import { createContext } from 'react'

export type Theme = 'light' | 'dark'

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

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

const STORAGE_KEY = 'expria-theme'

export function getInitialTheme(): Theme {
  const stored = localStorage.getItem(STORAGE_KEY)
  if (stored === 'light' || stored === 'dark') return stored
  if (window.matchMedia('(prefers-color-scheme: light)').matches) return 'light'
  return 'dark'
}

export function applyTheme(theme: Theme): void {
  document.documentElement.classList.toggle('light', theme === 'light')
}

export function persistTheme(theme: Theme): void {
  localStorage.setItem(STORAGE_KEY, theme)
}