feat: APIs for Articles (#4777)

Fixes: #4802

app/models/article.rb

@@ -2,25 +2,34 @@
 #
 # Table name: articles
 #
-#  id          :bigint           not null, primary key
-#  content     :text
-#  description :text
-#  status      :integer
-#  title       :string
-#  views       :integer
-#  created_at  :datetime         not null
-#  updated_at  :datetime         not null
-#  account_id  :integer          not null
-#  author_id   :integer
-#  category_id :integer
-#  folder_id   :integer
-#  portal_id   :integer          not null
+#  id                       :bigint           not null, primary key
+#  content                  :text
+#  description              :text
+#  status                   :integer
+#  title                    :string
+#  views                    :integer
+#  created_at               :datetime         not null
+#  updated_at               :datetime         not null
+#  account_id               :integer          not null
+#  author_id                :bigint
+#  category_id              :integer
+#  folder_id                :integer
+#  portal_id                :integer          not null
+#
+# Indexes
+#
+#  index_articles_on_author_id                 (author_id)
+#
+# Foreign Keys
+#
+#  fk_rails_...  (author_id => users.id)
 #
 class Article < ApplicationRecord
+  include PgSearch::Model
+
   belongs_to :account
   belongs_to :category
   belongs_to :portal
-  belongs_to :folder
   belongs_to :author, class_name: 'User'
 
   before_validation :ensure_account_id
@@ -32,6 +41,36 @@ class Article < ApplicationRecord
 
   enum status: { draft: 0, published: 1 }
 
+  scope :search_by_category_slug, ->(category_slug) { where(categories: { slug: category_slug }) if category_slug.present? }
+  scope :search_by_category_locale, ->(locale) { where(categories: { locale: locale }) if locale.present? }
+
+  # TODO: if text search slows down https://www.postgresql.org/docs/current/textsearch-features.html#TEXTSEARCH-UPDATE-TRIGGERS
+  pg_search_scope(
+    :text_search,
+    against: %i[
+      title
+      description
+      content
+    ],
+    using: {
+      tsearch: {
+        prefix: true
+      }
+    }
+  )
+
+  def self.search(params)
+    records = joins(
+      :category
+    ).search_by_category_slug(params[:category_slug]).search_by_category_locale(params[:locale])
+    records.text_search(params[:query]) if params[:query].present?
+    records.page(current_page(params))
+  end
+
+  def self.current_page(params)
+    params[:page] || 1
+  end
+
   private
 
   def ensure_account_id