'use client'
import { createContext, useContext, useEffect, useState } from 'react'

type Theme = 'dark' | 'light' | 'system'

type ThemeProviderProps = {
  children: React.ReactNode
  defaultTheme?: Theme
}

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' }: ThemeProviderProps) {
  const [theme, setTheme] = useState<Theme>(defaultTheme)
  const [mounted, setMounted] = useState(false)

  // Only access localStorage after component has mounted on the client
  useEffect(() => {
    setMounted(true)
    const storedTheme = localStorage.getItem('theme') as Theme
    if (storedTheme) {
      setTheme(storedTheme)
    }
  }, [])

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

    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, mounted])

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

  return <ThemeProviderContext.Provider 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
}