import { fetchWithRetry } from "./fetch-utils.js";
import type { PlatformSource, Paper, SearchResult, SearchParams } from "./types.js";
const BASE_URL = "https://api.crossref.org";
function buildHeaders(env: Env): Record<string, string> {
const email = env.CONTACT_EMAIL ?? "paper-search-mcp@users.noreply.github.com";
return {
"User-Agent": `paper-search-mcp/0.1.0 (mailto:${email})`,
};
}
function parseDateParts(item: any): string {
const parts =
item.published?.["date-parts"]?.[0] ??
item.issued?.["date-parts"]?.[0] ??
item.created?.["date-parts"]?.[0] ??
[];
if (parts.length === 0) return "";
const y = parts[0];
const m = String(parts[1] ?? 1).padStart(2, "0");
const d = String(parts[2] ?? 1).padStart(2, "0");
return `${y}-${m}-${d}`;
}
function parsePaper(item: any): Paper {
const authors = (item.author ?? []).map((a: any) =>
[a.given, a.family].filter(Boolean).join(" ")
);
let pdf_url = "";
if (item.resource?.primary?.URL) pdf_url = item.resource.primary.URL;
if (!pdf_url) {
const pdfLink = (item.link ?? []).find(
(l: any) => l["content-type"]?.includes("pdf")
);
if (pdfLink) pdf_url = pdfLink.URL;
}
return {
paper_id: item.DOI ?? "",
title: Array.isArray(item.title) ? item.title[0] ?? "" : item.title ?? "",
authors,
abstract: (item.abstract ?? "").replace(/<[^>]*>/g, ""),
doi: item.DOI ?? "",
url: item.URL ?? "",
pdf_url,
published_date: parseDateParts(item),
source: "crossref",
citations: item["is-referenced-by-count"] ?? 0,
categories: item.type ? [item.type] : [],
keywords: item.subject ?? [],
extra: {
publisher: item.publisher,
container_title: item["container-title"]?.[0],
volume: item.volume,
issue: item.issue,
page: item.page,
},
};
}
export const crossref: PlatformSource = {
name: "crossref",
displayName: "CrossRef",
async search(params: SearchParams, env: Env): Promise<SearchResult> {
const rows = Math.min(params.max_results ?? 10, 100);
const sp = new URLSearchParams({
query: params.query,
rows: String(rows),
});
if (params.sort) sp.set("sort", String(params.sort));
if (params.order) sp.set("order", String(params.order));
if (params.filter) sp.set("filter", String(params.filter));
const email = env.CONTACT_EMAIL ?? "paper-search-mcp@users.noreply.github.com";
sp.set("mailto", email);
const url = `${BASE_URL}/works?${sp}`;
const resp = await fetchWithRetry(url, { headers: buildHeaders(env) });
if (!resp.ok) {
throw new Error(`CrossRef API ${resp.status}: ${await resp.text()}`);
}
const json = (await resp.json()) as any;
const items = json.message?.items ?? [];
const papers = items.map(parsePaper);
return {
papers,
total_results: json.message?.["total-results"],
query: params.query,
source: "crossref",
};
},
async getById(doi: string, env: Env): Promise<Paper | null> {
const url = `${BASE_URL}/works/${encodeURIComponent(doi)}`;
const resp = await fetchWithRetry(url, { headers: buildHeaders(env) });
if (resp.status === 404) return null;
if (!resp.ok) {
throw new Error(`CrossRef API ${resp.status}: ${await resp.text()}`);
}
const json = (await resp.json()) as any;
return parsePaper(json.message);
},
};
