Keep IDE RightPane views aliveide-keep-right-pane-tabs-alive

**Why?**
- This is needed for the Web Terminal feature.
  https://gitlab.com/gitlab-org/gitlab-ee/issues/5426

**Notes:**
- Introduces a `pane` Vuex module.
- Some views should not be kept alive (i.e. job details).
  This is why a `keepAlive` flag was introduced for views.

16 files changed, 130 insertions, 42 deletions

diff --git a/app/assets/javascripts/ide/components/ide_status_bar.vue b/app/assets/javascripts/ide/components/ide_status_bar.vue
index 715dc1bfb42..a04d09ef374 100644
--- a/app/assets/javascripts/ide/components/ide_status_bar.vue
+++ b/app/assets/javascripts/ide/components/ide_status_bar.vue
@@ -50,7 +50,9 @@ export default {
     this.stopPipelinePolling();
   },
   methods: {
-    ...mapActions(['setRightPane']),
+    ...mapActions('rightPane', {
+      openRightPane: 'open',
+    }),
     ...mapActions('pipelines', ['fetchLatestPipeline', 'stopPipelinePolling']),
     startTimer() {
       this.intervalId = setInterval(() => {
@@ -88,7 +90,7 @@ export default {
         <button
           type="button"
           class="p-0 border-0 h-50"
-          @click="setRightPane($options.rightSidebarViews.pipelines)"
+          @click="openRightPane($options.rightSidebarViews.pipelines)"
         >
           <ci-icon
             v-tooltip
diff --git a/app/assets/javascripts/ide/components/panes/right.vue b/app/assets/javascripts/ide/components/panes/right.vue
index 75a9a9e9b8f..bd07f372177 100644
--- a/app/assets/javascripts/ide/components/panes/right.vue
+++ b/app/assets/javascripts/ide/components/panes/right.vue
@@ -1,5 +1,6 @@
 <script>
 import { mapActions, mapState, mapGetters } from 'vuex';
+import _ from 'underscore';
 import { __ } from '~/locale';
 import tooltip from '../../../vue_shared/directives/tooltip';
 import Icon from '../../../vue_shared/components/icon.vue';
@@ -30,14 +31,10 @@ export default {
     },
   },
   computed: {
-    ...mapState(['rightPane', 'currentMergeRequestId', 'clientsidePreviewEnabled']),
+    ...mapState(['currentMergeRequestId', 'clientsidePreviewEnabled']),
+    ...mapState('rightPane', ['isOpen', 'currentView']),
     ...mapGetters(['packageJson']),
-    pipelinesActive() {
-      return (
-        this.rightPane === rightSidebarViews.pipelines ||
-        this.rightPane === rightSidebarViews.jobsDetail
-      );
-    },
+    ...mapGetters('rightPane', ['isActiveView', 'isAliveView']),
     showLivePreview() {
       return this.packageJson && this.clientsidePreviewEnabled;
     },
@@ -46,22 +43,26 @@ export default {
         {
           show: this.currentMergeRequestId,
           title: __('Merge Request'),
-          isActive: this.rightPane === rightSidebarViews.mergeRequestInfo,
-          view: rightSidebarViews.mergeRequestInfo,
+          views: [
+            rightSidebarViews.mergeRequestInfo,
+          ],
           icon: 'text-description',
         },
         {
           show: true,
           title: __('Pipelines'),
-          isActive: this.pipelinesActive,
-          view: rightSidebarViews.pipelines,
+          views: [
+            rightSidebarViews.pipelines,
+            rightSidebarViews.jobsDetail,
+          ],
           icon: 'rocket',
         },
         {
           show: this.showLivePreview,
           title: __('Live preview'),
-          isActive: this.rightPane === rightSidebarViews.clientSidePreview,
-          view: rightSidebarViews.clientSidePreview,
+          views: [
+            rightSidebarViews.clientSidePreview,
+          ],
           icon: 'live-preview',
         },
       ];
@@ -71,13 +72,26 @@ export default {
         .concat(this.extensionTabs)
         .filter(tab => tab.show);
     },
+    tabViews() {
+      return _.flatten(this.tabs.map(tab => tab.views));
+    },
+    aliveTabViews() {
+      return this.tabViews.filter(view => this.isAliveView(view.name));
+    },
   },
   methods: {
-    ...mapActions(['setRightPane']),
-    clickTab(e, view) {
+    ...mapActions('rightPane', ['toggleOpen', 'open']),
+    clickTab(e, tab) {
       e.target.blur();
 
