// === Configuration ========================================================

const HF_DATASET_BASE_URL = "https://huggingface.co/datasets/turnstilelabs/mathxiv/resolve/main/data";
const MAX_VERSION_TO_TRY = 9;
const CACHE_KEY_PREFIX = "arxigraph_meta_v3_"; // Incremented to force fresh cache logic

const inputEl = document.getElementById("arxiv-input");
const loadBtn = document.getElementById("load-btn");
const samplePapersEl = document.getElementById("sample-papers");
const heroCarouselEl = document.querySelector(".hero-carousel");
const homeTitleEl = document.getElementById("home-title");
const carouselPrevBtn = document.getElementById("carousel-prev");
const carouselNextBtn = document.getElementById("carousel-next");
const paperTitleEl = document.getElementById("paper-title");
const paperAuthorsEl = document.getElementById("paper-authors");
const paperAbstractEl = document.getElementById("paper-abstract");
const paperStatusTextEl = document.getElementById("paper-status-text");
const paperErrorTextEl = document.getElementById("paper-error-text");
const paperLinkEl = document.getElementById("paper-link");
const definitionBankEl = document.getElementById("definition-bank");
const paperAreaEl = document.getElementById("paper-area");
const paperHeaderEl = document.getElementById("paper-header");
const graphSectionEl = document.getElementById("graph-section");
const emptyStateEl = document.getElementById("empty-state");
const infoPanelEl = document.getElementById("info-panel");
const infoTitleEl = document.getElementById("info-title");
const infoBodyEl = document.getElementById("info-body");
const closeInfoPanelBtn = document.getElementById("close-info-panel");

const svg = d3.select("#graph");
const tooltip = d3.select("#tooltip");
let currentSimulation = null;

// Sample papers carousel state
let samplePapersData = [];
let sampleCarouselIndex = 0;

// Queue State
const metadataQueue = [];
let isProcessingQueue = false;

// Lightweight graph UI state
const graphState = {
  hiddenTypes: new Set(),
  selectedNodeElement: null,
};

const graphRefs = {
  nodeGroups: null,
  links: null,
  simulation: null,
};

if (closeInfoPanelBtn && infoPanelEl) {
  closeInfoPanelBtn.addEventListener("click", () => {
    infoPanelEl.classList.remove("visible");
    if (graphState.selectedNodeElement) {
      graphState.selectedNodeElement.classList.remove("selected");
      graphState.selectedNodeElement = null;
    }
  });
}

// === Helpers ==============================================================

function cleanLatex(content) {
  if (!content) return "";
  // Normalize whitespace and remove common LaTeX artifacts
  const normalized = String(content).replace(/\\\\/g, "\\").replace(/\s+/g, ' ');
  return normalized.replace(/\\label\{[^}]*\}/g, "").trim();
}

async function typesetMath(elements) {
  try {
    if (typeof window === "undefined") return;
    const filtered = (elements || []).filter(Boolean);
    if (!filtered.length) return;
    const mj = window.MathJax;
    if (!mj || typeof mj.typesetPromise !== "function") return;
    if (mj.startup && mj.startup.promise) {
      await mj.startup.promise;
    }
    await mj.typesetPromise(filtered);
  } catch (e) {
    console.warn("MathJax typesetting failed", e);
  }
}

function setStatus(msg, kind = "info") {
  if (!paperStatusTextEl || !paperErrorTextEl) return;
  if (kind === "error") {
    paperStatusTextEl.textContent = "";
    paperErrorTextEl.textContent = msg;
  } else {
    paperErrorTextEl.textContent = "";
    paperStatusTextEl.textContent = msg;
  }
}

function normalizeInputId(raw) {
  let id = String(raw || "").trim();
  if (!id) return "";
  id = id.replace(/^arxiv:/i, "");
  id = id.replace(/^arxiv_/i, "");
  return id;
}

function hasExplicitVersion(id) {
  return /v\d+$/i.test(id);
}

function stripArxivVersion(id) {
  return String(id || "").replace(/v\d+$/i, "");
}

function buildCandidateIds(baseId) {
  if (!baseId) return [];
  if (hasExplicitVersion(baseId)) return [baseId];
  const candidates = [];
  for (let v = 1; v <= MAX_VERSION_TO_TRY; v++) {
    candidates.push(`${baseId}v${v}`);
  }
  return candidates;
}

