feat: add feature flag modal in local/staging environments (#4291)

* initial

* add feature flag modal

* updates

* help

* working now!

* SIMPLIFY

* useref delete

* naming

* move modal out

* rename

* make button

* rename

* work on vercel

* styling
Co-authored-by: Vignesh Mohankumar <me@vig.xyz>

src/components/FeatureFlagModal/FeatureFlagModal.tsx

+import { FeatureFlag, useUpdateFlag } from 'featureFlags'
+import { Phase0Variant, usePhase0Flag } from 'featureFlags/flags/phase0'
+import { ReactNode } from 'react'
+import { X } from 'react-feather'
+import { useModalIsOpen, useToggleFeatureFlags } from 'state/application/hooks'
+import { ApplicationModal } from 'state/application/reducer'
+import styled from 'styled-components/macro'
+
+const StyledModal = styled.div`
+  position: fixed;
+  display: flex;
+  left: 50%;
+  top: 50%;
+  transform: translate(-50%, -50%);
+  width: 400px;
+  height: fit-content;
+  color: ${({ theme }) => theme.textPrimary};
+  font-size: 18px;
+  padding: 20px;
+  background-color: ${({ theme }) => theme.backgroundSurface};
+  border-radius: 12px;
+  border: 1px solid ${({ theme }) => theme.backgroundOutline};
+  z-index: 100;
+  flex-direction: column;
+  gap: 8px;
+  border: 1px solid ${({ theme }) => theme.backgroundOutline};
+`
+
+function Modal({ open, children }: { open: boolean; children: ReactNode }) {
+  return open ? <StyledModal>{children}</StyledModal> : null
+}
+
+const Row = styled.div`
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: 8px 0px;
+`
+
+const CloseButton = styled.button`
+  cursor: pointer;
+  background: ${({ theme }) => theme.none};
+  border: none;
+  color: ${({ theme }) => theme.textPrimary};
+`
+
+const Header = styled(Row)`
+  font-weight: 600;
+  font-size: 20px;
+  border-bottom: 1px solid ${({ theme }) => theme.backgroundOutline};
+  margin-bottom: 8px;
+`
+
+function Variant({ option }: { option: string }) {
+  return <option value={option}>{option}</option>
+}
+
+function FeatureFlagOption({
+  variants,
+  featureFlag,
+  value,
+  label,
+}: {
+  variants: string[]
+  featureFlag: FeatureFlag
+  value: string
+  label: string
+}) {
+  const updateFlag = useUpdateFlag()
+  return (
+    <Row key={featureFlag}>
+      {featureFlag}: {label}
+      <select
+        id={featureFlag}
+        value={value}
+        onChange={(e) => {
+          updateFlag(featureFlag, e.target.value)
+          window.location.reload()
+        }}
+      >
+        {variants.map((variant) => (
+          <Variant key={variant} option={variant} />
+        ))}
+      </select>
+    </Row>
+  )
+}
+
+export default function FeatureFlagModal() {
+  const open = useModalIsOpen(ApplicationModal.FEATURE_FLAGS)
+  const toggle = useToggleFeatureFlags()
+
+  return (
+    <Modal open={open}>
+      <Header>
+        Feature Flag Settings
+        <CloseButton onClick={toggle}>
+          <X size={24} />
+        </CloseButton>
+      </Header>
+
+      <FeatureFlagOption
+        variants={Object.values(Phase0Variant)}
+        value={usePhase0Flag()}
+        featureFlag={FeatureFlag.phase0}
+        label="All Phase 0 changes (redesign, explore, header)."
+      />
+    </Modal>
+  )
+}

