const mdInput = document.getElementById("mdInput");
const preview = document.getElementById("preview");
const copyBtn = document.getElementById("copyBtn");
const docxBtn = document.getElementById("docxBtn");
const clearBtn = document.getElementById("clearBtn");
const statusEl = document.getElementById("status");

function setStatus(message, type = "info") {
  const colors = {
    info: "rgba(255,255,255,0.62)",
    ok: "rgba(34,197,94,0.95)",
    warn: "rgba(245,158,11,0.95)",
    err: "rgba(239,68,68,0.95)",
  };
  statusEl.textContent = message || "";
  statusEl.style.color = colors[type] || colors.info;
}

function getWordCss() {
  return `
    body{
      font-family: Calibri, "Microsoft YaHei", "PingFang SC", "SimSun", Arial, sans-serif;
      font-size: 11pt;
      line-height: 1.6;
      color: #111;
    }
    h1,h2,h3{ font-weight: 700; margin: 0.9em 0 0.4em; }
    p{ margin: 0.5em 0; }
    ul,ol{ margin: 0.5em 0 0.5em 1.2em; }
    blockquote{ margin: 0.7em 0; padding: 0.3em 0.8em; border-left: 3px solid #7c5cff; background: #f6f4ff; }
    code{ font-family: Consolas, "Courier New", monospace; background: #f3f4f6; padding: 0.05em 0.25em; border-radius: 4px; }
    pre{ font-family: Consolas, "Courier New", monospace; background: #f6f7f9; padding: 10px 12px; border-radius: 6px; }
    pre code{ background: transparent; padding: 0; }
    table{ border-collapse: collapse; width: 100%; }
    th,td{ border: 1px solid #d1d5db; padding: 6px 8px; vertical-align: top; }
    th{ background: #f3f4f6; }
    a{ color: #1d4ed8; text-decoration: underline; }
  `;
}

function ensureDeps() {
  const ok = typeof window.marked?.parse === "function" && typeof window.DOMPurify?.sanitize === "function";
  if (!ok) {
    setStatus("依赖加载失败：marked/DOMPurify 未就绪（可能被网络拦截）", "err");
  }
  return ok;
}

function hasMathDeps() {
  return typeof window.renderMathInElement === "function" && typeof window.katex !== "undefined";
}

function renderMath(root) {
  if (!hasMathDeps()) return;
  try {
    renderMathInElement(root, {
      delimiters: [
        { left: "$$", right: "$$", display: true },
        { left: "$", right: "$", display: false },
        { left: "\\(", right: "\\)", display: false },
        { left: "\\[", right: "\\]", display: true },
      ],
      throwOnError: false,
    });
  } catch {
    // ignore
  }
}

function normalizeMarkdownForMath(markdown) {
  let src = markdown || "";
  const original = src;

  // 1. 块级公式: \[ ... \] 或 \\[ ... \\] → $$ ... $$
  //    必须在 marked 解析前转换，否则反斜杠会被吃掉
  src = src.replace(/\\{1,2}\[([\s\S]*?)\\{1,2}\]/g, (match, formula) => {
    return `\n$$${formula.trim()}$$\n`;
  });

  // 2. 行内公式: \( ... \) 或 \\( ... \\) → $ ... $
  src = src.replace(/\\{1,2}\(([\s\S]*?)\\{1,2}\)/g, (match, formula) => {
    return `$${formula}$`;
  });

  // 3. AI 常见输出: 单独一行的 [ ... ] → $$ ... $$
  src = src.replace(/(^|\n)\s*\[\s*\n([\s\S]*?)\n\s*\]\s*(?=\n|$)/g, "\n$$\n$2\n$$\n");

  // Debug 输出
  if (src !== original) {
    console.log("=== 公式规范化 ===");
    console.log("原始:", original);
    console.log("转换后:", src);
  }

  return src;
}

function renderMarkdown(markdown) {
  if (!ensureDeps()) return { html: "", plain: markdown || "" };

  marked.setOptions({
    gfm: true,
    breaks: true,
    headerIds: false,
    mangle: false,
  });

  const normalized = normalizeMarkdownForMath(markdown || "");
  const rawHtml = marked.parse(normalized);
  const safeHtml = DOMPurify.sanitize(rawHtml, { USE_PROFILES: { html: true } });
  return { html: safeHtml, plain: normalized };
}

function updatePreview() {
  const { html } = renderMarkdown(mdInput.value);
  preview.innerHTML = html || `<div style="color: rgba(255,255,255,0.5);">这里会显示预览…</div>`;
  renderMath(preview);
}

