Persist slice of redux state in local storage

ui/src/App.tsx

@@ -26,7 +26,7 @@ import DoubleArrowIcon from "@material-ui/icons/DoubleArrow";
 import CloseIcon from "@material-ui/icons/Close";
 import { AppState } from "./store";
 import { paths } from "./paths";
-import { makeTheme } from "./theme";
+import { useTheme } from "./theme";
 import { closeSnackbar } from "./actions/snackbarActions";
 import ListItemLink from "./components/ListItemLink";
 import SchedulersView from "./views/SchedulersView";
@@ -146,7 +146,7 @@ function SlideUpTransition(props: TransitionProps) {
 }
 
 function App(props: ConnectedProps<typeof connector>) {
-  const theme = makeTheme(props.themePreference);
+  const theme = useTheme(props.themePreference);
   const classes = useStyles(theme)();
   const [open, setOpen] = useState(true);
   const toggleDrawer = () => setOpen(!open);

ui/src/actions/settingsActions.ts

@@ -1,5 +1,4 @@
 import { ThemePreference } from "../reducers/settingsReducer";
-
 // List of settings related action types.
 export const POLL_INTERVAL_CHANGE = "POLL_INTERVAL_CHANGE";
 export const THEME_PREFERENCE_CHANGE = "THEME_PREFERENCE_CHANGE";

ui/src/index.tsx

@@ -5,6 +5,11 @@ import { Provider } from "react-redux";
 import App from "./App";
 import store from "./store";
 import * as serviceWorker from "./serviceWorker";
+import { saveState } from "./localStorage";
+
+store.subscribe(() => {
+  saveState(store.getState());
+});
 
 ReactDOM.render(
   <React.StrictMode>

ui/src/localStorage.ts

@@ -0,0 +1,24 @@
+import { AppState } from "./store";
+
+const LOCAL_STORAGE_KEY = "asynqmon:state";
+
+export function loadState(): AppState | undefined {
+  try {
+    const serializedState = localStorage.getItem(LOCAL_STORAGE_KEY);
+    if (serializedState === null) {
+      return undefined;
+    }
+    return JSON.parse(serializedState);
+  } catch (err) {
+    return undefined;
+  }
+}
+
+export function saveState(state: AppState) {
+  try {
+    const serializedState = JSON.stringify({ settings: state.settings });
+    localStorage.setItem(LOCAL_STORAGE_KEY, serializedState);
+  } catch (err) {
+    console.error("saveState: could not save state: ", err);
+  }
+}

ui/src/store.ts

@@ -7,6 +7,7 @@ import schedulerEntriesReducer from "./reducers/schedulerEntriesReducer";
 import snackbarReducer from "./reducers/snackbarReducer";
 import queueStatsReducer from "./reducers/queueStatsReducer";
 import redisInfoReducer from "./reducers/redisInfoReducer";
+import { loadState } from "./localStorage";
 
 const rootReducer = combineReducers({
   settings: settingsReducer,
@@ -19,9 +20,14 @@ const rootReducer = combineReducers({
   redis: redisInfoReducer,
 });
 
+const preloadedState = loadState();
+
 // AppState is the top-level application state maintained by redux store.
 export type AppState = ReturnType<typeof rootReducer>;
 
-export default configureStore({
+const store = configureStore({
   reducer: rootReducer,
+  preloadedState,
 });
+
+export default store;

ui/src/theme.tsx

@@ -2,8 +2,7 @@ import { createMuiTheme, Theme } from "@material-ui/core/styles";
 import { ThemePreference } from "./reducers/settingsReducer";
 import useMediaQuery from "@material-ui/core/useMediaQuery";
 
-export function makeTheme(themePreference: ThemePreference): Theme {
-  // eslint-disable-next-line react-hooks/rules-of-hooks
+export function useTheme(themePreference: ThemePreference): Theme {
   let prefersDarkMode = useMediaQuery("(prefers-color-scheme: dark)");
   if (themePreference === ThemePreference.Always) {
     prefersDarkMode = true;

ui/src/views/SettingsView.tsx

@@ -63,14 +63,14 @@ function SettingsView(props: PropsFromRedux) {
     props.selectTheme(event.target.value as ThemePreference);
   };
   return (
-    <Container maxWidth="lg" className={classes.container}>
+    <Container maxWidth="md" className={classes.container}>
       <Grid container spacing={3}>
         <Grid item xs={12}>
           <Typography variant="h5" color="textPrimary">
             Settings
           </Typography>
         </Grid>
-        <Grid item xs={5}>
+        <Grid item xs={6}>
           <Paper className={classes.paper} variant="outlined">
             <Typography color="textPrimary">Polling Interval</Typography>
             <Typography gutterBottom color="textSecondary" variant="subtitle1">
@@ -93,22 +93,26 @@ function SettingsView(props: PropsFromRedux) {
             />
           </Paper>
         </Grid>
-        <FormControl variant="outlined" className={classes.formControl}>
-          <InputLabel id="theme-label">Dark theme</InputLabel>
-          <Select
-            labelId="theme-label"
-            id="theme-selected"
-            value={props.themePreference}
-            onChange={handleThemeChange}
-            label="theme preference"
-          >
-            <MenuItem value={ThemePreference.SystemDefault}>
-              System Default
-            </MenuItem>
-            <MenuItem value={ThemePreference.Always}>Always</MenuItem>
-            <MenuItem value={ThemePreference.Never}>Never</MenuItem>
-          </Select>
-        </FormControl>
+        <Grid item>
+          <Paper className={classes.paper} variant="outlined">
+            <FormControl variant="outlined" className={classes.formControl}>
+              <InputLabel id="theme-label">Dark theme</InputLabel>
+              <Select
+                labelId="theme-label"
+                id="theme-selected"
+                value={props.themePreference}
+                onChange={handleThemeChange}
+                label="theme preference"
+              >
+                <MenuItem value={ThemePreference.SystemDefault}>
+                  System Default
+                </MenuItem>
+                <MenuItem value={ThemePreference.Always}>Always</MenuItem>
+                <MenuItem value={ThemePreference.Never}>Never</MenuItem>
+              </Select>
+            </FormControl>
+          </Paper>
+        </Grid>
       </Grid>
     </Container>
   );