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