87 lines
2.4 KiB
TypeScript
87 lines
2.4 KiB
TypeScript
import { createContext, useContext, useEffect, useMemo, useState } from 'react';
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import type { ReactNode } from 'react';
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type Theme = 'light' | 'dark';
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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 STORAGE_KEY = 'trading-dashboard-theme-v2';
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const ThemeContext = createContext<ThemeContextValue | null>(null);
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function applyTheme(theme: Theme) {
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const root = document.documentElement;
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root.classList.toggle('dark', theme === 'dark');
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root.dataset.theme = theme;
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}
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function readStoredTheme(): Theme | null {
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if (typeof window === 'undefined') return null;
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try {
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const storage = window.localStorage;
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if (typeof storage?.getItem !== 'function') return null;
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const stored = storage.getItem(STORAGE_KEY);
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return stored === 'light' || stored === 'dark' ? stored : null;
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} catch {
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return null;
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}
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}
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function writeStoredTheme(theme: Theme) {
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try {
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const storage = window.localStorage;
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if (typeof storage?.setItem === 'function') {
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storage.setItem(STORAGE_KEY, theme);
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}
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} catch {
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// Theme persistence is best-effort; restricted storage should not break UI.
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}
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}
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function resolveInitialTheme(): Theme {
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if (typeof window === 'undefined') return 'light';
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const stored = readStoredTheme();
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if (stored) return stored;
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return 'light';
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}
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export function ThemeProvider({ children }: { children: ReactNode }) {
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const [theme, setThemeState] = useState<Theme>(() => resolveInitialTheme());
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useEffect(() => {
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applyTheme(theme);
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writeStoredTheme(theme);
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}, [theme]);
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useEffect(() => {
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const media = window.matchMedia?.('(prefers-color-scheme: dark)');
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if (!media) return;
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const handleChange = () => {
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if (readStoredTheme()) return;
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setThemeState(media.matches ? 'dark' : 'light');
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};
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media.addEventListener?.('change', handleChange);
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return () => media.removeEventListener?.('change', handleChange);
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}, []);
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const value = useMemo<ThemeContextValue>(() => ({
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theme,
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setTheme: setThemeState,
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toggleTheme: () => setThemeState(prev => (prev === 'dark' ? 'light' : 'dark')),
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}), [theme]);
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return <ThemeContext.Provider value={value}>{children}</ThemeContext.Provider>;
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}
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export function useTheme() {
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const ctx = useContext(ThemeContext);
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if (!ctx) {
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throw new Error('useTheme must be used within ThemeProvider');
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}
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return ctx;
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}
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