104 lines
3 KiB
TypeScript
104 lines
3 KiB
TypeScript
import { createContext, useCallback, useContext, useEffect, useMemo, useState, type ReactNode } from "react";
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import { Moon, Sun } from "lucide-react";
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export type Theme = "light" | "dark";
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const storageKey = "telesrv.admin.theme";
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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 applyTheme(theme: Theme) {
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document.documentElement.setAttribute("data-theme", theme);
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document.documentElement.style.colorScheme = theme;
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}
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export function ThemeProvider({ children }: { children: ReactNode }) {
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const [theme, setThemeState] = useState<Theme>(() => initialTheme());
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useEffect(() => {
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applyTheme(theme);
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try {
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localStorage.setItem(storageKey, theme);
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} catch {
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// Theme persistence is best-effort.
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}
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}, [theme]);
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// Follow the OS preference until the user makes an explicit choice.
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useEffect(() => {
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if (!window.matchMedia) {
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return;
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}
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const media = window.matchMedia("(prefers-color-scheme: dark)");
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const onChange = (event: MediaQueryListEvent) => {
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let stored: string | null = null;
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try {
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stored = localStorage.getItem(storageKey);
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} catch {
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stored = null;
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}
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if (stored !== "light" && stored !== "dark") {
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setThemeState(event.matches ? "dark" : "light");
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}
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};
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media.addEventListener("change", onChange);
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return () => media.removeEventListener("change", onChange);
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}, []);
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const setTheme = useCallback((next: Theme) => setThemeState(next), []);
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const toggleTheme = useCallback(() => setThemeState((current) => (current === "dark" ? "light" : "dark")), []);
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const value = useMemo<ThemeContextValue>(() => ({ 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 value = useContext(ThemeContext);
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if (!value) {
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throw new Error("useTheme must be used inside ThemeProvider");
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}
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return value;
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}
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export function ThemeSwitch() {
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const { theme, toggleTheme } = useTheme();
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const nextIsDark = theme === "light";
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const label = nextIsDark ? "Switch to dark theme" : "Switch to light theme";
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return (
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<button
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className="theme-toggle"
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type="button"
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onClick={toggleTheme}
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aria-label={label}
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title={label}
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>
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{theme === "dark" ? <Sun size={16} /> : <Moon size={16} />}
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</button>
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);
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}
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function initialTheme(): Theme {
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try {
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const stored = localStorage.getItem(storageKey);
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if (stored === "light" || stored === "dark") {
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return stored;
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}
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} catch {
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// Storage is optional.
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}
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try {
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if (window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches) {
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return "dark";
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}
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} catch {
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// matchMedia can be unavailable in unusual embedded contexts.
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}
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return "light";
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}
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