SanYeCao-blog/src/components/Posts/PostMenu.astro

---
interface Heading {
    depth: number;
    slug: string;
    text: string;
}

interface Props {
    headings: Heading[];
}

const { headings = [] } = Astro.props;
const tocHeadings = headings.filter((h) => h.depth === 2 || h.depth === 3);
---

{
    tocHeadings.length > 0 && (
        <>
            <button
                class="post-menu-mobile-toggle"
                type="button"
                aria-expanded="false"
                aria-controls="post-menu-panel"
                aria-label="目录"
            >
                <span
                    class="post-menu-mobile-preview"
                    data-post-menu-preview
                    data-default-text={tocHeadings[0]?.text ?? "本文目录"}
                >
                    {tocHeadings[0]?.text ?? "本文目录"}
                </span>

                <span class="post-menu-mobile-icon" aria-hidden="true">
                    <svg
                        viewBox="0 0 24 24"
                        width="16"
                        height="16"
                        fill="none"
                        xmlns="http://www.w3.org/2000/svg"
                    >
                        <path
                            d="M5 6.5H19M5 12H19M5 17.5H19"
                            stroke="currentColor"
                            stroke-width="1.8"
                            stroke-linecap="round"
                        />
                        <circle cx="3.5" cy="6.5" r="1" fill="currentColor" />
                        <circle cx="3.5" cy="12" r="1" fill="currentColor" />
                        <circle cx="3.5" cy="17.5" r="1" fill="currentColor" />
                    </svg>
                </span>
            </button>

            <aside class="post-menu" id="post-menu-panel">
                <nav aria-label="Table of contents">
                    <p class="post-menu-title">目录</p>
                    <ul class="post-menu-list">
                        {tocHeadings.map((heading) => (
                            <li class={`post-menu-item depth-${heading.depth}`}>
                                <a
                                    href={`#${heading.slug}`}
                                    data-heading-link
                                    data-heading-text={heading.text}
                                >
                                    {heading.text}
                                </a>
                            </li>
                        ))}
                    </ul>
                </nav>
            </aside>
        </>
    )
}

<style is:global>
    :where(h1, h2, h3, h4, h5, h6) {
        scroll-margin-top: 4rem;
    }
</style>

<style>
    .post-menu {
        box-sizing: border-box;
    }

    .post-menu-title {
        margin: 0 0 0.7rem;
        padding-top: 0.65rem;

        background-image: linear-gradient(
            to right,
            rgba(65, 65, 65, 0.8) 0,
            rgba(65, 65, 65, 0.8) 8px,
            transparent 8px,
            transparent 14px
        );
        background-repeat: repeat-x;
        background-size: 14px 2px;
        background-position: top left;

        font-size: 1.1rem;
        font-weight: 600;
        opacity: 0.72;
    }

    .post-menu-list {
        position: relative;
        list-style: none;
        margin: 0;
        padding: 0 0 0 0.9rem;
        font-size: 1rem;
    }

    .post-menu-list::before {
        content: "";
        position: absolute;
        left: 0.15rem;
        top: 0.25rem;
        bottom: 0.25rem;
        width: 1px;
        background: rgba(128, 128, 128, 0.55);
    }

    .post-menu-item {
        position: relative;
        margin: 0.42rem 0;
        line-height: 1.45;
    }

    .post-menu-item.depth-3 {
        padding-left: 0.85rem;
        opacity: 0.82;
        font-size: 0.94em;
    }

    .post-menu a {
        color: inherit;
        text-decoration: none;
    }

    .post-menu a:hover {
        text-decoration: underline;
    }

    .post-menu-mobile-toggle {
        display: none;
    }

    @media (min-width: 1300px) {
        .post-menu {
            --content-width: 90ch;
            --menu-width: 180px;
            --menu-gap: 2.2rem;

            position: fixed;
            top: 8.5rem;
            width: var(--menu-width);

            left: calc(
                50vw - var(--content-width) / 2 - var(--menu-gap) -
                    var(--menu-width)
            );

            max-height: calc(100vh - 10rem);
            overflow: auto;
            padding: 0.2rem 0.2rem 0.2rem 0;
            opacity: 0.9;
        }
    }

    @media (max-width: 1299px) {
        .post-menu-mobile-toggle {
            display: inline-flex;
            align-items: center;
            gap: 0.25rem;
            position: fixed;
            top: 0.75rem;
            right: 0.8rem;
            z-index: 30;
            max-width: min(78vw, 22rem);
            padding: 0.6rem 0.75rem;
            border: 1.5px solid #536493;
            border-radius: 999px;
            background: rgba(255, 255, 255, 0.92);
            backdrop-filter: blur(6px);
            color: inherit;
            font-size: 0.85rem;
            cursor: pointer;
            opacity: 0;
            transform: translateY(calc(-100% - 0.6rem));
            pointer-events: none;
            transition:
                transform 0.28s ease,
                opacity 0.22s ease;
        }