function buildFileUrl(arxivIdWithVersion) {
  const safeId = arxivIdWithVersion.replace("/", "_");
  const fileName = `arxiv_${safeId}.json`;
  return `${HF_DATASET_BASE_URL}/${fileName}`;
}

async function fetchFirstExisting(candidates) {
  for (const id of candidates) {
    const url = buildFileUrl(id);
    try {
      const res = await fetch(url, { cache: "no-store" });
      if (!res.ok) continue;
      const data = await res.json();
      return { arxivId: id, data, url };
    } catch (err) {
      // ignore
    }
  }
  return null;
}

function truncate(text, max = 160) {
  if (!text) return "";
  if (text.length <= max) return text;
  const t = text.slice(0, max);
  const lastSpace = t.lastIndexOf(" ");
  return (lastSpace > 40 ? t.slice(0, lastSpace) : t) + "...";
}

function clearGraph() {
  svg.selectAll("*").remove();
  if (currentSimulation) {
    currentSimulation.stop();
    currentSimulation = null;
  }
}

function resetToLandingView() {
  if (heroCarouselEl) heroCarouselEl.classList.remove("hidden");
  if (inputEl) inputEl.value = "";
  setStatus("", "info");
  clearGraph();
  renderDefinitionBank(null);
  if (paperAreaEl) paperAreaEl.classList.add("hidden");
  if (paperHeaderEl) paperHeaderEl.classList.add("hidden");
  if (graphSectionEl) graphSectionEl.classList.add("hidden");
  if (emptyStateEl) emptyStateEl.classList.remove("hidden");
  if (infoPanelEl) infoPanelEl.classList.remove("visible");
  window.scrollTo({ top: 0, behavior: "smooth" });
}

function delay(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

// === Caching & Queuing System =============================================

function getCachedMetadata(arxivId) {
  try {
    const raw = localStorage.getItem(CACHE_KEY_PREFIX + arxivId);
    if (raw) return JSON.parse(raw);
  } catch (e) { /* ignore */ }
  return null;
}

function setCachedMetadata(arxivId, data) {
  try {
    if (data && (data.title || data.authors)) {
      localStorage.setItem(CACHE_KEY_PREFIX + arxivId, JSON.stringify(data));
    }
  } catch (e) { /* ignore */ }
}

function requestMetadata(arxivId, urgent = false) {
  return new Promise((resolve) => {
    // 1. Check Cache
    const cached = getCachedMetadata(arxivId);
    if (cached) {
      resolve(cached);
      return;
    }

    // 2. Add to Queue
    const task = { arxivId, resolve };
    if (urgent) {
      metadataQueue.unshift(task);
    } else {
      metadataQueue.push(task);
    }

    // 3. Process
    if (!isProcessingQueue) {
      processQueue();
    }
  });
}

async function processQueue() {
  if (isProcessingQueue) return;
  isProcessingQueue = true;

  while (metadataQueue.length > 0) {
    const { arxivId, resolve } = metadataQueue.shift();

    let result = null;
    try {
      result = await fetchMetadataWithStrategies(arxivId);
    } catch (e) {
      console.warn(`Failed to load meta for ${arxivId}`, e);
    }

    if (result) {
      setCachedMetadata(arxivId, result);
    }

    resolve(result);

    // Throttle requests (1.2s)
    if (metadataQueue.length > 0) {
      await delay(1200);
    }
  }

  isProcessingQueue = false;
}

// === Metadata Strategies ================================================

async function fetchMetadataWithStrategies(arxivId) {
  // Strategy 1: Semantic Scholar
  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 6000);

    const baseId = stripArxivVersion(arxivId);
    const url = `https://api.semanticscholar.org/graph/v1/paper/ARXIV:${baseId}?fields=title,abstract,authors`;

    const res = await fetch(url, { signal: controller.signal });
    clearTimeout(timeout);

    if (res.status === 429) throw new Error("Rate Limited");
    if (!res.ok) throw new Error("S2 Failed");

    const data = await res.json();
    return {
      title: data.title,
      // Handle rare case where S2 returns title but null abstract
      abstract: data.abstract || null,
      authors: (data.authors || []).map(a => a.name)
    };
  } catch (err) {
    // Strategy 2: ArXiv Proxy
    return await fetchArxivProxy(arxivId);
  }
}

