add search to notes

priv/repo/migrations/20220726000552_create_notes.exs

@@ -1,17 +1,41 @@
 defmodule Memex.Repo.Migrations.CreateNotes do
   use Ecto.Migration
 
-  def change do
+  def up do
     create table(:notes, primary_key: false) do
       add :id, :binary_id, primary_key: true
       add :title, :string
       add :content, :text
-      add :tags, {:array, :string}
+      add :tags, {:array, :citext}
       add :visibility, :string
 
       add :user_id, references(:users, on_delete: :delete_all, type: :binary_id)
 
       timestamps()
     end
+
+    flush()
+
+    execute """
+    CREATE FUNCTION immutable_array_to_string(text[], text)
+      RETURNS text LANGUAGE sql IMMUTABLE as $$SELECT array_to_string($1, $2)$$
+    """
+
+    execute """
+    ALTER TABLE notes
+      ADD COLUMN search tsvector
+      GENERATED ALWAYS AS (
+        setweight(to_tsvector('english', coalesce(title, '')), 'A') ||
+        setweight(to_tsvector('english', coalesce(immutable_array_to_string(tags, ' '), '')), 'B') ||
+        setweight(to_tsvector('english', coalesce(content, '')), 'C')
+      ) STORED
+    """
+
+    execute("CREATE INDEX notes_trgm_idx ON notes USING GIN (search)")
+  end
+
+  def down do
+    drop table(:notes)
+    execute("DROP FUNCTION immutable_array_to_string(text[], text)")
   end
 end