(() => {
  document.addEventListener("DOMContentLoaded", () => {
    // ---- Inject floating logos into .background ----
    const bg = document.querySelector(".background");
    if (bg && !bg.querySelector(".floating-logo")) {
      const isPost = !!document.querySelector(".article");
      const logoSrc = isPost ? "../logo.svg" : "logo.svg";
      for (let i = 0; i < 5; i++) {
        const img = document.createElement("img");
        img.src = logoSrc;
        img.className = "floating-logo";
        img.alt = "";
        img.setAttribute("aria-hidden", "true");
        bg.appendChild(img);
      }
    }

    // ---- Copy buttons on <pre> ----
    document.querySelectorAll("pre").forEach((pre) => {
      if (pre.querySelector(".copy-btn")) return;
      const code = pre.querySelector("code") || pre;
      const btn = document.createElement("button");
      btn.className = "copy-btn";
      btn.textContent = "Copy";
      btn.addEventListener("click", async () => {
        try {
          await navigator.clipboard.writeText(code.innerText);
          btn.textContent = "Copied!";
          setTimeout(() => (btn.textContent = "Copy"), 1200);
        } catch {
          btn.textContent = "Error";
          setTimeout(() => (btn.textContent = "Copy"), 1200);
        }
      });
      pre.appendChild(btn);
    });

    // ---- Article-only features: sidebar + collapsible code ----
    const article = document.querySelector(".article");
    if (!article) return;

    // Collect headings for TOC
    const headings = article.querySelectorAll("h1, h2, h3");
    const codeBlocks = article.querySelectorAll("pre");

    // Determine filenames from preceding h2
    const codeFiles = [];
    codeBlocks.forEach((pre, idx) => {
      let name = null;
      let el = pre.previousElementSibling;
      while (el) {
        if (el.tagName === "H2" || el.tagName === "H3") {
          const text = el.textContent.trim();
          if (text.match(/\.\w{1,5}$/) || text.match(/\.\w{1,5}\s/)) {
            name = text.replace(/\s*\(.*\)/, "").trim();
          }
          break;
        }
        el = el.previousElementSibling;
      }
      if (!name) name = `code-block-${idx + 1}.txt`;
      codeFiles.push({ name, pre });
    });

    // Make code blocks collapsible
    codeBlocks.forEach((pre, idx) => {
      const wrapper = document.createElement("div");
      wrapper.className = "code-collapsible";

      const toggle = document.createElement("button");
      toggle.className = "code-toggle";
      const fileName = codeFiles[idx].name;
      toggle.innerHTML = `<span class="code-toggle-arrow">▶</span> <span class="code-toggle-name">${fileName}</span>`;
      toggle.setAttribute("aria-expanded", "false");

      pre.parentNode.insertBefore(wrapper, pre);
      wrapper.appendChild(toggle);
      wrapper.appendChild(pre);
      pre.classList.add("collapsed");

      toggle.addEventListener("click", () => {
        const expanded = pre.classList.toggle("collapsed");
        toggle.setAttribute("aria-expanded", !expanded);
        toggle.querySelector(".code-toggle-arrow").textContent = expanded ? "▶" : "▼";
      });
    });

    // Build sidebar
    const sidebar = document.createElement("nav");
    sidebar.className = "article-sidebar";

    // TOC section
    const tocTitle = document.createElement("div");
    tocTitle.className = "sidebar-title";
    tocTitle.textContent = "Contents";
    sidebar.appendChild(tocTitle);

    const tocList = document.createElement("ul");
    tocList.className = "sidebar-toc";

    headings.forEach((h, i) => {
      if (!h.id) h.id = "heading-" + i;
      const li = document.createElement("li");
      li.className = "toc-" + h.tagName.toLowerCase();
      const a = document.createElement("a");
      a.href = "#" + h.id;
      a.textContent = h.textContent;
      a.addEventListener("click", (e) => {
        e.preventDefault();
        h.scrollIntoView({ behavior: "smooth", block: "start" });
      });
      li.appendChild(a);
      tocList.appendChild(li);
    });
    sidebar.appendChild(tocList);

    // Files section
    if (codeFiles.length > 0) {
      const filesTitle = document.createElement("div");
      filesTitle.className = "sidebar-title";
      filesTitle.textContent = "Files";
      sidebar.appendChild(filesTitle);

      const fileList = document.createElement("ul");
      fileList.className = "sidebar-files";

      codeFiles.forEach(({ name, pre }) => {
        const li = document.createElement("li");
        const btn = document.createElement("button");
        btn.className = "sidebar-file-btn";
        btn.innerHTML = `<svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/><polyline points="7 10 12 15 17 10"/><line x1="12" y1="15" x2="12" y2="3"/></svg> ${name}`;

        btn.addEventListener("click", () => {
          const code = pre.querySelector("code") || pre;
          const text = code.innerText;
          const blob = new Blob([text], { type: "text/plain" });
          const url = URL.createObjectURL(blob);
          const a = document.createElement("a");
          a.href = url;
          a.download = name;
          a.click();
          URL.revokeObjectURL(url);
        });

        li.appendChild(btn);
        fileList.appendChild(li);
      });
      sidebar.appendChild(fileList);
    }

    document.body.appendChild(sidebar);

    // Highlight active TOC item on scroll
    const tocLinks = tocList.querySelectorAll("a");
    const observer = new IntersectionObserver(
      (entries) => {
        entries.forEach((entry) => {
          if (entry.isIntersecting) {
            tocLinks.forEach((l) => l.classList.remove("active"));
            const link = tocList.querySelector(`a[href="#${entry.target.id}"]`);
            if (link) link.classList.add("active");
          }
        });
      },
      { rootMargin: "-80px 0px -70% 0px" }
    );
    headings.forEach((h) => observer.observe(h));
  });
})();