84 lines
2.2 KiB
TypeScript
84 lines
2.2 KiB
TypeScript
import React, { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react'
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const STORAGE_KEY = 'zui-theme'
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export type Theme = 'light' | 'dark'
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function readStored(): Theme | null {
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try {
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const s = localStorage.getItem(STORAGE_KEY)
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if (s === 'light' || s === 'dark') return s
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} catch (_) {}
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return null
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}
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function systemPrefersDark(): boolean {
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try {
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return window.matchMedia('(prefers-color-scheme: dark)').matches
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} catch (_) {
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return false
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}
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}
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type ThemeContextValue = {
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theme: Theme
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setTheme: (theme: Theme) => void
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toggleTheme: () => void
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}
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const ThemeContext = createContext<ThemeContextValue | null>(null)
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export function ThemeProvider({ children }: { children: React.ReactNode }) {
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const [theme, setThemeState] = useState<Theme>(() => {
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const stored = readStored()
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if (stored) return stored
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return systemPrefersDark() ? 'dark' : 'light'
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})
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useEffect(() => {
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const root = document.documentElement
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if (theme === 'dark') {
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root.classList.add('dark')
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} else {
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root.classList.remove('dark')
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}
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}, [theme])
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useEffect(() => {
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const m = window.matchMedia('(prefers-color-scheme: dark)')
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const handler = () => {
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if (readStored() != null) return
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setThemeState(m.matches ? 'dark' : 'light')
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}
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m.addEventListener('change', handler)
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return () => m.removeEventListener('change', handler)
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}, [])
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const setTheme = useCallback((next: Theme) => {
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setThemeState(next)
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try {
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localStorage.setItem(STORAGE_KEY, next)
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} catch (_) {}
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}, [])
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const toggleTheme = useCallback(() => {
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setThemeState((prev) => {
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const next = prev === 'light' ? 'dark' : 'light'
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try {
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localStorage.setItem(STORAGE_KEY, next)
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} catch (_) {}
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return next
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})
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}, [])
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const value = useMemo(() => ({ theme, setTheme, toggleTheme }), [theme, setTheme, toggleTheme])
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return <ThemeContext.Provider value={value}>{children}</ThemeContext.Provider>
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}
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export function useTheme(): ThemeContextValue {
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const ctx = useContext(ThemeContext)
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if (!ctx) throw new Error('useTheme must be used within ThemeProvider')
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return ctx
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}
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