From da0139ff4e4870d035ca799e364e0c7e424e17d7 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Sun, 2 Jun 2024 22:46:07 -0500
Subject: [PATCH] Suggestions: add offset based pagination

---
 src/controllers/api/suggestions.ts | 78 +++++++++++++++++++-----------
 src/utils/api.ts                   | 12 +++--
 2 files changed, 60 insertions(+), 30 deletions(-)

diff --git a/src/controllers/api/suggestions.ts b/src/controllers/api/suggestions.ts
index 012244a..620de68 100644
--- a/src/controllers/api/suggestions.ts
+++ b/src/controllers/api/suggestions.ts
@@ -1,51 +1,75 @@
-import { NStore } from '@nostrify/nostrify';
+import { NostrFilter } from '@nostrify/nostrify';
+import { matchFilter } from 'nostr-tools';
 
-import { AppController } from '@/app.ts';
+import { AppContext, AppController } from '@/app.ts';
 import { Conf } from '@/config.ts';
 import { hydrateEvents } from '@/storages/hydrate.ts';
+import { listPaginationSchema, paginatedList, PaginatedListParams } from '@/utils/api.ts';
 import { getTagSet } from '@/utils/tags.ts';
 import { accountFromPubkey, renderAccount } from '@/views/mastodon/accounts.ts';
 
 export const suggestionsV1Controller: AppController = async (c) => {
-  const store = c.get('store');
   const signal = c.req.raw.signal;
-  const accounts = await renderSuggestedAccounts(store, signal);
-
-  return c.json(accounts);
+  const params = listPaginationSchema.parse(c.req.query());
+  const suggestions = await renderV2Suggestions(c, params, signal);
+  const accounts = suggestions.map(({ account }) => account);
+  return paginatedList(c, params, accounts);
 };
 
 export const suggestionsV2Controller: AppController = async (c) => {
-  const store = c.get('store');
   const signal = c.req.raw.signal;
-  const accounts = await renderSuggestedAccounts(store, signal);
-
-  const suggestions = accounts.map((account) => ({
-    source: 'staff',
-    account,
-  }));
-
-  return c.json(suggestions);
+  const params = listPaginationSchema.parse(c.req.query());
+  const suggestions = await renderV2Suggestions(c, params, signal);
+  return paginatedList(c, params, suggestions);
 };
 
-async function renderSuggestedAccounts(store: NStore, signal?: AbortSignal) {
-  const [follows] = await store.query(
-    [{ kinds: [3], authors: [Conf.pubkey], limit: 1 }],
-    { signal },
-  );
+async function renderV2Suggestions(c: AppContext, params: PaginatedListParams, signal?: AbortSignal) {
+  const { offset, limit } = params;
 
-  // TODO: pagination
-  const pubkeys = [...getTagSet(follows?.tags ?? [], 'p')].slice(0, 20);
+  const store = c.get('store');
+  const signer = c.get('signer');
+  const pubkey = await signer?.getPublicKey();
+
+  const filters: NostrFilter[] = [
+    { kinds: [3], authors: [Conf.pubkey], limit: 1 },
+  ];
+
+  if (pubkey) {
+    filters.push({ kinds: [3], authors: [pubkey], limit: 1 });
+    filters.push({ kinds: [10000], authors: [pubkey], limit: 1 });
+  }
+
+  const events = await store.query(filters, { signal });
+
+  const [suggestedEvent, followsEvent, mutesEvent] = [
+    events.find((event) => matchFilter({ kinds: [3], authors: [Conf.pubkey] }, event)),
+    pubkey ? events.find((event) => matchFilter({ kinds: [3], authors: [pubkey] }, event)) : undefined,
+    pubkey ? events.find((event) => matchFilter({ kinds: [10000], authors: [pubkey] }, event)) : undefined,
+  ];
+
+  const [suggested, follows, mutes] = [
+    getTagSet(suggestedEvent?.tags ?? [], 'p'),
+    getTagSet(followsEvent?.tags ?? [], 'p'),
+    getTagSet(mutesEvent?.tags ?? [], 'p'),
+  ];
+
+  const ignored = follows.union(mutes);
+  const pubkeys = suggested.difference(ignored);
+
+  const authors = [...pubkeys].slice(offset, offset + limit);
 
   const profiles = await store.query(
-    [{ kinds: [0], authors: pubkeys, limit: pubkeys.length }],
+    [{ kinds: [0], authors, limit: authors.length }],
     { signal },
   )
     .then((events) => hydrateEvents({ events, store, signal }));
 
-  const accounts = await Promise.all(pubkeys.map((pubkey) => {
+  return Promise.all(authors.map((pubkey) => {
     const profile = profiles.find((event) => event.pubkey === pubkey);
-    return profile ? renderAccount(profile) : accountFromPubkey(pubkey);
-  }));
 
-  return accounts.filter(Boolean);
+    return {
+      source: suggested.has(pubkey) ? 'staff' : 'global',
+      account: profile ? renderAccount(profile) : accountFromPubkey(pubkey),
+    };
+  }));
 }
diff --git a/src/utils/api.ts b/src/utils/api.ts
index 5ab4cc6..3cc8b7d 100644
--- a/src/utils/api.ts
+++ b/src/utils/api.ts
@@ -202,11 +202,16 @@ function buildListLinkHeader(url: string, params: { offset: number; limit: numbe
   return `<${next}>; rel="next", <${prev}>; rel="prev"`;
 }
 
+interface PaginatedListParams {
+  offset: number;
+  limit: number;
+}
+
 /** paginate a list of tags. */
 function paginatedList(
   c: AppContext,
-  params: { offset: number; limit: number },
-  entities: (Entity | undefined)[],
+  params: PaginatedListParams,
+  entities: unknown[],
   headers: HeaderRecord = {},
 ) {
   const link = buildListLinkHeader(c.req.url, params);
@@ -217,7 +222,7 @@ function paginatedList(
   }
 
   // Filter out undefined entities.
-  const results = entities.filter((entity): entity is Entity => Boolean(entity));
+  const results = entities.filter(Boolean);
   return c.json(results, 200, headers);
 }
 
@@ -255,6 +260,7 @@ export {
   localRequest,
   paginated,
   paginatedList,
+  type PaginatedListParams,
   type PaginationParams,
   paginationSchema,
   parseBody,