Frontend/components/theme-toggle.tsx

'use client'

import { useTheme } from 'next-themes'
import { useEffect, useState } from 'react'
import { Moon, Sun } from 'lucide-react'
import { Button } from '@/components/ui/button'

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

  useEffect(() => {
    setMounted(true)
  }, [])

  const toggleTheme = () => {
    const newTheme = resolvedTheme === 'dark' ? 'light' : 'dark'
    setTheme(newTheme)
  }

  // Show placeholder during SSR/hydration
  if (!mounted) {
    return (
      <Button
        variant="outline"
        size="icon"
        className="w-9 h-9 rounded-full border-border bg-transparent"
        aria-label="Toggle theme"
        disabled
      >
        <div className="w-4 h-4 bg-muted rounded-full animate-pulse" />
      </Button>
    )
  }

  const isDark = resolvedTheme === 'dark'

  return (
    <Button
      variant="outline"
      size="icon"
      onClick={toggleTheme}
      className="w-9 h-9 rounded-full border-border hover:bg-muted transition-colors bg-transparent"
      aria-label={isDark ? 'Switch to light mode' : 'Switch to dark mode'}
    >
      {isDark ? (
        <Sun className="w-4 h-4 text-amber-400" />
      ) : (
        <Moon className="w-4 h-4 text-slate-700" />
      )}
    </Button>
  )
}