async function fetchArxivProxy(arxivId) {
  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 8000);

    const target = `https://export.arxiv.org/api/query?search_query=id:${arxivId}&max_results=1`;
    const proxyUrl = `https://corsproxy.io/?${encodeURIComponent(target)}`;

    const res = await fetch(proxyUrl, { signal: controller.signal });
    clearTimeout(timeout);

    if (!res.ok) return null;

    const text = await res.text();
    const parser = new DOMParser();
    const doc = parser.parseFromString(text, "application/xml");
    const entry = doc.getElementsByTagName("entry")[0];

    if (!entry) return null;

    return {
      title: entry.getElementsByTagName("title")[0]?.textContent?.trim(),
      abstract: entry.getElementsByTagName("summary")[0]?.textContent?.trim(),
      authors: Array.from(entry.getElementsByTagName("author")).map(a => a.textContent.trim())
    };
  } catch (e) {
    return null;
  }
}

// === Sample Papers Carousel =============================================

function formatAuthorList(authors, maxVisible = 2) {
  if (!Array.isArray(authors) || !authors.length) return "";
  if (authors.length <= maxVisible) return authors.join(", ");
  const visible = authors.slice(0, maxVisible).join(", ");
  return `${visible} et al.`;
}

async function updateCardMetadata(card, arxivId) {
  const authorsEl = card.querySelector(".sample-paper-authors");
  const meta = await requestMetadata(arxivId, false);
  if (meta && meta.authors && authorsEl) {
    authorsEl.textContent = formatAuthorList(meta.authors);
  }
}

function renderSamplePapers() {
  if (!samplePapersEl || !Array.isArray(samplePapersData) || !samplePapersData.length) return;

  samplePapersEl.innerHTML = "";
  const total = samplePapersData.length;
  const visibleCount = Math.min(3, total);

  for (let i = 0; i < visibleCount; i++) {
    const idx = (sampleCarouselIndex + i) % total;
    const paper = samplePapersData[idx];
    if (!paper || !paper.arxiv_id) continue;

    const card = document.createElement("button");
    card.type = "button";
    card.className = "sample-paper-card";

    const titleEl = document.createElement("p");
    titleEl.className = "sample-paper-title";
    titleEl.textContent = truncate(paper.title || paper.arxiv_id, 80);
    card.appendChild(titleEl);

    const authorsEl = document.createElement("p");
    authorsEl.className = "sample-paper-authors";

    if (paper.authors) {
      authorsEl.textContent = Array.isArray(paper.authors) ? formatAuthorList(paper.authors) : paper.authors;
    } else {
      authorsEl.textContent = paper.arxiv_id;
      updateCardMetadata(card, paper.arxiv_id);
    }
    card.appendChild(authorsEl);

    card.addEventListener("click", () => {
      inputEl.value = paper.arxiv_id;
      handleLoadClick();
    });

    samplePapersEl.appendChild(card);
  }
}

async function initSamplePapers() {
  if (!samplePapersEl) return;
  try {
    const res = await fetch("./data/data.json", { cache: "no-store" });
    if (!res.ok) return;
    const papers = await res.json();
    samplePapersData = Array.isArray(papers) ? papers : [];
    sampleCarouselIndex = 0;
    renderSamplePapers();

    if (carouselPrevBtn && carouselNextBtn) {
      carouselPrevBtn.onclick = () => {
        sampleCarouselIndex = (sampleCarouselIndex - 1 + samplePapersData.length) % samplePapersData.length;
        renderSamplePapers();
      };
      carouselNextBtn.onclick = () => {
        sampleCarouselIndex = (sampleCarouselIndex + 1) % samplePapersData.length;
        renderSamplePapers();
      };
    }
  } catch (err) {
    console.warn("Failed to load sample papers", err);
  }
}

