From a942d42008be8dfb05e36a3b022ab7b2f3fe8e8f Mon Sep 17 00:00:00 2001
From: Marcus Eide <eide@spotify.com>
Date: Tue, 22 Sep 2020 13:24:03 +0200
Subject: [PATCH] Refactor toggling of featureFlags

---
 .../src/apis/definitions/FeatureFlagsApi.ts   | 12 ++--
 packages/core-api/src/app/App.tsx             |  2 +-
 packages/core-api/src/app/FeatureFlags.tsx    | 10 +--
 .../src/components/FeatureFlagsItem.tsx       | 64 +++++++------------
 .../src/components/FeatureFlagsList.tsx       | 64 +++++++++++++++----
 5 files changed, 89 insertions(+), 63 deletions(-)

diff --git a/packages/core-api/src/apis/definitions/FeatureFlagsApi.ts b/packages/core-api/src/apis/definitions/FeatureFlagsApi.ts
index b6aac75620..dd9657d7d8 100644
--- a/packages/core-api/src/apis/definitions/FeatureFlagsApi.ts
+++ b/packages/core-api/src/apis/definitions/FeatureFlagsApi.ts
@@ -15,11 +15,8 @@
  */
 
 import { createApiRef } from '../ApiRef';
-import {
-  UserFlags,
-  FeatureFlagsRegistry,
-  FeatureFlagsRegistryItem,
-} from '../../app/FeatureFlags';
+import { UserFlags, FeatureFlagsRegistry } from '../../app/FeatureFlags';
+import { FeatureFlagName } from '../../plugin';
 
 /**
  * The feature flags API is used to toggle functionality to users across plugins and Backstage.
@@ -55,6 +52,11 @@ export interface FeatureFlagsApi {
   getRegisteredFlags(): FeatureFlagsRegistry;
 }
 
+export interface FeatureFlagsRegistryItem {
+  pluginId: string;
+  name: FeatureFlagName;
+}
+
 export const featureFlagsApiRef = createApiRef<FeatureFlagsApi>({
   id: 'core.featureflags',
   description: 'Used to toggle functionality in features across Backstage',
diff --git a/packages/core-api/src/app/App.tsx b/packages/core-api/src/app/App.tsx
index 9dd2fb138f..c222c3c420 100644
--- a/packages/core-api/src/app/App.tsx
+++ b/packages/core-api/src/app/App.tsx
@@ -30,12 +30,12 @@ import {
   SignInPageProps,
 } from './types';
 import { BackstagePlugin } from '../plugin';
-import { FeatureFlagsRegistryItem } from './FeatureFlags';
 import {
   featureFlagsApiRef,
   AppThemeApi,
   ConfigApi,
   identityApiRef,
+  FeatureFlagsRegistryItem,
 } from '../apis/definitions';
 import { AppThemeProvider } from './AppThemeProvider';
 
diff --git a/packages/core-api/src/app/FeatureFlags.tsx b/packages/core-api/src/app/FeatureFlags.tsx
index 3db2a18a02..7a69fa5456 100644
--- a/packages/core-api/src/app/FeatureFlags.tsx
+++ b/packages/core-api/src/app/FeatureFlags.tsx
@@ -15,7 +15,11 @@
  */
 
 import { FeatureFlagName } from '../plugin/types';
-import { FeatureFlagState, FeatureFlagsApi } from '../apis/definitions';
+import {
+  FeatureFlagState,
+  FeatureFlagsApi,
+  FeatureFlagsRegistryItem,
+} from '../apis/definitions';
 
 /**
  * Helper method for validating compatibility and flag name.
@@ -129,10 +133,6 @@ export class UserFlags extends Map<FeatureFlagName, FeatureFlagState> {
  * This acts as a holding data structure for feature flags
  * that plugins wish to register for use in Backstage.
  */
-export interface FeatureFlagsRegistryItem {
-  pluginId: string;
-  name: FeatureFlagName;
-}
 
 export class FeatureFlagsRegistry extends Array<FeatureFlagsRegistryItem> {
   static from(entries: FeatureFlagsRegistryItem[]) {
diff --git a/plugins/user-settings/src/components/FeatureFlagsItem.tsx b/plugins/user-settings/src/components/FeatureFlagsItem.tsx
index bc327061ef..760aa25a34 100644
--- a/plugins/user-settings/src/components/FeatureFlagsItem.tsx
+++ b/plugins/user-settings/src/components/FeatureFlagsItem.tsx
@@ -15,7 +15,6 @@
  */
 
 import React from 'react';
-import { FeatureFlagName, useApi, featureFlagsApiRef } from '@backstage/core';
 import {
   ListItem,
   ListItemSecondaryAction,
@@ -24,46 +23,31 @@ import {
 } from '@material-ui/core';
 import CheckIcon from '@material-ui/icons/CheckCircle';
 import { ToggleButton } from '@material-ui/lab';
-
-export type Item = {
-  name: FeatureFlagName;
-  pluginId: string;
-};
+import { FeatureFlagsRegistryItem } from '@backstage/core';
 
 type Props = {
-  featureFlag: Item;
+  flag: FeatureFlagsRegistryItem;
+  enabled: boolean;
+  toggleHandler: Function;
 };
 
