Add: theme selector

frontend/src/components/LightModeToggle.tsx

@@ -0,0 +1,39 @@
+import { Moon, Sun } from "lucide-react"
+
+import { Button } from "@/components/ui/button"
+import {
+    DropdownMenu,
+    DropdownMenuContent,
+    DropdownMenuItem,
+    DropdownMenuTrigger,
+} from "@/components/ui/dropdown-menu"
+import { useTheme } from "@/components/ThemeProvider"
+
+export function LightModeToggle() {
+    const { setTheme } = useTheme()
+
+    return (
+        <DropdownMenu>
+            <DropdownMenuTrigger asChild>
+                <Button variant="link" size="icon">
+                    <Sun className="h-[1.2rem] w-[1.2rem] rotate-0 scale-100 transition-all dark:-rotate-90 dark:scale-0" />
+                    <Moon className="absolute h-[1.2rem] w-[1.2rem] rotate-90 scale-0 transition-all dark:rotate-0 dark:scale-100" />
+                    <span className="sr-only">Toggle theme</span>
+                </Button>
+            </DropdownMenuTrigger>
+            <DropdownMenuContent align="end">
+                <DropdownMenuItem onClick={() => setTheme("light")}>
+                    Light
+                </DropdownMenuItem>
+                <DropdownMenuItem onClick={() => setTheme("dark")}>
+                    Dark
+                </DropdownMenuItem>
+                <DropdownMenuItem onClick={() => setTheme("system")}>
+                    System
+                </DropdownMenuItem>
+            </DropdownMenuContent>
+        </DropdownMenu>
+    )
+}
+
+export default LightModeToggle

frontend/src/components/ThemeProvider.tsx

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+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 = "vite-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 = () => {
+    const context = useContext(ThemeProviderContext)
+
+    if (context === undefined)
+        throw new Error("useTheme must be used within a ThemeProvider")
+
+    return context
+}
+