module Gitlab
  class OmniauthInitializer
    def initialize(devise_config)
      @devise_config = devise_config
    end

    def execute(providers)
      providers.each do |provider|
        add_provider(provider['name'].to_sym, *arguments_for(provider))
      end
    end

    private

    def add_provider(*args)
      @devise_config.omniauth(*args)
    end

    def arguments_for(provider)
      provider_arguments = []

      %w[app_id app_secret].each do |argument|
        provider_arguments << provider[argument] if provider[argument]
      end

      case provider['args']
      when Array
        # An Array from the configuration will be expanded.
        provider_arguments.concat provider['args']
      when Hash
        hash_arguments = provider['args'].merge(provider_defaults(provider))

        # A Hash from the configuration will be passed as is.
        provider_arguments << hash_arguments.symbolize_keys
      end

      provider_arguments
    end

    def provider_defaults(provider)
      case provider['name']
      when 'cas3'
        { on_single_sign_out: cas3_signout_handler }
      when 'authentiq'
        { remote_sign_out_handler: authentiq_signout_handler }
      when 'shibboleth'
        { fail_with_empty_uid: true }
      else
        {}
      end
    end

    def cas3_signout_handler
      lambda do |request|
        ticket = request.params[:session_index]
        raise "Service Ticket not found." unless Gitlab::Auth::OAuth::Session.valid?(:cas3, ticket)

        Gitlab::Auth::OAuth::Session.destroy(:cas3, ticket)
        true
      end
    end

    def authentiq_signout_handler
      lambda do |request|
        authentiq_session = request.params['sid']
        if Gitlab::Auth::OAuth::Session.valid?(:authentiq, authentiq_session)
          Gitlab::Auth::OAuth::Session.destroy(:authentiq, authentiq_session)
          true
        else
          false
        end
      end
    end
  end
end