add clear cache button for session

src/domain/SessionPickerViewModel.js

@@ -7,6 +7,7 @@ class SessionItemViewModel extends EventEmitter {
         this._pickerVM = pickerVM;
         this._sessionInfo = sessionInfo;
         this._isDeleting = false;
+        this._isClearing = false;
         this._error = null;
     }
 
@@ -29,10 +30,29 @@ class SessionItemViewModel extends EventEmitter {
         }
     }
 
+    async clear() {
+        this._isClearing = true;
+        this.emit("change", "isClearing");
+        try {
+            await this._pickerVM.clear(this.id);
+        } catch(err) {
+            this._error = err;
+            console.error(err);
+            this.emit("change", "error");
+        } finally {
+            this._isClearing = false;
+            this.emit("change", "isClearing");
+        }
+    }
+
     get isDeleting() {
         return this._isDeleting;
     }
 
+    get isClearing() {
+        return this._isClearing;
+    }
+
     get id() {
         return this._sessionInfo.id;
     }
@@ -73,6 +93,10 @@ export default class SessionPickerViewModel {
         this._sessions.remove(idx);
     }
 
+    async clear(id) {
+        await this._storageFactory.delete(id);
+    }
+
     get sessions() {
         return this._sessions;
     }

src/ui/web/login/SessionPickerView.js

@@ -5,22 +5,35 @@ class SessionPickerItem extends TemplateView {
     constructor(vm) {
         super(vm, true);
         this._onDeleteClick = this._onDeleteClick.bind(this);
+        this._onClearClick = this._onClearClick.bind(this);
     }
 
     _onDeleteClick(event) {
         event.stopPropagation();
         event.preventDefault();
+        if (confirm("Are you sure?")) {
             this.viewModel.delete();
         }
+    }
+
+    _onClearClick(event) {
+        event.stopPropagation();
+        event.preventDefault();
+        this.viewModel.clear();
+    }
 
     render(t) {
         const deleteButton = t.button({
             disabled: vm => vm.isDeleting,
-            onClick: event => this._onDeleteClick(event)
+            onClick: this._onDeleteClick,
         }, "Delete");
+        const clearButton = t.button({
+            disabled: vm => vm.isClearing,
+            onClick: this._onClearClick,
+        }, "Clear");
         const userName = t.span({className: "userId"}, vm => vm.userId);
         const errorMessage = t.if(vm => vm.error, t => t.span({className: "error"}, vm => vm.error));
-        return t.li([userName, errorMessage, deleteButton]);
+        return t.li([userName, errorMessage, clearButton, deleteButton]);
     }
 }