# A generic way of constructing a mergeable configuration
class Cratus::Config < OpenStruct
  # Construct a base config using the following order of precedence:
  #   * environment variables
  #   * YAML file
  #   * defaults
  def load
    # First, apply the defaults
    defaults = {
      group_dn_attribute: :cn,
      group_member_attribute: :member,
      group_description_attribute: :description,
      group_objectclass: :group,
      group_basedn: 'ou=groups,dc=example,dc=com',
      group_memberof_attribute: :memberOf,
      user_dn_attribute: :samaccountname,
      user_objectclass: :user,
      user_basedn: 'ou=users,dc=example,dc=com',
      user_department_attribute: :department,
      user_lockout_attribute: :lockouttime,
      user_mail_attribute: :mail,
      user_displayname_attribute: :displayName,
      user_memberof_attribute: :memberOf,
      host: 'ldap.example.com',
      port: 389,
      basedn: 'dc=example,dc=com',
      username: 'username',
      password: 'p@assedWard!',
    }
    merge defaults

    # Then apply the config file, if one exists
    begin
      apprc_dir = File.expand_path('~')
      config_file = File.expand_path(File.join(apprc_dir, '.cratus.yml'))
      merge YAML.load_file(config_file) if File.readable?(config_file)
    rescue => e
      puts "WARNING: Unable to read from #{config_file}"
    end

    # Finally, apply any environment variables specified
    env_conf = {}
    defaults.keys.each do |key|
      cratus_key = "CRATUS_#{key}".upcase
      env_conf[key] = ENV[cratus_key] if ENV.key?(cratus_key)
    end
    merge env_conf unless env_conf.empty?
  end

  def merge(data)
    raise 'Invalid Config Data' unless data.is_a?(Hash)
    data.each do |k, v|
      self[k.to_sym] = v
    end
  end
end

# Make the config available as a singleton
module Cratus
  class << self
    def config
      @config ||= Config.new
    end
  end
end