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/// <reference lib="dom" />
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function getTargetRow(rowId: string): HTMLElement | null {
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  const row = document.getElementById(rowId);
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  if (!row || !row.classList.contains("code-line")) {
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    return null;
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  }
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  return row;
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}
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function clearCurrentHighlight() {
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  document.querySelector("#blob-code .line-highlight")?.classList.remove("line-highlight");
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}
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function highlightRow(rowId: string, smooth: boolean) {
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  const row = getTargetRow(rowId);
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  if (!row) {
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    clearCurrentHighlight();
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    return;
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  }
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  clearCurrentHighlight();
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  row.classList.add("line-highlight");
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  row.scrollIntoView({ block: "center", behavior: smooth ? "smooth" : "auto" });
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}
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function highlightCurrentHash(smooth: boolean) {
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  const hash = window.location.hash;
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  if (!/^#L\d+$/.test(hash)) {
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    clearCurrentHighlight();
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    return;
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  }
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  highlightRow(hash.slice(1), smooth);
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}
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export function initCodeLineAnchors() {
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  if (!document.getElementById("blob-code")) {
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    return;
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  }
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  document.addEventListener("click", (event) => {
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    const target = event.target as HTMLElement;
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    const link = target.closest<HTMLAnchorElement>('#blob-code .line-num a[href^="#L"]');
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    const href = link?.getAttribute("href") || "";
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    if (!link || !/^#L\d+$/.test(href)) {
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      return;
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    }
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    const rowId = href.slice(1);
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    if (!getTargetRow(rowId)) {
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      return;
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    }
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    event.preventDefault();
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    const nextHash = `#${rowId}`;
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    if (window.location.hash === nextHash) {
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      highlightRow(rowId, true);
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      return;
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    }
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    history.pushState(null, "", nextHash);
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    highlightRow(rowId, true);
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  });
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  window.addEventListener("hashchange", () => {
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    highlightCurrentHash(true);
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  });
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  highlightCurrentHash(false);
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}