-      this.setRightPane(view);
+      if (this.isActiveTab(tab)) {
+        this.toggleOpen();
+      } else {
+        this.open(tab.views[0]);
+      }
+    },
+    isActiveTab(tab) {
+      return tab.views.some(view => this.isActiveView(view.name));
     },
   },
 };
@@ -88,15 +102,22 @@ export default {
     class="multi-file-commit-panel ide-right-sidebar"
   >
     <resizable-panel
-      v-if="rightPane"
+      v-show="isOpen"
       :collapsible="false"
       :initial-width="350"
       :min-size="350"
-      :class="`ide-right-sidebar-${rightPane}`"
+      :class="`ide-right-sidebar-${currentView}`"
       side="right"
       class="multi-file-commit-panel-inner"
     >
-      <component :is="rightPane" />
+      <div
+        v-for="tabView in aliveTabViews"
+        v-show="isActiveView(tabView.name)"
+        :key="tabView.name"
+        class="h-100"
+      >
+        <component :is="tabView.name" />
+      </div>
     </resizable-panel>
     <nav class="ide-activity-bar">
       <ul class="list-unstyled">
@@ -109,13 +130,13 @@ export default {
             :title="tab.title"
             :aria-label="tab.title"
             :class="{
-              active: tab.isActive
+              active: isActiveTab(tab) && isOpen
             }"
             data-container="body"
             data-placement="left"
             class="ide-sidebar-link is-right"
             type="button"
-            @click="clickTab($event, tab.view)"
+            @click="clickTab($event, tab)"
           >
             <icon
               :size="16"
diff --git a/app/assets/javascripts/ide/components/repo_editor.vue b/app/assets/javascripts/ide/components/repo_editor.vue
index d3a73e84cc7..b2599128213 100644
--- a/app/assets/javascripts/ide/components/repo_editor.vue
+++ b/app/assets/javascripts/ide/components/repo_editor.vue
@@ -22,12 +22,14 @@ export default {
     },
   },
   computed: {
+    ...mapState('rightPane', {
+      rightPaneIsOpen: 'isOpen',
+    }),
     ...mapState([
       'rightPanelCollapsed',
       'viewer',
       'panelResizing',
       'currentActivityView',
-      'rightPane',
     ]),
     ...mapGetters([
       'currentMergeRequest',
@@ -99,7 +101,7 @@ export default {
         this.editor.updateDimensions();
       }
     },
-    rightPane() {
+    rightPaneIsOpen() {
       this.editor.updateDimensions();
     },
   },
diff --git a/app/assets/javascripts/ide/constants.js b/app/assets/javascripts/ide/constants.js
index 8caa5b86a9b..3b201f006aa 100644
--- a/app/assets/javascripts/ide/constants.js
+++ b/app/assets/javascripts/ide/constants.js
@@ -29,10 +29,10 @@ export const diffModes = {
 };
 
 export const rightSidebarViews = {
-  pipelines: 'pipelines-list',
-  jobsDetail: 'jobs-detail',
-  mergeRequestInfo: 'merge-request-info',
-  clientSidePreview: 'clientside',
+  pipelines: { name: 'pipelines-list', keepAlive: true },
+  jobsDetail: { name: 'jobs-detail', keepAlive: false },
+  mergeRequestInfo: { name: 'merge-request-info', keepAlive: true },
+  clientSidePreview: { name: 'clientside', keepAlive: false },
 };
 
 export const stageKeys = {
diff --git a/app/assets/javascripts/ide/stores/actions.js b/app/assets/javascripts/ide/stores/actions.js
index b8b64aead30..e10a132ab4b 100644
--- a/app/assets/javascripts/ide/stores/actions.js
+++ b/app/assets/javascripts/ide/stores/actions.js
@@ -184,10 +184,6 @@ export const burstUnusedSeal = ({ state, commit }) => {
   }
 };
 
