emrgilhzp: Proxy the home feed with cursor paging

src/lib/feed.ts

@@ -0,0 +1,90 @@
+import { FEED_BASE_URL } from "./env";
+import { ensureFreshSession, refreshSession } from "./session-refresh";
+
+// Home-feed proxy logic. Reads one page of the person's home feed from Minnect
+// with their server-held feed token. Tokens never leave the server and are
+// never logged. Card-field extraction is a later task; items pass through raw.
+
+export const DEFAULT_LIMIT = 20;
+export const MAX_LIMIT = 50;
+
+export type FeedPageResult =
+  | { ok: true; items: unknown[]; nextCursor: string | null }
+  | { ok: false; status: 401 | 502; error: "sign_in" | "feed_unavailable" };
+
+interface FeedOptions {
+  fetchImpl?: typeof fetch;
+  now?: number;
+}
+
+/** Clamp a requested page size to 1..50, defaulting to 20. */
+export function clampLimit(raw: string | number | null | undefined): number {
+  const n = typeof raw === "number" ? raw : Number.parseInt(raw ?? "", 10);
+  if (!Number.isFinite(n) || n < 1) return DEFAULT_LIMIT;
+  return Math.min(Math.floor(n), MAX_LIMIT);
+}
+
+function buildUrl(cursor: string | null, limit: number): string {
+  const params = new URLSearchParams({ limit: String(limit) });
+  if (cursor) params.set("cursor", cursor);
+  return `${FEED_BASE_URL}/api/v1/feeds/home/items?${params.toString()}`;
+}
+
+async function callFeed(
+  token: string,
+  cursor: string | null,
+  limit: number,
+  doFetch: typeof fetch,
+): Promise<Response> {
+  return doFetch(buildUrl(cursor, limit), {
+    method: "GET",
+    headers: { Accept: "application/json", Authorization: `Bearer ${token}` },
+  });
+}
+
+export async function getHomeFeedPage(
+  sessionId: string | undefined,
+  cursor: string | null,
+  limit: number,
+  options: FeedOptions = {},
+): Promise<FeedPageResult> {
+  const signIn = { ok: false, status: 401, error: "sign_in" } as const;
+  const doFetch = options.fetchImpl ?? fetch;
+
+  let session = await ensureFreshSession(sessionId, options);
+  if (!session || !sessionId) return signIn;
+
+  let res: Response;
+  try {
+    res = await callFeed(session.feedAccessToken, cursor, limit, doFetch);
+    if (res.status === 401) {
+      // One refresh, then one retry. A second 401 means sign in again.
+      session = await refreshSession(sessionId, options);
+      if (!session) return signIn;
+      res = await callFeed(session.feedAccessToken, cursor, limit, doFetch);
+      if (res.status === 401) return signIn;
+    }
+  } catch {
+    return { ok: false, status: 502, error: "feed_unavailable" };
+  }
+  if (res.status !== 200) {
+    return { ok: false, status: 502, error: "feed_unavailable" };
+  }
+
+  let body: unknown;
+  try {
+    body = await res.json();
+  } catch {
+    return { ok: false, status: 502, error: "feed_unavailable" };
+  }
+  const root = body && typeof body === "object" ? (body as Record<string, unknown>) : {};
+  const meta =
+    root.metadata && typeof root.metadata === "object"
+      ? (root.metadata as Record<string, unknown>)
+      : {};
+  return {
+    ok: true,
+    items: Array.isArray(root.data) ? root.data : [],
+    nextCursor: typeof meta.nextCursor === "string" && meta.nextCursor ? meta.nextCursor : null,
+  };
+}