'use client'

import { createContext, useContext, useState, useEffect, type ReactNode } from 'react'

type Theme = 'light' | 'dark'

interface ThemeContextValue {
  theme: Theme
  toggleTheme: () => void
  setTheme: (theme: Theme) => void
}

const ThemeContext = createContext<ThemeContextValue | null>(null)

export function ThemeProvider({ children }: { children: ReactNode }) {
  const [theme, setThemeState] = useState<Theme>(() => {
    // Check localStorage first
    const stored = localStorage.getItem('theme') as Theme | null
    if (stored === 'light' || stored === 'dark') return stored
    // Fall back to system preference
    if (typeof window !== 'undefined' && window.matchMedia('(prefers-color-scheme: light)').matches) {
      return 'light'
    }
    return 'dark'
  })

  useEffect(() => {
    // Update document class and localStorage when theme changes
    document.documentElement.classList.remove('light', 'dark')
    document.documentElement.classList.add(theme)
    localStorage.setItem('theme', theme)
  }, [theme])

  const toggleTheme = () => {
    setThemeState(prev => prev === 'dark' ? 'light' : 'dark')
  }

  const setTheme = (newTheme: Theme) => {
    setThemeState(newTheme)
  }

  return (
    <ThemeContext.Provider value={{ theme, toggleTheme, setTheme }}>
      {children}
    </ThemeContext.Provider>
  )
}

export function useTheme() {
  const context = useContext(ThemeContext)
  if (!context) {
    throw new Error('useTheme must be used within a ThemeProvider')
  }
  return context
}