Added links to EU Supply tenders, as there are to Find a Tender notices

web/src/lib/opportunities.ts

@@ -13,14 +13,6 @@ export function mergeOpportunities(
   return [...byUuid.values()];
 }
 
-/** The source the backend gives opportunities fetched from Find a Tender. */
-const FIND_A_TENDER_SOURCE = 'FindATender';
-
-/** Whether the opportunity was fetched from Find a Tender, so its releases are notices there. */
-export function isFromFindATender(opportunity: Opportunity): boolean {
-  return opportunity.source === FIND_A_TENDER_SOURCE;
-}
-
 /** The opportunity's newest release, or undefined if it has none. */
 export function latestRelease(opportunity: Opportunity): OpportunityRelease | undefined {
   let latest: OpportunityRelease | undefined;
@@ -36,3 +28,58 @@ export function latestRelease(opportunity: Opportunity): OpportunityRelease | un
 export function findATenderNoticeUrl(releaseId: string): string {
   return `https://www.find-tender.service.gov.uk/notice/${encodeURIComponent(releaseId)}`;
 }
+
+// EU Supply's releases are the portal's tenders, as the backend stores them
+// (internal/eusupply's Tender), with the address of the tender's page.
+const isRecord = (value: unknown): value is Record<string, unknown> =>
+  typeof value === 'object' && value !== null;
+
+const isWebAddress = (address: string): boolean => {
+  try {
+    const { protocol } = new URL(address);
+    return protocol === 'https:' || protocol === 'http:';
+  } catch {
+    return false;
+  }
+};
+
+/**
+ * The page of an EU Supply tender: the url in its release's data, as it is,
+ * or undefined if there's none. Only http and https addresses are used, so
+ * a malformed or javascript: one is never opened.
+ */
+export function euSupplyTenderUrl(data: string): string | undefined {
+  let tender: unknown;
+  try {
+    tender = JSON.parse(data);
+  } catch {
+    return undefined;
+  }
+  if (!isRecord(tender) || typeof tender.url !== 'string') return undefined;
+  return isWebAddress(tender.url) ? tender.url : undefined;
+}
+
+/** A site an opportunity's releases can be opened on. */
+export interface NoticeSite {
+  /** The site's name, for labels: "Open the latest notice on <name>". */
+  name: string;
+  /** The page of release on the site, or undefined if it has none. */
+  urlFor: (release: OpportunityRelease) => string | undefined;
+}
+
+// By the source the backend gives the opportunities fetched from each site.
+const NOTICE_SITES: Record<string, NoticeSite> = {
+  FindATender: {
+    name: 'Find a Tender',
+    urlFor: (release) => findATenderNoticeUrl(release.release_id),
+  },
+  'EU Supply - UK': {
+    name: 'EU Supply',
+    urlFor: (release) => euSupplyTenderUrl(release.data),
+  },
+};
+
+/** The site the opportunity's releases can be opened on, or undefined for sources without one. */
+export function noticeSite(opportunity: Opportunity): NoticeSite | undefined {
+  return NOTICE_SITES[opportunity.source];
+}