,
     isFork: Observable<boolean>,
     isFiddle: Observable<boolean>,
     isRecoveryMode: Observable<boolean>,
+    userOverride: Observable<UserOverride|null>,
     isSnapshot?: Observable<boolean>,
     isPublic?: Observable<boolean>,
   }
@@ -118,11 +121,17 @@ export function docBreadcrumbs(
         }
         if (use(options.isRecoveryMode)) {
           return cssAlertTag('recovery mode',
-                             dom('a', dom.on('click', async () => {
-                               await options.cancelRecoveryMode()
-                             }), icon('CrossSmall')),
+                             dom('a', dom.on('click', () => options.cancelRecoveryMode()),
+                                 icon('CrossSmall')),
                              testId('recovery-mode-tag'));
         }
+        const userOverride = use(options.userOverride);
+        if (userOverride) {
+          return cssAlertTag(userOverride.user?.email || 'override',
+                             dom('a', dom.on('click', () => options.cancelUserOverride()),
+                                 icon('CrossSmall')),
+                             testId('user-override-tag'));
+        }
         if (use(options.isFiddle)) {
           return cssTag('fiddle', tooltip({title: fiddleExplanation}), testId('fiddle-tag'));
         }