ThemeToggle.tsx

'use client'
import { useTheme } from 'next-themes'
import { useEffect, useState } from 'react'
import { Sun, Moon, Monitor } from 'lucide-react'

const ICONS = { light: Sun, dark: Moon, system: Monitor }
const MODES = ['light', 'dark', 'system'] as const

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

  // Avoid hydration mismatch — only render after mount
  useEffect(() => setMounted(true), [])
  if (!mounted) return <div className="w-9 h-9" />

  const cycle = () => {
    const idx = MODES.indexOf((theme as (typeof MODES)[number]) ?? 'system')
    const next = MODES[(idx + 1) % MODES.length]
    setTheme(next)
  }
  const ThemeIcon = ICONS[(theme as keyof typeof ICONS) ?? 'system']

  return (
    <button
      onClick={cycle}
      aria-label={`Current theme: ${theme}. Click to switch.`}
      className="p-2 rounded-lg hover:bg-muted min-h-[44px] min-w-[44px] flex items-center justify-center transition-colors"
    >
      <ThemeIcon className="size-[1.2rem]" />
    </button>
  )
}