mirror of
https://github.com/jakejarvis/jarv.is.git
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98 lines
3.7 KiB
TypeScript
98 lines
3.7 KiB
TypeScript
import { createContext, useCallback, useEffect, useMemo, useState } from "react";
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import useLocalStorage from "../hooks/useLocalStorage";
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import useMedia from "../hooks/useMedia";
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import { themeStorageKey } from "../lib/styles/stitches.config";
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import type { Context, PropsWithChildren } from "react";
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export const ThemeContext: Context<{
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/**
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* If the user's theme preference is unset, this returns whether the system preference resolved to "light" or "dark".
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* If the user's theme preference is set, the preference is returned instead, regardless of their system's theme.
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*/
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activeTheme: string;
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/** Update the theme manually and save to local storage. */
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setTheme: (theme: string) => void;
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}> = createContext({
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activeTheme: "",
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// eslint-disable-next-line @typescript-eslint/no-unused-vars, @typescript-eslint/no-empty-function
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setTheme: (_) => {},
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});
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// provider used once in _app.tsx to wrap entire app
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export const ThemeProvider = ({
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classNames,
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children,
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}: PropsWithChildren<{
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/** Mapping of theme name ("light", "dark") to the corresponding `<html>`'s class names. */
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classNames: {
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[themeName: string]: string;
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};
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}>) => {
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// keep track of if/when the user has set their theme *on this site*
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const [preferredTheme, setPreferredTheme] = useLocalStorage(themeStorageKey);
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// keep track of changes to the user's OS/browser dark mode setting
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const [systemTheme, setSystemTheme] = useState("");
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// hook into system `prefers-dark-mode` setting
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// https://web.dev/prefers-color-scheme/#the-prefers-color-scheme-media-query
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const isSystemDark = useMedia("(prefers-color-scheme: dark)");
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// get the theme names (light, dark) via passed-in classnames' keys
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const themeNames = Object.keys(classNames);
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// updates the DOM and optionally saves the new theme to local storage
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const changeTheme = useCallback(
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(theme: string, updateStorage?: boolean) => {
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if (updateStorage) {
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setPreferredTheme(theme);
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}
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// remove all theme classes first to start fresh
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const all = Object.values(classNames);
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document.documentElement.classList.remove(...all);
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document.documentElement.classList.add(classNames[theme]);
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},
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[classNames, setPreferredTheme]
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);
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// listen for changes in OS preference
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useEffect(() => {
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// translate boolean to theme string
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const systemResolved = isSystemDark ? "dark" : "light";
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// keep track of the system theme whether or not we override it manually
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setSystemTheme(systemResolved);
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// only actually change the theme if preference is unset (and *don't* save new theme to storage)
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if (!preferredTheme || !themeNames.includes(preferredTheme)) {
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changeTheme(systemResolved, false);
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}
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}, [changeTheme, themeNames, preferredTheme, isSystemDark]);
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// color-scheme handling (tells browser how to render built-in elements like forms, scrollbars, etc.)
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useEffect(() => {
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// only "light" and "dark" are valid here
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// https://web.dev/color-scheme/#the-color-scheme-css-property
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const colorScheme = preferredTheme && ["light", "dark"].includes(preferredTheme) ? preferredTheme : systemTheme;
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document.documentElement.style?.setProperty("color-scheme", colorScheme);
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}, [preferredTheme, systemTheme]);
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const providerValues = useMemo(
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() => ({
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activeTheme: preferredTheme && themeNames.includes(preferredTheme) ? preferredTheme : systemTheme,
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setTheme: (theme: string) => {
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// force save to local storage
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changeTheme(theme, true);
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},
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}),
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[changeTheme, preferredTheme, systemTheme, themeNames]
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);
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return <ThemeContext.Provider value={providerValues}>{children}</ThemeContext.Provider>;
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};
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// debugging help pls
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if (process.env.NODE_ENV !== "production") {
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ThemeContext.displayName = "ThemeContext";
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}
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