Added localstorage support

src/main.jsx

@@ -10,6 +10,7 @@ import { Icon } from './components/Icon.jsx'
 import { Popup } from './components/Popup.jsx'
 import { Toolbar } from './components/Toolbar.jsx'
 import { OptionBar } from './components/OptionBar.jsx'
+import { usePersistentState } from './utils.jsx'
 
 window._ = _
 window.dataBuffer = {}
@@ -68,15 +69,15 @@ async function loadEventi(ids) {
 
 const App = ({}) => {
     // Data Sources
-    const [source, setSource] = useState('magistrale')
+    const [source, setSource] = usePersistentState('orario.source', 'magistrale')
     const [eventi, setEventi] = useState([])
 
     // View Modes
-    const [mode, setMode] = useState(MODE_COURSE)
+    const [mode, setMode] = usePersistentState('orario.mode', MODE_COURSE)
 
     // Selection
-    const [selectedCourses, setSelectedCourses] = useState([])
-    const [hideOtherCourses, setHideOtherCourses] = useState(false)
+    const [selectedCourses, setSelectedCourses] = usePersistentState('orario.selection', [])
+    const [hideOtherCourses, setHideOtherCourses] = usePersistentState('orario.hide-other', false)
 
     // Menus
     const [helpVisible, setHelpVisible] = useState(false)
@@ -99,19 +100,18 @@ const App = ({}) => {
 
         if (
             selectedCourses.length === 0 ||
-            selectedCourses.filter(id => groupIds.has(id)).length === 0
+            (eventi.length > 0 && selectedCourses.filter(id => groupIds.has(id)).length === 0)
         ) {
             setHideOtherCourses(false)
         }
     }, [eventi, selectedCourses.length])
 
-    const [theme, setTheme] = useState(
-        localStorage.getItem('theme') ??
-            (window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light')
+    const [theme, setTheme] = usePersistentState(
+        'orario.theme',
+        window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'
     )
 
     document.body.classList.toggle('dark-mode', theme === 'dark')
-    localStorage.setItem('theme', theme)
 
     return (
         <>

src/utils.jsx

@@ -1,5 +1,7 @@
 // Calendar
 
+import { useEffect, useState } from 'preact/hooks'
+
 export const WEEK_DAYS = [
     'Domenica',
     'Lunedì',
@@ -53,3 +55,19 @@ export const withClasses = classes =>
               .filter(([, value]) => value)
               .map(([key]) => key)
               .join(' ')
+
+// Hooks
+
+export const usePersistentState = (key, initialValue) => {
+    const previousValue = localStorage.getItem(key)
+
+    const [value, setValue] = useState(
+        previousValue !== null ? JSON.parse(previousValue) : initialValue
+    )
+
+    useEffect(() => {
+        localStorage.setItem(key, JSON.stringify(value))
+    }, [value])
+
+    return [value, setValue]
+}