first commit

packages/frontend/src/lib/useTheme.ts

@@ -0,0 +1,21 @@
+import {useEffect, useState} from 'react'
+
+type Theme = 'dark' | 'light'
+
+function getStored(): Theme {
+    const v = localStorage.getItem('floci-theme')
+    return v === 'light' ? 'light' : 'dark'
+}
+
+export function useTheme() {
+    const [theme, setTheme] = useState<Theme>(getStored)
+
+    useEffect(() => {
+        document.documentElement.setAttribute('data-theme', theme)
+        localStorage.setItem('floci-theme', theme)
+    }, [theme])
+
+    const toggle = () => setTheme(t => t === 'dark' ? 'light' : 'dark')
+
+    return {theme, toggle}
+}