SanYeCao-blog/src/components/ThemeIcon.astro

---
const pathname = Astro.url.pathname;
const segments = pathname.split("/").filter(Boolean);

const currentLang = segments[0] === "en" ? "en" : "zh";
const nextLang = currentLang === "zh" ? "en" : "zh";
const switchLabel = currentLang === "zh" ? "EN" : "中文";

if (segments.length > 0) {
    segments[0] = nextLang;
}

const switchHref = "/" + segments.join("/");
---

<div class="top-actions">
    <button id="themeToggle" aria-label="Toggle theme">
        <svg
            aria-hidden="true"
            width="30px"
            xmlns="http://www.w3.org/2000/svg"
            viewBox="0 0 24 24"
        >
            <path
                class="sun"
                fill-rule="evenodd"
                d="M12 17.5a5.5 5.5 0 1 0 0-11 5.5 5.5 0 0 0 0 11zm0 1.5a7 7 0 1 0 0-14 7 7 0 0 0 0 14zm12-7a.8.8 0 0 1-.8.8h-2.4a.8.8 0 0 1 0-1.6h2.4a.8.8 0 0 1 .8.8zM4 12a.8.8 0 0 1-.8.8H.8a.8.8 0 0 1 0-1.6h2.5a.8.8 0 0 1 .8.8zm16.5-8.5a.8.8 0 0 1 0 1l-1.8 1.8a.8.8 0 0 1-1-1l1.7-1.8a.8.8 0 0 1 1 0zM6.3 17.7a.8.8 0 0 1 0 1l-1.7 1.8a.8.8 0 1 1-1-1l1.7-1.8a.8.8 0 0 1 1 0zM12 0a.8.8 0 0 1 .8.8v2.5a.8.8 0 0 1-1.6 0V.8A.8.8 0 0 1 12 0zm0 20a.8.8 0 0 1 .8.8v2.4a.8.8 0 0 1-1.6 0v-2.4a.8.8 0 0 1 .8-.8zM3.5 3.5a.8.8 0 0 1 1 0l1.8 1.8a.8.8 0 1 1-1 1L3.5 4.6a.8.8 0 0 1 0-1zm14.2 14.2a.8.8 0 0 1 1 0l1.8 1.7a.8.8 0 0 1-1 1l-1.8-1.7a.8.8 0 0 1 0-1z"
            ></path>
            <path
                class="moon"
                fill-rule="evenodd"
                d="M16.5 6A10.5 10.5 0 0 1 4.7 16.4 8.5 8.5 0 1 0 16.4 4.7l.1 1.3zm-1.7-2a9 9 0 0 1 .2 2 9 9 0 0 1-11 8.8 9.4 9.4 0 0 1-.8-.3c-.4 0-.8.3-.7.7a10 10 0 0 0 .3.8 10 10 0 0 0 9.2 6 10 10 0 0 0 4-19.2 9.7 9.7 0 0 0-.9-.3c-.3-.1-.7.3-.6.7a9 9 0 0 1 .3.8z"
            ></path>
        </svg>
    </button>

    <a class="lang-switch" href={switchHref}>
        {switchLabel}
    </a>
</div>

<style>
    .top-actions {
        display: flex;
        align-items: center;
        gap: 0.7rem;
    }

    #themeToggle {
        border: 0;
        background: none;
        cursor: pointer;
        padding: 0.35rem;
        display: inline-flex;
        align-items: center;
        justify-content: center;
        border-radius: 999px;
        transition:
            transform 0.2s ease,
            opacity 0.2s ease;
        transform-origin: center;
    }

    #themeToggle:hover {
        transform: rotate(12deg);
    }

    #themeToggle:active {
        transform: rotate(18deg) scale(0.96);
    }

    .lang-switch {
        color: black; !important
        font-weight: 700; !important
        font-size: 0.95rem; !important
        text-decoration: none; !important
        line-height: 1; !important
    }

    .lang-switch:hover {
        text-decoration: underline; !important
    }

    .sun {
        fill: black;
    }

    .moon {
        fill: transparent;
    }

    :global(.dark) .sun {
        fill: transparent;
    }

    :global(.dark) .moon {
        fill: white;
    }

    :global(.dark) .lang-switch {
        color: #eaeaea;
    }
</style>

<script is:inline>
    function applyTheme() {
    const localStorageTheme = localStorage?.getItem("theme") ?? "";
    let theme = "light";

    if (["dark", "light"].includes(localStorageTheme)) {
      theme = localStorageTheme;
    } else if (window.matchMedia("(prefers-color-scheme: dark)").matches) {
      theme = "dark";
    }

    document.documentElement.classList.toggle("dark", theme === "dark");
    window.localStorage.setItem("theme", theme);
  }

  function bindThemeToggle() {
    const button = document.getElementById("themeToggle");
    if (!button) return;

    button.onclick = () => {
      const element = document.documentElement;
      element.classList.toggle("dark");

      const isDark = element.classList.contains("dark");
      localStorage.setItem("theme", isDark ? "dark" : "light");
    };
  }

  applyTheme();
  bindThemeToggle();

  document.addEventListener("astro:after-swap", () => {
    applyTheme();
    bindThemeToggle();
  });
</script>