Initial commit: AI platform app (server, views, lib, data, deploy docs)

Made-with: Cursor

lib/link-preview.js

@@ -0,0 +1,97 @@
+/**
+ * 외부 URL의 HTML에서 Open Graph / Twitter 카드 이미지 URL 추출 (link.ncue.net 등과 유사한 미리보기)
+ */
+
+const OG_FETCH_TIMEOUT_MS = 15000;
+const DEFAULT_UA =
+  "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36";
+
+function decodeBasicHtmlEntities(s) {
+  return (s || "")
+    .replace(/&/g, "&")
+    .replace(/"/g, '"')
+    .replace(/'/g, "'")
+    .replace(/&lt;/g, "<")
+    .replace(/&gt;/g, ">");
+}
+
+function resolveUrl(src, baseHref) {
+  try {
+    const t = (src || "").trim();
+    if (!t) return null;
+    return new URL(t, baseHref).href;
+  } catch {
+    return null;
+  }
+}
+
+function extractOgImageFromHtml(html) {
+  if (!html || typeof html !== "string") return null;
+  const patterns = [
+    /<meta\s[^>]*property=["']og:image["'][^>]*content=["']([^"']+)["']/i,
+    /<meta\s[^>]*content=["']([^"']+)["'][^>]*property=["']og:image["']/i,
+    /<meta\s[^>]*name=["']twitter:image:src["'][^>]*content=["']([^"']+)["']/i,
+    /<meta\s[^>]*content=["']([^"']+)["'][^>]*name=["']twitter:image:src["']/i,
+    /<meta\s[^>]*name=["']twitter:image["'][^>]*content=["']([^"']+)["']/i,
+    /<meta\s[^>]*content=["']([^"']+)["'][^>]*name=["']twitter:image["']/i,
+  ];
+  for (const p of patterns) {
+    const m = html.match(p);
+    if (m && m[1]) return decodeBasicHtmlEntities(m[1].trim());
+  }
+  return null;
+}
+
+/**
+ * @param {string} pageUrl
+ * @returns {Promise<string|null>} 절대 URL의 og:image, 없으면 null
+ */
+async function fetchOpenGraphImageUrl(pageUrl) {
+  const normalized = (pageUrl || "").trim();
+  if (!normalized) return null;
+  let base;
+  try {
+    base = new URL(normalized);
+  } catch {
+    return null;
+  }
+  if (base.protocol !== "http:" && base.protocol !== "https:") return null;
+
+  const controller = new AbortController();
+  const timer = setTimeout(() => controller.abort(), OG_FETCH_TIMEOUT_MS);
+  try {
+    const res = await fetch(base.href, {
+      redirect: "follow",
+      signal: controller.signal,
+      headers: {
+        "User-Agent": DEFAULT_UA,
+        Accept: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
+        "Accept-Language": "ko-KR,ko;q=0.9,en-US;q=0.8,en;q=0.7",
+      },
+    });
+    if (!res.ok) return null;
+    const ct = (res.headers.get("content-type") || "").toLowerCase();
+    if (!ct.includes("text/html") && !ct.includes("application/xhtml")) {
+      return null;
+    }
+    const html = await res.text();
+    const raw = extractOgImageFromHtml(html);
+    if (!raw) return null;
+    const abs = resolveUrl(raw, base.href);
+    if (!abs) return null;
+    let imgUrl;
+    try {
+      imgUrl = new URL(abs);
+    } catch {
+      return null;
+    }
+    if (imgUrl.protocol !== "http:" && imgUrl.protocol !== "https:") return null;
+    return imgUrl.href;
+  } catch {
+    return null;
+  } finally {
+    clearTimeout(timer);
+  }
+}
+
+module.exports = { fetchOpenGraphImageUrl };