80 lines
2.1 KiB
TypeScript
80 lines
2.1 KiB
TypeScript
import { useEffect, useState } from "react";
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type ThemeMode = "light" | "dark" | "auto";
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function getInitialMode(): ThemeMode {
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if (typeof window === "undefined") {
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return "auto";
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}
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const stored = window.localStorage.getItem("theme");
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if (stored === "light" || stored === "dark" || stored === "auto") {
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return stored;
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}
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return "auto";
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}
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function applyThemeMode(mode: ThemeMode) {
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const prefersDark = window.matchMedia("(prefers-color-scheme: dark)").matches;
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const resolved = mode === "auto" ? (prefersDark ? "dark" : "light") : mode;
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document.documentElement.classList.remove("light", "dark");
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document.documentElement.classList.add(resolved);
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if (mode === "auto") {
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document.documentElement.removeAttribute("data-theme");
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} else {
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document.documentElement.setAttribute("data-theme", mode);
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}
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document.documentElement.style.colorScheme = resolved;
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}
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export default function ThemeToggle() {
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const [mode, setMode] = useState<ThemeMode>("auto");
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useEffect(() => {
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const initialMode = getInitialMode();
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setMode(initialMode);
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applyThemeMode(initialMode);
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}, []);
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useEffect(() => {
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if (mode !== "auto") {
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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 = () => applyThemeMode("auto");
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media.addEventListener("change", onChange);
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return () => {
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media.removeEventListener("change", onChange);
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};
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}, [mode]);
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function toggleMode() {
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const nextMode: ThemeMode = mode === "light" ? "dark" : mode === "dark" ? "auto" : "light";
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setMode(nextMode);
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applyThemeMode(nextMode);
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window.localStorage.setItem("theme", nextMode);
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}
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const label =
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mode === "auto"
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? "Theme mode: auto (system). Click to switch to light mode."
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: `Theme mode: ${mode}. Click to switch mode.`;
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return (
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<button
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type="button"
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onClick={toggleMode}
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aria-label={label}
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title={label}
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className="rounded-full border border-[var(--chip-line)] bg-[var(--chip-bg)] px-3 py-1.5 text-sm font-semibold text-[var(--sea-ink)] shadow-[0_8px_22px_rgba(30,90,72,0.08)] transition hover:-translate-y-0.5"
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>
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{mode === "auto" ? "Auto" : mode === "dark" ? "Dark" : "Light"}
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</button>
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);
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}
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