-export const setRightPane = ({ commit }, view) => {
-  commit(types.SET_RIGHT_PANE, view);
-};
-
 export const setLinks = ({ commit }, links) => commit(types.SET_LINKS, links);
 
 export const setErrorMessage = ({ commit }, errorMessage) =>
diff --git a/app/assets/javascripts/ide/stores/index.js b/app/assets/javascripts/ide/stores/index.js
index 877d88bb060..f1f544b52b2 100644
--- a/app/assets/javascripts/ide/stores/index.js
+++ b/app/assets/javascripts/ide/stores/index.js
@@ -9,6 +9,7 @@ import pipelines from './modules/pipelines';
 import mergeRequests from './modules/merge_requests';
 import branches from './modules/branches';
 import fileTemplates from './modules/file_templates';
+import paneModule from './modules/pane';
 
 Vue.use(Vuex);
 
@@ -24,6 +25,7 @@ export const createStore = () =>
       mergeRequests,
       branches,
       fileTemplates: fileTemplates(),
+      rightPane: paneModule(),
     },
   });
 
diff --git a/app/assets/javascripts/ide/stores/modules/pane/actions.js b/app/assets/javascripts/ide/stores/modules/pane/actions.js
new file mode 100644
index 00000000000..7f5d167a14f
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/actions.js
@@ -0,0 +1,30 @@
+import * as types from './mutation_types';
+
+export const toggleOpen = ({ dispatch, state }, view) => {
+  if (state.isOpen) {
+    dispatch('close');
+  } else {
+    dispatch('open', view);
+  }
+};
+
+export const open = ({ commit }, view) => {
+  commit(types.SET_OPEN, true);
+
+  if (view) {
+    const { name, keepAlive } = view;
+
+    commit(types.SET_CURRENT_VIEW, name);
+
+    if (keepAlive) {
+      commit(types.KEEP_ALIVE_VIEW, name);
+    }
+  }
+};
+
+export const close = ({ commit }) => {
+  commit(types.SET_OPEN, false);
+};
+
+// prevent babel-plugin-rewire from generating an invalid default during karma tests
+export default () => {};
diff --git a/app/assets/javascripts/ide/stores/modules/pane/getters.js b/app/assets/javascripts/ide/stores/modules/pane/getters.js
new file mode 100644
index 00000000000..c346cf13689
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/getters.js
@@ -0,0 +1,4 @@
+export const isActiveView = state => view => state.currentView === view;
+
+export const isAliveView = (state, getters) => view =>
+  state.keepAliveViews[view] || (state.isOpen && getters.isActiveView(view));
diff --git a/app/assets/javascripts/ide/stores/modules/pane/index.js b/app/assets/javascripts/ide/stores/modules/pane/index.js
new file mode 100644
index 00000000000..5f61cb732c8
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/index.js
@@ -0,0 +1,12 @@
+import * as actions from './actions';
+import * as getters from './getters';
+import mutations from './mutations';
+import state from './state';
+
+export default () => ({
+  namespaced: true,
+  state: state(),
+  actions,
+  getters,
+  mutations,
+});
diff --git a/app/assets/javascripts/ide/stores/modules/pane/mutation_types.js b/app/assets/javascripts/ide/stores/modules/pane/mutation_types.js
new file mode 100644
index 00000000000..abdebc4d913
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/mutation_types.js
@@ -0,0 +1,3 @@
+export const SET_OPEN = 'SET_OPEN';
+export const SET_CURRENT_VIEW = 'SET_CURRENT_VIEW';
+export const KEEP_ALIVE_VIEW = 'KEEP_ALIVE_VIEW';
diff --git a/app/assets/javascripts/ide/stores/modules/pane/mutations.js b/app/assets/javascripts/ide/stores/modules/pane/mutations.js
new file mode 100644
index 00000000000..c16484b4402
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/mutations.js
@@ -0,0 +1,19 @@
+import * as types from './mutation_types';
+
+export default {
+  [types.SET_OPEN](state, isOpen) {
+    Object.assign(state, {
+      isOpen,
+    });
+  },
+  [types.SET_CURRENT_VIEW](state, currentView) {
+    Object.assign(state, {
+      currentView,
+    });
+  },
+  [types.KEEP_ALIVE_VIEW](state, viewName) {
+    Object.assign(state.keepAliveViews, {
+      [viewName]: true,
+    });
+  },
+};
diff --git a/app/assets/javascripts/ide/stores/modules/pane/state.js b/app/assets/javascripts/ide/stores/modules/pane/state.js
new file mode 100644
index 00000000000..353065b5735
--- /dev/null
+++ b/app/assets/javascripts/ide/stores/modules/pane/state.js
@@ -0,0 +1,5 @@
+export default () => ({
+  isOpen: false,
+  currentView: null,
+  keepAliveViews: {},
+});
diff --git a/app/assets/javascripts/ide/stores/modules/pipelines/actions.js b/app/assets/javascripts/ide/stores/modules/pipelines/actions.js
index 3e67b222e66..8fa86995ef0 100644
--- a/app/assets/javascripts/ide/stores/modules/pipelines/actions.js
+++ b/app/assets/javascripts/ide/stores/modules/pipelines/actions.js
@@ -113,7 +113,7 @@ export const toggleStageCollapsed = ({ commit }, stageId) =>
 