src/components/Menu/index.tsx

 // eslint-disable-next-line no-restricted-imports
 import { t, Trans } from '@lingui/macro'
 import { useWeb3React } from '@web3-react/core'
+import FeatureFlagModal from 'components/FeatureFlagModal/FeatureFlagModal'
 import { PrivacyPolicyModal } from 'components/PrivacyPolicy'
 import { L2_CHAIN_IDS } from 'constants/chains'
 import { LOCALE_LABEL, SUPPORTED_LOCALES, SupportedLocale } from 'constants/locales'
@@ -214,6 +215,7 @@ export default function Menu() {
   const toggleMenu = useToggleModal(ApplicationModal.MENU)
   useOnClickOutside(node, open ? toggleMenu : undefined)
   const togglePrivacyPolicy = useToggleModal(ApplicationModal.PRIVACY_POLICY)
+  const openFeatureFlagsModal = useToggleModal(ApplicationModal.FEATURE_FLAGS)
   const openClaimModal = useToggleModal(ApplicationModal.ADDRESS_CLAIM)
   const showUNIClaimOption = Boolean(!!account && !!chainId && !L2_CHAIN_IDS.includes(chainId))
 
@@ -299,12 +301,16 @@ export default function Menu() {
                         <Trans>Claim UNI</Trans>
                       </UNIbutton>
                     )}
+                    {['development', 'staging'].includes(process.env.NODE_ENV) && (
+                      <ToggleMenuItem onClick={openFeatureFlagsModal}>Feature Flags</ToggleMenuItem>
+                    )}
                   </MenuFlyout>
                 )
             }
           })()}
       </StyledMenu>
       <PrivacyPolicyModal />
+      <FeatureFlagModal />
     </>
   )
 }

src/featureFlags/index.tsx

-import { createContext, ReactNode, useContext } from 'react'
+import { useAtom } from 'jotai'
+import { atomWithStorage, useAtomValue } from 'jotai/utils'
+import { createContext, ReactNode, useCallback, useContext } from 'react'
 
 interface FeatureFlagsContextType {
   isLoaded: boolean
@@ -16,16 +18,28 @@ export function useFeatureFlagsContext(): FeatureFlagsContextType {
   }
 }
 
+/* update and save feature flag settings */
+export const featureFlagSettings = atomWithStorage<Record<string, string>>('featureFlags', {})
+
+export function useUpdateFlag() {
+  const [featureFlags, setFeatureFlags] = useAtom(featureFlagSettings)
+
+  return useCallback(
+    (featureFlag: string, option: string) => {
+      featureFlags[featureFlag] = option
+      setFeatureFlags(featureFlags)
+    },
+    [featureFlags, setFeatureFlags]
+  )
+}
+
 export function FeatureFlagsProvider({ children }: { children: ReactNode }) {
   // TODO(vm): `isLoaded` to `true` so `App.tsx` will render. Later, this will be dependent on
   // flags loading from Amplitude, with a timeout.
-  const variant = process.env.NODE_ENV === 'development' ? 'enabled' : 'control'
+  const featureFlags = useAtomValue(featureFlagSettings)
   const value = {
     isLoaded: true,
-    flags: {
-      phase0: variant,
-      phase1: variant,
-    },
+    flags: featureFlags,
   }
   return <FeatureFlagContext.Provider value={value}>{children}</FeatureFlagContext.Provider>
 }
@@ -35,8 +49,12 @@ export function useFeatureFlagsIsLoaded(): boolean {
 }
 
 export enum BaseVariant {
-  Control = 'Control',
-  Enabled = 'Enabled',
+  Control = 'control',
+  Enabled = 'enabled',
+}
+
+export enum FeatureFlag {
+  phase0 = 'phase0',
 }
 
 export function useBaseFlag(flag: string): BaseVariant {

src/state/application/hooks.ts

@@ -70,6 +70,10 @@ export function useToggleTimeSelector(): () => void {
   return useToggleModal(ApplicationModal.TIME_SELECTOR)
 }
 
+export function useToggleFeatureFlags(): () => void {
+  return useToggleModal(ApplicationModal.FEATURE_FLAGS)
+}
+
 // returns a function that allows adding a popup
 export function useAddPopup(): (content: PopupContent, key?: string, removeAfterMs?: number) => void {
   const dispatch = useAppDispatch()

src/state/application/reducer.ts

@@ -31,6 +31,7 @@ export enum ApplicationModal {
   TIME_SELECTOR,
   SHARE,
   NETWORK_FILTER,
+  FEATURE_FLAGS,
 }
 
 type PopupList = Array<{ key: string; show: boolean; content: PopupContent; removeAfterMs: number | null }>