// === Metadata Display on Main View ======================================

function renderMetadataSkeleton(arxivId) {
  paperTitleEl.textContent = `Loading ${arxivId}…`;
  paperAuthorsEl.textContent = "";
  paperAbstractEl.textContent = "";
  paperLinkEl.href = arxivId ? `https://arxiv.org/abs/${arxivId}` : "https://arxiv.org/";
}

function applyMetadataFromDataset(arxivId, rawData) {
  const meta = rawData.metadata || rawData.meta || {};

  const titleCandidate =
    meta.title || rawData.title || rawData.paper_title || rawData.paperTitle || null;

  const abstractCandidate =
    meta.abstract || rawData.abstract || rawData.summary || rawData.paper_abstract || "";

  let authorsCandidate = [];
  if (Array.isArray(meta.authors)) authorsCandidate = meta.authors;
  else if (Array.isArray(rawData.authors)) authorsCandidate = rawData.authors;
  else if (typeof meta.authors === "string") authorsCandidate = meta.authors.split(",").map(s => s.trim());

  if (titleCandidate) paperTitleEl.textContent = titleCandidate;
  else paperTitleEl.textContent = arxivId;

  if (authorsCandidate.length > 0) paperAuthorsEl.textContent = authorsCandidate.join(", ");

  if (abstractCandidate) {
    paperAbstractEl.textContent = abstractCandidate;
    void typesetMath([paperAbstractEl]);
  }
}

async function enhanceMetadata(arxivId) {
  // Urgent request to queue
  const meta = await requestMetadata(arxivId, true);
  if (!meta) return;

  // --- FIX: Unconditional Overwrite Strategy ---
  // Always prefer the API data over the static dataset data for the view

  if (meta.title && meta.title.length > 0) {
    paperTitleEl.textContent = meta.title;
  }

  if (meta.authors && meta.authors.length > 0) {
    paperAuthorsEl.textContent = meta.authors.join(", ");
  }

  // Always overwrite abstract if the API returned one (even if dataset had one)
  // The API is the "source of truth".
  if (meta.abstract && meta.abstract.length > 0) {
    paperAbstractEl.textContent = meta.abstract;
    void typesetMath([paperAbstractEl]);
  }
}

// === Graph rendering with D3 ============================================

function typeColor(type) {
  const t = String(type || "").toLowerCase();
  if (["theorem", "proposition", "lemma"].includes(t)) return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-theorem").trim();
  if (["fact", "example"].includes(t)) return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-example").trim();
  if (["remark", "observation"].includes(t)) return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-remark").trim();
  if (t === "corollary") return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-corollary").trim();
  if (t === "definition") return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-definition").trim();
  if (["external_reference", "external", "citation"].includes(t)) return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-external").trim();
  return getComputedStyle(document.documentElement).getPropertyValue("--graph-node-generic").trim();
}

function applyLegendVisibility() {
  if (!graphRefs.nodeGroups || !graphRefs.links) return;
  graphRefs.nodeGroups.style("display", (d) => graphState.hiddenTypes.has(String(d.type || "").toLowerCase()) ? "none" : null);
  graphRefs.links.style("display", (d) => {
    const sType = String(d.source.type || "").toLowerCase();
    const tType = String(d.target.type || "").toLowerCase();
    return (!graphState.hiddenTypes.has(sType) && !graphState.hiddenTypes.has(tType)) ? null : "none";
  });
  if (graphRefs.simulation) graphRefs.simulation.alpha(0.3).restart();
}

function setupLegend(nodes, links, onResetView) {
  const nodeLegendContainer = document.getElementById("node-legend-container");
  const legendStatsEl = document.getElementById("legend-stats");
  const legendToggleBtn = document.getElementById("legend-toggle");
  const legendRoot = document.getElementById("legend-root");

  if (!nodeLegendContainer) return;
  nodeLegendContainer.innerHTML = "";

  if (legendStatsEl) legendStatsEl.textContent = `${nodes.length} artifacts · ${links.length} links`;

  const typeSet = new Set(nodes.map(n => String(n.type || "").toLowerCase()));
  Array.from(typeSet).sort().forEach(type => {
    const item = document.createElement("div");
    item.className = "legend-item";
    const color = document.createElement("div");
    color.className = "legend-color";
    color.style.backgroundColor = typeColor(type);
    const label = document.createElement("span");
    label.textContent = type.charAt(0).toUpperCase() + type.slice(1).replace(/_/g, " ");
    item.appendChild(color);
    item.appendChild(label);
    item.onclick = () => {
      if (graphState.hiddenTypes.has(type)) {
        graphState.hiddenTypes.delete(type);
        item.classList.remove("inactive");
      } else {
        graphState.hiddenTypes.add(type);
        item.classList.add("inactive");
      }
      applyLegendVisibility();
    };
    nodeLegendContainer.appendChild(item);
  });

