Replace hidden flag with post state.

Store post state as text so Go owns the allowed values and future states such as locked remain representable without a database enum migration.

db/queries/posts.sql

@@ -1,6 +1,6 @@
 -- name: CreatePost :exec
 INSERT INTO posts (
-  id, parent_id, author_id, title, body, city, post_date, hidden, created_at, updated_at
+  id, parent_id, author_id, title, body, city, post_date, post_state, created_at, updated_at
 )
 VALUES (
   sqlc.arg(id),
@@ -10,7 +10,7 @@ VALUES (
   sqlc.arg(body),
   sqlc.arg(city),
   sqlc.arg(post_date),
-  sqlc.arg(hidden),
+  sqlc.arg(post_state),
   sqlc.arg(created_at),
   sqlc.arg(updated_at)
 );
@@ -18,7 +18,7 @@ VALUES (
 -- name: GetPost :one
 SELECT
   p.id, p.parent_id, p.author_id, u.name AS author_name, u.role AS author_role,
-  p.title, p.body, p.city, p.post_date, p.hidden, p.created_at, p.updated_at
+  p.title, p.body, p.city, p.post_date, p.post_state, p.created_at, p.updated_at
 FROM posts p
 JOIN users u ON u.id = p.author_id
 WHERE p.id = sqlc.arg(id);
@@ -39,7 +39,7 @@ SELECT
   thread.id, thread.parent_id, thread.author_id,
   u.name AS author_name, u.role AS author_role,
   thread.title, thread.body, thread.city, thread.post_date,
-  thread.hidden, thread.created_at, thread.updated_at
+  thread.post_state, thread.created_at, thread.updated_at
 FROM thread
 JOIN users u ON u.id = thread.author_id
 ORDER BY thread.created_at, thread.id;
@@ -57,7 +57,7 @@ WITH RECURSIVE roots AS (
   FROM posts p
   WHERE p.parent_id IS NULL
     AND p.post_date = sqlc.arg(post_date)
-    AND p.hidden = 0
+    AND p.post_state <> sqlc.arg(hidden_state)
 ),
 thread AS (
   SELECT roots.id AS root_id, child.id AS post_id, child.author_id
@@ -86,7 +86,7 @@ SELECT
   roots.id, roots.parent_id, roots.author_id,
   u.name AS author_name, u.role AS author_role,
   roots.title, roots.body, roots.city, roots.post_date,
-  roots.hidden, roots.created_at, roots.updated_at,
+  roots.post_state, roots.created_at, roots.updated_at,
   COALESCE(scores.score, 0)::bigint AS score,
   (answered.root_id IS NOT NULL)::bool AS answered,
   COALESCE(viewer_vote.value, 0)::bigint AS user_vote
@@ -104,7 +104,9 @@ LIMIT sqlc.arg(row_limit);
 SELECT EXISTS(
   SELECT 1
   FROM posts
-  WHERE id = sqlc.arg(id) AND parent_id IS NULL AND hidden = 0
+  WHERE id = sqlc.arg(id)
+    AND parent_id IS NULL
+    AND post_state <> sqlc.arg(hidden_state)
 )::bool;
 
 -- name: DeletePostVote :exec
@@ -118,6 +120,6 @@ SELECT sqlc.arg(user_id), sqlc.arg(post_id), sqlc.arg(value)
 FROM posts p
 WHERE p.id = sqlc.arg(post_id)
   AND p.parent_id IS NULL
-  AND p.hidden = 0
+  AND p.post_state <> sqlc.arg(hidden_state)
 ON CONFLICT (user_id, post_id) DO UPDATE
 SET value = excluded.value;