        .post-menu-mobile-toggle.is-visible {
            opacity: 1;
            transform: translateY(calc(env(safe-area-inset-top) + 0.4rem));
            pointer-events: auto;
        }

        .post-menu-mobile-icon {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            flex: 0 0 auto;
            opacity: 0.78;
        }

        .post-menu-mobile-preview {
            display: inline-block;
            width: 10rem;
            /* height: 1rem; */
            overflow: hidden;
            text-overflow: ellipsis;
            white-space: nowrap;
            text-align: left;
        }

        .post-menu {
            display: none;
            position: fixed;
            top: calc(env(safe-area-inset-top) + 4.2rem);
            right: 0.8rem;
            z-index: 29;
            width: min(88vw, 24rem);
            max-height: min(65vh, 32rem);
            overflow: auto;
            padding: 0.9rem 1rem;
            border: 1.5px solid rgba(128, 128, 128, 0.55);
            background: rgba(255, 255, 255, 0.96);
            backdrop-filter: blur(8px);
            box-shadow: 0 6px 24px rgba(0, 0, 0, 0.08);
        }

        .post-menu-title {
            padding-top: 0;
            background-image: none;
        }

        .post-menu.is-open {
            display: block;
        }
    }
</style>

<script is:inline>
    (() => {
        const setupPostMenu = () => {
            const btn = document.querySelector(".post-menu-mobile-toggle");
            const panel = document.querySelector("#post-menu-panel");
            const preview = document.querySelector("[data-post-menu-preview]");
            const headingLinks = Array.from(
                document.querySelectorAll("[data-heading-link]"),
            );

            if (!btn || !panel || !preview || headingLinks.length === 0) return;
            if (btn.dataset.bound === "true") return;
            btn.dataset.bound = "true";

            const defaultText =
                preview.getAttribute("data-default-text") || "本文目录";

            const getHeadingElements = () =>
                headingLinks
                    .map((link) => {
                        const href = link.getAttribute("href");
                        if (!href || !href.startsWith("#")) return null;

                        const el = document.getElementById(href.slice(1));
                        if (!el) return null;

                        return {
                            link,
                            el,
                            text:
                                link.getAttribute("data-heading-text") ||
                                el.textContent ||
                                defaultText,
                        };
                    })
                    .filter(Boolean);

            let headingItems = getHeadingElements();

            const closeMenu = () => {
                panel.classList.remove("is-open");
                btn.setAttribute("aria-expanded", "false");
            };

            document.addEventListener("click", (e) => {
                const target = e.target;
                if (!(target instanceof Node)) return;

                const clickedInsidePanel = panel.contains(target);
                const clickedButton = btn.contains(target);

                if (!clickedInsidePanel && !clickedButton) {
                    closeMenu();
                }
            });

            const updateVisibility = () => {
                if (window.innerWidth >= 1300) {
                    btn.classList.remove("is-visible");
                    closeMenu();
                    return;
                }

                const shouldShow = window.scrollY > 80;
                btn.classList.toggle("is-visible", shouldShow);

                if (!shouldShow) {
                    closeMenu();
                }
            };

            const updateCurrentHeading = () => {
                if (window.innerWidth >= 1300) return;

                headingItems = getHeadingElements();

                let current = null;
                const triggerLine = 140;

                for (const item of headingItems) {
                    const rect = item.el.getBoundingClientRect();
                    if (rect.top <= triggerLine) {
                        current = item;
                    } else {
                        break;
                    }
                }

                preview.textContent = current ? current.text : defaultText;

                headingLinks.forEach((link) =>
                    link.classList.remove("is-current"),
                );
                if (current) current.link.classList.add("is-current");
            };

            const toggleMenu = () => {
                const expanded = btn.getAttribute("aria-expanded") === "true";
                btn.setAttribute("aria-expanded", String(!expanded));
                panel.classList.toggle("is-open", !expanded);
            };

            btn.addEventListener("click", toggleMenu);

            panel.addEventListener("click", (e) => {
                const target = e.target;
                if (!(target instanceof Element)) return;

                const link = target.closest("a[data-heading-link]");
                if (!link) return;

                const href = link.getAttribute("href");
                if (!href || !href.startsWith("#")) return;

                const el = document.getElementById(href.slice(1));
                if (!el) return;

                e.preventDefault();

                el.scrollIntoView({
                    behavior: "smooth",
                    block: "start",
                });

                history.replaceState(null, "", href);
                closeMenu();
            });

            const onScroll = () => {
                updateVisibility();
                updateCurrentHeading();
            };

            window.addEventListener("scroll", onScroll, { passive: true });
            window.addEventListener("resize", onScroll);

            updateVisibility();
            updateCurrentHeading();
        };

        setupPostMenu();
        document.addEventListener("astro:page-load", setupPostMenu);
    })();
</script>