Some comment count fixes.

- Make sure an update to deleted decreases the count. Fixes #1676
- Don't allow the post creator to comment necro-bump their own post.
  Fixes #1675

migrations/2021-08-02-002342_comment_count_fixes/down.sql

@@ -0,0 +1,28 @@
+drop trigger post_aggregates_comment_set_deleted on comment;
+drop function post_aggregates_comment_deleted;
+
+create or replace function post_aggregates_comment_count()
+returns trigger language plpgsql
+as $$
+begin
+  IF (TG_OP = 'INSERT') THEN
+    update post_aggregates pa
+    set comments = comments + 1,
+    newest_comment_time = NEW.published
+    where pa.post_id = NEW.post_id;
+
+    -- A 2 day necro-bump limit
+    update post_aggregates pa
+    set newest_comment_time_necro = NEW.published
+    where pa.post_id = NEW.post_id
+    and published > ('now'::timestamp - '2 days'::interval);
+  ELSIF (TG_OP = 'DELETE') THEN
+    -- Join to post because that post may not exist anymore
+    update post_aggregates pa
+    set comments = comments - 1
+    from post p
+    where pa.post_id = p.id
+    and pa.post_id = OLD.post_id;
+  END IF;
+  return null;
+end $$;

migrations/2021-08-02-002342_comment_count_fixes/up.sql

@@ -0,0 +1,61 @@
+-- Creating a new trigger for when comment.deleted is updated
+
+create or replace function post_aggregates_comment_deleted()
+returns trigger language plpgsql
+as $$
+begin
+  IF NEW.deleted = TRUE THEN
+    update post_aggregates pa
+    set comments = comments - 1
+    where pa.post_id = NEW.post_id;
+  ELSE 
+    update post_aggregates pa
+    set comments = comments + 1
+    where pa.post_id = NEW.post_id;
+  END IF;
+  return null;
+end $$;
+
+create trigger post_aggregates_comment_set_deleted 
+after update of deleted on comment
+for each row
+execute procedure post_aggregates_comment_deleted();
+
+-- Fix issue with being able to necro-bump your own post
+create or replace function post_aggregates_comment_count()
+returns trigger language plpgsql
+as $$
+begin
+  IF (TG_OP = 'INSERT') THEN
+    update post_aggregates pa
+    set comments = comments + 1,
+    newest_comment_time = NEW.published
+    where pa.post_id = NEW.post_id;
+
+    -- A 2 day necro-bump limit
+    update post_aggregates pa
+    set newest_comment_time_necro = NEW.published
+    from post p
+    where pa.post_id = p.id
+    and pa.post_id = NEW.post_id
+    -- Fix issue with being able to necro-bump your own post
+    and NEW.creator_id != p.creator_id
+    and pa.published > ('now'::timestamp - '2 days'::interval);
+
+  ELSIF (TG_OP = 'DELETE') THEN
+    -- Join to post because that post may not exist anymore
+    update post_aggregates pa
+    set comments = comments - 1
+    from post p
+    where pa.post_id = p.id
+    and pa.post_id = OLD.post_id;
+  ELSIF (TG_OP = 'UPDATE') THEN
+    -- Join to post because that post may not exist anymore
+    update post_aggregates pa
+    set comments = comments - 1
+    from post p
+    where pa.post_id = p.id
+    and pa.post_id = OLD.post_id;
+  END IF;
+  return null;
+end $$;