function htmlToPlainText(html) {
  const div = document.createElement("div");
  div.innerHTML = html;
  return div.innerText || div.textContent || "";
}

function convertKatexToMathML(root) {
  const displayNodes = Array.from(root.querySelectorAll(".katex-display"));
  for (const displayNode of displayNodes) {
    const math = displayNode.querySelector(".katex-mathml math") || displayNode.querySelector("math");
    if (!math) continue;
    const block = document.createElement("div");
    block.appendChild(math.cloneNode(true));
    displayNode.replaceWith(block);
  }

  const katexNodes = Array.from(root.querySelectorAll(".katex"));
  for (const node of katexNodes) {
    const math = node.querySelector(".katex-mathml math") || node.querySelector("math");
    if (!math) continue;
    node.replaceWith(math.cloneNode(true));
  }
}

function replaceKatexWithTexText(root) {
  const displayNodes = Array.from(root.querySelectorAll(".katex-display"));
  for (const displayNode of displayNodes) {
    const tex =
      displayNode.querySelector('annotation[encoding="application/x-tex"]')?.textContent ||
      displayNode.querySelector(".katex-mathml annotation")?.textContent ||
      "";
    if (!tex.trim()) continue;
    const div = document.createElement("div");
    div.textContent = `$$\n${tex}\n$$`;
    div.style.whiteSpace = "pre-wrap";
    div.style.fontFamily = 'ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace';
    displayNode.replaceWith(div);
  }

  const inlineNodes = Array.from(root.querySelectorAll(".katex"));
  for (const node of inlineNodes) {
    const tex =
      node.querySelector('annotation[encoding="application/x-tex"]')?.textContent ||
      node.querySelector(".katex-mathml annotation")?.textContent ||
      "";
    if (!tex.trim()) continue;
    const span = document.createElement("span");
    span.textContent = `$${tex}$`;
    span.style.whiteSpace = "pre-wrap";
    span.style.fontFamily = 'ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace';
    node.replaceWith(span);
  }
}

async function copyAsWord() {
  const markdown = mdInput.value.trim();
  if (!markdown) {
    setStatus("先粘贴一些 Markdown 再复制", "warn");
    return;
  }
  if (!ensureDeps()) return;

  const { html, plain: normalizedPlain } = renderMarkdown(markdown);

  const container = document.createElement("div");
  container.innerHTML = html;
  renderMath(container);
  // Clipboard: 使用 MathML 让 Word 能识别为可编辑公式
  convertKatexToMathML(container);

  const wordHtml = `<!doctype html><html><head><meta charset="utf-8"><style>${getWordCss()}</style></head><body>${container.innerHTML}</body></html>`;
  const plain = container.innerText || htmlToPlainText(html);

  try {
    if (!navigator.clipboard?.write) {
      throw new Error("Clipboard API 不可用");
    }
    const item = new ClipboardItem({
      "text/html": new Blob([wordHtml], { type: "text/html" }),
      "text/plain": new Blob([plain], { type: "text/plain" }),
    });
    await navigator.clipboard.write([item]);
    setStatus("已复制：去 Word/WPS 直接粘贴即可", "ok");
  } catch (e) {
    setStatus(`复制失败：${e?.message || e}`, "err");
  }
}

async function downloadDocx() {
  const markdown = mdInput.value.trim();
  if (!markdown) {
    setStatus("先粘贴一些 Markdown 再导出", "warn");
    return;
  }

  const { plain: normalized } = renderMarkdown(markdown);
  setStatus("正在生成 DOCX…", "info");

  try {
    const resp = await fetch("/api/docx", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ markdown: normalized, filename: "output.docx" }),
    });
    if (!resp.ok) {
      const text = await resp.text().catch(() => "");
      throw new Error(text || `HTTP ${resp.status}`);
    }
    const blob = await resp.blob();
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = "output.docx";
    document.body.appendChild(a);
    a.click();
    a.remove();
    URL.revokeObjectURL(url);
    setStatus("已生成 DOCX（公式可编辑）", "ok");
  } catch (e) {
    setStatus(`导出失败：${e?.message || e}`, "err");
  }
}

mdInput.addEventListener("input", () => {
  updatePreview();
  setStatus("");
});

copyBtn.addEventListener("click", copyAsWord);
docxBtn.addEventListener("click", downloadDocx);
clearBtn.addEventListener("click", () => {
  mdInput.value = "";
  updatePreview();
  setStatus("");
  mdInput.focus();
});

updatePreview();