import React, { createContext, useContext, useEffect, useState } from 'react';

type Theme = 'light' | 'dark';

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

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

export function ThemeProvider({ children }: { children: React.ReactNode }) {
  const [theme, setTheme] = useState<Theme>(() => {
    return (localStorage.getItem('theme') as Theme) || 'light';
  });

  useEffect(() => {
    const root = window.document.documentElement;

    // Admin panel forces light - never override it
    if (root.dataset.forceLight === 'true') {
      root.classList.remove('dark');
      root.style.colorScheme = 'light';
      return;
    }

    if (theme === 'dark') {
      root.classList.add('dark');
      root.style.colorScheme = 'dark';
    } else {
      root.classList.remove('dark');
      root.style.colorScheme = 'light';
    }

    localStorage.setItem('theme', theme);
  }, [theme]);

  const toggleTheme = () => setTheme((t) => (t === 'dark' ? 'light' : 'dark'));

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

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