2fa-tool/components/theme-provider.tsx

"use client"

import * as React from "react"
import { createContext, useContext, useEffect, useState } from "react"

type Theme = "dark" | "light" | "system"

type ThemeProviderProps = {
  children: React.ReactNode
  defaultTheme?: Theme
  storageKey?: string
  attribute?: string
  enableSystem?: boolean
  disableTransitionOnChange?: boolean
}

type ThemeProviderState = {
  theme: Theme
  setTheme: (theme: Theme) => void
  resolvedTheme?: string
}

const ThemeProviderContext = createContext<ThemeProviderState | undefined>(undefined)

export function ThemeProvider({
  children,
  defaultTheme = "system",
  storageKey = "theme",
  ...props
}: ThemeProviderProps) {
  const [theme, setTheme] = useState<Theme>(defaultTheme)
  const [resolvedTheme, setResolvedTheme] = useState<string | undefined>(undefined)
  const [mounted, setMounted] = useState(false)

  useEffect(() => {
    setMounted(true)
    const stored = localStorage.getItem(storageKey) as Theme | null
    if (stored) {
      setTheme(stored)
    }
  }, [storageKey])

  useEffect(() => {
    if (!mounted) return

    const root = window.document.documentElement

    root.classList.remove("light", "dark")

    let resolved: string
    if (theme === "system") {
      resolved = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light"
    } else {
      resolved = theme
    }

    root.classList.add(resolved)
    setResolvedTheme(resolved)
  }, [theme, mounted])

  useEffect(() => {
    if (!mounted || theme !== "system") return

    const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)")
    const handleChange = () => {
      const resolved = mediaQuery.matches ? "dark" : "light"
      const root = window.document.documentElement
      root.classList.remove("light", "dark")
      root.classList.add(resolved)
      setResolvedTheme(resolved)
    }

    mediaQuery.addEventListener("change", handleChange)
    return () => mediaQuery.removeEventListener("change", handleChange)
  }, [theme, mounted])

  const value = {
    theme,
    setTheme: (newTheme: Theme) => {
      localStorage.setItem(storageKey, newTheme)
      setTheme(newTheme)
    },
    resolvedTheme,
  }

  return (
    <ThemeProviderContext.Provider value={value}>
      {children}
    </ThemeProviderContext.Provider>
  )
}

export function useTheme() {
  const context = useContext(ThemeProviderContext)

  if (context === undefined) {
    throw new Error("useTheme must be used within a ThemeProvider")
  }

  return context
}