Adding hot ranking in sql, post listing view

server/migrations/2019-03-03-163336_create_post/down.sql

@@ -1,2 +1,4 @@
+drop function hot_rank;
+drop view post_listing;
 drop table post_like;
 drop table post;

server/migrations/2019-03-03-163336_create_post/up.sql

@@ -14,5 +14,7 @@ create table post_like (
   post_id int references post on update cascade on delete cascade not null,
   fedi_user_id text not null,
   score smallint not null, -- -1, or 1 for dislike, like, no row for no opinion
-  published timestamp not null default now()
+  published timestamp not null default now(),
+  unique(post_id, fedi_user_id)
 );
+

server/migrations/2019-03-30-212058_post_listing/down.sql

@@ -0,0 +1,2 @@
+drop view post_listing;
+drop function hot_rank;

server/migrations/2019-03-30-212058_post_listing/up.sql

@@ -0,0 +1,20 @@
+-- Rank = ScaleFactor * sign(Score) * log(1 + abs(Score)) / (Time + 2)^Gravity
+create or replace function hot_rank(
+  score numeric,
+  published timestamp without time zone)
+returns numeric as $$
+begin
+  -- hours_diff:=EXTRACT(EPOCH FROM (timezone('utc',now()) - published))/3600
+  return 10000*sign(score)*log(1 + abs(score)) / power(((EXTRACT(EPOCH FROM (timezone('utc',now()) - published))/3600) + 2), 1.8);
+end; $$
+LANGUAGE plpgsql;
+
+create view post_listing as 
+select post.*, 
+(select count(*) from comment where comment.post_id = post.id) as number_of_comments,
+coalesce(sum(post_like.score),0) as score,
+hot_rank(coalesce(sum(post_like.score),0), post.published) as hot_rank
+from post
+left join post_like
+on post.id = post_like.post_id
+group by post.id;

server/src/actions/comment.rs

@@ -152,7 +152,7 @@ impl CommentView {
 
     for like in likes.iter() {
       if like.score == 1 {
-        upvotes += 1
+        upvotes += 1;
       } else if like.score == -1 {
         downvotes += 1;
       }

ui/src/components/post.tsx

@@ -424,7 +424,6 @@ export class CommentForm extends Component<CommentFormProps, CommentFormState> {
     }  
   }
 
-
   render() {
     return (
       <div>