feat(exam-correct): setup basic session storage manager, add util stub

frontend/src/lib/storage-manager/storage-manager.js

@@ -4,10 +4,11 @@ import * as semver from 'semver';
 
 export const LOCATION = {
   LOCAL: 'local',
+  SESSION: 'session',
   WINDOW: 'window',
 };
 
-const LOCATION_SHADOWING = [ LOCATION.WINDOW, LOCATION.LOCAL ];
+const LOCATION_SHADOWING = [ LOCATION.WINDOW, LOCATION.SESSION, LOCATION.LOCAL ];
 
 export class StorageManager {
 
@@ -80,6 +81,10 @@ export class StorageManager {
           val = this._getFromLocalStorage()[key];
           break;
         }
+        case LOCATION.SESSION: {
+          val = this._getFromSessionStorage()[key];
+          break;
+        }
         case LOCATION.WINDOW: {
           val = this._getFromWindow()[key];
           break;
@@ -220,4 +225,47 @@ export class StorageManager {
       delete this._global.App.Storage[this.namespace];
     }
   }
+
+
+  _getFromSessionStorage() {
+    let state;
+
+    try {
+      state = JSON.parse(window.sessionStorage.getItem(this.namespace));
+    } catch {
+      state = null;
+    }
+
+    if (state === null || !state.version || !semver.satisfies(this.version, `^${state.version}`)) {
+      // remove item from session if it stores an invalid state
+      this._clearSessionStorage();
+      return {};
+    }
+
+    if ('state' in state)
+      return state.state;
+    else {
+      delete state.version;
+      return state;
+    }
+  }
+
+  _saveToSessionStorage(state) {
+    if (!state)
+      return this._clearSessionStorage();
+
+    let versionedState;
+    
+    if ('version' in state || 'state' in state) {
+      versionedState = { version: this.version, state: state };
+    } else {
+      versionedState = { version: this.version, ...state };
+    }
+    
+    window.sessionStorage.setItem(this.namespace, JSON.stringify(versionedState));
+  }
+
+  _clearSessionStorage() {
+    window.sessionStorage.removeItem(this.namespace);
+  }
 }

frontend/src/utils/exam-correct/exam-correct.js

@@ -0,0 +1,33 @@
+import { Utility } from '../../core/utility';
+import { StorageManager, LOCATION } from '../../lib/storage-manager/storage-manager';
+// import './exam-correct.sass';
+
+const EXAM_CORRECT_IDENT = 'uw-exam-correct';
+
+@Utility({
+  selector: `[${EXAM_CORRECT_IDENT}]`,
+})
+export class ExamCorrect {
+
+  _storageManager = new StorageManager('EXAM_CORRECT', '0.0.0', { location: LOCATION.SESSION, encrypted: true });
+
+  _element;
+
+  constructor(element) {
+    if (!element) {
+      throw new Error('Exam Correct utility cannot be setup without an element!');
+    }
+
+    this._element = element;
+
+    if (this._element.tagName !== 'TABLE') {
+      throw new Error('Exam Correct utility can only be setup with a <table> element!');
+    }
+
+  }
+
+  destroy() {
+    console.log('TBD: destroy ExamCorrect');
+  }
+
+}

frontend/src/utils/utils.js

@@ -13,6 +13,7 @@ import { CourseTeaser } from './course-teaser/course-teaser';
 import { NavbarUtils } from './navbar/navbar';
 import { PageActionsUtils } from './pageactions/pageactions';
 import { HideColumns } from './hide-columns/hide-columns';
+import { ExamCorrect } from './exam-correct/exam-correct';
 
 export const Utils = [
   Alerts,
@@ -31,4 +32,5 @@ export const Utils = [
   ...NavbarUtils,
   ...PageActionsUtils,
   HideColumns,
+  ExamCorrect,
 ];

templates/exam-correct.hamlet

@@ -2,7 +2,7 @@ $newline never
 
 <section>
   <div uw-hide-columns="exam-correct">
-    <table uw-exam-correct .table .table--striped>
+    <table .table .table--striped uw-exam-correct=#{intercalate "-" [toPathPiece tid, toPathPiece ssh, toPathPiece csh, toPathPiece examn]}>
       <thead>
         <tr .table__row .table__row--head>
           <th .table__th .sortable .sorted-desc uw-hide-column-header="date">