ThemeToggle.tsx

import { useEffect, useState } from "preact/hooks";
import { IS_BROWSER } from "fresh/runtime";

export default function ThemeToggle() {
  const getPreferredTheme = () => {
    if (!IS_BROWSER) return "light";
    const storedTheme = localStorage.getItem("theme");
    if (storedTheme) return storedTheme;
    return window.matchMedia("(prefers-color-scheme: dark)").matches
      ? "dark"
      : "light";
  };

  const [theme, setTheme] = useState(getPreferredTheme);

  useEffect(() => {
    document.documentElement.classList.remove("light", "dark");
    document.documentElement.classList.add(theme);
    document.documentElement.setAttribute("data-theme", theme);
    localStorage.setItem("theme", theme);
  }, [theme]);

  const toggleTheme = () => {
    setTheme((prev) => (prev === "light" ? "dark" : "light"));
  };

  return (
    <button
      onClick={toggleTheme}
      class="dark-mode-toggle button p-1 rounded bg-background-primary mr-3"
      aria-label="Toggle Theme"
    >
      {theme === "light"
        ? (
          <>
            <svg
              class="fill-foreground-primary hover:fill-fresh w-6 h-6"
              viewBox="0 0 20 20"
              xmlns="http://www.w3.org/2000/svg"
            >
              <path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z">
              </path>
            </svg>
          </>
        )
        : (
          <>
            <svg
              class="fill-foreground-primary hover:fill-fresh w-6 h-6"
              viewBox="0 0 20 20"
              xmlns="http://www.w3.org/2000/svg"
            >
              <path
                d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1
                  0 100-2H3a1 1 0 000 2h1z"
                fill-rule="evenodd"
                clip-rule="evenodd"
              >
              </path>
            </svg>
          </>
        )}
    </button>
  );
}