-export const FlagItem = ({ featureFlag }: Props) => {
-  const api = useApi(featureFlagsApiRef);
-
-  const [enabled, setEnabled] = React.useState(
-    Boolean(api.getFlags().get(featureFlag.name)),
-  );
-
-  const toggleFlag = () => {
-    const newState = api.getFlags().toggle(featureFlag.name);
-    setEnabled(Boolean(newState));
-  };
-
-  return (
-    <ListItem>
-      <ListItemText
-        primary={featureFlag.name}
-        secondary={`Registered in ${featureFlag.pluginId} plugin`}
-      />
-      <ListItemSecondaryAction>
-        <ToggleButton
-          size="small"
-          value="flag"
-          selected={enabled}
-          onChange={toggleFlag}
-        >
-          <Tooltip placement="top" arrow title={enabled ? 'Disable' : 'Enable'}>
-            <CheckIcon />
-          </Tooltip>
-        </ToggleButton>
-      </ListItemSecondaryAction>
-    </ListItem>
-  );
-};
+export const FlagItem = ({ flag, enabled, toggleHandler }: Props) => (
+  <ListItem>
+    <ListItemText
+      primary={flag.name}
+      secondary={`Registered in ${flag.pluginId} plugin`}
+    />
+    <ListItemSecondaryAction>
+      <ToggleButton
+        size="small"
+        value="flag"
+        selected={enabled}
+        onChange={() => toggleHandler(flag.name)}
+      >
+        <Tooltip placement="top" arrow title={enabled ? 'Disable' : 'Enable'}>
+          <CheckIcon />
+        </Tooltip>
+      </ToggleButton>
+    </ListItemSecondaryAction>
+  </ListItem>
+);
diff --git a/plugins/user-settings/src/components/FeatureFlagsList.tsx b/plugins/user-settings/src/components/FeatureFlagsList.tsx
index 5687446511..0d7404c6fd 100644
--- a/plugins/user-settings/src/components/FeatureFlagsList.tsx
+++ b/plugins/user-settings/src/components/FeatureFlagsList.tsx
@@ -14,19 +14,59 @@
  * limitations under the License.
  */
 
-import React from 'react';
-import List from '@material-ui/core/List';
-import ListSubheader from '@material-ui/core/ListSubheader';
-import { FlagItem, Item } from './FeatureFlagsItem';
+import React, { useState, useEffect } from 'react';
+import { List, ListSubheader } from '@material-ui/core';
+import {
+  useApi,
+  featureFlagsApiRef,
+  FeatureFlagName,
+  FeatureFlagState,
+  FeatureFlagsRegistryItem,
+} from '@backstage/core';
+import { FlagItem } from './FeatureFlagsItem';
 
 type Props = {
-  featureFlags: Item[];
+  featureFlags: FeatureFlagsRegistryItem[];
 };
 
-export const FeatureFlagsList = ({ featureFlags }: Props) => (
-  <List dense subheader={<ListSubheader>Feature Flags</ListSubheader>}>
-    {featureFlags.map(featureFlag => (
-      <FlagItem key={featureFlag.name} featureFlag={featureFlag} />
-    ))}
-  </List>
-);
+export const FeatureFlagsList = ({ featureFlags }: Props) => {
+  const featureFlagApi = useApi(featureFlagsApiRef);
+  const [state, setState] = useState<Record<FeatureFlagName, FeatureFlagState>>(
+    {},
+  );
+
+  useEffect(() => {
+    featureFlags.map(featureFlag => {
+      setState({
+        [featureFlag.name]: featureFlagApi.getFlags().get(featureFlag.name),
+      });
+    });
+  }, [featureFlagApi, featureFlags]);
+
+  const toggleFlag = (flagName: FeatureFlagName) => {
+    const newState = featureFlagApi.getFlags().toggle(flagName);
+
+    setState(prevState => ({
+      ...prevState,
+      [flagName]: newState,
+    }));
+    featureFlagApi.getFlags().save();
+  };
+
+  return (
+    <List dense subheader={<ListSubheader>Feature Flags</ListSubheader>}>
+      {featureFlags.map(featureFlag => {
+        const enabled = Boolean(state[featureFlag.name]);
+
+        return (
+          <FlagItem
+            key={featureFlag.name}
+            flag={featureFlag}
+            enabled={enabled}
+            toggleHandler={toggleFlag}
+          />
+        );
+      })}
+    </List>
+  );
+};