40 lines
1.2 KiB
TypeScript
40 lines
1.2 KiB
TypeScript
import { createContext, useContext, useEffect, useState, type ReactNode } from "react";
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export type Theme = "dark" | "light";
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const STORAGE_KEY = "ui_theme";
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function detectInitialTheme(): Theme {
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const stored = localStorage.getItem(STORAGE_KEY);
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if (stored === "dark" || stored === "light") return stored;
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return window.matchMedia?.("(prefers-color-scheme: light)").matches ? "light" : "dark";
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}
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interface ThemeContextValue {
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theme: Theme;
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toggleTheme: () => void;
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}
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const ThemeContext = createContext<ThemeContextValue | undefined>(undefined);
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export function ThemeProvider({ children }: { children: ReactNode }) {
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const [theme, setTheme] = useState<Theme>(detectInitialTheme);
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useEffect(() => {
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document.documentElement.dataset.theme = theme;
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localStorage.setItem(STORAGE_KEY, theme);
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}, [theme]);
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function toggleTheme() {
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setTheme((current) => (current === "dark" ? "light" : "dark"));
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}
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return <ThemeContext.Provider value={{ theme, toggleTheme }}>{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 a ThemeProvider");
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return ctx;
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}
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