Add modal dialog for leave group action

app/assets/javascripts/groups/components/app.vue

 <script>
 /* global Flash */
 
+import { s__ } from '~/locale';
+import loadingIcon from '~/vue_shared/components/loading_icon.vue';
+import modal from '~/vue_shared/components/modal.vue';
+import { getParameterByName } from '~/lib/utils/common_utils';
+import { mergeUrlParams } from '~/lib/utils/url_utility';
+
 import eventHub from '../event_hub';
-import { getParameterByName } from '../../lib/utils/common_utils';
-import loadingIcon from '../../vue_shared/components/loading_icon.vue';
 import { COMMON_STR } from '../constants';
-import { mergeUrlParams } from '../../lib/utils/url_utility';
 import groupsComponent from './groups.vue';
 
 export default {
   components: {
     loadingIcon,
+    modal,
     groupsComponent,
   },
   props: {
@@ -32,6 +36,10 @@ export default {
       isLoading: true,
       isSearchEmpty: false,
       searchEmptyMessage: '',
+      showModal: false,
+      groupLeaveConfirmationMessage: '',
+      targetGroup: null,
+      targetParentGroup: null,
     };
   },
   computed: {
@@ -48,7 +56,7 @@ export default {
 
     eventHub.$on('fetchPage', this.fetchPage);
     eventHub.$on('toggleChildren', this.toggleChildren);
-    eventHub.$on('leaveGroup', this.leaveGroup);
+    eventHub.$on('showLeaveGroupModal', this.showLeaveGroupModal);
     eventHub.$on('updatePagination', this.updatePagination);
     eventHub.$on('updateGroups', this.updateGroups);
   },
@@ -58,7 +66,7 @@ export default {
   beforeDestroy() {
     eventHub.$off('fetchPage', this.fetchPage);
     eventHub.$off('toggleChildren', this.toggleChildren);
-    eventHub.$off('leaveGroup', this.leaveGroup);
+    eventHub.$off('showLeaveGroupModal', this.showLeaveGroupModal);
     eventHub.$off('updatePagination', this.updatePagination);
     eventHub.$off('updateGroups', this.updateGroups);
   },
@@ -141,14 +149,23 @@ export default {
         parentGroup.isOpen = false;
       }
     },
-    leaveGroup(group, parentGroup) {
-      const targetGroup = group;
-      targetGroup.isBeingRemoved = true;
-      this.service.leaveGroup(targetGroup.leavePath)
+    showLeaveGroupModal(group, parentGroup) {
+      this.targetGroup = group;
+      this.targetParentGroup = parentGroup;
+      this.showModal = true;
+      this.groupLeaveConfirmationMessage = s__(`GroupsTree|Are you sure you want to leave the "${group.fullName}" group?`);
+    },
+    hideLeaveGroupModal() {
+      this.showModal = false;
+    },
+    leaveGroup() {
+      this.showModal = false;
+      this.targetGroup.isBeingRemoved = true;
+      this.service.leaveGroup(this.targetGroup.leavePath)
         .then(res => res.json())
         .then((res) => {
           $.scrollTo(0);
-          this.store.removeGroup(targetGroup, parentGroup);
+          this.store.removeGroup(this.targetGroup, this.targetParentGroup);
           Flash(res.notice, 'notice');
         })
         .catch((err) => {
@@ -157,7 +174,7 @@ export default {
             message = COMMON_STR.LEAVE_FORBIDDEN;
           }
           Flash(message);
-          targetGroup.isBeingRemoved = false;
+          this.targetGroup.isBeingRemoved = false;
         });
     },
     updatePagination(headers) {
@@ -190,5 +207,14 @@ export default {
       :search-empty-message="searchEmptyMessage"
       :page-info="pageInfo"
     />
+    <modal
+      v-show="showModal"
+      :primary-button-label="__('Leave')"
+      kind="warning"
+      :title="__('Are you sure?')"
+      :text="groupLeaveConfirmationMessage"
+      @cancel="hideLeaveGroupModal"
+      @submit="leaveGroup"
+    />
   </div>
 </template>