rename /src to /internal (sorry i'll fix the prs)

internal/site/src/components/theme-provider.tsx

@@ -0,0 +1,61 @@
+import { createContext, useContext, useEffect, useState } from "react"
+
+type Theme = "dark" | "light" | "system"
+
+type ThemeProviderProps = {
+	children: React.ReactNode
+	defaultTheme?: Theme
+	storageKey?: string
+}
+
+type ThemeProviderState = {
+	theme: Theme
+	setTheme: (theme: Theme) => void
+}
+
+const initialState: ThemeProviderState = {
+	theme: "system",
+	setTheme: () => null,
+}
+
+const ThemeProviderContext = createContext<ThemeProviderState>(initialState)
+
+export function ThemeProvider({
+	children,
+	defaultTheme = "system",
+	storageKey = "ui-theme",
+	...props
+}: ThemeProviderProps) {
+	const [theme, setTheme] = useState<Theme>(() => (localStorage.getItem(storageKey) as Theme) || defaultTheme)
+
+	useEffect(() => {
+		const root = window.document.documentElement
+
+		root.classList.remove("light", "dark")
+
+		if (theme === "system") {
+			const systemTheme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light"
+
+			root.classList.add(systemTheme)
+			return
+		}
+
+		root.classList.add(theme)
+	}, [theme])
+
+	const value = {
+		theme,
+		setTheme: (theme: Theme) => {
+			localStorage.setItem(storageKey, theme)
+			setTheme(theme)
+		},
+	}
+
+	return (
+		<ThemeProviderContext.Provider {...props} value={value}>
+			{children}
+		</ThemeProviderContext.Provider>
+	)
+}
+
+export const useTheme = () => useContext(ThemeProviderContext)