Extract relay-agnostic forum fetchers from the stores

src/lib/forum/thread.ts

@@ -0,0 +1,56 @@
+import { tag, tags, type Query } from "./query";
+
+export type PostData = {
+  id: string;
+  pubkey: string;
+  createdAt: number;
+  content: string;
+};
+
+export type ThreadDetail = {
+  id: string;
+  title: string;
+  labels: string[];
+  groupId: string; // the thread's NIP-29 group (its `h` tag)
+  op: PostData;
+  replies: PostData[];
+};
+
+// A thread (kind 11) with its flat replies (kind 1111), oldest first. Null
+// when the relay returns nothing: no such thread, or one the visitor can't
+// read. `fallbackGroup` covers OPs missing an `h` tag.
+export async function fetchThread(
+  q: Query,
+  id: string,
+  fallbackGroup = "",
+): Promise<ThreadDetail | null> {
+  const [threadEvents, replyEvents] = await Promise.all([
+    q({ kinds: [11], ids: [id] }),
+    q({ kinds: [1111], "#E": [id] }),
+  ]);
+  const event = threadEvents[0];
+  if (!event) return null;
+  const replies = replyEvents.sort((a, b) => a.created_at - b.created_at);
+  return {
+    id: event.id,
+    title: tag(event, "title") ?? "(untitled)",
+    labels: tags(event, "t"),
+    groupId: tag(event, "h") ?? fallbackGroup,
+    op: {
+      id: event.id,
+      pubkey: event.pubkey,
+      createdAt: event.created_at,
+      content: event.content,
+    },
+    replies: replies.map((r) => ({
+      id: r.id,
+      pubkey: r.pubkey,
+      createdAt: r.created_at,
+      content: r.content,
+    })),
+  };
+}
+
+export function threadAuthors(t: ThreadDetail): string[] {
+  return [...new Set([t.op.pubkey, ...t.replies.map((r) => r.pubkey)])];
+}