ThemeProvider.tsx

"use client"

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

interface ThemeContextType {
  mode: string;
  setMode: (mode: string) => void;
}

const ThemeContext = createContext<ThemeContextType | undefined>(undefined);

export function ThemeProvider({ children }: { children: React.ReactNode }) {
  const [mode, setMode] = useState('');

  const handleThemeChange = () => {
    if(
      localStorage.theme === 'dark' || 
      (!("theme" in localStorage) && 
      window.matchMedia("(prefers-color-scheme: dark)").matches)
    ) {
      setMode('dark');
      document.documentElement.classList.add('dark');
    } else {
      setMode('light');
      document.documentElement.classList.remove('dark');
    }
  }

  useEffect(() => {
    handleThemeChange();
  }, [mode])
  
  return (
    <ThemeContext.Provider value={{ mode, setMode }}>
      {children}
    </ThemeContext.Provider>
  )
}

export function useTheme() {
  const context = useContext(ThemeContext);

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

  return context;
}