class CreateMaterials < ActiveRecord::Migration[8.0]
  def change
    create_table :materials do |t|
      t.string :url
      t.references :parent, index: true, foreign_key: { to_table: :materials }
      t.references :tag, index: true, foreign_key: true
      t.references :created_by_user, foreign_key: { to_table: :users }
      t.references :updated_by_user, foreign_key: { to_table: :users }
      t.timestamps
      t.datetime :discarded_at, index: true
      t.virtual :active_url, type: :string,
                             as: 'IF(discarded_at IS NULL, url, NULL)',
                             stored: false

      t.index :active_url, unique: true
    end

    create_table :material_versions do |t|
      t.references :material, null: false, foreign_key: true
      t.integer :version_no, null: false
      t.string :url, index: true
      t.references :parent, index: true, foreign_key: { to_table: :materials }
      t.references :tag, index: true, foreign_key: true
      t.references :created_by_user, foreign_key: { to_table: :users }
      t.references :updated_by_user, foreign_key: { to_table: :users }
      t.timestamps
      t.datetime :discarded_at, index: true

      t.index [:material_id, :version_no],
              unique: true,
              name: 'index_material_versions_on_material_id_and_version_no'
    end
  end
end