assistant-ui--assistant-ui/apps/docs/components/shared/theme-toggle.tsx

"use client";

import { useTheme } from "next-themes";
import { useEffect, useState } from "react";
import { Moon, Sun } from "lucide-react";

export function ThemeToggle() {
  const { resolvedTheme, setTheme } = useTheme();
  const [mounted, setMounted] = useState(false);

  useEffect(() => setMounted(true), []);

  const toggleTheme = () => {
    setTheme(resolvedTheme === "dark" ? "light" : "dark");
  };

  return (
    <button
      type="button"
      onClick={toggleTheme}
      className="text-muted-foreground hover:text-foreground flex size-8 items-center justify-center transition-colors"
      aria-label="Toggle theme"
    >
      {mounted ? (
        resolvedTheme === "dark" ? (
          <Moon className="size-4" />
        ) : (
          <Sun className="size-4" />
        )
      ) : (
        <div className="size-4" />
      )}
    </button>
  );
}