feat: add GraphQL query for top post comments

__tests__/comments.ts

@@ -408,6 +408,48 @@ describe('query userComments', () => {
   });
 });
 
+describe('query topComments', () => {
+  const QUERY = `query TopComments($postId: ID!, $first: Int) {
+    topComments(postId: $postId, first: $first) {
+      id
+      numUpvotes
+      content
+    }
+  }`;
+
+  it('should return comments ordered by upvotes descending', async () => {
+    // Set different upvote counts for comments on p1
+    await con.getRepository(Comment).update({ id: 'c1' }, { upvotes: 5 });
+    await con.getRepository(Comment).update({ id: 'c3' }, { upvotes: 10 });
+    await con.getRepository(Comment).update({ id: 'c6' }, { upvotes: 3 });
+
+    const res = await client.query(QUERY, { variables: { postId: 'p1' } });
+    expect(res.errors).toBeFalsy();
+    expect(res.data.topComments).toHaveLength(3);
+    // Should be ordered by upvotes descending
+    expect(res.data.topComments[0].id).toEqual('c3');
+    expect(res.data.topComments[0].numUpvotes).toEqual(10);
+    expect(res.data.topComments[1].id).toEqual('c1');
+    expect(res.data.topComments[1].numUpvotes).toEqual(5);
+    expect(res.data.topComments[2].id).toEqual('c6');
+    expect(res.data.topComments[2].numUpvotes).toEqual(3);
+  });
+
+  it('should support querying by post slug', async () => {
+    // The slug is auto-generated from title and id: 'P1' + 'p1' -> 'p1-p1'
+    await con.getRepository(Comment).update({ id: 'c1' }, { upvotes: 5 });
+    await con.getRepository(Comment).update({ id: 'c3' }, { upvotes: 10 });
+
+    const res = await client.query(QUERY, {
+      variables: { postId: 'p1-p1' },
+    });
+    expect(res.errors).toBeFalsy();
+    expect(res.data.topComments).toHaveLength(3);
+    expect(res.data.topComments[0].id).toEqual('c3');
+    expect(res.data.topComments[0].numUpvotes).toEqual(10);
+  });
+});
+
 describe('query commentFeed', () => {
   const QUERY = `query CommentFeed($after: String, $first: Int) {
     commentFeed(after: $after, first: $first) {

src/schema/comments.ts

@@ -433,6 +433,21 @@ export const typeDefs = /* GraphQL */ `
       """
       id: ID!
     ): CommentBalance!
+
+    """
+    Get top comments of a post ordered by upvotes
+    """
+    topComments(
+      """
+      Post id
+      """
+      postId: ID!
+
+      """
+      Number of comments to return (max 20)
+      """
+      first: Int
+    ): [Comment!]!
   }
 
   extend type Mutation {
@@ -521,6 +536,11 @@ export interface GQLUserCommentsArgs extends ConnectionArguments {
   userId: string;
 }
 
+export interface GQLTopCommentsArgs {
+  postId: string;
+  first?: number;
+}
+
 export interface MentionedUser {
   id: string;
   username?: string;
@@ -986,6 +1006,34 @@ export const resolvers: IResolvers<unknown, BaseContext> = traceResolvers<
 
       return result;
     },
+    topComments: async (
+      _,
+      args: GQLTopCommentsArgs,
+      ctx: Context,
+      info,
+    ): Promise<GQLComment[]> => {
+      const maxLimit = 20;
+      const limit = Math.min(args.first ?? maxLimit, maxLimit);
+
+      const post = await ctx.con.getRepository(Post).findOneOrFail({
+        select: ['id', 'sourceId'],
+        where: [{ id: args.postId }, { slug: args.postId }],
+      });
+      await ensureSourcePermissions(ctx, post.sourceId);
+
+      return graphorm.query<GQLComment>(ctx, info, (builder) => {
+        builder.queryBuilder = builder.queryBuilder
+          .andWhere(`${builder.alias}.postId = :postId`, {
+            postId: post.id,
+          })
+          .andWhere(`${builder.alias}.parentId is null`)
+          .andWhere(whereVordrFilter(builder.alias, ctx.userId))
+          .orderBy(`${builder.alias}.upvotes`, 'DESC')
+          .limit(limit);
+
+        return builder;
+      });
+    },
   },
   Mutation: {
     commentOnPost: async (