(() => {
  // Inject Quote buttons into Pandoc-style headings and copy a section-range quote to clipboard.
  //
  // Assumptions (matches your sample):
  // - Headings are h1/h2 with stable ids (anchors).
  // - A "section" is: the heading + all following sibling elements until the next heading
  //   of the same or higher level (H2 stops at next H2 or H1; H1 stops at next H1).
  //
  // Primary target: GroupMe. We optimize text/plain to be readable and "quote-like".
  // We still provide text/html for rich paste targets (Docs/Email).
  //
  // No dependencies.

  const HEADING_SELECTOR = "h1[id], h2[id]"; // change to "h2[id]" if you only want section-level

  document.addEventListener("DOMContentLoaded", () => {
    injectQuoteButtons();
  });

  function injectQuoteButtons() {
    document.querySelectorAll(HEADING_SELECTOR).forEach((heading) => {
      // Avoid double-injection
      if (heading.querySelector(":scope > .quote-btn")) return;

      const btn = document.createElement("button");
      btn.type = "button";
      btn.className = "quote-btn";
      btn.textContent = "";
      btn.innerHTML = `
      <span class="quote-icon" aria-hidden="true"></span>
      `;
      btn.addEventListener("click", (e) => {
        e.preventDefault();
        e.stopPropagation();
        onQuoteClick(btn, heading);
      });

      // Add a little separation from heading text
      heading.appendChild(document.createTextNode(" "));
      heading.appendChild(btn);
    });
  }

  async function onQuoteClick(btn, heading) {
    const originalText = btn.textContent;

    try {
      btn.textContent = "Copying…";
      btn.disabled = true;

      await copyQuotedSection(heading);

      btn.textContent = "Copied";
      setTimeout(() => {
        btn.textContent = originalText;
        btn.disabled = false;
      }, 800);
    } catch (err) {
      console.error(err);
      btn.textContent = "Failed";
      setTimeout(() => {
        btn.textContent = originalText;
        btn.disabled = false;
      }, 1200);
    }
  }

  async function copyQuotedSection(heading) {
    if (!heading.id) throw new Error("Heading missing id.");

    const level = heading.tagName; // H1 or H2

    // Clone heading + subsequent siblings for the quote range
    const nodes = [];
    nodes.push(heading.cloneNode(true));

    let el = heading.nextElementSibling;
    while (el) {
      if (isBoundary(level, el)) break;
      nodes.push(el.cloneNode(true));
      el = el.nextElementSibling;
    }

    // Remove injected button from cloned heading (so it doesn't show up in pasted content)
    nodes[0].querySelector(".quote-btn")?.remove();

    const container = document.createElement("div");
    nodes.forEach((n) => container.appendChild(n));

    const href = buildAnchorUrl(heading.id);

    // HTML (for rich paste targets)
    const html = buildHtmlQuote(container.innerHTML, href);

    // Plain text (optimized for GroupMe)
    const plain = buildGroupMePlainQuote(container, href);

    await writeClipboardMultiFormat({ html, plain, url: href });
  }

  function isBoundary(level, el) {
    // Stop at next heading of same or higher rank.
    // H2 stops at next H1 or H2.
    // H1 stops at next H1.
    if (level === "H1") return el.tagName === "H1";
    if (level === "H2") return el.tagName === "H1" || el.tagName === "H2";
    return false;
  }

  function buildAnchorUrl(id) {
    const url = new URL(window.location.href);
    url.hash = id;
    return url.toString();
  }

  function buildHtmlQuote(innerHtml, href) {
    const safeHref = escapeHtmlAttr(href);
    const safeText = escapeHtml(href);

    return `
      <blockquote>
        ${innerHtml}
        <p><a href="${safeHref}">${safeText}</a></p>
      </blockquote>
    `.trim();
  }

  function buildGroupMePlainQuote(container, href) {
    // Create a readable quote-like block:
    // - Prefix lines with "> " to visually indicate quoting (works even if not rendered specially)
    // - Include Source link
    const text = normalizePlainText(container);

    const quoted = text
      .split("\n")
      .map((line) => (line.trim().length ? `> ${line}` : `>`))
      .join("\n");

    return `${quoted}\n> \n> Source: ${href}`;
  }

  function normalizePlainText(container) {
    // Use innerText to approximate what the user sees (captures list numbering reasonably in many browsers).
    // Then normalize spacing.
    return (container.innerText || "")
      .replace(/\r\n/g, "\n")
      .replace(/\n{3,}/g, "\n\n")
      .trim();
  }

  async function writeClipboardMultiFormat({ html, plain, url }) {
    // Best path: multi-format clipboard write (Chromium/Edge, etc.)
    if (navigator.clipboard?.write) {
      const item = new ClipboardItem({
        "text/html": new Blob([html], { type: "text/html" }),
        "text/plain": new Blob([plain], { type: "text/plain" }),
        // Best-effort URL type; some paste targets prefer this
        "text/uri-list": new Blob([url], { type: "text/uri-list" }),
      });
      await navigator.clipboard.write([item]);
      return;
    }

    // Fallback: plain text only
    if (navigator.clipboard?.writeText) {
      await navigator.clipboard.writeText(plain);
      return;
    }

    throw new Error("Clipboard API unavailable.");
  }

  function escapeHtml(s) {
    return String(s)
      .replaceAll("&", "&amp;")
      .replaceAll("<", "&lt;")
      .replaceAll(">", "&gt;")
      .replaceAll('"', "&quot;")
      .replaceAll("'", "&#39;");
  }

  function escapeHtmlAttr(s) {
    return escapeHtml(s);
  }
})();