  if (legendToggleBtn && legendRoot) {
    legendToggleBtn.onclick = () => {
      legendRoot.classList.toggle("legend--collapsed");
      legendToggleBtn.textContent = legendRoot.classList.contains("legend--collapsed") ? "▾" : "▸";
    };
  }
}

function renderGraph(graph) {
  clearGraph();
  const container = document.querySelector(".graph-container");
  const width = container.clientWidth || 800;
  const height = container.clientHeight || 600;

  const nodes = (graph.nodes || []).map(n => ({ ...n }));
  const idMap = new Map(nodes.map(n => [n.id, n]));
  const links = (graph.edges || []).map(e => ({
    source: idMap.get(e.source) || e.source,
    target: idMap.get(e.target) || e.target,
    type: e.type || "edge"
  })).filter(e => typeof e.source === 'object' && typeof e.target === 'object');

  const degrees = new Map();
  links.forEach(l => {
    degrees.set(l.source.id, (degrees.get(l.source.id) || 0) + 1);
    degrees.set(l.target.id, (degrees.get(l.target.id) || 0) + 1);
  });
  const radiusScale = d3.scaleSqrt().domain([0, 10]).range([10, 25]).clamp(true);

  const zoom = d3.zoom().scaleExtent([0.1, 4]).on("zoom", (e) => g.attr("transform", e.transform));
  svg.attr("viewBox", `0 0 ${width} ${height}`).call(zoom);
  const g = svg.append("g");

  g.append("defs").append("marker")
    .attr("id", "arrow").attr("viewBox", "0 -5 10 10")
    .attr("refX", 18).attr("refY", 0).attr("markerWidth", 6).attr("markerHeight", 6)
    .attr("orient", "auto").append("path").attr("d", "M0,-5L10,0L0,5").attr("fill", "#777");

  const link = g.append("g").selectAll("line")
    .data(links).enter().append("line")
    .attr("stroke", "#555").attr("stroke-opacity", 0.6).attr("stroke-width", 1)
    .attr("marker-end", "url(#arrow)");

  const node = g.append("g").selectAll("g")
    .data(nodes).enter().append("g").attr("class", "graph-node")
    .call(d3.drag().on("start", dragStarted).on("drag", dragged).on("end", dragEnded));

  node.append("circle")
    .attr("r", d => radiusScale(degrees.get(d.id) || 0))
    .attr("fill", d => typeColor(d.type))
    .attr("stroke", "#000");

  node.append("text")
    .attr("y", d => radiusScale(degrees.get(d.id) || 0) + 12)
    .attr("text-anchor", "middle")
    .attr("class", "node-label")
    .text(d => truncate(d.display_name || d.id, 20));

  node.on("mouseenter", (e, d) => {
    tooltip.style("opacity", 1)
      .html(`<b>${d.display_name || d.id}</b><br>${d.type}`)
      .style("left", (e.pageX + 10) + "px").style("top", (e.pageY + 10) + "px");
  }).on("mousemove", (e) => {
    tooltip.style("left", (e.pageX + 10) + "px").style("top", (e.pageY + 10) + "px");
  }).on("mouseleave", () => tooltip.style("opacity", 0))
    .on("click", (e, d) => {
      e.stopPropagation();
      showNodeInfo(d, e.currentTarget);
    });

  svg.on("click", () => {
    if (infoPanelEl) infoPanelEl.classList.remove("visible");
    if (graphState.selectedNodeElement) {
      graphState.selectedNodeElement.classList.remove("selected");
      graphState.selectedNodeElement = null;
    }
  });

  currentSimulation = d3.forceSimulation(nodes)
    .force("link", d3.forceLink(links).id(d => d.id).distance(100))
    .force("charge", d3.forceManyBody().strength(-300))
    .force("center", d3.forceCenter(width / 2, height / 2))
    .force("collide", d3.forceCollide().radius(d => radiusScale(degrees.get(d.id) || 0) + 5))
    .on("tick", () => {
      link.attr("x1", d => d.source.x).attr("y1", d => d.source.y)
        .attr("x2", d => d.target.x).attr("y2", d => d.target.y);
      node.attr("transform", d => `translate(${d.x},${d.y})`);
    });