 export const setDetailJob = ({ commit, dispatch }, job) => {
   commit(types.SET_DETAIL_JOB, job);
-  dispatch('setRightPane', job ? rightSidebarViews.jobsDetail : rightSidebarViews.pipelines, {
+  dispatch('rightPane/open', job ? rightSidebarViews.jobsDetail : rightSidebarViews.pipelines, {
     root: true,
   });
 };
diff --git a/app/assets/javascripts/ide/stores/mutation_types.js b/app/assets/javascripts/ide/stores/mutation_types.js
index 5a7991d2fa7..a5f8098dc17 100644
--- a/app/assets/javascripts/ide/stores/mutation_types.js
+++ b/app/assets/javascripts/ide/stores/mutation_types.js
@@ -68,8 +68,6 @@ export const UPDATE_TEMP_FLAG = 'UPDATE_TEMP_FLAG';
 export const TOGGLE_FILE_FINDER = 'TOGGLE_FILE_FINDER';
 export const BURST_UNUSED_SEAL = 'BURST_UNUSED_SEAL';
 
-export const SET_RIGHT_PANE = 'SET_RIGHT_PANE';
-
 export const CLEAR_PROJECTS = 'CLEAR_PROJECTS';
 export const RESET_OPEN_FILES = 'RESET_OPEN_FILES';
 
diff --git a/app/assets/javascripts/ide/stores/mutations.js b/app/assets/javascripts/ide/stores/mutations.js
index 2c8535bda59..78cdfda74f0 100644
--- a/app/assets/javascripts/ide/stores/mutations.js
+++ b/app/assets/javascripts/ide/stores/mutations.js
@@ -166,11 +166,6 @@ export default {
       unusedSeal: false,
     });
   },
-  [types.SET_RIGHT_PANE](state, view) {
-    Object.assign(state, {
-      rightPane: state.rightPane === view ? null : view,
-    });
-  },
   [types.SET_LINKS](state, links) {
     Object.assign(state, { links });
   },
diff --git a/app/assets/javascripts/ide/stores/state.js b/app/assets/javascripts/ide/stores/state.js
index 46b52fa00fc..d400b9831a9 100644
--- a/app/assets/javascripts/ide/stores/state.js
+++ b/app/assets/javascripts/ide/stores/state.js
@@ -23,7 +23,6 @@ export default () => ({
   currentActivityView: activityBarViews.edit,
   unusedSeal: true,
   fileFindVisible: false,
-  rightPane: null,
   links: {},
   errorMessage: null,
   entryModal: {