refactor: unify pagination helpers

src/lib/paginate-cursor.ts

@@ -0,0 +1,73 @@
+export type CursorPage<T> =
+  | {
+      success: true;
+      items: T[];
+      cursor?: string;
+    }
+  | {
+      success: false;
+      error: string;
+    };
+
+export type CursorPaginationResult<T> =
+  | {
+      success: true;
+      items: T[];
+      nextCursor?: string;
+    }
+  | {
+      success: false;
+      error: string;
+      items?: T[];
+      nextCursor?: string;
+    };
+
+export async function paginateCursor<T>(opts: {
+  cursor?: string;
+  maxPages?: number;
+  pageDelayMs?: number;
+  sleep: (ms: number) => Promise<void>;
+  getKey: (item: T) => string;
+  fetchPage: (cursor?: string) => Promise<CursorPage<T>>;
+}): Promise<CursorPaginationResult<T>> {
+  const { maxPages, pageDelayMs = 1000 } = opts;
+  const seen = new Set<string>();
+  const items: T[] = [];
+  let cursor: string | undefined = opts.cursor;
+  let pagesFetched = 0;
+
+  while (true) {
+    if (pagesFetched > 0 && pageDelayMs > 0) {
+      await opts.sleep(pageDelayMs);
+    }
+
+    const page = await opts.fetchPage(cursor);
+    if (!page.success) {
+      if (items.length > 0) {
+        return { success: false, error: page.error, items, nextCursor: cursor };
+      }
+      return page;
+    }
+    pagesFetched += 1;
+
+    for (const item of page.items) {
+      const key = opts.getKey(item);
+      if (seen.has(key)) {
+        continue;
+      }
+      seen.add(key);
+      items.push(item);
+    }
+
+    const pageCursor = page.cursor;
+    if (!pageCursor || pageCursor === cursor) {
+      return { success: true, items, nextCursor: undefined };
+    }
+
+    if (maxPages !== undefined && pagesFetched >= maxPages) {
+      return { success: true, items, nextCursor: pageCursor };
+    }
+
+    cursor = pageCursor;
+  }
+}