feat: add chains dynamicconfig for feature flags (#7389)

* feat: add feature flags dynamic config for chains

* fix

* add better chainid error checking

* quiet linter

* refactor & should be quick_route_chains only

src/featureFlags/dynamicConfig/index.tsx

@@ -0,0 +1,10 @@
+import { DynamicConfig, useConfig } from 'statsig-react'
+
+export enum DynamicConfigName {
+  quickRouteChains = 'quick_route_chains',
+}
+
+export function useDynamicConfig(configName: DynamicConfigName): DynamicConfig {
+  const { config } = useConfig(configName)
+  return config
+}

src/featureFlags/dynamicConfig/quickRouteChains.ts

@@ -0,0 +1,15 @@
+import { ChainId } from '@uniswap/sdk-core'
+
+import { DynamicConfigName, useDynamicConfig } from '.'
+
+// eslint-disable-next-line import/no-unused-modules
+export function useQuickRouteChains(): ChainId[] {
+  const config = useDynamicConfig(DynamicConfigName.quickRouteChains)
+  const chains = config.get('chains', [])
+  if (chains.every((c) => Object.values(ChainId).includes(c))) {
+    return chains as ChainId[]
+  } else {
+    console.error('feature flag config chains contain invalid ChainId')
+    return []
+  }
+}

src/featureFlags/index.tsx

@@ -57,7 +57,7 @@ export function useUpdateFlag() {
 }
 
 export function FeatureFlagsProvider({ children }: { children: ReactNode }) {
-  // TODO(vm): `isLoaded` to `true` so `App.tsx` will render. Later, this will be dependent on
+  // TODO: `isLoaded` to `true` so `App.tsx` will render. Later, this will be dependent on
   // flags loading from Amplitude, with a timeout.
   const featureFlags = useAtomValue(featureFlagSettings)
   const value = {