  graphRefs.nodeGroups = node;
  graphRefs.links = link;
  graphRefs.simulation = currentSimulation;

  setupLegend(nodes, links, () => { });

  function dragStarted(e, d) {
    if (!e.active) currentSimulation.alphaTarget(0.3).restart();
    d.fx = d.x; d.fy = d.y;
  }
  function dragged(e, d) { d.fx = e.x; d.fy = e.y; }
  function dragEnded(e, d) {
    if (!e.active) currentSimulation.alphaTarget(0);
    d.fx = null; d.fy = null;
  }

  function showNodeInfo(d, el) {
    infoTitleEl.textContent = d.display_name || d.id;
    let html = "";
    if (d.content) html += `<h4>Content</h4><div class="math-content">${cleanLatex(d.content)}</div>`;
    infoBodyEl.innerHTML = html;
    infoPanelEl.classList.add("visible");
    typesetMath([infoBodyEl]);

    if (graphState.selectedNodeElement) graphState.selectedNodeElement.classList.remove("selected");
    el.classList.add("selected");
    graphState.selectedNodeElement = el;
  }
}

function renderDefinitionBank(bank) {
  if (!definitionBankEl) return;
  if (!bank || Object.keys(bank).length === 0) {
    definitionBankEl.classList.add("hidden");
    return;
  }
  definitionBankEl.classList.remove("hidden");
  definitionBankEl.innerHTML = "<h3>Definition Bank</h3>";
  const list = document.createElement("div");
  list.className = "definition-bank-list";
  Object.values(bank).forEach(def => {
    const item = document.createElement("div");
    item.className = "definition-item-card";
    item.innerHTML = `<strong>${def.term}</strong><div class="math-content">${cleanLatex(def.definition_text)}</div>`;
    list.appendChild(item);
  });
  definitionBankEl.appendChild(list);
  typesetMath([definitionBankEl]);
}

// === Main Flow ==========================================================

async function handleLoadClick() {
  const raw = inputEl.value;
  const normalized = normalizeInputId(raw);
  if (!normalized) {
    setStatus("Please enter an arXiv ID.", "error");
    return;
  }

  loadBtn.disabled = true;
  clearGraph();

  if (heroCarouselEl) heroCarouselEl.classList.add("hidden");
  paperAreaEl.classList.add("hidden");
  paperHeaderEl.classList.add("hidden");
  graphSectionEl.classList.add("hidden");
  if (emptyStateEl) emptyStateEl.classList.add("hidden");

  setStatus("Searching HuggingFace dataset...", "info");

  const candidates = buildCandidateIds(normalized);
  const result = await fetchFirstExisting(candidates.length ? candidates : [normalized]);

  if (!result) {
    setStatus("Paper not found in dataset.", "error");
    renderMetadataSkeleton(normalized);
    paperAreaEl.classList.remove("hidden");
    if (heroCarouselEl) heroCarouselEl.classList.remove("hidden");
    loadBtn.disabled = false;
    return;
  }

  setStatus("", "info");
  const { arxivId, data } = result;

  paperAreaEl.classList.remove("hidden");
  paperHeaderEl.classList.remove("hidden");
  graphSectionEl.classList.remove("hidden");
  if (emptyStateEl) emptyStateEl.classList.add("hidden");

  renderMetadataSkeleton(arxivId);
  applyMetadataFromDataset(arxivId, data);

  // Try to get better metadata (Semantic Scholar/ArXiv) via Queue
  enhanceMetadata(arxivId);

  if (data.graph) {
    setTimeout(() => renderGraph(data.graph), 50);
  } else {
    setStatus("No graph data available.", "error");
  }

  renderDefinitionBank(data.definition_bank);
  loadBtn.disabled = false;
}

loadBtn.addEventListener("click", (e) => { e.preventDefault(); handleLoadClick(); });
inputEl.addEventListener("keydown", (e) => { if (e.key === "Enter") { e.preventDefault(); handleLoadClick(); } });
if (homeTitleEl) homeTitleEl.addEventListener("click", resetToLandingView);

// Initialize
initSamplePapers();