ThemeContext.tsx

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// distributed with this work for additional information
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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
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import React, { createContext, useContext, useState, useEffect } from 'react'
import { ThemeProvider } from '@mui/material/styles'
import { CssBaseline } from '@mui/material'
import { lightTheme, darkTheme } from '../theme/themes'

type ThemeMode = 'light' | 'dark' | 'system'

const ThemeContext = createContext<{
  themeMode: ThemeMode
  setThemeMode: (mode: ThemeMode) => void
}>({
  themeMode: 'system',
  setThemeMode: () => {}
})

export const useTheme = () => useContext(ThemeContext)

export const CustomThemeProvider: React.FC<{ children: React.ReactNode }> = ({ children }) => {
  const [themeMode, setThemeMode] = useState<ThemeMode>('system')
  const [systemPrefersDark, setSystemPrefersDark] = useState(false)

  useEffect(() => {
    if (typeof window !== 'undefined' && window.localStorage) {
      const saved = localStorage.getItem('theme-mode') as ThemeMode
      if (saved) setThemeMode(saved)
    }
    if (typeof window !== 'undefined' && window.matchMedia) {
      setSystemPrefersDark(window.matchMedia('(prefers-color-scheme: dark)').matches)
    }
  }, [])

  useEffect(() => {
    if (typeof window !== 'undefined' && window.localStorage) {
      localStorage.setItem('theme-mode', themeMode)
    }
  }, [themeMode])

  useEffect(() => {
    if (typeof window !== 'undefined' && window.matchMedia) {
      const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)')
      const handler = (e: MediaQueryListEvent) => setSystemPrefersDark(e.matches)
      mediaQuery.addEventListener('change', handler)
      return () => mediaQuery.removeEventListener('change', handler)
    }
  }, [])

  const isDark = themeMode === 'dark' || (themeMode === 'system' && systemPrefersDark)
  const currentTheme = isDark ? darkTheme : lightTheme

  return (
    <ThemeContext.Provider value={{ themeMode, setThemeMode }}>
      <ThemeProvider theme={currentTheme}>
        <CssBaseline />
        {children}
      </ThemeProvider>
    </ThemeContext.Provider>
  )
}