iachat/app/models/concerns/featurable.rb

module Featurable
  extend ActiveSupport::Concern

  QUERY_MODE = {
    flag_query_mode: :bit_operator,
    check_for_column: false
  }.freeze

  FEATURE_LIST = YAML.safe_load(Rails.root.join('config/features.yml').read).freeze

  FEATURES = FEATURE_LIST.each_with_object({}) do |feature, result|
    result[result.keys.size + 1] = "feature_#{feature['name']}".to_sym
  end

  def self.feature_flag_value(feature_name)
    feature_index = FEATURE_LIST.index { |f| f['name'] == feature_name }
    return 0 if feature_index.nil?

    value = 2**feature_index
    # Convert to signed 64-bit representation for PostgreSQL bigint compatibility.
    # Values >= 2^63 overflow signed bigint; two's complement conversion fixes this.
    value >= (1 << 63) ? value - (1 << 64) : value
  end

  included do
    include FlagShihTzu
    has_flags FEATURES.merge(column: 'feature_flags').merge(QUERY_MODE)

    before_create :enable_default_features
  end

  def enable_features(*names)
    names.each do |name|
      send("feature_#{name}=", true)
    end
  end

  def enable_features!(*)
    enable_features(*)
    save!
  end

  def disable_features(*names)
    names.each do |name|
      send("feature_#{name}=", false)
    end
  end

  def disable_features!(*)
    disable_features(*)
    save!
  end

  def feature_enabled?(name)
    send("feature_#{name}?")
  end

  def all_features
    FEATURE_LIST.pluck('name').index_with do |feature_name|
      feature_enabled?(feature_name)
    end
  end

  def enabled_features
    all_features.select { |_feature, enabled| enabled == true }
  end

  def disabled_features
    all_features.select { |_feature, enabled| enabled == false }
  end

  private

  def enable_default_features
    config = InstallationConfig.find_by(name: 'ACCOUNT_LEVEL_FEATURE_DEFAULTS')
    return true if config.blank?

    features_to_enabled = config.value.select { |f| f[:enabled] }.pluck(:name)
    enable_features(*features_to_enabled)
  end
end