add bot custom feed

at/feed-generator/src/algos/cmd.ts

@@ -0,0 +1,43 @@
+import { InvalidRequestError } from '@atproto/xrpc-server'
+import { QueryParams } from '../lexicon/types/app/bsky/feed/getFeedSkeleton'
+import { AppContext } from '../config'
+
+// max 15 chars
+export const shortname = 'cmd'
+
+export const handler = async (ctx: AppContext, params: QueryParams) => {
+  let builder = ctx.db
+    .selectFrom('post')
+    .selectAll()
+    .orderBy('indexedAt', 'desc')
+    .orderBy('cid', 'desc')
+    .limit(params.limit)
+
+  if (params.cursor) {
+    const [indexedAt, cid] = params.cursor.split('::')
+    if (!indexedAt || !cid) {
+      throw new InvalidRequestError('malformed cursor')
+    }
+    const timeStr = new Date(parseInt(indexedAt, 10)).toISOString()
+    builder = builder
+      .where('post.indexedAt', '<', timeStr)
+      .orWhere((qb) => qb.where('post.indexedAt', '=', timeStr))
+      .where('post.cid', '<', cid)
+  }
+  const res = await builder.execute()
+
+  const feed = res.map((row) => ({
+    post: row.uri,
+  }))
+
+  let cursor: string | undefined
+  const last = res.at(-1)
+  if (last) {
+    cursor = `${new Date(last.indexedAt).getTime()}::${last.cid}`
+  }
+
+  return {
+    cursor,
+    feed,
+  }
+}